Response surface optimization of enzymatic hydrolysis condition of lead tree (Leucaena leucocephala) seed hydrolysate

Abstract

The enzymatic hydrolysis of lead tree seed protein with alcalase to obtain Lead Tree Seed Hydrosylate (LTSH) was optimized using response surface methodology (RSM). A threetiered, factor face centered, central composite design (CCD) was used to study the influence of four independent variables namely: pH (7–9); hydrolysis temperature (50oC, 55oC, 60oC); hydrolysis time (30 min, 60 min, 90 min); and enzyme/substrate (1%, 2%, 3%) ratio on both yield and antioxidant activity. The CCD consisted of twenty-four experimental points and six replicates of central points. All data were analyzed using Design-Expert Software. The optimum conditions obtained from experiments were a pH of 9; an enzyme to substrate ratio of 2%; a hydrolysis time of 90 min; and a temperature of 55°C. Results showed that LTSH derived from optimized hydrolysis exhibited effective ferrous ion chelating activity (92.79%) and strong reducing power (A700 = 3.82) at a concentration of 20 mg/ml. LTSH also demonstrated high DPPH radical scavenging activity (76.21%; IC50 1.99 mg/ml), as well as hydroxyl radical scavenging activity (66.72%; IC50 2.45 mg/ml). Superoxide anion scavenging activity was 55.71% (IC50 3.89 mg/ml) at 20 mg/ml. These results suggest that LTSH has potential as a natural antioxidant of functional food and for use in food processing