Improving the processing properties of frozen dough has certain practical significance for realizing large-scale production of high-quality convenient steamed bread. Hauv txoj kev tshawb no, ib hom tshiab ntawm hydrophilic colloid (hydroxypropylulose, Yang, MC) tau thov rau khov ua khob noom cookie. The effects of 0.5%, 1%, 2%) on the processing properties of frozen dough and the quality of steamed bread were evaluated to evaluate the improvement effect of HPMC. Cuam tshuam rau cov qauv thiab cov khoom ntawm cov khoom siv (cov hmoov nplej nplej, nplej hmoov nplej thiab cov poov xab).
Nplej gluten yog cov khoom siv hauv paus rau kev tsim ntawm lub khob noom cookie network. Kev sim nrhiav tau hais tias qhov kev sib txuas ntawm I - IPMC tau txo qis tawg ntawm YD thiab Disulfide Bonds ntawm cov nplej gluten protein thaum khov khaws cia. In addition, the results of low-field nuclear magnetic resonance and differential scanning the water state transition and recrystallization phenomena are limited, and the content of freezable water in the dough is reduced, thereby suppressing the effect of ice crystal growth on the gluten microstructure and its spatial conformation. Scanning electron microscope showed intuitively that the addition of HPMC could maintain the stability of gluten network structure.
Cov hmoov txhuv nplej siab yog qhov muaj ntau tshaj plaws muaj teeb meem qhuav hauv lub khob noom cookie, thiab hloov pauv hauv nws cov qauv yuav cuam tshuam ncaj qha rau cov yam ntxwv gelatinization ncaj thiab qhov zoo ntawm cov khoom kawg. X. The results of X-ray diffraction and DSC showed that the relative crystallinity of starch increased and the gelatinization enthalpy increased after frozen storage. With the prolongation of frozen storage time, the swelling power of starch without HPMC addition decreased gradually, while the starch gelatinization characteristics (peak viscosity, minimum viscosity, final viscosity, decay value and retrogradation value) all increased significantly; During the storage time, compared with the control group, with the increase of HPMC addition, the changes of starch crystal structure and gelatinization properties gradually decreased.
Key words: steamed bread; frozen dough; hydroxypropyl methylcellulose; Nplej Gluten; Cov hmoov txhuv nplej siab; poov xab.
Cov txheej txheem
Tshooj 1 Ua Ntej ....................................................................... 1
1.1.2 Kev tshawb fawb ntawm cov buns ................................................... Cov. ………… 1
1.1.5 Research status of frozen dough……………………………………. ............................................... 4
1.1.6 daim ntawv thov ntawm hydrocolloids nyob rau hauv khov ua khob noom cookie zoo ..................... .5
1.1.7 HydroxyPropyyl methyl cellulose (hydroxypropyl methyl cellulose, i-IPMC) .......... 5
2.2.1 Kev sim cov ntaub ntawv ................................................................................ 8
2.2.2 Kev sim cov cuab yeej thiab cov khoom siv ........................................................................... 8
2.3 Cov txiaj ntsig sim thiab sib tham thiab sib tham ............................................................................................................... 11
2.3.4 The effect of HPMC addition and freezing time on the rheological properties of dough…………………………. .................................................................................................15
2.2 Tshooj Lus Qhia .......................................................................... 21
3.2.3 Kev sim tshuaj tiv thaiv ........................................................................................................................................................................................................................................................................................................... ………………25
3.2.4 Kev sim cov hau kev ....................................................................... 25
3. Cov txiaj ntsig thiab kev sib tham ........................................................................ 29
3.3.2 The effect of adding amount of HPMC and freezing storage time on the freezable moisture content (CFW) and thermal stability……………………………………………………………………. 30
3.3.3 Effects of HPMC addition amount and freezing storage time on free sulfhydryl content (C vessel) …………………………………………………………………………………………………………. Cov. 34
3.3.4 Qhov cuam tshuam ntawm HPMC ntxiv cov nqi thiab khov lub sijhawm cia rau ntawm lub sijhawm so (n) ntub dej
3.9 Ntsiab Lus Tshooj ........................................................................... 43
4.1 Qhia ................................................................................... 44
4.2 Experimental materials and methods ................................................................................． 45
4.2.3 Kev sim xyaum ............................................................................................ 45
4.3 Kev Tshawb Fawb thiab Sib Tham ........................................................................... 48
4.3.1 cov ntsiab lus ntawm cov txheej txheem theem pib ntawm cov nplej hmoov nplej ....................................................... 48
4.3.2 Qhov cuam tshuam ntawm I-IPMC ntxiv cov nqi thiab cov khoom khov kho kom khov ntawm cov tsiaj txhu cov tsiaj ua kom khov ntawm cov nplej hmoov nplej ............................................................................................................................................................................................................................................................................................................................ .48
4.3.3 Effects of HPMC addition and freezing storage time on the shear viscosity of starch paste………………………………………………………………………………………………………………………………………. 52
4.3.6 Effects of I-IPMC addition amount and frozen storage time on the thermodynamic properties of starch ………………………………………………………………………………………………………. ． 57
4.4 Tshooj Lus Qhia ............................................................... 6 1
Chapter 5 Effects of HPMC addition on yeast survival rate and fermentation activity under frozen storage conditions………………………………………………………………………………………………. ． 62
5.1NtroDuction ................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 62
5.2 Cov ntaub ntawv thiab cov hau kev ....................................................... 62
5.2.2 Experimental methods . Cov. Cov. ． ． …………………………………………………………………………. 63
5.3 Results and Discussion ..............................................................................................................． 64
5.3.1 Cov nyhuv ntawm HPMC ntxiv thiab lub sijhawm khov ntawm cov pov thawj qhov siab ntawm cov ua khob noom cookie ...................................................................................................
5.3.3 The effect of adding amount of HPMC and freezing time on the content of glutathione in dough……………………………………………………………………………………………………………66. "
5.4 Chapter Summary .......................................................................................................................． 67
6.1 Xaus Lus ........................................................................................ 68
6.2 Outlook .........................................................................................................................................． 68
Figure 1.1 The structural formula of hydroxypropyl methylcellulose………………………. ． 6
Daim duab 2.3 Cov nyhuv ntawm HPMC ntxiv thiab lub sijhawm khov ntawm lub pob zeb tawv ntawm cov qhob cij ............................................................................................................................................................................ ... 19
Figure 2.4 The effect of HPMC addition and freezing time on the elasticity of steamed bread………………………………………………………………………………………………………………………………. ． 20
Figure 3.1 The effect of HPMC addition and freezing time on the rheological properties of wet gluten…………………………………………………………………………………………………………………………. 30
Figure 3.2 Effects of HPMC addition and freezing time on the thermodynamic properties of wheat gluten………………………………………………………………………………………………………………. Cov. 34
Daim duab 3.4 Qhov cuam tshuam ntawm HPMC ntxiv qhov nyiaj thiab khov lub sijhawm khaws cia rau lub sijhawm sib hloov ...........................................................
Daim duab 3.7 cov nyhuv ntawm HPMC ntxiv thiab khov lub sijhawm ntawm lub microscopic gluten network qauv ...................................................................................................................................................................................................................................................................................................................................................................................... .... 43
Daim duab 4.1 hmoov txhuv nplej siab ua cim ............................................... 51
Figure 4.2 Fluid thixotropy of starch paste ................................................................................． 52
Daim duab 4.3 cuam tshuam ntawm ntxiv pes tsawg ntawm MC thiab khov lub sijhawm ntawm cov viscoelastic ntawm cov hmoov txhuv nplej siab .................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. .... 57
Daim duab 4.4 Cov nyhuv ntawm HPMC ntxiv thiab khov cov sijhawm khaws cia rau ntawm cov hmoov txhuv nplej siab o.
Figure 4.5 Effects of HPMC addition and freezing storage time on the thermodynamic properties of starch…………………………………………………………………………………………………………. Cov. 59
Daim duab 4.6 Qhov cuam tshuam ntawm HPMC ntxiv thiab ua kom khov rau lub sijhawm ntawm XRD cov hmoov txhuv nplej siab ........................................................................... .62
Daim duab 5.1 Cov nyhuv ntawm HPMC ntxiv thiab khov lub sijhawm ntawm qhov ua pov thawj qhov siab ntawm cov uake ntawm cov paj fookie ................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. ... 66
Daim duab 5.2 Cov nyhuv ntawm HPMC ntxiv thiab lub sijhawm khov ntawm cov poov yeej muaj sia nyob ................................................................................................................................................................. .... 67
Figure 5.3 Microscopic observation of yeast (microscopic examination) …………………………………………………………………………………………………………………………. 68
Sau cov ntawv
Cov lus 2.1 cov ntsiab lus yooj yim ntawm cov hmoov nplej hmoov nplej ntawm cov hmoov nplej hmoov .................................................................................... 11
Cov lus 2.5 Qhov cuam tshuam ntawm I-IPMC ntxiv cov nqi thiab khov lub sijhawm khaws cia rau ntawm cov qhob cij ................................................... .21
Table 3.2 Effects of I-IPMC addition amount and freezing storage time on the phase transition enthalpy (Yi IV) and freezer water content (e chat) of wet gluten………………………. 31
Cov Lus Qhia 3.3 cuam tshuam ntawm HPMC ntxiv qhov nyiaj thiab khov lub sijhawm khaws cia rau ntawm lub ncov kub (khoom) ntawm cov nplej denaturation ntawm nplej gluten ................................... 33
Cov Lus 3.5 Qhov cuam tshuam ntawm HPMC ntxiv thiab khov lub sijhawm ntawm cov qauv hauv tsev theem nrab ntawm cov qauv ntsiab lus ntawm cov qauv nplej ...................................................................................... .40
Cov Lus 3.6 Qhov cuam tshuam ntawm I-IPC ntxiv thiab khov lub sijhawm khaws cia rau saum npoo Hydrophlomic ntawm cov nplej Gluten .................................................................................................................... 41
Table 4.3 Effects of I-IPMC addition and freezing time on the shear viscosity of wheat starch paste…………………………………………………………………………………………………………………………. 55
Table 4.4 Effects of I-IPMC addition amount and frozen storage time on the thermodynamic properties of starch gelatinization……………………………………………………………….60
1.1.1introduction rau steamed cij
Tam sim no, kev tshawb fawb ntawm cov qhob cij steamed tsuas yog tsom rau cov hauv qab no:
1)Development of new characteristic steamed buns. Los ntawm kev tsim kho tshiab ntawm steamed cij raw khoom thiab ntxiv cov tshuaj lom neeg ua haujlwm tau tsim, uas muaj cov khoom noj khoom haus thiab ua haujlwm zoo. Established the evaluation standard for the quality of miscellaneous grain steamed bread by principal component analysis; Fu et a1. (2015) Ntxiv cov txiv qaub pom kev uas muaj cov qhob cij thiab cov qhob noom cookie, thiab ntsuas cov dej num antioxidant ntawm cov qhob cij; Hao & beta (2012) Kawm txog Barley Bran thiab Flaxseed (Rich nyob rau hauv bioactive cov tshuaj) Lub ncuav ntau lawm ntawm cov qhob cij [5]; Shiau ET A1. (2015) Ntsuas cov nyhuv ntawm kev ntxiv pineapple pulp fiber ntau rau cov khob noom cookie rheological khoom thiab steamed qhob cij zoo [6].
2)Research on the processing and compounding of special flour for steamed bread. The effect of flour properties on the quality of dough and steamed buns and the research on new special flour for steamed buns, and based on this, an evaluation model of flour processing suitability was established [7]; Piv txwv li, qhov cuam tshuam ntawm cov hmoov nplej sib txawv ntawm cov hmoov nplej zoo thiab cov buns [7] 8]; The effect of the compounding of several waxy wheat flours on the quality of steamed bread [9J et al.; Zhu, Huang, &Khan (2001) evaluated the effect of wheat protein on the quality of dough and northern steamed bread, and considered that gliadin/ Glutenin was significantly negatively correlated with dough properties and steamed bread quality [lo]; Zhang, et a1. (2007) analyzed the correlation between gluten protein content, protein type, dough properties and steamed bread quality, and concluded that the content of high molecular weight glutenin subunit (1ligh.molecular-weight, HMW) and total protein content are all related to the quality of northern steamed bread. have a significant impact [11].
3) Kev tshawb fawb ntawm cov khob noom cookie npaj thiab cov qhob cij ua tshuab. Kev tshawb fawb txog kev cuam tshuam ntawm cov qhob cij ntau lawm ntau lawm rau nws cov kev ua tau zoo thiab ua kom zoo dua qub; Liu protghong li al. (2009) showed that in the process of dough conditioning, process parameters such as water addition, dough mixing time, and dough pH value have an impact on the whiteness value of steamed bread. It has a significant impact on sensory evaluation. If the process conditions are not suitable, it will cause the product to turn blue, dark or yellow. Cov txiaj ntsig kev tshawb fawb tau qhia tias thaum lub sijhawm ua khob noom cookie npaj ua ntej 45%, thiab cov tshuaj pleev ntsej muag zoo ntawm cov neeg tawv ncauj yog qhov ntsuas ntawm Whiteness yog qhov zoo tshaj plaws. When rolling the dough 15-20 times at the same time, the dough is flaky, smooth, elastic and shiny surface; when the rolling ratio is 3:1, the dough sheet is shiny, and the whiteness of the steamed bread increases [l to; Li, et a1. (2015) explored the production process of compound fermented dough and its application in steamed bread processing [13].
4) Kev tshawb fawb ntawm kev txhim kho kom zoo ntawm cov qhob cij. Kev tshawb fawb ntawm qhov sib ntxiv thiab kev thov ntawm cov qhob cij mov yooj yim dua; mainly including additives (such as enzymes, emulsifiers, antioxidants, etc.) and other exogenous proteins [14], starch and modified starch [15], etc. The addition and optimization of the corresponding process It is particularly noteworthy that in recent years, through the use of some exogenous proteins and other additives, gluten-free (free. gluten) pasta products have been developed to meet the requirements of celiac disease (Dietary needs of patients with Coeliac Disease [16.1 cit.
5)Preservation and anti-aging of steamed bread and related mechanisms. Pan Lijun et al. (2010) Ua kom zoo rau cov lus sib xyaw nrog cov kev laus los tiv thaiv kev laus los ntawm kev tsim qauv [u tsis ua; Wang, thiab A1. (2015) Kawm txog cov kev cuam tshuam ntawm gluten protein polymerancy-moist moist,, thiab Starch Recrystallization ntawm qhov nce ntawm cov khoom siv lub cev thiab tshuaj lom neeg ntawm cov qhob cij. The results showed that water loss and starch recrystallization were the main reasons for the aging of steamed bread [20].
6) Kev tshawb fawb ntawm daim ntawv thov ntawm cov kab mob fermented tshiab thiab sourdough. Jiang, thiab A1. (2010) Daim ntawv thov ntawm chaetomium sp. fermented to produce xylanase (with thermostable) in steamed bread [2l'; Gerez, et a1. (2012) Siv ob hom lactic acid bacteria hauv fermented hmoov khoom thiab ntsuas lawv cov khoom tau zoo [221; WU, li al. (2012) studied the influence of sourdough fermented by four kinds of lactic acid bacteria (Lactobacillus plantarum, Lactobacillus, sanfranciscemis , Lactobacillus brevis and Lactobacillus delbrueckii subsp bulgaricus) on the quality (specific volume, texture, fermentation flavor, etc.) of northern steamed bread [23]; thiab gerez, thiab A1. (2012) used the fermentation characteristics of two kinds of lactic acid bacteria to accelerate the hydrolysis of gliadin to reduce the allergenicity of flour products [24] and other aspects.
Among them, steamed bread is prone to aging under conventional storage conditions, which is an important factor restricting the development of steamed bread production and processing industrialization. After aging, the quality of steamed bread is reduced - the texture becomes dry and hard, dregs, shrinks and cracks, the sensory quality and flavor deteriorate, the digestion and absorption rate decreases, and the nutritional value decreases. This not only affects its shelf life, but also creates a lot of waste. Raws li kev txheeb cais, kev poob txhua xyoo vim muaj kev laus yog 3% ntawm cov zis ntawm cov hmoov nplej. 7%. With the improvement of people's living standards and health awareness, as well as the rapid development of the food industry, how to industrialize the traditional popular staple noodle products including steamed bread, and obtain products with high quality, long shelf life and easy preservation to meet the needs of the growing demand for fresh, safe, high-quality and convenient food is a long-standing technical problem. Raws li cov keeb kwm no, khov ua ke ua khob noom cookie tuaj rau hauv kev ua, thiab nws txoj kev loj hlob tseem nyob hauv Ascendant.
