Preparation And Application Of Low Bitter Soybean Antioxidant Pepide

This paper by using enzymatic modification of soybean protein isolated (SPI)was to obtain a product of soy peptides and free amino acides, which humans couldeasily absorb and digest. Soy peptides as a kind of bioactive peptides had theirphysiological activity like anti-oxidation, anti-fatigue, anti-bacterial, otherwise, it hadbitterness. Soybean peptides bitterness directly affected food flavor which hinderedthe application of soybean peptides. This paper focused on the preparation of a lowbitterness and high anti-oxidation soybean peptides and its liquid product.Andioxidant activity used ORAC method, DPPH method and reducing force, thebitterness value used sensory evaluation.SPI had a pretreatment before enzymatic period, at first adjusted pH to5.0, heatedto100℃for15min then adjusted pH to the protease’s optimal pH. By combiningthe product’s hydrolysis characteristic, andioxidant activity and bitterness we foundthe one which used alkaline protease, pancreatic enzyme, flavor protease were betterthan used other protease. Therefore, we obtained a higher andioxidant activity andlower bitterness soybean peptides by using the same amount of alkaline protease,pancreatic enzyme and flavor protease three enzymolysis which costed17h.Adding different molar weight amino acids before enzymatic hydrolysis, we got ithad a certain degree of product’s hydrolysis characteristic, andioxidant activity andbitterness. The product which adding0.001moL, tyrosine had the highest antioxidantactivity, the ORAC value was1717.82Trolox equivalent, the bitterness was5.87. Asdetermining the SPI and water ratio of1:5, we found3kDa peptides relative contentwas over70%.Lyophilized power and different kinds of sugar had maillard reaction, the onewhich was xylose reaction product had higher antioxidant activity and lowerbitterness. A range of reaction temperature, reaction time had positive correlation tothe maillard reaction evaluation, antioxidant activity and bitterness, then determinedthe reaction temperature was110℃, reaction time was90min. PH changes coulddirectly affect the maillard reaction speed, the formation of the intermediate and end product and their physical and chemical properties, determined the reaction liquid pHvalue was9.0. Condensed the freeze-drying maillard products to make maillardpeptides liquid.