Effects of enzymatic hydrolysis on the antioxidant activity of protein hydrolysate derived from the larvae of black soldier fly (Hermetia illucens L.)

Abstract

Black soldier fly (Hermetia illucens L.) larvae (BSFL) are capable to convert various organic waste into highprotein biomass. This study aimed to obtain protein hydrolysate from BSFL by pre-treatment with acid or alkaline solutions prior to hydrolysis utilizing a bromelain enzyme. Protein extraction from the BSFL was carried out using hydrochloric acid and sodium hydroxide with different extraction time (30–60 min) and temperature (25–50°C). The BSFL used in this study contains 32.11% protein with a maximum protein recovery of 38.42% after extraction with sodium hydroxide at 50°C for 30 min. The extracted protein solution was then hydrolyzed using bromelain enzyme at different concentrations (2–4%), pH (7–9), and hydrolysis time (4–24 h) to determine the greatest conditions for the hydrolysis procedure in terms of degree of hydrolysis and antioxidant activity of the protein hydrolysate using a response surface method with a face-centered central composite design. At the optimum conditions (3% enzyme, pH 8, 24 h), the degree of hydrolysis was 58.52%. The antioxidant activity of the protein hydrolysate was measured with an IC50 of 1.15%. The amino acid content of the protein was also identified and primarily consists of glutamic acid (3.7%), leucine (2.1%), and valine (2.0%).