DPPH radical scavenging activity of fish protein powder enzymatic hydrolysates

The effects of substrate concentration,the ratio of enzyme and substrate,hydrolysis p H,hydrolysis temperature and hydrolysis time on the DPPH radical-scavenging activity were studied,using the fish protein powder as material and Alcalase 2. 4L as hydrolase. The results showed that all of those factors had effects on the DPPH radical-scavenging activity of the hydrolysates. On the basis of single factors experiments,the preparing conditions of enzymatic hydrolysates were optimized,and they were: substrate concentration 18. 05 %( w /v),the ratio of enzyme and substrate 2. 40 %( w /w),hydrolysis p H 8. 04,hydrolysis temperature49. 0 ℃,and hydrolysis time 4. 0 h. Under these conditions,the degree of hydrolysis and DPPH radicalscavenging ratio of the hydrolysate were 9. 81 % and 76. 10 %,respectively. The DPPH radical-scavenging activity of the hydrolysate was equal to that of 120 g / m L reduced glutathione. The results showed that the fish protein powder enzymatic hydrolysates have good capacity of DPPH radical-scavenging activity,and it can provide a reference for the development and utilization of fish protein powder.