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Study on Limited Enzymatic Hydrolysis of Soy Protein Concentrate and Soy Protein Isolate and Modification in Functional Properties

Author: HouYao
Tutor: ZhaoXinHuai
School: Northeast Agricultural University
Course: Of Food Science
Keywords: Soy protein concentrate Soy protein isolate Restriction enzyme hydrolysis Functional
CLC: TS214.2
Type: Master's thesis
Year: 2008
Downloads: 784
Quote: 6
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Abstract

Soy protein rich in nutritional value, but also has good functional properties. Shown by the dissolution, water, oil, emulsion, gel, etc. features, it is widely used in food and other industries. Modified soy protein functional studies, food science is a hot issue. In this study, enzyme modification techniques, the soy protein concentrate (SPC), soy protein isolate (SPI) for restriction enzyme hydrolysis (neutral protease or trypsin), control the degree of hydrolysis degree of hydrolysis of the enzyme preparation of low-modified soy protein product ; through the evaluation of the changes in the nature of its function to find a new method of soybean protein modification in order to achieve improved functional properties to keep some important purposes. In addition, by enzymatic hydrolysis products analyzed by gel electrophoresis, protein digestion patterns and explore the functional properties of the intrinsic link changes, which is to reveal the function of the changing nature of the key. Specific results are as follows: (1) to the SPC protein content by orthogonal test to determine the suitability of the soy protein concentrate extraction conditions. The first extraction conditions were: ethanol concentration 65%, extraction temperature 50 ℃, extraction time 60 min, the solid-liquid ratio 1:10; second extraction conditions were: 70% -80% ethanol concentration, extraction temperature 70 ℃ -75 ℃, extraction time 5 min. Laboratory tests showed that, with the ultrasonic treatment time, SPC increased the protein content and the maximum; continue to extend the processing time, the protein content decreased. Optimal conditions for the ultrasonic treatment 15 min. Ultrasonic power also affect the quality of the SPC, SPC with the power to increase the protein content showed an increasing trend, indicating that the ultrasound-assisted treatments on egg quality soy protein concentrate has a positive effect. (2) the use of neutral protease and trypsin restrictive hydrolyzed soy protein concentrate, hydrolysis conditions to give the corresponding parameters. Neutral protease hydrolysis conditions: original pH, temperature 25 ℃, 10% of substrate concentration, enzyme dosage 400 U · g-1; limited trypsin hydrolysis conditions: original pH, temperature 35 ℃, substrate concentration 10% , enzyme dosage 1700 U · g-1. The use of neutral protease and trypsin restrictive hydrolyzed soy protein isolate, the corresponding parameters hydrolysis conditions. Neutral protease hydrolysis conditions: original pH, temperature 25 ℃, substrate concentration of 7.5%, enzyme dosage 250 U · g-1; limited trypsin hydrolysis conditions: original pH, temperature 35 ℃, substrate concentration of 7.5% , enzyme dosage 610 U · g-1. (3) gel electrophoresis analysis showed that the catalytic specificity of various differences in the low degree of hydrolysis, the protein hydrolysis modes. Neutral protease, the two enzyme-modified protein fragment short peptide molecule, and in the low molecular weight range there are two new peptide fragment; trypsinized, the two enzyme-modified protein fragment of the peptide molecule is relatively large, and No new fragments generated. Enzyme digestion pattern differences will impact the functional properties of modified products have different effects. (4) enzyme-modified soy protein concentrate significantly enhanced solubility (NSI increased by about 25 times); retention, oil absorption improved to some extent, by about 14% and 29%; emulsifying activity and emulsion stability were significantly improved, The gelation is greatly reduced. These changes are consistent with the enzymatic mode. Enzyme-modified soy protein concentrate, its solubility, oil, emulsifying targets close to or better than commercial soy protein isolate, soy protein concentrate showed restrictive hydrolysis can really improve a destination, retaining some functional properties of soy protein . Same with the SPC, SPI enzymatic patterns and functional properties of the enzyme-modified product variation also exists intrinsically linked. Modified Trypsin product contains more macromolecular fragments, so the water retention, gel strength, emulsification, etc. are superior to neutral protease modified products, in particular the degree of hydrolysis of 1% of the product, but in the solubility is relatively low; enzyme-modified product of several important functional properties, such as solubility (NSI increased about 29-fold), emulsifying activity, trypsin-modified protein isolate products, emulsion stability, as well as significantly better than the commercially available absorbent SPI . Thus, the restriction enzyme hydrolyzed soy protein, to achieve improvements to keep some important functional properties purposes. By gel electrophoresis analysis showed that changes in enzyme patterns and functional properties of the intrinsic link, which is the nature of change, and research functions effectively control the functional properties was provided.

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