Functional alteration of soybean 11S globulin through glycation

Glucose-conjugated soybean 11S globulin was prepared by mixing soybean 11S globulin and glucose at a ratio of 1:11.7 (w/w) and incubating at 52 degrees C and 38 000 relative humidity for up to 72 h. The glycated soybean globulin in 15 mM phosphate buffer (pH 6.4) without NaCl was almost insoluble at 0 h, but solubility increased to approximately 68 % at 36 h and 40 % at 72 h. During this reaction, the available lysine content rapidly decreased, whereas the quantity of fructosamine increased, indicating glucose binding to soybean 11S globulin. Glucose-conjugated soybean 11S globulin after the 72 h reaction showed a hydroxyl radical antioxidant capacity of approximately 8.2 mu mol gallic acid equivalent/g protein, and the average particle size of its emulsions tended to be smaller than that of the soybean 11S globulin, resulting in superior stability of its emulsions compared to native globulin emulsions.