1.1.3 spintroduction rau khov ua khob noom cookie
Lub khob noom cookie khov yog qhov tshiab ntawm kev ua thiab kev tsim cov hmoov nplej tsim hauv xyoo 1950. It mainly refers to the use of wheat flour as the main raw material and water or sugar as the main auxiliary materials. Baked, packed or unpacked, quick-freezing and other processes make the product reach a frozen state, and in. For products frozen at 18"C, the final product needs to be thawed, proofed, cooked, etc. [251].
a) Lub khob noom cookie khov: Lub khob noom cookie tau muab faib ua ib qho, khov, khov, ua pov thawj, thiab siav, tshiav, thiab lwm yam)
c) ua ntej-ua tiav khov ua khob noom cookie: lub khob noom
d) tag nrho cov ua khov ua khob noom cookie: Lub khob noom cookie tau ua rau ib qho thiab tsim, ces tag nrho cov ntaub ntawv ua pov thawj tab sis khov, khov thiab khaws cia-yaj.
The emergence of frozen dough not only creates conditions for the industrialization, standardization, and chain production of fermented pasta products, it can effectively shorten processing time, improve production efficiency, and reduce production time and labor costs. Yog li ntawd, kev laus tshwm sim ntawm cov zaub mov nplej zom tau zoo nyob rau hauv, thiab cov txiaj ntsig ntawm lub neej ntev ntawm cov khoom lag luam tau tiav. Therefore, especially in Europe, America, Japan and other countries, frozen dough is widely used in white bread (Bread), French Sweet Bread (French Sweet Bread), small muffin (muffin), bread rolls (Rolls), French baguette (- Stick), cookies and frozen
Ncuav thiab lwm cov khoom nplej zom muaj qib sib txawv ntawm daim ntawv thov [26-27]. Raws li cov txheeb cais tsis tiav, los ntawm 1990, 80% ntawm Bakeries hauv Tebchaws Meskas siv khov ua khob noom cookie; 50% ntawm Bakeries hauv Nyij Pooj kuj siv ua kas fes. kaum tsib caug xyoo
Feem ntau cov kev tshawb fawb tau pom tias kev tsim thiab kev loj hlob ntawm cov zaub mov nab hauv cov khoom noj khov yog qhov tseem ceeb ntawm cov khoom lag luam zoo [291]. Cov dej khov tsis tsuas yog txo cov poov xab muaj sia, tab sis kuj ua rau cov hmoov txhuv nplej siab, thiab ua kom muaj kev puas tsuaj rau cov roj ua kom muaj peev xwm ntawm gluten. Ib qho ntxiv, nyob rau hauv cov ntaub ntawv ntawm khov cia, qhov kub hloov pauv tuaj yeem ua rau cov muaju khov kom loj hlob vim recrystallization [30]. Therefore, how to control the adverse effects of ice crystal formation and growth on starch, gluten and yeast is the key to solving the above problems, and it is also a hot research field and direction. Hauv kaum xyoo dhau los, ntau cov kws tshawb nrhiav tau koom ua txoj haujlwm no thiab ua tiav qee cov txiaj ntsig kev tshawb fawb txog cov txiv ntoo. However, there are still some gaps and some unresolved and controversial issues in this field, which need to be further explored, such as:
b) Vim tias muaj qee qhov sib txawv hauv kev ua lag luam thiab cov khoom siv sib txawv ntawm cov hmoov sib txawv tshwj xeeb ua ke nrog cov khoom sib txawv.
c)Expand, optimize and use new frozen dough quality improvers, which is conducive to the optimization of production enterprises and the innovation and cost control of product types. Nyob rau tam sim no, nws tseem yuav tsum tau ntxiv dag zog ntxiv thiab nthuav dav;
i.Study the changes in the structure and properties of frozen dough with the extension of freezing storage time, in order to explore the reasons for the deterioration of product quality, especially the effect of ice crystallization on biological macromolecules (protein, starch, etc.), for example, ice crystallization. Tsim thiab kev loj hlob thiab nws txoj kev sib raug zoo nrog dej lub xeev thiab faib; Cov kev hloov pauv ntawm cov qauv nplej gluten protein, kev sib raug zoo thiab cov khoom [31]; kev hloov pauv ntawm cov qauv hmoov txhuv nplej siab thiab cov khoom; changes in dough microstructure and related properties, etc. 361.
Ii. Txhim kho ntawm khov ua khob noom cookie cov txheej txheem, khov cia khoom thiab cov mis. During the production of frozen dough, temperature control, proofing conditions, pre-freezing treatment, freezing rate, freezing conditions, moisture content, gluten protein content, and thawing methods will all affect the processing properties of frozen dough [37]. Feem ntau, siab dua khov khov tsim cov muaju dej khov uas me dua thiab muaj cov khoom siv khov nab kuab loj uas tsis muaj kev faib tawm. In addition, a lower freezing temperature even below the glass transition temperature (CTA) can effectively maintain its quality, but the cost is higher, and the actual production and cold chain transportation temperatures are usually small. Tsis tas li ntawd, kev hloov pauv ntawm qhov khov txias yuav ua rau recrystallization, uas yuav cuam tshuam rau qhov zoo ntawm lub khob noom cookie.
III. Using additives to improve the product quality of frozen dough. Txhawm rau txhim kho cov khoom lag luam ua khov ua khob noom cookie, ntau cov kws tshawb fawb los tswj hwm qhov kev ruaj khov ntawm cov khoom sib txawv ntawm cov khoom sib txawv ntawm cov qauv ua kom khov kho Feem ntau suav nrog, Kuv) enzyme npaj, xws li, transglutaminase, o [. Amylase; II) emulsifiers, xws li monoglyceride stearate, datem, SSL, CSL, DATEM, thiab lwm yam .; III) antioxidants, ascorbic acid, thiab lwm yam; iv) polysaccharide hydrocolloids, such as guar gum, yellow Originalgum, gum Arabic, konjac gum, sodium alginate, etc.; v) other functional substances, such as Xu, et a1. (2009) added Ice-structuring Proteins to wet gluten mass under freezing conditions, and studied its protective effect and mechanism on the structure and function of gluten protein [y71.
Ⅳ. Kev yug me nyuam ntawm Antifruurin Poov xab thiab daim ntawv thov ntawm cov poov xab kuj tseem ceeb [58-59]. Sasano, thiab A1. (2013) obtained freeze-tolerant yeast strains through hybridization and recombination between different strains [60-61], and S11i, Yu, & Lee (2013) studied a biogenic ice nucleating agent derived from Erwinia Herbicans used to protect the fermentation viability of yeast under freezing conditions [62J.
1.1.6appation ntawm hydrocolloids nyob rau hauv khov ua khob noom cookie zoo dua qub txhim kho
The chemical nature of hydrocolloid is a polysaccharide, which is composed of monosaccharides (glucose, rhamnose, arabinose, mannose, etc.) through 0 [. 1-4. Glycosidic bond or/and a. 1--"6. Glycosidic bond or B. 1-4. Glycosidic bond and 0 [.1-3. The high molecular organic compound formed by the condensation of glycosidic bond has a rich variety and can be roughly divided into: ① Cellulose derivatives , such as methyl cellulose (MC), carboxymethyl cellulose (CMC); ② plant polysaccharides, such as konjac gum, guar gum, gum Arabic ; ③ seaweed polysaccharides, such as seaweed gum, carrageenan; ④ microbial polysaccharides, such as Xanthan gum .Polysaccharide has strong hydrophilicity because it contains a large number of hydroxyl groups that are easy to form hydrogen bonds with water, and has the functions of controlling the migration, state and distribution of water in the food system. Therefore, the addition of hydrophilic colloids gives food Many functions, properties, and qualities of hydrocolloids are closely related to the interaction between polysaccharides and water and other macromolecular substances. At the same time, due to the multiple functions of thickening, stabilizing, and water retention, hydrocolloids are widely used to include in the food processing of flour products. Wang Xin li al. (2007) Kawm txog cov nyhuv ntawm kev ntxiv seaweed polysaccharides thiab gelatin ntawm lub khob hloov kub ntawm ua khob noom cookie [631. Wang Yusheng li al. (2013) believed that compound addition of a variety of hydrophilic colloids can significantly change the flow of dough. Change the properties, improve the tensile strength of the dough, enhance the elasticity of the dough, but reduce the extensibility of the dough [delete.
Vim tias muaj cov muaj ntawm cov qauv ntawm hydrogen hauv cov kab hlau kab thiab corstalline thiab cellulose ua solubility tsis zoo, uas tseem txwv nws daim ntawv thov. Txawm li cas los xij, muaj cov kev hloov pauv ntawm HPMC so cov kev sib tsoo hydropecular [66L], uas tuaj yeem ruaj khov rau kev sib cais tuab ntawm qis kub khi. Raws li lub cellulose derivative-raws li hydrophilic colloid, Hydmc tau siv dav hauv cov ntaub ntawv, cov ntawv sau, cov kws tshuaj pleev, tshuaj pleev tshuaj ntxuav tes thiab khoom noj [6 71]. Tshwj xeeb, vim nws cov kev hloov kho thermo-gelling cov khoom, HPMC feem ntau siv los ua tshuaj ntsiav tshuaj ntsiav tshuaj; Hauv cov khoom noj, HPMC kuj tseem raug siv los ua surfactant, thickeners, thickeners, pulsifiers, stabilizers, thiab lwm yam nyob rau hauv kev txhim kho cov khoom lag luam uas muaj feem xyuam thiab paub txog cov haujlwm tshwj xeeb. Piv txwv li, qhov kev sib ntxiv ntawm HPMC tuaj yeem hloov pauv cov yam ntxwv ntawm cov hmoov txhuv nplej siab thiab txo cov gel lub zog ntawm cov hmoov txhuv nplej siab. , HPMC can reduce the loss of moisture in food, reduce the hardness of bread core, and effectively inhibit the aging of bread.
Txawm hais tias HPMC tau siv nyob rau hauv cov nplej zom rau qee yam, nws yog siv los ua cov khoom lag luam tshwj xeeb thiab lwm yam tuaj yeem txhim kho cov khoom lag luam rau lub ncuav, thiab lwm yam. However, compared with hydrophilic colloids such as guar gum, xanthan gum, and sodium alginate [75-771], there are not many studies on the application of HPMC in frozen dough, whether it can improve the quality of steamed bread processed from frozen dough. Tseem muaj qhov tsis muaj feem cuam tshuam ntawm nws cov nyhuv.
Tam sim no, daim ntawv thov thiab cov kev tsim loj loj thiab cov kev tsim khoom loj ntawm cov khov ua khob noom cookie ua tshuab hauv kuv lub teb chaws ib yam nkaus yog tseem nyob hauv theem kev txhim kho. At the same time, there are certain pitfalls and deficiencies in the frozen dough itself. These comprehensive factors undoubtedly restrict the further application and promotion of frozen dough. on the other hand,this also means that the application of frozen dough has great potential and broad prospects, especially from the perspective of combining frozen dough technology with the industrialized production of traditional Chinese noodles (non-)fermented staple food, to develop more products that meet the needs of Chinese residents. It is of practical significance to improve the quality of the frozen dough based on the characteristics of Chinese pastry and the dietary habits, and is suitable for the processing characteristics of Chinese pastry.
Nws yog feem ntau ntseeg tias ua khob noom cookie yog ib qho kev sib xyaw ua ke zoo nkauj nrog cov yam ntxwv ntawm ntau feem, ntau-theem, thiab ntau qhov ntsuas.
Qhov cuam tshuam ntawm kev ntxiv cov nyiaj thiab lub sijhawm khov ntawm cov qauv thiab cov qauv ntawm cov qhob noom ua kom khov, cov khoom siv ntawm cov qhob noom khob noom cookie, cov khoom siv ntawm cov hmoov nplej nplej nplej, thiab cov khoom ua haujlwm ntawm cov poov xab. Based on the above considerations, the following experimental design was made in this research topic:
1)Select a new type of hydrophilic colloid, hydroxypropyl methylcellulose (HPMC) as an additive, and study the addition amount of HPMC under different freezing time (0, 15, 30, 60 days; the same below) conditions. (0%, 0.5%, 1%, 2%; the same below) on the rheological properties and microstructure of frozen dough, as well as on the quality of the dough product - steamed bread (including the specific volume of steamed bread) , texture), investigate the effect of adding HPMC to the frozen dough on the processing properties of the dough and the quality of steamed bread, and evaluate the improvement effect of HPMC on the processing properties of Lub khob noom cookie khov;
Tshooj 2 Qhov cuam tshuam ntawm I-IPCC ntxiv rau Freszing Cookie Ua Khoom Siv thiab Steamed qhob cij zoo
Feem ntau hais lus, cov ntaub ntawv sib xyaw ua ke rau kev ua cov hmoov nplej fermented (cov poov xab, thiab yog tsim los ntawm cov kab mob muaj sia (thiab yog tsim los ntawm cov kab mob roj ntsha A stable and complex material system with a special structure has been developed. Ntau cov kev tshawb fawb tau pom tias cov khoom ntawm lub khob noom cookie muaj qhov cuam tshuam tseem ceeb ntawm qhov zoo ntawm cov khoom kawg. Yog li ntawd, los ntawm kev txhim kho kom tau raws li cov khoom lag luam tshwj xeeb thiab nws yog cov kev tshawb fawb los txhim kho cov khoom siv ua khob noom cookie thiab thev naus laus zis los siv; Ntawm qhov tod tes, txhim kho lossis txhim kho cov khoom ntawm cov khoom noj mov cookie thiab khaws cia kom ntseeg tau tias lossis txhim kho qhov teeb meem tshawb pom tseem ceeb.
ZHongyu nplej hmoov binzhou zhongyu zaub mov Co., Ltd.; Angel Active Dry Yeast Angel Yeast Co., Ltd.; HPMC (methyl hloov degree ntawm 28% .30%, HydroxyProps hloov pauv degree ntawm 7% .12 Aladdin (Shanghai) Cov tuam txhab siv hluav taws xob. Txhua cov tshuaj reagents siv nyob rau hauv cov kev sim no yog ntawm qib kev ntsuas;
Ta-Xt Ntxiv Rau Lub Tsev Khoom Vaj Tsev
BSAL24S RAU HAUV INFORATIONAL SEEV
C21. KT2134 Induction Cooker
Cov hmoov me me. Tus e
Extensometer. Tus e
Fd. 1b. 50 Vacuum Freeze Dryer
SX2.4.10 muffle rauv taws
Tus tsim
Shanghai Yiheng Scientific Ntsuas Co., Ltd.
Qhaib micro nruab, UK
Shanghai Yiheng Scientific Ntsuas Co., Ltd.
Cov Khoom Siv Hauv Pa Khoom Rau Sab Saum Paus Khoom Co., Ltd.
Guangdong Midlea Lub Neej Kev Lag Luam Raug Cai Co., Ltd.
Brabender, Lub teb chaws Yelemees
Brabender, Lub teb chaws Yelemees
Danish Tuam Txhab Foss
Raws li GB 50093.2010, GB 5009.5--9.9.91008, GB50094.201], GB50094.201], Protein, Cov hmoov txhuv nplej siab thiab hmoov av.
2.2.3.2.2 Kev txiav txim siab ntawm cov muaj zog ntawm cov movies
Saib rau lub khob noom cookie ua txheej txheem ntawm GB / T 17320.1998 [84]. Hnyav 450 g ntawm cov hmoov nplej thiab 5 g ntawm cov poov xab qhuav rau ntawm lub tub yees ntawm cov poov xab), tom qab ntawd ua ntej tso tawm hauv lub khob noom cookie thiab faib ua ntej ua ntej 180g / feem, knead nws a cylindrical shape, then seal it with a ziplock bag, and put it in. Freeze at 18°C for 15, 30, and 60 days. Add 0.5%, 1%, 2% (w/w, dry basis) HPMC to replace the corresponding proportion of flour quality to make dough, and the rest of the production methods remain unchanged. The 0-day frozen storage (unfrozen storage) was used as the control experimental group.
Nqa tawm cov khob noom cookie hnoos tom qab lub sijhawm khov, muab tso rau hauv lub tub yees ntawm 4 h, thiab tom qab ntawd muab lawv tso rau hauv chav sov kom txog thaum ua rau cov khoom siv khob noom cookie tau yaj tag. The sample processing method is also applicable to the experimental part of 2.3.6.
