Synthesis and fractionation of Protein Hydrolysate from Hermetia illucens L. pre-treated with Lactobacillus spp.

This study aimed to determine the effects of fermentation pretreatment using Lactobacillus spp. on the protein content of black soldier fly larvae, and the protein recovery, degree of hydrolysis, and amino acid composition of protein hydrolysate from black soldier fly larvae. Solid state fermentation of black soldier fly larvae with Lactobacillus spp. carried out for 72 h at 37℃ increased the protein and fat content from 32.35 to 36.75–41.99% and 36.91 to 40.03–41.99%, respectively. Protein content in the fermented samples was extracted using an alkaline extraction method which resulted in a protein recovery of 31.41 to 35.99%. The protein extract was then hydrolyzed using bromelain enzymes for 24 h to produce protein hydrolysates with a degree of hydrolysis in the range of 47.64 to 52.61%. The protein hydrolysate was further fractionated using size-exclusion chromatography with the flow rate of 0.5 to 1.5 mL/min. The protein concentration of each fraction was determined using a UV-visible spectrophotometer and the result varied from 0.51 to 1414.69 mg/mL with the highest protein concentration obtained when the flow rate of the chromatography was set at 1 mL/min. Amino acid composition of the fractionated protein hydrolysate was determined using the ultra-high-performance liquid chromatography. The results show that the fractionated protein hydrolysates fermented with Lactobacillus spp. contained several amino acids such as glycine, and L-methionine, which was significantly different than the unfermented samples. The findings highlight that fermentation of black soldier fly larvae using Lactobacillus spp. positively influence the protein and amino acid composition of protein hydrolysate from black soldier fly larvae.