Food Processing Characteristics of Soybean Proteins

Part II. Effect of Sulfhydryl Groups on Physical Properties of Tofu-gel

Abstract

Relation between sulfhydryl groups in soybean proteins and the physical properties of tofu was studied. Changes in the amount of sulfhydryl groups by heating or treatment with urea were more rapid in 11S protein as compared with 7S protein. Moreover, by changing the amount of sulfhydryl groups in proteins by N-ethylmaleimide, 2-mercapto-ethanol and dithiothreitol, the physical properties of tofu from 11S protein were more significantly effected than that from 7S protein. Namely, tofu-gel from I1S. protein got harder and stronger as the amount of sulfhydryl groups increased.
The results may suggest that tofu prepared from 11S protein has more disulfide bonds in its gel than that from 7S protein.