Antioxidant and Antimicrobial Activities of Enzymatic Hydrolysis Products from Sunflower Protein Isolate

Abstract

Abstract: The goal of the present work was to prepare bioactive hydrolysates and peptides from sunflower protein isolate (free of chlorogenic acid). To reach this goal the protein isolate was hydrolysed using several enzymes and enzyme mixtures, including: pepsin, trypsin, chymotrypsin and a mixture of the three enzymes (mixture I); also alcalase, flavourzyme and a mixture of the two enzymes (mixture II). These enzymes were used at 2 % concentration and at pH and temperature reported by the manufacturer. During hydrolysis, at certain time intervals, 30, 60 and 120 min. aliquots were withdrawn from the reaction mixture to give peptide fractions and at the end of 3h give hydrolysate. The peptic fractions exhibited prooxidant activities at 30, 60 and 120 min. Other hydrolysis products revealed moderate antioxidant activity (AOA). Tryptic peptide at 60 min. hydrolysis showed the highest AOA (94.32%), followed by 61.21 % for the hydrolysate at 180 min. and very low AOA values were exhibited by all chymotryptic peptides and hydrolysate. The peptides resulting from enzyme mixture I were prooxidative after 30 and 60 min. because they resulted from peptic hydrolysis then on adding the two other enzymes, the AOA was raised to 38.75 and 44.06 % after 120 and 180 min., respectively. Hydrolysis using alcalase and flavourzyme gave peptides with moderate AOA ranging from 31.10-48.44 % and from 10.5-43.19 %, respectively. Upon using the mixture II the AOA was improved to 53.05 and 79.37%, after 120 and 180 min., respectively. Some peptides and hydrolysates were chosen for testing their antimicrobial activity. All