Function Character And Structure Of Hydrolyzed Protein And Application In Pork Paste

In this study, trypsin digestion improved emulsifying properties of soy protein isolate. And on this basis, enzyme hydrolyzed soy protein was separated by ultrafiltration, analyzing the physical and chemical properties and secondary structure differences of different ultrafiltration fractions, furthermore, applying column chromatography to analyze the molecular weight distribution of ultrafiltration fractions. The effects of temperature on gelation properties and chemical forces involved in mixed myofibrillar gels with soy protein,7S globulin and different enzyme hydrolyzed soy proteins were investigated. The aim was to explore the mechanism behind the different gelation between myofibrillar and non-meat protein. It was anticipated to offer theoretical foundation for improving the quality of frozen pork paste. The results were as follows:1 The hydrolysates of soy protein isolate were obtained by hydrolysis with trypsin.Their emulsifying activity and emulsion stability was evaluated by turbidimetric technique. We designed five factors experiments for researching into the influences on emulsifying properties, and offering the consults. A 4-factor and 2-degree orthogonal rotary was used to analyze emulsifying properties. We attained the optimal enzymatic hydrolysis condition (pH=7.0, [E]/[S]=2.7%, pydrolysis time 4.1hr while 40.3℃)and the results showed that the emulsifying activity of hydrolysates ascend 67% than its mother protein.2 Within all the samples, molecular weight range of 6-10kDa peptide presented best emulsifying activity. Emulsifying activity of polypeptide with molecular weight range below 20kDa was much higher than soy protein isolate. Ultrafiltering the lOkDa peptides can significantly improve the emulsifying activity of enzyme soy protein. Furthermore, molecular weight range of 4-6kDa peptide presented best emulsion stability. The emulsion stability of enzyme hydrolyzed soy protein was better than UF and soy protein isolate. It was more important that peptides could improve of emulsion stability, at the present of protein. molecular weight range of 2-20kDa peptide presented best molecular flexibility and above 10 kDa had best surface hydrophobicity. Concerning aspartate and glutamate content, amino acid content, molecular weight range of below 6 kDa had less amount. However, it had more hydrophobic amino acids and indispensable amino acid, especially in leucine, tryptophan, phenylalanine. In addition, other amino acid presented no significant differences. By Raman spectroscopy and circular dichroism, the results showed that: soy protein isolate contained onlyβ-sheet, and random coil structure. Enzyme hydrolyzed soy proteinα-helix,β-fold,β-turn and random coil structure. Hydrolysising process influenced the structure of protein. All ultrafiltration peptides had not theα-helical structure, indicating that ultrafiltration may lead to the disappearance ofα-helix. All samples had both C-H stretching vibration and bending vibration. Soybean 7S globulin, soy protein isolate and enzyme hydrolyzed soy protein had three kinds of disulfide bonds:twisted-twisted-twisted, twisted-twisted-trans, trans-twisted-trans. Hydrolysising process did not change the disulfide bonds of protein. Different molecular weight ultrafiltration components had different form of disulfide bonds. Tyrosine of larger molecular weight polypeptide were embedded in the hydrophobic environment of, but the tyrosine of less than 6kDa peptides embedded in the hydrophobic environment as a hydrogen bond donor. After 6 kDa and 10kDa membrane separation, content of soybean peptide with molecular weight between 6-10 kDa was 37.4%, no significant difference in their hydrophobicity.3 In this paper, Sephadex G-200 gel chromatography and cellulose-DE-52 ion-exchange chromatography were used to separate and purify crude 7S globunin in Soybean extracted by Saio. And crude 7S globunin in Soybean was further identified by SDS-PAGE and capillary electrophoresis.4 The mixed protein gels were prepared adding soy protein isolate (SPI),7S globulin, enzyme hydrolyzed soy proteins,10-100 kDa ultrafiltration fraction and 0.5-10 kDa ultrafiltration fraction to myofibril protein isolate (MPI) gels, and five chemical interactions including nonspecific associations, ionic bonds, hydrogen bonds, hydrophobic interactions and disulfide bonds in these gels were investigated by means of determining