A sample (about 2 g) of the central part of the partially melted dough was cut and placed on the bottom plate of the rheometer (Discovery R3). Ua ntej, cov qauv tau raug rau kev siv lub hom phiaj. The specific experimental parameters were set as follows: A parallel plate with a diameter of 40 mm was used, the gap was set to 1000 mln, the temperature was 25 °C, and the scanning range was 0.01%. 100%, cov qauv so lub sijhawm yog 10 min, thiab zaus tau teev rau 1Hz. Txoj kab Viscoelasticity cheeb tsam (LVR) ntawm cov hnoos qeev tau raug txiav txim los ntawm kev sib tw ntsuas. Then, the sample was subjected to a dynamic frequency sweep, and the specific parameters were set as follows: the strain value was 0.5% (in the LVR range), the resting time, the fixture used, the spacing, and the temperature were all consistent with the strain sweep parameter settings. Tsib cov ntsiab lus cov ntaub ntawv (cov ntaub ntawv) tau sau tseg hauv Rheology nkhaus rau txhua 10-khawm nce hauv hom ntau (hom tawm). After each clamp depression, the excess sample was gently scraped with a blade, and a layer of paraffin oil was applied to the edge of the sample to prevent water loss during the experiment. Each sample was repeated three times.
After the corresponding freezing time, the frozen dough was taken out, first equilibrated in a 4°C refrigerator for 4 h, and then placed at room temperature until the frozen dough was completely thawed. Divide the dough into about 70 grams per portion, knead it into shape, and then put it into a constant temperature and humidity box, and proof it for 60 minutes at 30°C and a relative humidity of 85%. Tom qab cov ntawv pov thawj, chav rau 20 min, thiab tom qab ntawd txias rau 1 h ntawm chav tsev kub los ntsuas qhov zoo ntawm cov qhob cij steamed.
2.2.3.8 Kev Tshuaj Ntsuam Xyuas Cov Khoom Siv Hluav Taws Xob Zoo
Raws li GB / T 20981.2007 [871, lub zog rapeseed kev ntsuas (m) ntawm cov beamed buns raug ntsuas siv hluav taws xob sib npaug. Txhua tus qauv tau ua dua peb zaug.
(2) Kev txiav txim siab ntawm kev ntxhib los ntawm cov qhob cij mov ci
2.3 Tshawb nrhiav cov txiaj ntsig thiab kev sib tham
2.3.1 cov ntawv sau yooj yim ntawm cov hmoov nplej
Tab 2.1 cov ntsiab lus ntawm cov hmoov txhuv nplej qis ntawm cov hmoov nplej
2.3.3 nyhuv ntawm HPMC ntxiv rau ntawm cov khoom siv ua khob noom cookie cov khoom
Table 2.3 lists the effects of different amounts of HPMC (O, 0.5%, 1% and 2%) and different proofing 1'9 (45 min, 90 min and 135 min) on the dough tensile properties (energy, stretch resistance, maximum stretch resistance, elongation, stretch ratio and maximum stretch ratio). The experimental results show that the tensile properties of all dough samples increase with the extension of the proofing time except the elongation which decreases with the extension of the proofing time. Rau lub zog tus nqi, los ntawm 0 mus rau 90 min, lub zog tus nqi ntawm cov khoom noj mov paj tau nce ntxiv rau tag nrho cov khob noom cookie kuaj nce zuj zus. Tsis muaj kev hloov pauv tseem ceeb. This shows that when the proofing time is 90 min, the network structure of the dough (cross-linking between molecular chains) is completely formed. Therefore, the proofing time is further extended, and there is no significant difference in the energy value. At the same time, this can also provide a reference for determining the proofing time of the dough. As the proofing time prolongs, more secondary bonds between molecular chains are formed and the molecular chains are more closely cross-linked, so the tensile resistance and the maximum tensile resistance increase gradually. At the same time, the deformation rate of molecular chains also decreased with the increase of secondary bonds between molecular chains and the tighter cross-linking of molecular chains, which led to the decrease of the elongation of the dough with the excessive extension of the proofing time. The increase in tensile resistance/maximum tensile resistance and the decrease in elongation resulted in an increase in tensile LL/maximum tensile ratio.
Daim duab 2.1 nyhuv ntawm HPMC ntxiv rau rheological cov yam ntxwv ntawm khov ua khob noom cookie
Figure 2.1 shows the change of storage modulus (elastic modulus, G') and loss modulus (viscous modulus, G") of dough with different HPMC content from 0 days to 60 days. The results showed that with the prolongation of freezing storage time, the G' of the dough without adding HPMC decreased significantly, while the change of G" was relatively small, and the /an Q (G''/G') increased. This may be due to the fact that the network structure of the dough is damaged by ice crystals during freezing storage, which reduces its structural strength and thus the elastic modulus decreases significantly. Txawm li cas los xij, nrog rau kev nce HPMC ntxiv, sib txawv ntawm G 'maj mam poob. Tshwj xeeb, thaum ntxiv nyiaj ntawm HPMC yog 2%, qhov sib txawv ntawm G 'yog qhov me tshaj plaws. This shows that HPMC can effectively inhibit the formation of ice crystals and the increase in the size of ice crystals, thereby reducing the damage to the dough structure and maintaining the structural strength of the dough. In addition, the G' value of dough is greater than that of wet gluten dough, while the G" value of dough is smaller than that of wet gluten dough, mainly because the dough contains a large amount of starch, which can be adsorbed and dispersed on the gluten network structure. It increases its strength while retaining excess moisture.
2.3.5 Qhov cuam tshuam ntawm HPMC ntxiv cov nqi thiab khov lub sijhawm khaws cia rau ntawm cov dej ntws dawb (tshuav) hauv khob noom cookie khov
Not all the moisture in the dough can form ice crystals at a certain low temperature, which is related to the state of the moisture (free-flowing, restricted, combined with other substances, etc.) and its environment. Freezable water is the water in the dough that can undergo phase transformation to form ice crystals at low temperatures. The amount of freezable water directly affects the number, size and distribution of ice crystal formation. In addition, the freezable water content is also affected by environmental changes, such as the extension of freezing storage time, the fluctuation of freezing storage temperature, and the change of material system structure and properties. For the frozen dough without added HPMC, with the prolongation of freezing storage time, Q silicon increased significantly, from 32.48±0.32% (frozen storage for 0 days) to 39.13±0.64% (frozen storage for 0 days). Tibetan rau 60 hnub), nce nqi yog 20.47%. However, after 60 days of frozen storage, with the increase of HPMC addition, the increase rate of CFW decreased, followed by 18.41%, 13.71%, and 12.48% (Table 2.4). At the same time, the o∥ of the unfrozen dough decreased correspondingly with the increase of the amount of HPMC added, from 32.48a-0.32% (without adding HPMC) to 31.73±0.20% in turn. (adding0.5% HPMC), 3 1.29+0.03% (adding 1% HPMC) and 30.44±0.03% (adding 2% HPMC) Water holding capacity, inhibits the free flow of water and reduces the amount of water that can be frozen. In the process of freezing storage, along with recrystallization, the dough structure is destroyed, so that part of the non-freezable water is converted into freezable water, thus increasing the content of freezable water. However, HPMC can effectively inhibit the formation and growth of ice crystals and protect the stability of the dough structure, thus effectively inhibiting the increase of the freezable water content. This is consistent with the change law of the freezable water content in the frozen wet gluten dough, but because the dough contains more starch, the CFW value is smaller than the G∥ value determined by the wet gluten dough (Table 3.2).
Cov khoom ntim tshwj xeeb ntawm cov qhob cij tuaj yeem zoo dua pom cov tsos thiab zoo nkauj ntawm cov qhob cij steamed. The larger the specific volume of the steamed bread, the larger the volume of the steamed bread of the same quality, and the specific volume has a certain influence on the appearance, color, texture, and sensory evaluation of the food. Generally speaking, steamed buns with larger specific volume are also more popular with consumers to a certain extent.
Daim duab 2.2 Cov nyhuv ntawm HPMC ntxiv thiab khov cia rau ntawm cov ntim tshwj xeeb ntawm cov qhob cij
Cov khoom ntim tshwj xeeb ntawm cov qhob cij tuaj yeem zoo dua pom cov tsos thiab zoo nkauj ntawm cov qhob cij steamed. The larger the specific volume of the steamed bread, the larger the volume of the steamed bread of the same quality, and the specific volume has a certain influence on the appearance, color, texture, and sensory evaluation of the food. Generally speaking, steamed buns with larger specific volume are also more popular with consumers to a certain extent.
Txawm li cas los xij, cov khoom ntim tshwj xeeb ntawm cov qhob cij steamed ua los ntawm cov khob noom cookie khov ua rau ncua sijhawm ntawm lub sijhawm khov. Ntawm lawv, cov khoom ntim tshwj xeeb ntawm cov qhob cij ua los ntawm lub khob noom cookie khov yam tsis muaj HPMC yog 2.835 ± 0.064 CM3 / g (khov cia). 0 days) down to 1.495±0.070 cm3/g (frozen storage for 60 days); while the specific volume of steamed bread made from frozen dough added with 2% HPMC dropped from 3.160±0.041 cm3/g to 2.160±0.041 cm3/g. 451±0.033 cm3/g, therefore, the specific volume of the steamed bread made from the frozen dough added with HPMC decreased with the increase of the added amount. Since the specific volume of steamed bread is not only affected by the yeast fermentation activity (fermentation gas production), the moderate gas holding capacity of the dough network structure also has an important impact on the specific volume of the final product [96'9 cited. The measurement results of the above rheological properties show that the integrity and structural strength of the dough network structure are destroyed during the freezing storage process, and the degree of damage is intensified with the extension of the freezing storage time. During the process, its gas holding capacity is poor, which in turn leads to a decrease in the specific volume of the steamed bread. However, the addition of HPMC can more effectively protect the integrity of the dough network structure, so that the air-holding properties of the dough are better maintained, therefore, in O. During the 60-day frozen storage period, with the increase of HPMC addition, the specific volume of the corresponding steamed bread decreased gradually.
TPA (Textural Profile Analyses) physical property test can comprehensively reflect the mechanical properties and quality of pasta food, including hardness, elasticity, cohesion, chewiness and resilience. Daim duab 2.3 qhia cov nyhuv ntawm HPMC ntxiv thiab lub sijhawm khov ntawm lub hardness ntawm cov qhob cij steamed. The results show that for fresh dough without freezing treatment, with the increase of HPMC addition, the hardness of steamed bread significantly increases. decreased from 355.55±24.65g (blank sample) to 310.48±20.09 g (add O.5% HPMC), 258.06±20.99 g (add 1% t-IPMC) and 215.29 + 13.37 g (2% HPMC added). Qhov no yuav cuam tshuam nrog kev nce ntxiv hauv cov mov ci ntawm cov mov ci. Ib qho ntxiv, raws li tuaj yeem pom los ntawm daim duab 2.4, raws li tus mob HPMC ntxiv, lub caij nplooj ua khob noom cookie ntau dua, ntawm 0.006 (dawb paug) rau 1, feem. .020 ± 0.004 (add 0.5% HPMC), 1.073 ± 0.006 (add 1% I-IPMC) and 1.176 ± 0.003 (add 2% HPMC). Cov kev hloov pauv ntawm lub hardness thiab elasticity ntawm cov qhob cij steamed qhia tias kev sib ntxiv ntawm HPMC tuaj yeem txhim kho cov mov ci zoo. This is consistent with the research results of Rosell, Rojas, Benedito de Barber (2001) [95] and Barcenas, Rosell (2005) [worms], that is, HPMC can significantly reduce the hardness of bread and improve the quality of bread.
On the other hand, with the prolongation of the frozen storage time of frozen dough, the hardness of the steamed bread made by it increased significantly (P<0.05), while the elasticity decreased significantly (P<0.05). Txawm li cas los xij, lub hardness ntawm steamed buns ua los ntawm khov ua khob noom cookie yam tsis tau ntxiv ntawm 358.244 ± 34.254 g (khov cia rau 60 hnub);
Lub hardness ntawm steamed qhob cij ua los ntawm khov ua khob noom cookie nrog 28.233 ± 15.566 g (khov cia rau 52,849 g (khov cia rau 60 hnub). Fig 2．4 Effect of HPMC addition and frozen storage on springiness of Chinese steamed bread In terms of elasticity, the elasticity of steamed bread made from frozen dough without adding HPMC decreased from 0.968 ± 0.006 (freezing for 0 days) to 0.689 ± 0.022 (frozen for 60 days); Khov nrog 2% HPMC ntxiv cov elasticity ntawm cov buns uas poob qis ntawm 1.176 ± 0.003 (kom khov rau 0.962 rau 0.003 (kom khov rau 60 hnub). Pom tseeb, nce nqi ntawm kev tawv thiab txo tus nqi ntawm kev nce ntawm HPMC hauv lub caij ua ke khov thaum lub sijhawm khov. Qhov no qhia tau hais tias ntxiv ntawm HPMC tuaj yeem txhim kho qhov zoo ntawm cov qhob cij steamed. Ntxiv rau, lub rooj 2.5 teev cov teebmeem ntawm HPMC ntxiv thiab lub sijhawm ua kom khov rau lwm qhov kev ntsuas ntawm cov ncuav. ) Tsis muaj kev hloov pauv tseem ceeb (P> 0.05); Txawm li cas los xij, ntawm 0 hnub ntawm khov, nrog kev nce HPMC ntxiv, cov pos hniav thiab cov neeg nyiam ua rau muaj ntau (p
Ntawm qhov tod tes, nrog lub caij nyoog ntawm lub sijhawm khov, cov cohesion thiab rov ua kom lub zog ua haujlwm ntawm cov qhob cij steamedly. For steamed bread made from frozen dough without adding HPMC, its cohesion was increased by O. 86-4-0.03 g (frozen storage 0 days) was reduced to 0.49+0.06 g (frozen storage for 60 days), while the restoring force was reduced from 0.48+0.04 g (frozen storage for 0 days) to 0.17±0.01 (frozen storage for 0 days) 60 days); however, for steamed buns made from frozen dough with 2% HPMC added, the cohesion was reduced from 0.93+0.02 g (0 days frozen) to 0.61+0.07 g (frozen storage for 60 days), while the restoring force was reduced from 0.53+0.01 g (frozen storage for 0 days) to 0.27+4-0.02 (frozen storage for 60 days). Tsis tas li ntawd, nrog lub caij nyoog ntawm khov cia sij hawm, cov nplaum thiab zom zom kom loj dua. Rau lub khob noom cookie ua los ntawm cov khob noom cookie khov yam tsis muaj HPMC ntxiv, cov ntawv nplaum tau nce los ntawm 336.54 + 37. 24 (0 days of frozen storage) increased to 1232.86±67.67 (60 days of frozen storage), while chewiness increased from 325.76+34.64 (0 days of frozen storage) to 1005.83+83.95 (frozen for 60 days); however, for the steamed buns made from frozen dough with 2% HPMC added, the stickiness increased from 206.62+1 1.84 (frozen for 0 days) to 472.84. 96+45.58 (frozen storage for 60 days), while chewiness increased from 200.78+10.21 (frozen storage for 0 days) to 404.53+31.26 (frozen storage for 60 days). This shows that the addition of HPMC can effectively inhibit the changes in the texture properties of steamed bread caused by freezing storage. In addition, the changes in the texture properties of steamed bread caused by freezing storage (such as the increase of stickiness and chewiness and the decrease of recovery force) There is also a certain internal correlation with the change of steamed bread specific volume. Thus, dough properties (eg, farinality, elongation, and rheological properties) can be improved by adding HPMC to frozen dough, and HPMC inhibits the formation, growth, and redistribution of ice crystals (recrystallization process), making frozen dough The quality of the processed steamed buns is improved.
