Inactivation Of Allergic Proteins In Soybean By Exogenous Proteases

Soybean is widespread in our country, and is rich in protein. It is the major protein source for livestock production. But the allergic proteins in soybean could cause immune hypersensitivity. and result in diarrhoea and mortality of animals. The protein with strong allergenic activity is resistant to heating and other processing .The purification of p-conglycinin which is the most critical dietary antigen in soybean is studied in this subject. Then it is studied to destroy allergic protein by hydrolysis with proteases.p-conglycinin in soybean is purified by salt precipitate on 70%~90% saturation and gel filtration on a Sepharise 6B column(80 X 2.5cm). The result of immunoelectrophoresis illustrated the purified p-conglycinin is not contaminated by the other proteins in soybean. The purified p-conglycinin is heterogeneous, and is composed of six kinds of subunits. Based on SDS-PAGE the molecular weights of subnits were estimated at 72746Da, 6774 7Da, 63998Da, 60249Da; 57750 Da,52751Da and 48000Da respectively.The method to determine the quantity of p-conglycinin in soybean was made by rocket immuno-electrophoresis. The model was established:H=0.0681C+0.4571 R2-0.994H-height of 'rocket' (mm) C-concentration of P-conglycinin (ug/mL)Soybean meal was hydrolyzed by Alcalase, Nutrase, AS1 398 and Papain respectively. When the degree of hydrolysis reach 5% the concentration of p-conglycinin is 57.6 mg/g,58 mg/g .58.2 mg/g and 56.4 mg/g. The result shows there is few difference in the speciality to hydrolyze the allergic protein among these enzymes.The concentration of p-conglycinin in soybean meal was compared after different degree of hydrolysis. There is little effect on the quantity of p-conglycinin when the DH is below 10%. The p-conglycinin in soybean meal was inactivatesd wholly when the DH reach 25%. Hydrolysis could not improve the susceptibility of p-conglycinin to pepsin.To sum up, allergic protein is destroyed after sufficient hydrolysis by protease. This contributes a new method to make hypoallergenic soybean products.