Abstract:

Alcalase 2.4L FG was used to hydrolyze soybean protein isolate (SPI) to prepare soybean protein hydrolysates with the highest antioxidant activity, which showed a degree of hydrolysis of 14.0% and an ABTS+ radical scavenging rate of 43.6%.  The prepared hydrolysates were modified with Alcalase 2.4L FG by plastein reaction and the optimal enzyme dosage, substrate concentration and temperature to maximize the reduction of free amino groups were determined by response surface methodology to be 1037 U/g protein, 30 g/100 mL, and 20 ℃, respectively. The maximum degree of reaction and antioxidant activity were obtained after reaction for 6 h under these conditions. Moreover, the antioxidant activity of the SPI hydrolysates and their modification products obtained after reaction for 1, 3 h and 6 h was better than that of SPI. The DPPH and superoxide anion radical scavenging activity and reducing power of the hydrolysates and modification products showed no significant difference, while a significant difference was observed in their hydroxyl radical scavenging activity.

Key words: soybean protein hydrolysates, plastein reaction, antioxidant activity, response surface analysis