Enzymatic hydrolysis of soy protein isolate and effect of succinylation on the functional properties of resulting protein hydrolysates

Commercial defatted soy meal was solubilized in an aqueous solution at pH 8.5 to prepare a soy protein isolate (SPI) with 90.45% protein and 95% solubility. Soy protein hydrolysate (SPH) was obtained by enzymatic hydrolysis of the SPI using a neutral proteinase at different degrees of hydrolysis (DH = 4, 6, 8 and 10). A previous heat treatment of native SPI at 80 degrees C for 10 and 30 min caused a gradual dissociation and/or unfolding of some fractions of the soy protein leading to a decrease in high molecular weight fractions. Gel filtration chromatography of SPH with DH=8 indicated that the soluble fraction consisted mostly of low molecular weight peptides having a molecular weight less than 12.5 kDa. Combined hydrolysis and succinylation greatly increased protein solubility and caused marked changes in other functional properties depending on the degree of modification. (C) 1999 Canadian Institute of Food Science and Technology. Published by Elsevier Science Ltd. All rights reserved.