Abstract:

Response surface methodology was employed to optimize the preparation conditions of antioxidant peptides
by enzymatic hydrolysis of chickpea protein isolate (CPI), prepared by alkaline extraction and acid precipitation from
chickpea seeds, with trypsin. The response variable was the percentage scavenging of superoxide anion radical. The results
showed that all samples collected throughout the hydrolysis process had significant antioxidant activity and the optimal
conditions were determined as substrate concentration 2%, enzyme/substrate ([E]/[S]) ratio 1 800 U/g, reaction time
35 min, temperature 32 ℃ and pH 7.0. Under these conditions, the percentage scavenging of superoxide anion radical
by chickpea antioxidant peptides was 67.59%. Chickpea peptide fractions with molecular weight cut-off of 1 kD from
chickpea protein hydrolysates by ultrafiltration were analyzed by liquid chromatography-mass spectroscopy (LC-MS).
A pentapeptide with molecular weight of 668.40 in chickpea peptide fractions was achieved, whose amino acid
sequence was determined to be RQLPR.

Key words: chickpea protein isolate, trypsin, antioxidant activity, response surface methodology