Optimisation of enzymatic protein hydrolysis of mud crab (Scylla sp.) to obtain maximum angiotensin-converting enzyme inhibitory (ACEI) activity using response surface methodology

Abstract

Optimisation is commonly employed to find the conditions that produce the best possible response, thus minimizing the cost and time of a particular process. Response Surface Methodology (RSM) is a widely used tool in optimisation. This study reported the optimisation of enzymatic hydrolysis of mud crab meat using RSM by employing a face-centered Central Composite Design (CCD) to obtain maximum angiotensin-converting enzyme inhibitory (ACEI) activity. Screening of commercial food grade proteinases was carried out using Alcalase®, Protamex®, Neutrase® and papain shows that Protamex® gave the highest ACEI activity. The enzymatic hydrolysis conditions used in the optimisation were temperature (45-65ºC), pH (pH 5.5-7.5), hydrolysis time (1-4 hours) and Protamex® enzyme to substrate (E/S) ratio (1-3%). It was found that quadratic model was able to explain the relationship between the hydrolysis conditions and ACEI activity. The optimum conditions were obtained at 65ºC, pH 5.6, 1% E/S ratio and 4 hours of hydrolysis time. The experimental ACEI activity (88.93±1.02%) was not significantly difference (p>0.05) with the predicted ACEI activity (91.10%). It was found that the IC50 of the mud crab hydrolysate prepared at optimum condition was 1.96±0.13 mg/mL. This study shows that RSM can be used to explain the relationship between enzymatic hydrolysis conditions of mud crab meat and its ACEI activity.