Preparation And Characterization Of Fortified Soybean Protein And Peptide Using Biological Enzymatic Methods

Isoflavone is a a kind of flavone seperated from leguminous plants which has estrogenactivity. Howere, the isoflavones in soybean is mainly glucosides which is difficult to beabosrbed by human. What’s worse, the content of phytate acid in soybean is high, which hasan unfavorable effect on the absorption of mineral element. As a traditional preparation of soyprotein, acid precipitation is a chemical process. Acid precipitated soy protein usuallycontains a lot of anti-nutrtion element such as phytate acid, and the content of aglycones isvery low, together with a low binding capability of Calcium, which affects the nutrition of soyprotein seriously. In a word, the development of a less ecnomic-consuming andnutrition-fortified soybean protein and peptides would satisfy the need of human body. Thestudy aims to prepare fortified soybean protein and peptides which contain less phytate acid,more isoflavone aglycones, high Calcium-binding ability and better flavor through biologicalenzyme-physical methods. The results were showed as followed:(1) Nutrition fortified soy protein isolate (SPI) was prepared from White Soy Flake usingbiological enzyme(β-glucosidase, phytase and acid protease)-counter current extraction. Theresults showed that: compared with the acid precipitated soy protein, peotein yield ofCP-Cocktail increased to74.83%, the content of phytate acid decreased by50%andaglycones were2.68higher. The flavor, surface hydrophobicity and thermal stability of CP-DENwas also significantly improved.(2) Nutrition fortified SPI was prepared from thermal denatured soy meal(TDSM) usingbiological enzyme(β-glucosidase and Protease M)-subcritical water treatment. Thephysicochemical properties, structural properties and antioxidation of SPI were investigated.The results showed that: compared with the acid precipitated soy protein, peotein yield ofβ-glucosidase-subcritical water treatment increased to60.39%and all the glucosides werebioconversed to aglycones. The aglycones content in protein prepared from ProteaseM-subcritical water treatment was15.15umol/g and the ABTS scanvenging activity was82.94%, while the aglycones content and ABTS scanvenging activity of acid precipitated soyprotein were3.74umol/g and55.67%respectively.(3) The aglycone-peptide-Calcium complex was prepared from TDSM using bioconversional treatment. The results showed that: the aglycone content of the peptide increased to69.24umol/g, which was18.75times higher than that of the acid precipitated soy protein. TheCalcium content increased to69.24umol/g, while that of the control was7.86%. The DPPHscanvenging activity, ABTS scanvenging activity and reducing power of the peptide was64.89%,96.67%, and0.467respectively, which was much higher than those of the acidprecipitated soy protein.