Development Of Low Bitterness Soybean Peptide And Its Application In Beverage

Soybean peptides have properties of easily absorptive, low hypersensitivity and antigenicity, good solubility, and a variety of physiological activities. As a result,more and more attention has been paid on the study of soybean peptides.This paper shows the preparation of soybean peptides by using the method of enzymolysis. Firstly, comparing the enzymolysis effects of compound Protamex,Flavourzyme and Neutrase, and with the evaluation of degree of hydrolysis and bitter taste for reference, I select the appropriate enzyme. Secondly, On the basis single factor analysis such as enzymatic hydrolysis time, temperature, pH, the addition of enzyme and so on, through orthogonal experiment, it is concluded that the optimal condition is to use Flavourzyme, with temperature of 50 ○C, enzyme amount of 5%,pH 7.0, enzymolysis time of 4 h. In this condition, the degree of hydrolysis can reach13.5±0.6 %.With ultrafiltration technology, soybean peptides are isolated according to the different molecular weight, and molecular weight can be obtained in such a range of stage as below 1 K, 1 K to 3 K, 3 K to 5 K and 5 K to 10 K. By using Fourier infrared spectroscopic analysis, amino acid analysis and fluorescence spectrum analysis, the relationship and regularity between hydrophobicity, secondary structure, amino acid composition, the bitter value and oxidative stability in different molecular weight are researched. It is concluded that below 1 K molecular weight has maximum bitter value, highest oxidation resistance, and strongest surface hydrophobicity, the leastα-helical conformation content, maximum share of hydrophobic amino acids. There is a certain positive correlation between bitter value, oxidation resistance, and surface hydrophobic hydraulic. The surface hydrophobicity shows a negative correlation with alpha helix structure, and shows the similar trend with hydrophobic amino acid content.Soybean peptides can be developed into energy beverages containing peptides.Through orthogonal test, it is determined that the best formula for soybean peptide is the soybean peptide powder 2%, sugar 2.5%, citric acid 3% and β-cyclodextrin 1.0%on the condition that molecular weight after ultrafiltration is below 1 K. It also needs to satisfy the condition that soybean peptides beveragethe has the solid content above 5%, protein content above 1.5%, conforming to GB 16322-2003 standard,reserving 50 days under low temperature(4 °C).