2.4 Tshooj Lus Qhia
Hydroxypropyl methylcellulose (HPMC) is a kind of hydrophilic colloid, and its application research in frozen dough with Chinese-style pasta food (such as steamed bread) as the final product is still lacking. The main purpose of this study is to evaluate the effect of HPMC improvement by investigating the effect of HPMC addition on the processing properties of frozen dough and the quality of steamed bread, so as to provide some theoretical support for the application of HPMC in steamed bread and other Chinese-style flour products. The results show that HPMC can improve the farinaceous properties of the dough. Thaum qhov kev sib ntxiv ntawm HPMC yog 2%, cov dej nqus tus nqi ntawm cov ua khob noom cookie nce los ntawm 58.10% hauv pawg tswj kom 60.60%; 2 min increased to 12.2 min; at the same time, the dough formation time decreased from 2.1 min in the control group to 1.5 mill; Qhov chaws tsis muaj zog poob qis los ntawm 55 fu hauv pawg tswj hwm rau 18 teev. In addition, HPMC also improved the tensile properties of the dough. Nrog kev nce nyob rau hauv tus nqi HPMC ntxiv, elongation ntawm lub khob noom cookie nce ntau; ho txo qis. In addition, during the frozen storage period, the addition of HPMC reduced the increase rate of the freezable water content in the dough, thereby inhibiting the damage to the dough network structure caused by ice crystallization, maintaining the relative stability of the dough viscoelasticity and the integrity of the network structure, thereby improving the stability of the dough network structure. Qhov zoo ntawm cov khoom kawg yog lav.
Ntawm qhov tod tes, cov kev sim ua kom pom tias ntxiv ntawm HPMC kuj tau muaj kev tswj hwm zoo thiab txhim kho cov khoom siv ua ke los ntawm lub khob noom cookie khov. For the unfrozen samples, the addition of HPMC increased the specific volume of the steamed bread and improved the texture properties of the steamed bread - reduced the hardness of the steamed bread, increased its elasticity, and at the same time reduced the stickiness and chewiness of the steamed bread. In addition, the addition of HPMC inhibited the deterioration of the quality of steamed buns made from frozen dough with the extension of freezing storage time - reducing the degree of increase in the hardness, stickiness and chewiness of the steamed buns, as well as reducing the elasticity of the steamed buns, Cohesion and recovery force decrease.
Tshooj 3 Muaj cov teebmeem ntawm HPMC ntxiv rau cov qauv thiab cov khoom ntawm cov nplej gluten nyob rau hauv khov kho
Wheat gluten is the most abundant storage protein in wheat grains, accounting for more than 80% of the total protein. According to the solubility of its components, it can be roughly divided into glutenin (soluble in alkaline solution) and gliadin (soluble in alkaline solution). in ethanol solution). Among them, the molecular weight (mw) of glutenin is as high as 1x107Da, and it has two subunits, which can form intermolecular and intramolecular disulfide bonds; Thaum lub cev hnyav molecular ntawm GLIADIN tsuas yog 1x104da, thiab tsuas muaj ib tus subunit, uas tuaj yeem tsim cov molecules sab hauv disulfide daim ntawv cog lus [100]. Campos, Steffe, & Ng (1 996) divided the formation of dough into two processes: energy input (mixing process with dough) and protein association (formation of dough network structure). It is generally believed that during dough formation, glutenin determines the elasticity and structural strength of the dough, while gliadin determines the viscosity and fluidity of the dough [102]. It can be seen that gluten protein has an indispensable and unique role in the formation of the dough network structure, and endows the dough with cohesion, viscoelasticity and water absorption.
In addition, from a microscopic point of view, the formation of the three-dimensional network structure of dough is accompanied by the formation of intermolecular and intramolecular covalent bonds (such as disulfide bonds) and non-covalent bonds (such as hydrogen bonds, hydrophobic forces) [103]. Txawm hais tias lub zog ntawm kev sib raug zoo thib ob
Kom muaj nuj nqis thiab kev ruaj khov yog tsis muaj zog dua li txoj kev sib khi lus, tab sis lawv ua lub luag haujlwm tseem ceeb hauv kev tswj cov kev sib txuam ntawm gluten [1041].
For frozen dough, under freezing conditions, the formation and growth of ice crystals (crystallization and recrystallization process) will cause the dough network structure to be physically squeezed, and its structural integrity will be destroyed, and microscopically. Nrog kev hloov pauv ntawm cov qauv thiab cov khoom ntawm gluten protein [105'1061. Raws li Zhao, thiab A1. (2012) found that with the prolongation of freezing time, the molecular weight and molecular gyration radius of gluten protein decreased [107J, which indicated that gluten protein partially depolymerized. In addition, the spatial conformational changes and thermodynamic properties of gluten protein will affect the dough processing properties and product quality. Therefore, in the process of freezing storage, it is of certain research significance to investigate the changes of water state (ice crystal state) and the structure and properties of gluten protein under different freezing storage time conditions.
Raws li tau hais nyob rau hauv cov lus qhia, raws li lub cellulose derivative hydrocolloid me, thiab kev tshawb fawb ntawm nws cov txheej txheem kev ua haujlwm yog txawm tsawg dua.
Therefore, the purpose of this experiment is to use the wheat gluten dough (Gluten Dough) as the research model to investigate the content of HPMC (0, 0.5%) under different freezing storage time (0, 15, 30, 60 days) , 1%, 2%) on the state and distribution of water in the wet gluten system, gluten protein rheological properties, thermodynamic properties, and its physicochemical properties, and then Tshawb nrhiav cov laj thawj ntawm cov kev hloov pauv ntawm cov khoom siv khov, thiab lub luag haujlwm ntawm HPMC mechanism teeb meem, yog li txhawm rau txhawm rau txhim kho kev nkag siab txog cov teeb meem ntsig txog.
3.2.1 sim khoom
Gluten Anhui Rui Fu Xiang Zaub Mov Co., Ltd.; Hydroxypropyl Methylcellulose (HPMC, same as above) Aladdin Chemical Reagent Co., Ltd.
3.2.2 D sim ua Apparatus
BC / BD. 272SC refrigerator
BCD BCD. 201ntaij teb
Kuv. 5 ultra-microelectronic tshuav nyiaj
Tsis siv neeg Microplate nyeem
Nicolet 67 Fourier Transform Infrated Spectrometer
Fd. 1b. 50 Vacuum Freeze Dryer
KDC. 160hr high-ceev lub tub yees rau hauv centrifuge
Pb. Qauv 10 Ph ''
SX2.4.10 muffle rauv taws
Kjeltec TM 8400 tsis siv neeg Kjeldahl nitrogen analalyzer
Tus tsim
Shanghai Nemet Tuam Txhab
Nippon Electronics Raug Co., Ltd.
Jintan Jincheng Guoseng Sim Ua Ntsuas Ntsuas Lub Hoobkas
Qingdao Hisier Group
Hefei Mei Ling Co., Ltd.
Thermo Fisher, USA
Anhui Zhong ke Zhong Jia Scientific Ntsuas Co., Ltd.
Thermo Fisher, USA
Danish Tuam Txhab Foss
3.2.4 Kev sim txuj ci
Raws li GB 5009.5_2010, GB 50093.2010, cov ntsiab lus ntawm cov protein, noo noo, cov kab mob muaj txiaj ntsig tau pom muaj nyob rau hauv Table 3.1 qhia.
Zaus cheb, cov kev sim ua zaus tau teeb tsa yog ua raws li hauv qab no - CLINE yog 0.5% (ntawm LVR), thiab qhov ntau tshaj cheb ntau yog 0.1 HZ. 10 Hz, hz, hz, lwm yam tsis muaj tib yam li txoj kev cheb cheb. Scanning data is acquired in logarithmic mode, and 5 data points (plots) are recorded in the rheological curve for every 10-fold increase in frequency, so as to obtain the frequency as the abscissa, the storage modulus (G') and the loss modulus (G') is the rheological discrete curve of the ordinate. It is worth noting that after each time the sample is pressed by the clamp, the excess sample needs to be gently scraped with a blade, and a layer of paraffin oil is applied to the edge of the sample to prevent moisture during the experiment. of loss. Each sample was replicated three times.
A 15 mg sample of wet gluten was weighed and sealed in an aluminum crucible (suitable for liquid samples). The determination procedure and parameters are as follows: equilibrate at 20°C for 5 min, then drop to .30°C at a rate of 10°C/min, keep the temperature for 10 min, and finally increase to 25°C at a rate of 5°C/min, purge the gas (Purge Gas) was nitrogen (N2) and its flow rate was 50 mL/min, and a blank sealed aluminum crucible was used as a reference. Cov tau txais DSC nkhaus tau raug tshuaj xyuas siv cov software software universal tsom 2000, los ntawm kev tshuaj xyuas cov peaks nyob ib puag ncig 0 ° C. ° C. Integral to get the melting enthalpy of ice crystals (Yu day). Then, the freezable water content (CFW) is calculated by the following formula [85-86]:
Ntawm lawv, peb, sawv cev rau latent tshav kub ntawm noo noo, thiab nws cov nqi yog 334 j / g; MC represents the total moisture content of the wet gluten measured (measured according to GB 50093.2010 [. 78]). Each sample was replicated three times.
(2) Kev txiav txim siab ntawm Thermal Denaturation Peak Kub (TP) ntawm cov nplej gluten protein
Freeze-dry the frozen-storage-treated sample, grind it again, and pass it through a 100-mesh sieve to obtain gluten protein powder (this solid powder sample is also applicable to 2.8). Ib qho 10 mg gluten protein qauv tau hnyav thiab kaw nyob rau hauv txhuas crucible (rau cov qauv khoom). The DSC measurement parameters were set as follows, equilibrated at 20 °C for 5 min, and then increased to 100 °C at a rate of 5 °C/min, using nitrogen as the purge gas, and its flow rate was 80 mL/min. Using a sealed empty crucible as a reference, and use the analysis software Universal Analysis 2000 to analyze the obtained DSC curve to obtain the peak temperature of thermal denaturation of wheat gluten protein (Yes). Each sample is replicated three times.
Sodium sodium (SDS). TRIS-Hydroxymethyl Aminomethane (Tris). Glycine (gly). Tetraacetic acid 7, amine (EDTA) buffer (10.4% Tris, 6.9 g glycine and 1.2 g EDTA/L, pH 8.0, abbreviated as TGE, and then 2.5% SDS It was added to the above TGE solution (that is, prepared into SDS-TGE buffer), incubated at 25°C for 30 min, and shaken every 10 min. Then, the supernatant was obtained after centrifugation rau 10 min ntawm 4 ° C thiab 5000 × g. Ua ntej, rau cov ntsiab lus muaj zog tshaj plaws (DTRobbenzoic acid, 4 Rag / ml), tom qab 30 feeb ntawm tsim kom loj hlob hauv 2512 nuaj suarbance, thiab cov lus saum toj no tau raug suav raws li cov qauv hauv qab no:
According to Kontogiorgos, Goff, & Kasapis (2007) method [1111, 2 g of wet gluten mass was placed in a 10 mm diameter nuclear magnetic tube, sealed with plastic wrap, and then placed in a low-field nuclear magnetic resonance apparatus to measure the transverse relaxation time (n), the specific parameters are set as follows: 32 ℃ equilibrium for 3 min, the field strength is 0.43 T, cov zaus cov zaus yog 18.169 Hz, thiab 1 800 tau teeb tsa qhov kev cuam tshuam me me ntawm 900 thiab 2500 tau teev tseg rau kev cuam tshuam thiab kev sib txawv ntawm txoj kev nkhaus. In this experiment, it was set to O. 5 m s. Each assay was scanned 8 times to increase the signal-to-noise ratio (SNR), with a 1 s interval between each scan. The relaxation time is obtained from the following integral equation:
Siv cov algorithm txuas ntxiv hauv cov software kev txheeb xyuas software ua ke nrog kev hloov pauv chaw dawb, cov inversion yog ua kom tau txais kev sib tw mus txuas ntxiv. Each sample was repeated three times
In this experiment, a Fourier transform infrared spectrometer equipped with an attenuated single reflection attenuated total reflection (ATR) accessory was used to determine the secondary structure of gluten protein, and a cadmium mercury telluride crystal was used as the detector. Ob tus qauv thiab tom qab sau tau luam tawm 64 lub sijhawm nrog kev daws teeb meem ntawm 4 CM ~ thiab cov khoom siv tsoo ntawm 4000 cmq-500 cm ~. Spread a small amount of protein solid powder on the surface of the diamond on the ATR fitting, and then, after 3 turns clockwise, you can start to collect the infrared spectrum signal of the sample, and finally get the wavenumber (Wavenumber, cm-1) as the abscissa, and absorbance as the abscissa. (Absorption) is the infrared spectrum of the ordinate.
Use OMNIC software to perform automatic baseline correction and advanced ATR correction on the obtained full wavenumber infrared spectrum, and then use Peak. Fit 4.12 software performs baseline correction, Fourier deconvolution and second derivative fitting on the amide III band (1350 cm-1.1200 cm'1) until the fitted correlation coefficient (∥) reaches 0. 99 or more, the integrated peak area corresponding to the secondary structure of each protein is finally obtained, and the relative content of each secondary structure is calculated. Tus nqi (%), uas yog, lub ncov huab cua / tag nrho cov cheeb tsam. Peb txoj kev sib tw tau ua rau txhua qhov qauv.
3.2.4.8 Kev Txiav Txim Siab Txog Hydrophobicity ntawm Gluten Protein
3.2.4.9 electron tsom tsom iav tsom iav
Tom qab khov-kom qhuav lub ntub gluten loj yam tsis muaj kev ntxiv hpmc thiab ntxiv 2 xyoos uas tau muab tso tawm rau hauv lub tshuab hluav taws xob tau txiav tawm (JSM.6490LV). Morphological observation was carried out. Qhov nrawm nrawm tau teeb tsa 20 kV thiab lub magnification yog 100 zaug.
Txhua qhov kev tshwm sim yog qhia raws li txhais tau tias yog txhais tau tias 4-qauv kev sib txawv, thiab cov kev sim saum toj no tau rov qab tsawg kawg peb zaug tshwj tsis yog kev ntsuas hluav taws xob. Siv cov keeb kwm 8.0 kos duab kos, thiab siv cov UPSS 19.0 rau ib. Kev tshuaj ntsuam ntawm variance thiab Duncan ntau qhov kev xeem, qib tseem ceeb yog 0.05.
3. Cov txiaj ntsig thiab kev sib tham
3.3.1 Qhov cuam tshuam ntawm HPMC ntxiv qhov nyiaj thiab khov cia lub sijhawm rau ntawm lub zog rheological ntawm ntub gluten loj
Rheological properties are an effective way to reflect the structure and properties of food materials and to predict and evaluate product quality [113J. Raws li peb txhua tus paub, gluten protein yog cov khoom siv tseem ceeb uas muab ua khob noom cookie viscoelasticity. Raws li pom hauv daim duab 3.1, lub zog nrawm tshaj plaws cheb (0.1.1 Hz) Cov txiaj ntsig tau ntau dua li cov txiaj ntsig ntub dej (Daim Duab 3.1, AD). Qhov no cov txiaj ntsig thiab intramolecular gluwsenin The mutual cross-linking structure formed by covalent or non-covalent interaction is the backbone of the dough network structure [114]. At the same time, Sin Qu & Singh (2013) also believed that the rheological properties of dough are related to their protein components [114]. 115]. In addition, with the prolongation of freezing time, the G' and G' moduli of wet gluten doughs with 0%, 0.5% and 1% HPMC added showed different degrees of decrease (Fig. 3.1, 115). AC), and the degree of decrease was negatively correlated with the addition of HPMC, so that the G and G" moduli of wet gluten doughs with 2% HPMC addition did not show a significant increase with the freezing storage time from 0 to 60 days. Sexual differences (Figure 3.1, D). This indicates that the three-dimensional network structure of the wet gluten mass without HPMC was destroyed by the ice crystals formed during the freezing process, which is consistent with the results found by Kontogiorgos, Goff, & Kasapis (2008), who believed that the prolonged freezing time caused the functionality and stability of the dough structure were seriously reduced.
Note: Among them, A is the oscillating frequency scanning result of wet gluten without adding HPMC: B is the oscillating frequency scanning result of wet gluten adding 0.5% HPMC; C Yog qhov zaus zaus tshuaj ntsuam xyuas cov txiaj ntsig los ntawm kev ntxiv 1% HPMC: D yog qhov xwm txheej oscillating kev ntxiv 2%
Thaum lub sijhawm khov, noo noo nyob rau hauv ntub gluten loj crystallization ntawm lub sijhawm noo noo, thiab nws yog qhov ntsuas muaj cov muaju ua kom khov kho, thiab nws muaj cov khoom siv noo noo bonds through physical extrusion. Txawm li cas los xij, los ntawm kev sib piv ntawm cov pab pawg pom tias qhov sib ntxiv ntawm HPMC tuaj yeem tiv thaiv kev ua kom muaj zog thiab lub zog ntawm cov nyhuv correlated nrog tus nqi HPMC ntxiv.
