Reducing Allergenicity of Soy Protein Isolate from Several Varieties of Soybean Through Glycation with Lactose

Food allergy is a specific immunological response caused by allergens contained in food. Soybean is one of the eight types of food products that most frequently cause allergies, which may lower its quality in terms of safety aspects. Soybean processing can reduce the risk of allergies by modifying the soy protein structure so as to produce hypoallergenic food. Processing involving Maillard reaction by conjugating proteins with reducing sugars has the potential to reduce allergenicity. This research aims to: (1) determine the degree of glycation based on the formation of soy protein isolates (SPI) -lactose conjugate and free amino; (2) determine the molecular weight profile of SPI and SPI-lactose conjugate: and (3) analyze the allergenicity of SPI and SPI-lactose conjugate. Protein isolation was carried out by protein precipitation of imported soybean (GMO and non-GMO) and local soybean varieties (Anjasmoro and Grobogan) at their isoelectric point or using a pH arrangement. Then the SPI was reacted with lactose under pH 9.5 and 95 degrees C for 60 minutes. The determination of glycation degree of SPI-lactose conjugate was carried out using two methods, namely the thiobarbituric acid reactive substances (TBARS) method and Bradford method for free amino acids. The protein molecular weight profile was analyzed using the SDS-PAGE electrophoresis method. The allergenicity of SPI and SPI-lactose conjugate were analyzed quantitatively using the Enzyme-Linked Immunosorbent Assay (ELISA) method.The analysis results from local varieties (Anjasmoro and Grobogan) showed that the higher SPI protein content causes higher glycation degree of SPI-lactose conjugate. SDS-PAGE electrophoresis results showed that molecular weight profiles of SPI from GMO, non-GMO, Anjasmoro and Grobogan were 11-147.7 kDa, 12.9-150.3 kDa, 11.3-144.2 kDa and 10.7-159.0 kDa, respectively. Glycation process can eliminate or reduce the intensity of protein bands suspected to be the major allergen proteins in soybeans, namely Gly m Bd 60K, Gly m Bd 30K or P34, and Gly m Bd 28K. The glycation reaction can reduce allergenicity in all soybean varieties tested by 43.12% to 29.85%.