Abstract:

The enzymatic hydrolysis parameters of defatted goat brain protein with Bacillus subtilis neutral protease were
optimized by response surface methodology. The optimized parameters were determined as follows: substrate concentration,
3.03 g/100 mL; enzyme/substrate ratio, 5 653. 20 U/g; and hydrolysis temperature, 39.4 ℃. The maximum degree of protein
hydrolysis was (14.59±1.26) % with the optimized parameters. The antioxidant activity of the resultant hydrolysates was
investigated in vitro. The antioxidant activity presented its maximum value when the hydrolysis degree was (12.48±0.71)%.
The IC50 of the protein hydrolysates for scavenging 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl, superoxide anion, and
nitrite radicals were 2.49, 3.13, 10.37 and 10.89 mg/mL, respectively, and the IC50 for chelating Fe2+ ions was 7.48 mg/mL.
These results suggest that the protein hydrolysates possess excellent antioxidant activity.

Key words: goat brain protein, enzymatic hydrolysate, response surface methodology, antioxidant activity