Ice crystals are formed by the phase transition of freezable water at temperatures below its freezing point. Yog li ntawd, cov ntsiab lus ntawm cov dej khov khov ncaj qha cuam tshuam tus naj npawb, qhov loj me thiab faib dej khov muaju nyob hauv lub khob noom cookie khov. Qhov kev sim ua kev sim (rooj 3.2) qhia tau tias raws li lub sijhawm khov rau ntawm 0 hnub mus rau 60 hnub Tshwj xeeb, tom qab 60 hnub ntawm khov cia, lub theem hloov chaw (hnub), 19.59%. However, for the samples supplemented with 0.5%, 1% and 2% HPMC, after 60 days of freezing, the C-chat increased by 20.07%, 16, 63% and 15.96%, respectively, which is consistent with Matuda, et a1. (2008) Pom tias lub suab nrov heev (y) ntawm cov qauv nrog ntxiv hydrophilic colloids txo nrog cov qauv tsis sib xws [119].
The thermal stability of gluten has an important influence on the grain formation and product quality of thermally processed pasta [211]. Daim duab 3.2 qhia tau DSC nkhaus nrog kub (° C) raws li abscissa thiab kub ntws (mw) raws li cov eprinate. The experimental results (Table 3.3) found that the heat denaturation temperature of gluten protein without freezing and without adding I-IPMC was 52.95 °C, which was consistent with Leon, et a1. (2003) thiab Khatkar, Barak, & Mudgil (2013) qhia cov txiaj ntsig zoo sib xws [120M11. With the addition of 0% unfrozen, O. Compared with the heat denaturation temperature of gluten protein with 5%, 1% and 2% HPMC, the heat deformation temperature of gluten protein corresponding to 60 days increased by 7.40℃, 6.15℃, 5.02℃ and 4.58℃, respectively. Obviously, under the condition of the same freezing storage time, the increase of denaturation peak temperature (N) decreased sequentially with the increase of HPMC addition. Qhov no ua tau raws li kev hloov pauv ntawm cov txiaj ntsig ntawm kev quaj. In addition, for the unfrozen samples, as the amount of HPMC added increases, the N values decrease sequentially. This may be due to the intermolecular interactions between HPMC with molecular surface activity and gluten, such as the formation of covalent and non-covalent bonds [122J].
NCO TSEG: Cov ntawv sib txawv ntawm cov tsiaj ntawv me me txhais tau tias muaj ntau yam txiaj ntsig hydrophobic thiab koom nrog cov txheej txheem denaturation ntau dua li ntawm cov molecule [1231]. Yog li ntawd, pab pawg hydrophobic hauv gluten tau nthuav tawm thaum khov, thiab HPMC tuaj yeem ua rau cov molecular conformation ntawm gluten.
Fig 3.2 Raug DSC Thermograms ntawm gluten protein nrog 0% HPMC (1% HPMC (B); Nco tseg: A yog DSC nkhaus ntawm cov nplej gluten yam tsis muaj HPMC; B yog ntxiv ntawm O. DSC nkhaus ntawm cov nplej gluten nrog 5% HPMC; C yog DSC nkhaus ntawm cov nplej gluten nrog 1% hpmc; D is the DSC curve of wheat gluten with 2% HPMC 3.3.3 Effects of HPMC addition amount and freezing time on free sulfhydryl content (C-SH) Intermolecular and intramolecular covalent bonds are very important for the stability of dough network structure. A disulfide bond (-SS-) is a covalent linkage formed by dehydrogenation of two free sulfhydryl groups (.SH). Glutenin is composed of glutenin and gliadin, the former can form intramolecular and intermolecular disulfide bonds, while the latter can only form intramolecular disulfide bonds [1241] Therefore, disulfide bonds are an intramolecular/intermolecular disulfide bond. important way of cross-linking. Compared to adding 0%, O. The C-SH of 5% and 1% HPMC without freezing treatment and the C-SH of gluten after 60 days of freezing have different degrees of increase respectively. Specifically, the face with no HPMC added gluten C. SH increased by 3.74 "mol/g to 8.25 "mol/g, while C.sh, shellfish, with gluten supplemented with 0.5% and 1% HPMC increased by 2.76 "mol/g to 7.25""mol/g and 1.33 "mol/g to 5.66 "mol/g (Fig. 3.3). Zhao, et a1. (2012) found that after 120 days of frozen storage, the content of free thiol groups increased significantly [ 1071. It is worth noting that the C-SH of gluten protein was significantly lower than that of other frozen storage periods when the freezing period was 15 days, which may be attributed to the freezing shrinkage effect of gluten protein structure, which makes the More intermolecular and intramolecular disulfide bonds were locally formed in a shorter freezing time [1161. Wang, et a1. (2014) found that the C-SH of glutenin-rich proteins was also significantly increased after 15 days of freezing. Decreased [1251. However, the gluten protein supplemented with 2% HPMC did not increase significantly except for C-SH, which also decreased significantly at 15 days, with the extension of freezing time.
Fig 3．3 Effect of HPMC addition and frozen storage on the content of free-SH for gluten proteins As mentioned above, freezable water can form ice crystals at low temperatures and distribute in the interstices of the gluten network. Therefore, with the prolongation of freezing time, the ice crystals become larger, which squeezes the gluten protein structure more seriously, and leads to the breakage of some intermolecular and intramolecular disulfide bonds, which increases the content of free sulfhydryl groups. On the other hand, the experimental results show that HPMC can protect the disulfide bond from the extrusion damage of ice crystals, thereby inhibiting the depolymerization process of gluten protein. 3.3.4 Effects of HPMC addition amount and freezing storage time on transverse relaxation time (T2) of wet gluten mass The distribution of Transverse Relaxation Time (T2) can reflect the model and dynamic process of water migration in food materials [6]. Figure 3.4 shows the distribution of wet gluten mass at 0 and 60 days with different HPMC additions, including 4 main distribution intervals, namely 0.1.1 ms (T21), 1.10 ms (T22), 10.100 ms (dead;) and 1 00-1 000 ms (T24). Bosmans et al. (2012) found a similar distribution of wet gluten mass [1261], and they suggested that protons with relaxation times below 10 ms could be classified as rapidly relaxing protons, which are mainly derived from poor mobility the bound water, therefore, may characterize the relaxation time distribution of bound water bound to a small amount of starch, while Dang may characterize the relaxation time distribution of bound water bound to gluten protein. In addition, Kontogiorgos (2007) - t11¨, the "strands" of the gluten protein network structure are composed of several layers (Sheets) about 5 nm apart, and the water contained in these layers is limited water (or Bulk water, phase water), the mobility of this water is between the mobility of bound water and free water. Thiab T23 tuaj yeem yog ntaus nqi rau lub sijhawm so lub sijhawm so ntawm cov dej txwv. The T24 distribution (>100 ms) has a long relaxation time, so it characterizes free water with strong mobility. Cov dej no muaj nyob hauv cov kab ke ntawm cov qauv network, thiab tsuas muaj ib qho tsis muaj zog capillary quab yuam nrog lub ntsej muag gluten protein.
Comparing the wet gluten doughs with different addition amounts of HPMC stored in frozen storage for 60 days and unfrozen storage respectively, it was found that the total distribution area of T21 and T24 did not show a significant difference, indicating that the addition of HPMC did not significantly increase the relative amount of bound water. Cov ntsiab lus, uas tej zaum yuav yog vim muaj cov khoom siv dej tseem ceeb (gluten protein nrog cov hmoov txhuv nplej siab me me) tsis tau hloov pauv me me ntawm HPMC. On the other hand, by comparing the distribution areas of T21 and T24 of wet gluten mass with the same amount of HPMC added for different freezing storage times, there is also no significant difference, which indicates that the bound water is relatively stable during the freezing storage process, and has a negative impact on the environment. Changes are less sensitive and less affected.
Txawm li cas los xij, muaj qhov sib txawv ntawm qhov siab thiab thaj tsam ntawm T23 kev faib tawm HPMC ntxiv uas tsis yog khov thiab muaj thaj tsam ntawm T23 kev faib tawm (Daim duab tau nce (Daim duab 3.4). This change shows that HPMC can significantly increase the relative content of limited water, and it is positively correlated with the added amount within a certain range. In addition, with the extension of freezing storage time, the height and area of T23 distribution of the wet gluten mass with the same HPMC content decreased to varying degrees. Yog li ntawd, piv nrog cov dej ua haujlwm, dej tsawg qhia qee cov txiaj ntsig ntawm cov khoom khov. Rhiab heev. Qhov kev sib cuam tshuam no qhia tias kev sib cuam tshuam ntawm lub gluten protein matrix thiab cov dej kaw tsis muaj zog dua. This may be because more hydrophobic groups are exposed during freezing, which is consistent with the thermal denaturation peak temperature measurements. In particular, the height and area of the T23 distribution for the wet gluten mass with 2% HPMC addition did not show a significant difference. This indicates that HPMC can limit the migration and redistribution of water, and can inhibit the transformation of the water state from the restricted state to the free state during the freezing process.
In addition, the height and area of the T24 distribution of the wet gluten mass with different contents of HPMC were significantly different (Fig. 3.4, A), and the relative content of free water was negatively correlated with the amount of HPMC added. Qhov no tsuas yog qhov fab ntxeev ntawm dang faib. Therefore, this variation rule indicates that HPMC has water holding capacity and converts free water to confined water. However, after 60 days of freezing, the height and area of T24 distribution increased to varying degrees, which indicated that the water state changed from restricted water to free-flowing state during the freezing process. This is mainly due to the change of the gluten protein conformation and the destruction of the "layer" unit in the gluten structure, which changes the state of the confined water contained in it. Txawm hais tias cov ntsiab lus ntawm cov dej khov ua haujlwm txiav txim siab los ntawm DSC kuj nce nrog qhov sib txawv ntawm ob, cov kab ke ntawm cov dej khov thiab dej khov thiab dej dawb tsis yog qhov sib npaug. Rau cov gluten ntub loj ntxiv nrog 2% hpmc, tom qab 60 hnub ntawm qhov chaw hpmc uas pom tau tias nws tus kheej cov dej muaj cov khoom siv thiab nws cov kev cuam tshuam nrog gluten. and stable liquidity.
Generally speaking, the secondary structure of protein is divided into four types, α-Spiral, β-folded, β-Corners and random curls. Qhov tseem ceeb tshaj plaws ntawm kev tsim kho rau tsim thiab ruaj khov ntawm qhov kev sib raug zoo ntawm cov protein yog hydrogen bonds. Yog li ntawd, protein denaturation yog txheej txheem ntawm hydrogen bur breaking thiab kev hloov pauv.
Fourier transform infrared spectroscopy (FT-IR) has been widely used for high-throughput determination of the secondary structure of protein samples. The characteristic bands in the infrared spectrum of proteins mainly include, amide I band (1700.1600 cm-1), amide II band (1600.1500 cm-1) and amide III band (1350.1200 cm-1). Correspondingly, the amide I band the absorption peak originates from the stretching vibration of the carbonyl group (-C=O-.), the amide II band is mainly due to the bending vibration of the amino group (-NH-) [1271], and the amide III band is mainly due to the amino bending vibration and .CN-．Synchronous compound vibration in the same plane of bond stretching vibration, and has a high rhiab heev los hloov hauv cov qauv protein theem nrab [1283T1. Txawm hais tias cov saum toj no peb cov xeeb ceem yog tag nrho cov xeeb ceem infrared nqus peaks, qhov kev nqus tau qhov tseeb ntawm cov qauv protein ntau dua yog cov neeg pluag; while the peak absorption intensity of amide I band is higher, so many researchers analyze the secondary structure of protein by this band [ 1301, but the absorption peak of water and the amide I band are overlapped at about 1640 cm. 1 wavenumber (Overlapped), which in turn affects the accuracy of the results. Yog li ntawd, qhov kev cuam tshuam ntawm cov dej txwv kev txiav txim siab ntawm txoj kev koom nrog kuv txoj hlua khi hauv cov protein theem nrab kev txiav txim siab. In this experiment, in order to avoid the interference of water, the relative contents of four secondary structures of gluten protein were obtained by analyzing the amide III band. Ncov txoj hauj lwm (wavenume ntu) ntawm
Cov lus qhia thiab kev tsim qauv muaj teev nyob rau hauv Table 3.4.
With the prolongation of frozen storage time, the secondary structure of gluten protein with different additions of HPMC changed to different degrees. It can be seen that both frozen storage and addition of HPMC have an effect on the secondary structure of gluten protein. Regardless of the amount of HPMC added, B. The folded structure is the most dominant structure, accounting for about 60%. After 60 days of frozen storage, add 0%, OB Gluten of 5% and 1% HPMC. The relative content of folds increased significantly by 3.66%, 1.87% and 1.16%, respectively, which was similar to the results determined by Meziani et al. (2011) [l33J]. However, there was no significant difference during frozen storage for gluten supplemented with 2% HPMC. In addition, when frozen for 0 days, with the increase of HPMC addition, p. The relative content of folds increased slightly, especially when the addition amount was 2%, p. The relative content of folds increased by 2.01%. D. Cov qauv txheej txheem tuaj yeem muab faib ua cov ntawv sib xyaw P. Folding (tshwm sim los ntawm kev sib cav ntawm cov protein molecules), antiparallel p. Quav thiab nias P. Peb txoj kev tsim tsa tau muab tais, thiab nws nyuaj rau kev txiav txim siab qhov kev ua uas tau tshwm sim thaum lub sijhawm khov
changed. Some researchers believe that the increase in the relative content of the B-type structure will lead to an increase in the rigidity and hydrophobicity of the steric conformation [41], and other researchers believe that p. Qhov nce hauv cov qauv forded yog vim ib feem ntawm cov txheej txheem tshiab β-lwg yog nrog rau cov txheej txheem muaj zog tswj los ntawm hydrogen bonding [421]. β- The increase in the folded structure indicates that the protein is polymerized through hydrophobic bonds, which is consistent with the results of the peak temperature of thermal denaturation measured by DSC and the distribution of transverse relaxation time measured by low-field nuclear magnetic resonance. Protein denaturation. On the other hand, added 0.5%, 1% and 2% HPMC gluten protein α-whirling. The relative content of helix increased by 0.95%, 4.42% and 2.03% respectively with the prolongation of freezing time, which is consistent with Wang, et a1. (2014) found similar results [134]. 0 of gluten without added HPMC. There was no significant change in the relative content of helix during the frozen storage process, but with the increase of the addition amount of freeze for 0 days. There were significant differences in the relative content of α-whirling structures.
Daim duab 3.6 Cov lus piav qhia ntawm hydrophobic moiety raug (a), dej kev faib tawm (b), thiab theem nrab kev hloov pauv (B), thiab theem nrab kev hloov pauv
Tag nrho cov qauv nrog kev ncua ntawm lub sijhawm khov, p. The relative contents of the corners were significantly reduced. Qhov no qhia tau tias β-tig yog rhiab heev rau kev kho kom khov [135. 1361], thiab seb HPMC ntxiv lossis tsis tau muaj tsis muaj qhov cuam tshuam. Kev Coj Zoo, thiab A1. (2005) proposed that the β-chain turn of gluten protein is related to the β-turn space domain structure of the glutenin polypeptide chain [l 37]. Except that the relative content of random coil structure of gluten protein added with 2% HPMC had no significant change in frozen storage, the other samples were significantly reduced, which may be caused by the extrusion of ice crystals. Ib qho ntxiv, thaum khov rau 0 hnub, cov txheeb ze ntawm α-helix, β-ntawv qauv ntawm gluten protein ntxiv nrog cov ntawm gluten protein tsis muaj HPMC. Qhov no yuav qhia tau tias muaj kev sib cuam tshuam ntawm HPMC thiab gluten protein, kev sib txuam hydrogen bonds thiab tom qab ntawd cuam tshuam rau kev sib txuas ntawm cov protein; or HPMC absorbs the water in the pore cavity of the protein space structure, which deforms the protein and leads to more changes between the subunits. kaw. The increase of the relative content of β-sheet structure and the decrease of the relative content of β-turn and α-helix structure are consistent with the above speculation. Thaum lub sij hawm ua cov txheej txheem khov, qhov sib txawv thiab kev tsiv teb tsaws thiab tsim cov dej khov ua kom puas tsuaj rau cov pab pawg hydrothobic ntawm cov protein. In addition, from the perspective of energy, the smaller the energy of the protein, the more stable it is. At low temperature, the self-organization behavior (folding and unfolding) of protein molecules proceeds spontaneously and leads to conformational changes.
