Production of protein hydrolysate containing antioxidant activity from Hermetia illucens

Abstract

Protein hydrolysate is a complex mixture of peptide and amino acids that can be produced from various biomass sources including insects, such as black soldier fly larvae (Hermetia illicens) due to its relatively high protein content. This study aimed to investigate the potential of protein hydrolysate from black soldier fly larvae as a bioactive hydrolysate through enzymatic hydrolysis using bromelain. Black soldier fly larvae contain 25.6% protein and 35.5% lipids as determined by a proximate analysis. Experiments for the enzymatic hydrolysis of black soldier fly larvae was designed using a central composite design with three factors particularly enzyme concentration (1-5%), pH (6-8) and time of hydrolysis (3-24 hours). The protein hydrolysate had a yield of 10.70 % (on a weight basis) based on defatted biomass with a productivity of 21 mg/L/batch. The protein concentration varied between 240-310 μg/ml with the degree of hydrolysis varied in the range of 10-43%. The protein hydrolysate had a molecular weight in the range of 14-25 kDa based on Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis. The amino acid composition of the protein hydrolysate was also determined and mainly consists of lysine (8.0%), leucine (7.7%), and valine (7.2%). The protein hydrolysate may find application as a bioactive hydrolysate with an antioxidant activity of 72.6 in terms of its ability to inhibit free radicals 2,2-diphenyl-2-picryl hydrazyl with IC₅₀ of 0.84%.

Keywords: Amino acid; Antioxidant activity; Biochemistry; Biotechnology; Black soldier fly larvae; Chemical engineering; Enzymatic hydrolysis; Protein hydrolysate.

Fig. 1

Composition of initial BSFL biomass and defatted BSFL.

Fig. 2

Schematic diagram to produce protein hydrolysate from BSFL.

Fig. 3

Surface response from the interaction between variables on the DH with respect to enzyme concentration and pH (A), enzyme concentration and time (B), and pH and time (C).

Fig. 4

Distribution of molecular weight of protein extract sample without enzyme (A), and protein hydrolysate from BSFL (enzyme concentration of 3%, pH 7, and hydrolysis time of 13.5 hours) (B).

Fig. 5

DPPH free radical inhibition profile of protein hydrolysates from BSFL and control at various concentrations (0–1.25% v/v).