Optimization of Preparation Protein Hydrolysate by Protease G6 Using Response Surface Methodology and Free Radical Scavenging Activities From Feather Meal

Abstract

The aim of this research was to study the optimal condition for chicken feather meal protein hydrolysate production using a microbial protease, Protease G6. The experimentation was conducted using Central Composite Design (CCD) and Response Surface Methodology (RSM). The three independent variables including temperature (?C), time and enzyme-substrate ratio were studied. Optimization process for obtaining high yield of chicken feather meal protein hydrolysate was performed using response surface methodology (RSM) by optimizing a combination of three independent variables namely, temperature (41.59 ? 58.41?C), time (0:38 - 7:21 h) and enzyme-substrate ratio (0.8 ? 9.2) with degree of hydrolysis (DH) as a response. The optimum hydrolysis conditions were obtained at temperature of 55?C, 4:40 h of incubation time and enzyme-substrate ration is 7.5. RSM generated model predicted that 53.97%of DH could be achieved at these conditions. Protein hydrolysate from optimal condition was separated by ultrafiltration with 10, 5, 3 and 0.65 kDa membranes and further analyzed for 2,2-diphenyl-1-picrylhydrazyl radical (DPPH?) scavenging activity and 2,2?-Azinobis-(3-ethylbenzothiazoline-6-sulphonate) radical cation (ABTS+?) scavenging activity. Among the fraction, protein with molecular weight less than 0.65 exhibited high activity (IC50 16.96 ? 1.08 ?g/ml and 1.24 ? 0.56 ?g/ml for DPPH? and ABTS+? scavenging activity, respectively). This separated protein hydrolysate fraction was further purified by RT-HPLC. High yield of DH obtained from the optimization process could produce chicken feather meal protein hydrolysate with good for use as a source of peptide drugs that can be further developed in the pharmaceutical industry or an ingredient in cosmetic products in the global market.