3.3.6 Qhov cuam tshuam ntawm HPMC ntxiv cov nqi thiab khov cia lub sijhawm rau saum npoo hydrophicity ntawm gluten protein
Protein molecules include both hydrophilic and hydrophobic groups. Generally, the protein surface is composed of hydrophilic groups, which can bind water through hydrogen bonding to form a hydration layer to prevent protein molecules from agglomerating and maintain their conformational stability. The interior of the protein contains more hydrophobic groups to form and maintain the secondary and tertiary structure of the protein through the hydrophobic force. Denaturation ntawm cov protein feem ntau nrog kev sib raug zoo los ntawm hydrophobic pawg thiab nce cov npoo hydrophicity.
Tab3.6 nyhuv ntawm HPMC ntxiv thiab khov cia rau saum npoo hydrophicity ntawm gluten
Cov ntawv sib txawv cov tsiaj ntawv hauv tib kem qhia qhov txawv tseem ceeb (<0.05);
After 60 days of frozen storage, add 0%, O. The surface hydrophobicity of gluten with 5%, 1% and 2% HPMC increased by 70.53%, 55.63%, 43.97% and 36.69%, respectively (Table 3.6). Tshwj xeeb, saum npoo hydrophobicity ntawm lub gluten protein yam tsis muaj kev ntxiv ntawm cov npoo ntawm 1%, thiab 2% hpmc ntxiv tom qab khov rau 60 hnub hydrophobicity. At the same time, after 60 days of frozen storage, the surface hydrophobicity of gluten protein added with different contents showed significant differences. However, after 60 days of frozen storage, the surface hydrophobicity of gluten protein added with 2% HPMC only increased from 19.749 to 26.995, which was not significantly different from the surface hydrophobicity value after 30 days of frozen storage, and was always lower than other the value of the surface hydrophobicity of the sample. This indicates that HPMC can inhibit the denaturation of gluten protein, which is consistent with the results of DSC determination of the peak temperature of heat deformation. This is because HPMC can inhibit the destruction of protein structure by recrystallization, and due to its hydrophilicity,
HPMC tuaj yeem sib txuas nrog cov pab pawg hydrophilic ntawm cov protein ntau los ntawm cov protein, yog li kev hloov pauv ntawm hydrophobic pawg (rooj 3.6).
Nco tseg: a yog microstructure ntawm gluten network yam tsis muaj kev ntxiv HPMC thiab khov rau 0 hnub; B yog microstructure ntawm gluten network yam tsis muaj HPMC thiab khov rau 60 hnub; C yog microstructure ntawm gluten network nrog 2% hpmc ntxiv thiab khov rau 0 hnub: d yog gluten network microstructure nrog 2% hpmc ntxiv thiab khov rau 60 hnub
Tom qab 60 hnub ntawm khov cia, microstructure ntawm cov ntub gluten loj tsis muaj HPMC tau hloov pauv (Daim duab 3.7, AB). Ntawm 0 hnub, lub gluten microstructures nrog 2% lossis 0% hpmc pom ua tiav cov duab, loj
Small approximate porous sponge-like morphology. Txawm li cas los xij, tom qab 60 hnub ntawm khov cia, lub hlwb nyob rau hauv lub gluten microstre, thiab tsis sib xws rau cov txheej txheem hauv qab no, thiab cov khoom siv khov kho kom khov disulfide bond, which affects the strength and integrity of the structure. As reported by Kontogiorgos & Goff (2006) and Kontogiorgos (2007), the interstitial regions of the gluten network are squeezed due to freeze-shrinkage, resulting in structural disruption [138. 1391]. In addition, due to dehydration and condensation, a relatively dense fibrous structure was produced in the spongy structure, which may be the reason for the decrease in free thiol content after 15 days of frozen storage, because more disulfide bonds were generated and frozen storage. The gluten structure was not severely damaged for a shorter time, which is consistent with Wang, et a1. (2014) observed similar phenomena [134]. At the same time, the destruction of the gluten microstructure leads to freer water migration and redistribution, which is consistent with the results of low-field time-domain nuclear magnetic resonance (TD-NMR) measurements. Some studies [140, 105] reported that after several freeze-thaw cycles, the gelatinization of rice starch and the structural strength of the dough became weaker, and the water mobility became higher. Nonetheless, after 60 days of frozen storage, the microstructure of gluten with 2% HPMC addition changed less, with smaller cells and more regular shapes than gluten without HPMC addition (Fig. 3.7, B, D). This further indicates that HPMC can effectively inhibit the destruction of gluten structure by recrystallization.
3.4 Tshooj Lus
This experiment investigated the rheology of wet gluten dough and gluten protein by adding HPMC with different contents (0%, 0.5%, 1% and 2%) during freezing storage (0, 15, 30 and 60 days). properties, thermodynamic properties, and effects of physicochemical properties. The study found that the change and redistribution of water state during the freezing storage process significantly increased the freezable water content in the wet gluten system, which led to the destruction of the gluten structure due to the formation and growth of ice crystals, and ultimately caused the processing properties of the dough to be different. Deterioration ntawm cov khoom zoo. The results of frequency scanning showed that the elastic modulus and viscous modulus of the wet gluten mass without adding HPMC decreased significantly during the freezing storage process, and the scanning electron microscope showed that its microstructure was damaged. The content of free sulfhydryl group was significantly increased, and its hydrophobic group was more exposed, which made the thermal denaturation temperature and surface hydrophobicity of gluten protein significantly increased. However, the experimental results show that the addition of I-IPMC can effectively inhibit the changes in the structure and properties of wet gluten mass and gluten protein during freezing storage, and within a certain range, this inhibitory effect is positively correlated with the addition of HPMC. This is because HPMC can reduce the mobility of water and limit the increase of the freezable water content, thereby inhibiting the recrystallization phenomenon and keeping the gluten network structure and the spatial conformation of the protein relatively stable. This shows that the addition of HPMC can effectively maintain the integrity of the frozen dough structure, thereby ensuring product quality.
4.1 Kev Taw Qhia
Cov hmoov txhuv nplej siab yog cov saw polysaccharide nrog cov piam thaj ua cov monomer. TSEEM) ob hom. From a microscopic point of view, starch is usually granular, and the particle size of wheat starch is mainly distributed in two ranges of 2-10 pro (B starch) and 25-35 pm (A starch). From the perspective of crystal structure, starch granules include crystalline regions and amorphous regions (je, non-crystalline regions), and the crystal forms are further divided into A, B, and C types (it becomes V-type after complete gelatinization). Feem ntau, thaj av crystalline muaj cov amylopectin thiab cov amorphous cheeb tsam muaj feem ntau ntawm amylose xwb. This is because, in addition to the C chain (main chain), amylopectin also has side chains composed of B (Branch Chain) and C (Carbon Chain) chains, which makes amylopectin appear "tree-like" in raw starch. The shape of the crystallite bundle is arranged in a certain way to form a crystal.
Starch is one of the main components of flour, and its content is as high as about 75% (dry basis). Nyob rau tib lub sijhawm, raws li carbohydrate dav tam sim no nyob rau hauv nplej, hmoov txhuv nplej siab kuj yog lub zog tseem ceeb lub zog khoom hauv cov zaub mov. Nyob rau hauv lub rooj ua khob noom cookie, hmoov txhuv nplej siab feem ntau faib thiab txuas nrog tus qauv network ntawm gluten protein. During processing and storage, starches often undergo gelatinization and aging stages.
Among them, starch gelatinization refers to the process in which starch granules are gradually disintegrated and hydrated in a system with high water content and under heating conditions. Nws tuaj yeem muab faib ua peb txoj kev tseem ceeb. 1) Reversible water absorption stage; before reaching the initial temperature of gelatinization, the starch granules in the starch suspension (Slurry) keep their unique structure unchanged, and the external shape and internal structure basically do not change. Tsuas yog me me soluble starch yog dispersed nyob rau hauv cov dej thiab tuaj yeem rov qab mus rau nws thawj lub xeev. 2) txoj hlab dej tsis haum dej; as the temperature increases, water enters the gap between the starch crystallite bundles, irreversibly absorbs a large amount of water, causing the starch to swell, the volume expands several times, and the hydrogen bonds between the starch molecules are broken. Nws ua xyab thiab lub muaju ploj. At the same time, the birefringence phenomenon of starch, that is, the Maltese Cross observed under a polarizing microscope, begins to disappear, and the temperature at this time is called the initial gelatinization temperature of starch. 3) Starch granule disintegration stage; starch molecules completely enter the solution system to form starch paste (Paste/Starch Gel), at this time the viscosity of the system is the largest, and the birefringence phenomenon completely disappears, and the temperature at this time is called the complete starch gelatinization temperature, the gelatinized starch is also called α-starch [141]. When the dough is cooked, the gelatinization of starch endows the food with its unique texture, flavor, taste, color, and processing characteristics.
Many studies have shown that the gel strength of starch paste decreases, it is easy to age, and its quality deteriorates under the condition of freezing storage, such as Canet, et a1. (2005) studied the effect of freezing temperature on the quality of potato starch puree; Ferrero, et a1. (1993) investigated the effects of freezing rate and different types of additives on the properties of wheat and corn starch pastes [151-156]. However, there are relatively few reports on the effect of frozen storage on the structure and properties of starch granules (native starch), which needs to be further explored. Khob noom cookie ua khov (tsis suav nrog ua ntej-ua ntej lub khob noom cookie khob noom cookie Therefore, studying the structure and structural changes of native starch by adding HPMC has a certain effect on improving the processing properties of frozen dough. Tseem ceeb.
4.2.1 sim cov ntaub ntawv
4.2.2 Kev sim ua cov apparatus
BSAL24S HAUV SEEM
BC / BD-272SC tub yees
SX2.4.10 muffle rauv taws
KDC. 160hr high-ceev lub tub yees rau hauv centrifuge
Nqe Q. 200 scanning sib txawv calorimeter
SX2.4.10 muffle rauv taws
Tus tsim
Hisier Group
Hefei Meiling Co., Ltd.
Shanghai Yiheng Scientific Ntsuas Co., Ltd.
Anhui Zhongke Zhongjia Scientific Ntsuas Co., Ltd.
Rigaku Raug Co., Ltd.
4.2.3 Kev sim txuj ci
Weigh 1 g of starch, add 9 mL of distilled water, fully shake and mix to prepare a 10% (w/w) starch suspension. Tom qab ntawd tso cov qauv daws teeb meem. 18 ℃ refrigerator, frozen storage for 0, 15 d, 30 d, 60 d, of which 0 day is the fresh control. Add 0.5%, 1%, 2% (w/w) HPMC instead of the corresponding quality starch to prepare samples with different addition amounts, and the rest of the treatment methods remain unchanged.
4.2.3.2 rheological cov yam ntxwv
In this experiment, a rheometer was used instead of a fast viscometer to measure the gelatinization characteristics of starch. See Bae et a1. (2014) method [1571] with slight modifications. The specific program parameters are set as follows: use a plate with a diameter of 40 mill, the gap (gap) is 1000 mm, and the rotation speed is 5 rad/s; I) ncos ntawm 50 ° C rau 1 min; II) thaum 5. C / min rhuab mus rau 95 ° C; iii) kept at 95°C for 2.5 min, iv) then cooled to 50°C at 5°C/min; v) lastly held at 50°C for 5 min.
Draw 1.5 mL of sample solution and add it to the center of the rheometer sample stage, measure the gelatinization properties of the sample according to the above program parameters, and obtain the time (min) as the abscissa, the viscosity (Pa s) and the temperature (°C) as the starch gelatinization curve of the ordinate. According to GB/T 14490.2008 [158], the corresponding gelatinization characteristic indicators—gelatinization peak viscosity (field), peak temperature (Ang), minimum viscosity (high), final viscosity (ratio) and decay value (Breakdown) are obtained. Value, BV) and regeneration value (Setback Value, SV), wherein, decay value = peak viscosity - minimum viscosity; Setback Tus nqi = zaum kawg viscosity - yam tsawg kawg viscosity. Txhua tus qauv tau rov ua peb zaug.
The above gelatinized starch paste was subjected to the Steady Flow Test, according to the method of Achayuthakan & Suphantharika [1591, the parameters were set to: Flow Sweep mode, stand at 25°C for 10 min, and the shear rate scan range was 1) 0.1 S one. 100S～, 2) 100s～. 0.1 S ~, cov ntaub ntawv tau sau nyob rau hauv logarithmic hom, thiab thaum kawg tus lej shear (cov kab mob shear (viscosity, Pai-·ologicalological. Use Origin 8.0 to perform nonlinear fitting of this curve and obtain the relevant parameters of the equation, and the equation satisfies the power law (Power Law), that is, t/=K), nI, where M is the shear viscosity (pa ·s), K is the consistency coefficient (Pa ·s), is the shear rate (s. 1), and n is the flow behavior index (Flow Behavior Index, dimensionless).
(1) Qauv npaj
Nqa 2.5 g ntawm amyloid thiab sib tov nws nrog dej distilled nyob rau hauv ib qho kev sib piv ntawm 1: 2 los ua cov mis laus. Nkoog ntawm 18 ° C rau 15 d, 30 d, thiab 60 d. Ntxiv 0.5, 1, 2% HPMC (w / w) los hloov cov hmoov txhuv nplej siab ntawm tib txoj kev ua tau zoo, thiab lwm txoj kev npaj npaj tsis hloov. Tom qab kev kho kom khov ua tiav tiav, coj nws tawm, e° C rau 4 h, thiab yaj thaum sov txog thaum nws sim.
Take 1.5 mL of sample solution and place it on the sample stage of the rheometer (Discovery.R3), press down the 40 m/n plate with a diameter of 1500 mm, and remove the excess sample solution, and continue to lower the plate to 1000 mm, on motor, the speed was set to 5 rad/s and rotated for 1 min to fully homogenize the sample solution and avoid the sedimentation of starch granules. Qhov ntsuas kub pib ntawm 25 ° C thiab xaus ntawm 5. C / min tau loj hlob mus rau 25 min, thiab tom qab ntawd nws qis rau 25 ° C ntawm 5 "C / min.
4.2.3.4 Thermodynamic Khoom
(1) Qauv npaj
Tom qab cov lus sib piv ua kom lub sijhawm kho kom khov, cov qauv tau coj tawm, yaj tag, thiab qhuav hauv qhov cub ntawm 40 ° C rau 48 h. Thaum kawg, nws tau nyob hauv av los ntawm 100-mesh sab cib kom tau txais cov khoom siv zoo coj los siv (haum rau xrd kuaj). See Xie, et a1. (2014) method for sample preparation and determination of thermodynamic properties '1611, weigh 10 mg of starch sample into a liquid aluminum crucible with an ultra-micro analytical balance, add 20 mg of distilled water in a ratio of 1:2, press and seal it and place it at 4 °C In the refrigerator, equilibrated for 24 h. Freeze at 18°C (0, 15, 30 and 60 days). Add 0.5%, 1%, 2% (w/w) HPMC to replace the corresponding quality of starch, and other preparation methods remain unchanged. After the freezing storage time is over, take out the crucible and equilibrate at 4 °C for 4 h.
4.2.3.5 XRD Kev Ntsuas
Cov yaj ua kom khov khov cov qauv tau qhuav hauv qhov cub ntawm 40 ° C rau 48-mesh sieve kom tau cov hmoov txhuv nplej siab kom tau cov hmoov txhuv nplej siab kom tau cov hmoov txhuv nplej siab. Take a certain amount of the above samples, use D/MAX 2500V type X. The crystal form and relative crystallinity were determined by X-ray diffractometer. Qhov kev sim sim yog voltage 40 kv, tam sim no 40 ma, siv CU. Ks as X. ray source. At room temperature, the scanning angle range is 30--400, and the scanning rate is 20/min. Relative crystallinity (%) = crystallization peak area/total area x 100%, where the total area is the sum of the background area and the peak integral area [1 62].
Take 0.1 g of the dried, ground and sieved amyloid into a 50 mL centrifuge tube, add 10 mL of distilled water to it, shake it well, let it stand for 0.5 h, and then place it in a 95°C water bath at a constant temperature. After 30 min, after gelatinization is complete, take out the centrifuge tube and place it in an ice bath for 10 min for rapid cooling. Thaum kawg, centrifuge thaum 5000 rpm rau 20 min, thiab muab hliv rau tus neeg tau txais kev ua si nag! Oping zog = nag lossis daus huab cua / qauv huab hwm tswj [163].
