Effect of hydrolysis time on nutritional, functional and antioxidant properties of protein hydrolysates prepared from gingerbread plum (Neocarya macrophylla) seeds

Nutritional, functional properties and antioxidant activities of enzymatic hydrolysates of gingerbread plum seed protein isolates (HGPSPIs) were investigated. HGPSPIs were prepared at different times (5 - 180 min) using two food-grade proteases. Pepsin was applied in the first hydrolysis stage followed by trypsin. The hydrolysis time showed a significant effect (p 0.05) on nutritional parameters such as amino acid score, essential amino acid index, biological value and protein efficiency ratios. Emulsifying activity index and foaming capacity decreased as hydrolysis time increases. During the whole hydrolysis period of 180 min, the antioxidant activities (hydroxyl radical scavenging, ferrous chelating, reducing power and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging) of HGPSPIs increased as function of incubation time. Furthermore, within all samples a large amount of small-sized peptides (500 - 3000 Da) was observed with increasing hydrolysis time. The above results indicated that hydrolysis time has positively affected nutritional and antioxidant parameters of HGPSPIs but had a negative impact on the functional properties studied.