DYNAMIC VISCOELASTIC STUDY ON THE GELATION PROPERTIES OF BETA-CONGLYCININ-RICH AND GLYCININ-RICH SOYBEAN PROTEIN ISOLATES

摘要

Preheated soybean protein isolates (SPIs) were prepared from new soybean lines that have extremely different compositions of beta-conglycinin and glycinin by a typical method for manufacturing commercial SPI. The gelation properties of these SPIs were investigated by dynamic viscoelastic measurements. The storage modulus G' of 12% SPI was measured at pH 7.0 when the temperature was increased from 30 to 80 degrees C and then lowered to 20 degrees C at 2 degrees C/min. Gelation properties of the preheated SPI were different from those of the non-pre-heated SPI. In the absence of NaCl, an increase in the storage modulus G' was observed for preheated beta-conglycinin-rich SPI and preheated control SPI, but not for preheated glycinin-rich SPI. On the other hand, in the presence of 2.5% NaCl, an increase in the storage modulus G' was observed for all preheated SPIs in the order beta-conglycinin-rich SPI >control SPI >glycinin-rich SPI. These results suggest that beta-conglycinin plays an important role in the heat-induced gel formation of commercial SPI.