All experiments were repeated at least three times unless otherwise specified, and the experimental results were expressed as mean and standard deviation. SPSS Statistic 19 tau siv rau kev soj ntsuam ntawm kev sib txawv (tsom xam ntawm kev sib txawv, anova) nrog qib tseem ceeb ntawm 0.05; correlation charts were drawn using Origin 8.0.
4.3 tsom xam thiab sib tham
The starch suspension with a certain concentration is heated at a certain heating rate to make the starch gelatinized. Tom qab pib gelatinize, lub turbid ua kua tau maj mam ua dhau los vim yog nthuav dav ntawm cov hmoov txhuv nplej siab, thiab viscosity nce tsis tu ncua. Subsequently, the starch granules rupture and the viscosity decreases. When the paste is cooled at a certain cooling rate, the paste will gel, and the viscosity value will further increase. Lub viscosity tus nqi thaum nws txias rau 50 ° C yog qhov kawg viscosity nqi (Daim duab 4.1).
Nrog 1% HPMC) thiab 393.614-45.94 CP (uas HPMC) rau 427.284-41.39 CP (15 HPMC ntxiv) thiab 357.85+21.00 CP (2% HPMC added). Qhov no thiab ntxiv rau ntawm cov tshuaj hydrocolloids xws li xanthan ntawm cov pos hniav thiab cov pos hniav guardithaka (2008) thiab Huang (2009) Qhov no yuav yog vim HPMC ua raws li hom ntawm hydrophilic colloid, thiab kev sib ntxiv ntawm Hydrophilic uas ua rau nws ntau Hydrophilic dua cov hmoov txhuv nplej siab ntawm chav tsev kub. Tsis tas li ntawd, qhov ntsuas kub ntawm cov txheej txheem thermal (cov txheej txheem thermid Yog li, qhov tsawg kawg nkaus viscosity thiab kawg viscosity ntawm starmosis gelatinization nce zuj zus ntawm HPMC cov ntsiab lus.
On the other hand, when the amount of HPMC added was the same, the peak viscosity, minimum viscosity, final viscosity, decay value and retrogradation value of starch gelatinization increased significantly with the extension of freezing storage time. Specifically, the peak viscosity of starch suspension without adding HPMC increased from 727.66±90.70 CP (frozen storage for 0 days) to 1584.44+68.11 CP (frozen storage for 60 days); adding 0.5 The peak viscosity of starch suspension with %HPMC increased from 758.514-48.12 CP (freezing for 0 days) to 1415.834-45.77 CP (freezing for 60 days); starch suspension with 1% HPMC added The peak viscosity of the starch liquid increased from 809.754-56.59 CP (freeze storage for 0 days) to 1298.19-±78.13 CP (frozen storage for 60 days); while the starch suspension with 2% HPMC CP added Gelatinization peak viscosity from 946.64 ± 9.63 CP (0 days frozen) increased to 1240.224-94.06 CP (60 days frozen). At the same time, the lowest viscosity of starch suspension without HPMC was increased from 391.02-41 8.97 CP (freezing for 0 days) to 556.77±29.39 CP (freezing for 60 days); Ntxiv 0.5 qhov tsawg kawg ntawm viscosity ntawm cov statch ncua sij hawm nrog% HPMC nce ntawm 454.934-72.22 cp (khov rau 60 hnub); the starch suspension with 1% HPMC added The minimum viscosity of the liquid increased from 485.564-54.05 CP (freezing for 0 days) to 625.484-67.17 CP (freezing for 60 days); while the starch suspension added 2% HPMC CP gelatinized The lowest viscosity increased from 553.034-55.57 CP (0 days frozen) to 682.58 ± 20.29 CP (60 days frozen).
Qhov kawg viscosity ntawm kev ncua cov hmoov txhuv nplej siab yam tsis muaj HPMC ntxiv los ntawm 794.62 ± 12.59 CP (khov cia rau 60 hnub). The peak viscosity of starch suspension increased from 882.24 ± 22.40 CP (frozen storage for 0 days) to 1322.86 ± 36.23 CP (frozen storage for 60 days); the peak viscosity of starch suspension added with 1% HPMC The viscosity increased from 846.04 ± 12.66 CP (frozen storage 0 days) to 1291.94 ± 88.57 CP (frozen storage for 60 days); and the gelatinization peak viscosity of starch suspension added with 2% HPMC increased from 91 0.88 ± 34.57 CP
(Frozen storage for 0 days) increased to 1198.09 ± 41.15 CP (frozen storage for 60 days). Correspondingly, the attenuation value of starch suspension without adding HPMC increased from 336.64 ± 71.73 CP (frozen storage for 0 days) to 1027.67 ± 38.72 CP (frozen storage for 60 days); adding 0.5 The attenuation value of starch suspension with %HPMC increased from 303.56±11.22 CP (frozen storage for 0 days) to 833.9±26.45 CP (frozen storage for 60 days); starch suspension with 1% HPMC added The attenuation value of the liquid was increased from 324.19 ± 2.54 CP (freezing for 0 days) to 672.71 ± 10.96 CP (freezing for 60 days); while adding 2% HPMC，the attenuation value of the starch suspension increased from 393.61 ± 45.94 CP (freezing for 0 days) to 557.64 ± 73.77 CP (freezing for 60 days); Thaum lub sijhawm ncua kev ncua tsis muaj HPMC ntxiv tus nqi retrogram tau nce los ntawm 403.60 ±23 C
P (frozen storage for 0 days) to 856.38 ± 16.20 CP (frozen storage for 60 days); the retrogradation value of starch suspension added with 0.5% HPMC increased from 427 .29±14.50 CP (frozen storage for 0 days) increased to 740.93±35.99 CP (frozen storage for 60 days); Tus nqi retrogradation tus nqi ntawm kev ncua ntawv STARCH ntxiv nrog 1% HPMC nce ntawm 360.48 ± 41. 39 CP (frozen storage for 0 days) increased to 666.46 ± 21.40 CP (frozen storage for 60 days); Thaum lub sijhawm rov qab tus nqi ntawm cov hnub qub kev kawm ntawv ntxiv nrog 2% HPMC nce ntawm 357.00 CP (khov cia rau 60 hnub). 0 hnub) nce mus rau 515.51 ± 20.86 cp (60 hnub khov).
It can be seen that with the prolongation of freezing storage time, the starch gelatinization characteristics index increased, which is consistent with Tao et a1. F2015) 1 This is mainly because in the process of freezing storage, the amorphous region (Amorphous Region) of starch granules is destroyed by ice crystallization, so that the amylose (the main component) in the amorphous region (non-crystalline region) undergoes phase separation (Phase. separated) phenomenon, and dispersed in the starch suspension, resulting in an increase in the viscosity of starch gelatinization, and an increase in the related attenuation value and retrogradation value. However, the addition of HPMC inhibited the effect of ice crystallization on starch structure. Therefore, the peak viscosity, minimum viscosity, final viscosity, decay value and retrogradation rate of starch gelatinization increased with the addition of HPMC during frozen storage. increase and decrease sequentially.
Fig 4.1 pasting rwg ntawm nplej uas tsis muaj HPMC (a) lossis nrog 2% hpmc①)
Daim duab 4.2 thixotropism ntawm Starch muab tshuaj txhuam yam tsis muaj HPMC (a) lossis nrog 2% hpmc (b)
It can be seen from Table 4.3 that all the flow characteristic indices, 2, are less than 1. Therefore, starch paste (whether HPMC is added or whether it is frozen or not) belongs to Pseudoplastic Fluid, and all show shearing Thinning phenomenon (as the shear rate increases, the shear viscosity of the fluid decreases). In addition, the shear rate scans ranged from 0.1 s, respectively. 1 increased to 100 s ~, and then decreased from 100 sd to O. The rheological curves obtained at 1 sd do not completely overlap, and the fitting results of K, s are also different, so the starch paste is a thixotropic pseudoplastic fluid (whether HPMC is added or whether it is frozen or not). However, under the same freezing storage time, with the increase of HPMC addition, the difference between the fitting results of the K n values of the two scans gradually decreased, which indicates that the addition of HPMC makes the structure of starch paste under shear stress. Nws nyob tsis tau raws li qhov kev ua thiab txo cov "thixotropic ntiv nplhaib"
(Thixotropic voj) thaj chaw, uas zoo ib yam li PSSIRIPONG, ET1. (2005) reported the same conclusion [167]. This may be mainly because HPMC can form intermolecular cross-links with gelatinized starch chains (mainly amylose chains), which "bound" the separation of amylose and amylopectin under the action of shearing force. , so as to maintain the relative stability and uniformity of the structure (Figure 4.2, the curve with shear rate as abscissa and shear stress as ordinate).
Ntawm qhov tod tes, rau cov hmoov txhuv nplej siab yam tsis muaj cov khoom khov, nws tus lej K 683 ± 1.035 PACHNN (ntxiv 0.230 · SN (ntxiv 2% ± 0.000 0.011 (yog tias tsis muaj HPMC) rau 0.277 ± 0.011). 310 ± 0.009 (add 0.5% HPMC), O. 323 ± 0.013 (add 1% HPMC) and O. 43 1 ± 0.0 1 3 (adding 2% HPMC), which is similar to the experimental results of Techawipharat, Suphantharika, & BeMiller (2008) and Turabi, Sumnu, & Sahin (2008), and the increase of n value shows that the addition of HPMC makes the fluid has a tendency to change from pseudoplastic to Newtonian [168'1691]. Nyob rau tib lub sijhawm, rau cov hmoov txhuv nplej siab khaws cia rau 60 hnub, K, N qhov tseem ceeb qhia tau tib txoj cai hloov pauv nrog kev nce HPMC ntxiv.
However, with the prolongation of freezing storage time, the values of K and n increased to different degrees, among which the value of K increased from 78.240 ± 1.661 Pa·sn (unadded, 0 days) to 95.570 ± 1, respectively. 2.421 Pa·sn (no addition, 60 days), increased from 65.683±1.035 Pa ·S n (addition of O. 5% HPMC, 0 days) to 51.384±1.350 Pa ·S n (Add to 0.5% HPMC, 60 days), increased from 43.122±1.047 Pa ·sn (adding 1% HPMC, 0 days) to 56.538±1.378 Pa ·sn (adding 1% HPMC, 60 days) ), and increased from 13.926 ± 0.330 Pa ·sn (adding 2% HPMC, 0 days) to 16.064 ± 0.465 Pa ·sn (adding 2% HPMC, 60 days); 0.277 ± 0.011 (without adding HPMC, 0 days) rose to O. 334±0.014 (no addition, 60 days), increased from 0.310±0.009 (0.5% HPMC added, 0 day) to 0.336±0.014 (0.5% HPMC added, 60 days), from 0.323 ± 0.013 (add 1% HPMC, 0 days) to 0.340 ± 0.013 (add 1% HPMC, 60 days), and from 0.431 ± 0.013 (add 1% HPMC, 60 days) 2% HPMC, 0 days) to 0.404+0.020 (add 2% HPMC, 60 days). By comparison, it can be found that with the increase of the addition amount of HPMC, the change rate of K and Knife value decreases successively, which shows that the addition of HPMC can make the starch paste stable under the action of shearing force, which is consistent with the measurement results of starch gelatinization characteristics. xwm yeem.
Note: A is the change of viscoelasticity of unadded HPMC starch with the extension of freezing storage time; B yog qhov kev sib ntxiv ntawm O. Cov kev hloov ntawm cov popcoelastic ntawm 5% hpmc hmoov nplej nrog txuas ntxiv ntawm lub sijhawm cia khoom khov; C yog cov kev hloov ntawm cov viscoelastictions ntawm 1% HPMC cov hmoov txhuv nplej siab nrog ncua ntawm lub sijhawm ua kom khov; D yog qhov hloov pauv ntawm cov viscoelasticity ntawm 2% HPMC cov hmoov txhuv nrog txuas ntxiv ntawm lub sijhawm ua kom khov
The starch gelatinization process is accompanied by the disintegration of starch granules, the disappearance of the crystalline region, and the hydrogen bonding between starch chains and moisture, the starch gelatinized to form a heat-induced (Heat. induced) gel with a certain gel strength. As shown in Figure 4.3, for starch without frozen storage, with the increase of HPMC addition, the G' of starch decreased significantly, while G" had no significant difference, and tan 6 increased (Liquid. 1ike), which shows that during the gelatinization process, HPMC interacts with starch, and due to the water retention of HPMC, the addition of HPMC reduces the water loss of starch during the gelatinization process. At the same time, Chaisawang & Suphantharika (2005) found that, adding guar gum and xanthan gum to tapioca starch, the G' of the starch paste also decreased [170]. In addition, with the extension of the freezing storage time, the G' of starch gelatinized decreased to different degrees. This is mainly because during the frozen storage process of starch, the amylose in the amorphous region of starch granules is separated to form damaged starch (Damaged Starch), which reduces the degree of intermolecular cross-linking after starch gelatinization and the degree of cross-linking after cross-linking. Stability and compactness, and the physical extrusion of ice crystals makes the arrangement of "micelles" (microcrystalline structures, mainly composed of amylopectin) in the starch crystallization area more compact, increasing the relative crystallinity of starch, and at the same time , resulting in insufficient combination of molecular chain and water after starch gelatinization, low extension of molecular chain (molecular chain mobility), and finally caused the gel strength of starch to decline. Txawm li cas los xij, nrog rau kev nce HPMC ntxiv, txoj kev txo qis ntawm G 'tau raug cem, thiab cov nyhuv no tau zoo sib xws ntawm HPMC. This indicated that the addition of HPMC could effectively inhibit the effect of ice crystals on the structure and properties of starch under frozen storage conditions.
4.3.5 Qhov cuam tshuam ntawm I-IPMC ntxiv cov nqi thiab lub sijhawm ntim khoom khov ntawm cov hmoov txhuv nplej siab o
The swelling ratio of starch can reflect the size of starch gelatinization and water swelling, and the stability of starch paste under centrifugal conditions. As shown in Figure 4.4, for starch without frozen storage, with the increase of HPMC addition, the swelling force of starch increased from 8.969+0.099 (without adding HPMC) to 9.282- -L0.069 (adding 2% HPMC), which shows that the addition of HPMC increases the swelling water absorption and makes starch more stable after gelatinization, which is consistent with the Xaus ntawm Starch Gelatinization Cov yam ntxwv. However, with the extension of frozen storage time, the swelling power of starch decreased. Compared with 0 days of frozen storage, the swelling power of starch decreased from 8.969-a:0.099 to 7.057+0 after frozen storage for 60 days, respectively. .007 (no HPMC added), reduced from 9.007+0.147 to 7.269-4-0.038 (with O.5% HPMC added), reduced from 9.284+0.157 to 7.777 +0.014 (adding 1% HPMC), reduced from 9.282+0.069 to 8.064+0.004 (adding 2% HPMC). The results showed that the starch granules were damaged after freezing storage, resulting in the precipitation of part of the soluble starch and centrifugation. Yog li ntawd, cov solubility ntawm cov hmoov txhuv nplej siab nce thiab qhov hluav taws kub txo qis. In addition, after freezing storage, starch gelatinized starch paste, its stability and water holding capacity decreased, and the combined action of the two reduced the swelling power of starch [1711]. On the other hand, with the increase of HPMC addition, the decline of starch swelling power gradually decreased, indicating that HPMC can reduce the amount of damaged starch formed during freezing storage and inhibit the degree of starch granule damage.
Daim duab 4.4 nyhuv ntawm HPMC ntxiv thiab khov cia rau ntawm oar lub zog ntawm cov hmoov txhuv nplej siab
The gelatinization of starch is an endothermic chemical thermodynamic process. Yog li, DSC feem ntau siv los txiav txim siab txog qhov kub thiab txias (rau), xaus kub (t p), thiab gelatinization kub ntawm cov hmoov txhuv nplej siab ntawm cov hmoov txhuv nplej siab. (Tc). 4.4 Qhia cov kab mob DSC ntawm cov hmoov txhuv nplej siab nrog 2% thiab tsis muaj HPMC ntxiv rau ntau lub sijhawm khov ntau lub sijhawm.
