Effect of succinylation on the physicochemical properties of soy protein hydrolysate

The combined effect of enzymatic hydrolysis of soy protein isolate and the influence of various levels of succinylation on the physicochemical properties of resulting soy protein hydrolysate (SPH) have been studied. The results indicated that proteolysis followed by succinylation resulted in a major soluble protein fraction having a molecular weight of 7 kDa. Depending on the level of modification, succinylation appeared to cause both dissociation of the higher molecular weight fractions (1000 and 400 kDa), and re-association of polypeptides as a result of intermolecular hydrophobic interactions. Surface hydrophobicity (S-0) of SPH decreased drastically due to the higher degree of hydrolysis value applied. Additionally, the significant increase in the net charge and elcectrostatic repulsion caused the molecules to expend and undergo conformational changes as reflected by the changes in the hydrophobicity and fluorescence intensity data. Total essential amino acid content was slightly lowered at the highest degree of modification. Low degrees of succinylation improved the in vitro digestibility of the soy protein hydrolysates, and the highest value was observed at 69.5% succinylation. (C) 2001 Elsevier Science Ltd. All rights reserved.