Abstract:

To improve functional properties, the thermoresistant protein extracted from rapeseed meal was limitedly hydrolyzed by alkaline protease hydrolysis. Also, the relationships between protein functions and degree of hydrolysis (DH) were investigated. The solubility, emulsifying capacity and oil absorption capacity of rapeseed thermoresistant protein all increased after alkaline protease hydrolysis. Its solubility increased with increasing DH, and the solubility of rapeseed thermoresistant protein with 10% DH was as high as 63.82% at pH 7, 2.1 times higher than before hydrolysis. The emulsifying capacity of the hydrolysate obtained at 2.0% DH was the best and the emulsifying index was 0.43 and 0.49 at pH 6.0 and pH 8.0, 0.13 and 0.11 higher than unhydrolyzed rapeseed thermoresistant protein, respectively. The hydrolysate obtained at 8% DH presented the highest oil absorption capacity, 4.39 g/g. Rapeseed thermoresistant protein was decomposed into peptides with a smaller molecular weight after the hydrolysis, so changes in some of its functional properties took place.

Key words: rapeseed thermoresistant protein, alkaline protease, degree of hydrolysis, functional properties