Daim duab 4.5 nyhuv ntawm HPMC ntxiv thiab khov cia rau ntawm cov khoom hluav taws xob ntawm cov hmoov nplej hmoov nplej nplej zom
On the other hand, starch gelatinization To, T p, Tc, △T and △Hall increased with the extension of freezing time. Tshwj xeeb, cov hmoov txhuv nplej siab nrog 1% lossis 2% hpmc ntxiv rau 602.340 ± 0.915 ± 0.915 ± 0.01) 71.613 ± 0.085 (frozen storage for 0 days) 60 days); Tom qab 60 hnub ntawm khov cia, txoj kev loj hlob ntawm cov hmoov txhuv nplej siab txo qis dua ntawm HPMC ntxiv, tsis muaj HPMC ntxiv los ntawm 77.530 ± 0.028 (khov cia rau 01.028. 408 ± 0.021 (khov cia rau 60 hnub), thaum lub hmoov txhuv nplej siab ntxiv nrog 78.60 tau rau 80 hnub) txog 80.032 (khov cia rau 60 hnub). days); in addition, ΔH also showed the same change rule, which increased from 9.450 ± 0.095 (no addition, 0 days) to 12.730 ± 0.070 (no addition, 60 days), respectively, from 8.450 ± 0.095 (no addition, 0 days) to 12.730 ± 0.070 (no addition, 60 days), respectively. 531 ± 0.030 (add 0.5%, 0 days) to 11.643 ± 0.019 (add 0.5%, 60 days), from 8.242 ± 0.080 (add 1%, 0 days) to 10.509 ± 0.029 (add 1%, 60 days), and from 7.736 ± O. 066 (2% addition, 0 days) rose to 9.450 ± 0.093 (2% addition, 60 days). The main reasons for the above-mentioned changes in the thermodynamic properties of starch gelatinization during the frozen storage process are the formation of damaged starch, which destroys the amorphous region (amorphous region) and increases the crystallinity of the crystalline region. The coexistence of the two increases the relative crystallinity of starch, which in turn leads to an increase in thermodynamic indexes such as starch gelatinization peak temperature and gelatinization enthalpy. However, through comparison, it can be found that under the same freezing storage time, with the increase of HPMC addition, the increase of starch gelatinization To, T p, Tc, ΔT and ΔH gradually decreases. It can be seen that the addition of HPMC can effectively maintain the relative stability of the starch crystal structure, thereby inhibiting the increase of the thermodynamic properties of starch gelatinization.
4.3.7 Qhov cuam tshuam ntawm I-IPC ntxiv thiab ua kom lub sijhawm cia rau ntawm cov txheeb ze crystalloinity ntawm cov hmoov txhuv nplej siab
X. Y-roor diffraction (XRD) yog tau los ntawm X. Xoo tshav ua txawv yog qhov qauv ntawm cov khoom siv, cov qauv ntawm cov atoms lossis lwg me me hauv cov khoom. Vim tias cov qauv hmoov txhuv nplej siab muaj cov qauv siv crysticly, XRD feem ntau siv los txheeb xyuas thiab txiav txim siab crystallogrinaphic daim ntawv thiab txheeb ze crystallinity ntawm starch muaju.
Daim duab 4.6. Raws li qhia hauv a, txoj haujlwm ntawm cov hmoov txhuv nplej siab crystallization peaks yog nyob ntawm 170, 180, feem ntau, thiab tsis muaj qhov tseem ceeb, thiab nws tau kho los ntawm qhov khov lossis kho HPMC. This shows that, as an intrinsic property of wheat starch crystallization, the crystalline form remains stable.
However, with the prolongation of freezing storage time, the relative crystallinity of starch increased from 20.40 + 0.14 (without HPMC, 0 days) to 36.50 ± 0.42 (without HPMC, frozen storage, respectively). 60 days), and increased from 25.75 + 0.21 (2% HPMC added, 0 days) to 32.70 ± 0.14 (2% HPMC added, 60 days) (Figure 4.6.B), this and Tao, et a1. (2016), cov kev cai hloov cov kev ntsuas ntawm kev ntsuas tau zoo ib yam [173-174]. Qhov nce nyob rau hauv tus txheeb ze crystallotrinity yog feem ntau tshwm sim los ntawm kev puas tsuaj ntawm thaj chaw amorphous thiab nce ntxiv nyob rau hauv lub crystallinity ntawm thaj chaw crystalline. In addition, consistent with the conclusion of the changes in the thermodynamic properties of starch gelatinization, the addition of HPMC reduced the degree of relative crystallinity increase, which indicated that during the freezing process, HPMC could effectively inhibit the structural damage of starch by ice crystals and maintain the Its structure and properties are relatively stable.
NCO TSEG: A IS X. X-ray diffraction qauv; B yog tus txheeb ze crystallinity tshwm sim ntawm cov hmoov txhuv nplej siab;
4.4 Tshooj Lus Qhia
Starch is the most abundant dry matter in dough, which, after gelatinization, adds unique qualities (specific volume, texture, sensory, flavor, etc.) to the dough product. Since the change of starch structure will affect its gelatinization characteristics, which will also affect the quality of flour products, in this experiment, the gelatinization characteristics, flowability and flowability of starch after frozen storage were investigated by examining starch suspensions with different contents of HPMC added. Changes in rheological properties, thermodynamic properties and crystal structure were used to evaluate the protective effect of HPMC addition on starch granule structure and related properties. The experimental results showed that after 60 days of frozen storage, the starch gelatinization characteristics (peak viscosity, minimum viscosity, final viscosity, decay value and retrogradation value) all increased due to the significant increase in the relative crystallinity of starch and the increase in the content of damaged starch. Lub gelatinization enhalpy nce, thaum lub gel lub zog ntawm cov hmoov txhuv nplej siab ua rau tsawg; however, especially the starch suspension added with 2% HPMC, the relative crystallinity increase and starch damage degree after freezing were lower than those in the control group Therefore, the addition of HPMC reduces the degree of changes in gelatinization characteristics, gelatinization enthalpy, and gel strength, which indicates that the addition of HPMC keeps the starch structure and its gelatinization properties relatively stable.
Tshooj 5 Qhov tshwm sim ntawm HPMC ntxiv rau cov poov xab muaj sia nyob thiab ua haujlwm fermentation nyob rau hauv cov khoom noj khov
Cov poov xab muaj cov ntawv thov ntau hauv fermented hmoov (sourdasugh Cov pa roj carbon dioxide tsim tuaj yeem ua rau lub khob noom cookie xoob, ntxeem tau thiab ntau. At the same time, the fermentation of yeast and its role as an edible strain can not only improve the nutritional value of the product, but also significantly improve the flavor characteristics of the product. Yog li ntawd, txoj haujlwm muaj sia nyob thiab cov kev ua haujlwm ntawm cov poov xab muaj qhov cuam tshuam tseem ceeb rau qhov zoo tshaj plaws ntawm cov khoom kawg (cov khoom siv tshwj xeeb, thiab cov tsw, thiab lwm yam).
Nyob rau hauv rooj plaub ntawm khov cia, poov mam yuav cuam tshuam los ntawm ib puag ncig kev ntxhov siab thiab cuam tshuam rau nws lub peev xwm. When the freezing rate is too high, the water in the system will rapidly crystallize and increase the external osmotic pressure of the yeast, thereby causing the cells to lose water; when the freezing rate is too high. If it is too low, the ice crystals will be too large and the yeast will be squeezed and the cell wall will be damaged; both will reduce the survival rate of the yeast and its fermentation activity. Tsis tas li ntawd, ntau cov kev tshawb fawb tau pom tias tom qab cov poov xab hlwb tau tawg ntawm cov qauv kev tsis txaus siab, uas tau ua kom txo cov khoom lag luam network, uas ua rau muaj cov khoom lag luam zoo tshaj plaws hauv cov khoom noj [176-177].
Vim tias HPMC muaj cov dej muaj zog thiab dej muaj peev xwm, ntxiv rau lub khob noom cookie system tuaj yeem cuam tshuam nrog kev tsim thiab kev loj hlob ntawm cov dej khov. Hauv qhov kev sim no, cov nyiaj HPMC sib txawv tau ntxiv rau lub khob noom cookie, thiab tom qab lub sijhawm ua haujlwm ntawm HPMC ntawm poov xab nyob rau cov poov huab txheej.
5.2 Cov ntaub ntawv thiab cov hau kev
Cov ntaub ntawv thiab cov khoom siv
Sp. Qauv 754 UV Spectrophatometer
KDC. 160hr high-ceev lub tub yees rau hauv centrifuge
BDS BDS. 200 inverted batholog tsom
Tus tsim
Shanghai Yiheng Scientific Ntsuas Co., Ltd.
Shanghai Spectrum Science Co., Ltd.
Jiangsu Tongjing Purification Khoom Co., Ltd.
Anhui Zhongke Zhongjia Scientific Ntsuas Co., Ltd.
Shanghai Zhicheng analyerical cov ntsuas kev lag luam lag luam Co., Ltd.
Chongqing Auto Optical Instrumical Co., Ltd.
5.2.2.1 Kev npaj ua kua poov xab
5.2.2.3 CFU (Colony-tsim cov chav nyob) suav
Nqus 1 g ntawm cov khob noom cookie, ntxiv rau nws mus rau lub raj ntsuas kev ntsuas nrog 94, sau cov kev xav tau ua tiav raws li 101, thiab tom qab ntawd cov kev xav tau rau hauv kev saib xyuas kom txog thaum 10'1. Draw 1 mL of dilution from each of the above tubes, add it to the center of the 3M yeast rapid count test piece (with strain selectivity), and place the above test piece in a 25°C incubator according to the operating requirements and culture conditions specified by 3M. 5 d, take out after the end of the culture, first observe the colony morphology to determine whether it conforms to the colony characteristics of yeast, and then count and microscopically examine [179]. Each sample was repeated three times.
The alloxan method was used to determine the glutathione content. The principle is that the reaction product of glutathione and alloxan has an absorption peak at 305 nl. Specific determination method: pipette 5 mL of yeast solution into a 10 mL centrifuge tube, then centrifuge at 3000 rpm for 10 min, take 1 mL of supernatant into a 10 mL centrifuge tube, add 1 mL of 0.1 mol/mL to the tube L alloxan solution, mixed thoroughly, then add 0.2 M PBS (pH 7.5) and 1 mL of 0.1 M, NaOH solution to it, mix well, let stand for 6 min, and immediately add 1 M, NaOH The solution was 1 mL, and the absorbance at 305 nm was measured with a UV spectrophotometer after thorough mixing. Cov ntsiab lus glutathione tau xam los ntawm kev nkhaus txheem txheem. Each sample was paralleled three times.
5.2.2.5 Cov ntaub ntawv ua haujlwm
5.3 Cov Ntsiab Lus thiab Kev Sib Tham
Daim duab 5.1 nyhuv ntawm HPMC ntxiv thiab khov cia rau ntawm qhov siab ntawm cov pov thawj ua khob noom cookie
Raws li pom hauv Daim duab 5.1, thaum khov rau 0 hnub, nrog kev nce ntawm HPMC ntxiv, cov ntaub ntawv pov thawj nce los ntawm 4.234-0. -0.12 cm (0.5% HPMC added), 4.314-0.19 cm (1% HPMC added), and 4.594-0.17 cm (2% HPMC added) This may be mainly due to HPMC Addition changes the properties of the dough network structure (see Chapter 2). However, after being frozen for 60 days, the proofing height of the dough decreased to varying degrees. Specifically, the proofing height of the dough without HPMC was reduced from 4.234-0.11 cm (freezing for 0 days) to 3 .18+0.15 cm (frozen storage for 60 days); Lub khob noom cookie ntxiv nrog 0.5% HPMC tau txo los ntawm 4.27 + 0.12 cm (khov cia rau 3.424-0.22 cm (khov cia rau 0 hnub). 60 hnub); Lub khob noom cookie txuas ntxiv nrog 1% HPMC txo qis ntawm 4.314-0.19 cm (khov cia rau 3.774-0.12 cm (khov cia rau 60 hnub); Thaum lub khob noom cookie txuas nrog 2% hpmc sawv. Cov plaub hau qhov siab tau txo los ntawm 4.594-0.17 cm (khov cia rau 0 hnub) rau 4.09- ± 0 hnub). It can be seen that with the increase of the addition amount of HPMC, the degree of decrease in the proofing height of the dough gradually decreases. Qhov no qhia tau hais tias nyob rau hauv kev mob ntawm khov cia, HPMC tsis muaj peev xwm tswj hwm tus txheeb xyuas roj ntau, yog kuj txo cov khoom noj muaj txiaj ntsig zoo, yog li txo cov khoom noj muaj txiaj ntsig zoo ntawm cov khoom noj qab zib fermented.
Daim duab 5.2 Cov nyhuv ntawm HPMC ntxiv thiab khov cia ntawm kev muaj sia nyob ntawm cov poov xab
It can be seen from Figure 5.2 that there is no significant difference in the number of yeast colonies in samples with different contents of HPMC added without freezing treatment. Qhov no zoo ib yam li cov txiaj ntsig tau txiav txim los ntawm Heitmann, Zannini, & Adendt (2015) [180]. However, after 60 days of freezing, the number of yeast colonies decreased significantly, from 3.08x106 CFU to 1.76x106 CFU (without adding HPMC); los ntawm 3.04x106 cfu rau 193x106 cfu (ntxiv 0.5% HPMC); txo los ntawm 3.12x106 cfu rau 2.14x106 cfu (ntxiv 1% HPMC); Txo los ntawm 3.02x106 cfu rau 2.55x106 cfu (ntxiv 2% hpmc). By comparison, it can be found that the freezing storage environment stress led to the decrease of the yeast colony number, but with the increase of HPMC addition, the degree of the decrease of the colony number decreased in turn. Qhov no qhia tau tias HPMC tuaj yeem tiv thaiv cov poov xab zoo dua hauv cov xwm txheej khov. The mechanism of protection may be the same as that of glycerol, a commonly used strain antifreeze, mainly by inhibiting the formation and growth of ice crystals and reducing the stress of low temperature environment to yeast. Figure 5.3 is the photomicrograph taken from the 3M yeast rapid counting test piece after preparation and microscopic examination, which is in line with the external morphology of yeast.
5.3.3 cuam tshuam ntawm HPMC ntxiv thiab lub sijhawm khov ntawm cov ntsiab lus glutathione hauv ua khob noom cookie
Glutathione yog Tripeptide composed ntawm glutamic acid, cysteine thiab glycine, thiab muaj ob hom: txo thiab oxidized. Thaum cov poov xab cell qauv raug rhuav tshem thiab tuag, lub permeability ntawm lub hlwb nce, thiab nws yog reductive. It is particularly worth noting that reduced glutathione will reduce the disulfide bonds (-SS-) formed by the cross-linking of gluten proteins, breaking them to form free sulfhydryl groups (.SH), which in turn affects the dough network structure. stability and integrity, and ultimately lead to the deterioration of the quality of fermented flour products. Usually, under environmental stress (such as low temperature, high temperature, high osmotic pressure, etc.), yeast will reduce its own metabolic activity and increase its stress resistance, or produce spores at the same time. When the environmental conditions are suitable for its growth and reproduction again, then restore the metabolism and proliferation vitality. Txawm li cas los xij, qee cov poov xab nrog cov kev ntxhov siab tsis zoo lossis muaj zog metabolic kev ua si tseem yuav tuag yog tias lawv khaws cia rau hauv ib qho chaw nres tsheb khov.
As shown in Figure 5.4, the glutathione content increased regardless of whether HPMC was added or not, and there was no significant difference between the different addition amounts. Qhov no yuav yog vim qee qhov ntawm cov poov xab ua kom qhuav los ua kom lub khob noom cookie muaj kev ntxhov siab tsis zoo thiab thev taus. Under the condition of low temperature freezing, the cells die, and then glutathione is released, which is only related to the characteristics of the yeast itself. Nws muaj feem xyuam rau ib puag ncig sab nraud, tab sis tsis muaj dab tsi ua nrog tus nqi HPMC ntxiv. Therefore, the content of glutathione increased within 15 days of freezing and there was no significant difference between the two. However, with the further extension of the freezing time, the increase of glutathione content decreased with the increase of HPMC addition, and the glutathione content of the bacterial solution without HPMC was increased from 2.329a: 0.040mg/ g (frozen storage for 0 days) increased to 3.8514-0.051 mg/g (frozen storage for 60 days); while the yeast liquid added 2% HPMC, its glutathione content increased from 2.307+0 .058 mg/g (frozen storage for 0 days) rose to 3.351+0.051 mg/g (frozen storage for 60 days). This further indicated that HPMC could better protect yeast cells and reduce the death of yeast, thereby reducing the content of glutathione released to the outside of the cell. This is mainly because HPMC can reduce the number of ice crystals, thereby effectively reducing the stress of ice crystals to yeast and inhibiting the increase of extracellular release of glutathione.
Lub Sijhawm Post: Kaum-08-2022