Improvements in functionalities of porcine serum protein hydrolysates induced by free hydroxyl radical

Hydrolysated peptides from kinds of proteins have been applied as natural ingredients in food industry, mainly due to their good functional properties. However, the fate of them under different processing conditions is rarely understood. In our study, changes of functional properties in porcine plasma protein hydrolysates (PPH) were evaluated in a free hydroxyl radical-mediated oxidation system. PPH was obtained by hydrolyzing porcine plasma protein with Alcalase for 5 h at pH 8.0, 55 degrees C. When exposed to free radical-mediated oxidation, functional properties of PPH improved dramatically with growing oxidant concentrations and reaction time, especially at 20 degrees C. Solubility, foaming capacity and emulsification of PPH increased significantly (P<0.05) during early stage of oxidation, with solubility increasing from 83.1% (non-oxidized PPH) to 97.4%(20 degrees C, 10mM H2O2, 5 h), emulsifying activity index and foaming capacity rising form 1.24m(2)/g to 2.73 m(2)/g, and 144% to 183%, respectively. Stability for emulsifying and foaming were also found to be reinforced. The improvements in functional properties of PPH helped to play theoretical basis for applying the peptides in food systems.