Aggregation of hydrophobic soybean protein hydrolysates: Changes in molecular weight distribution during storage

The stability and molecular weight of peptides play important roles in their functional and biological properties. In this study, soybean protein hydrolysates (SPHs) with different hydrophobic characteristics were used to evaluate the aggregation of peptides during storage at −20 °C. SPHs were isolated from immobilized metal affinity chromatography, and size expulsion HPLC showed the molecular weight distribution of them at different storage times. As time elapsed, some high molecular weight peptides formed from the original SPHs, and the content of the newly formed high molecular weight peptides produced from the highly hydrophobic SPHs was considerably large. The aggregation could be broken by 6 mol/l urea and 20 g/l SDS. The damage caused by 6 mol/l urea was stronger than that of 20 g/l SDS. The results suggested that hydrophobic interaction may promote the aggregation of SPHs during storage.