gel solubility within 20-75℃. Furthermore, correlations between gel strength and different chemical interactions were evaluated statistically by Pearson’s correlation test. The gels with 0.5-10 kDa fraction presented the biggest gel strength below 60℃, and the gels with SPI had better gel strength above 65℃. At different endpoint temperatures, nonspecific associations decreased in order of MPI mixed with 0.5-10 kDa fraction,10-100 kDa fraction, enzyme hydrolyzed soy proteins,7S globulin and SPI. Gels with ultrafiltration fractions had higher ionic bonds. Hydrogen bonds fluctuated in small scale below 55℃and reduced at higher temperature. Hydrophobic interactions increased to maximum before decreasing slowly as the temperature went on. In short, both hydrophobic interactions and ionic bonds had significantly positive correlation with gel strength for mixed gels with enzyme hydrolyzed soy proteins, whereas for the other four mixed gels, it was hydrophobic interactions and nonspecific associations.5 This article is about the physicochemical properties of myofibrillar protein isolate and soy protein complex. Compare the emulsifying activity, emulsion stability, dynamic test, gel strength, disulfide linkageand chemical interactions among myofibrillar in the pork and soy protein isolate,7S globulin, hydrolysates of soy protein isolate, peptides 10 kDa to 100 kDa and peptides 2 kDa to 10 kDa complex, which have showed that:(1) Emulsifying activity and emulsion stability grow with the ratios of proteins in the mixtures; (2) MPI-TSL、MPI-TS and MPI-SPI have better dynamic textures than other complex, MPI-TSL mainly shows better glutinosity, MPI-TS mainly shows elasticity, while MPI-SPI can show both6 Compound effects of sodium tripolyphosphate, microbial transglutaminase and enzyme hydrolyzed soy protein on texture properties, cook loss and sensory attributes of pork past were studied. The hardness and springiness of the pork paste depended on the amount of the TGase and enzyme hydrolyzed soy protein added (positive at P<0.05 and P<0.01, negative at P<0.001 and P<0.01, respectively). However, sodium tripolyphosphate did not affect textural characteristics significantly (P>0.05), at the presence of enzyme hydrolyzed soy protein. The effect of amount of enzyme hydrolyzed soy protein showed negative linear (P<0.001) and positive quadratic effects (P<0.01) on the cohesiveness and chewiness of pork paste. Interaction between TGase and enzyme hydrolyzed soy proteins had a positive effect (P<0.01) upon the cohesiveness of pork paste. Furthermore, the effect of amount of TGase showed positive linear (P<0.01) effects on the chewiness of pork paste. In addition, interaction between sodium tripolyphosphate and enzyme hydrolyzed soy protein weakened (P<0.05) the chewiness of pork paste. Concerning cook loss, hydrolyzed soy protein and MTGase showed positive effects (P<0.01 and P<0.05, respectively). Hardness and springiness (obtained from instrumental measure and sensory analysis) presented significant correlations (P< 0.01 and P< 0.001, respectively). Furthermore, texture properties had significant correlations with each other. Cohesiveness and chewiness significantly affected cook loss, sensory hardness, springiness and juiciness. Overall acceptability had poor correlation with instrumental attributes and either partial attribute. Result showed customers preferred intermediate values for overall acceptability.7 In this essay, using Box-Behnken response surface methodology as a main method to determine the optimum water holding capacity parameters of minced pork production, and study on effects of the properties from minced pork gel in the frozen storage time. Using texture properties, rate of expressible water, level of frozen water and microstructure of minced pork gel as main indicators. The results are:transglutaminase, soybean polypeptide and tripolyprosphate are relatively added 5.48%,3.4% and 0.217% of the total weight of minced pork production to achieve the optimum water holding capacity of the minced pork production, which is 34.90%. The frozen storage effects on minced pork gel are obvious. After a 90-day frozen storage, the hardness of minced pork gel is decreased by 21.6%, but the springiness is increased by 181.01%; the rate of centrifugal dewatering and level of frozen water are relatively increased by 14% and 9%. The microcosmic surface shape of minced pork gel is apparently degraded on the ultramicrostructural photographs.