Effects of Chemical Modification and Molecular Weight Distribution on Iron Binding Ability of Phytate-Removal Soybean Protein Isolate Hydrolysate

The aim of this study was focused on investigating the effects of chemical modifications and molecular weight distribution of phytate-removal Soybean Protein Isolate (SPI) hydrolysate on Degree of Hydrolysis (DH) and the iron binding ability. The chemical modifications included acid treatments, succinylation, acetylation and phosphorylation. Also the effects of molecular weight distribution of phosphorylated SPI trypsin hydrolysate on iron binding ability were studied. The results showed that acetic acid treatment can increase significantly the DH of SPI hydrolysate, but did not increase the iron-binding ability of SPI hydrolysate. Phosphorylation by Sodium Trimetaphosphate (STMP) can increase significantly the ironbinding ability, but did not change the DH. The STMP phosphorylation reaction time of 20 min was sufficient for improving the iron binding capacity and alkaline conditions were beneficial of phosphorylation reaction. The fraction of molecular size among 3 to 5 kDa exhibited highest iron binding ability, but there were no significant different in amino acid compositions between the four ultrafilteration fractions.