Impact of limited feed medium and different lipid extraction solvents in dealing with black soldier fly larvae

Abstract

The emergence of new potential lipid feedstock for biodiesel production has gravitated tremendous attentions from researchers off late. The lipid from insect feedstock is broadly extolled due to their short lifecycle, simple rearing need, high body mass gained, high lipid content and requires less energy, water and food inputs. Thus, the main objective of this study was to evaluate the performance of black soldier fly larvae (BSFL) to grow in limited feed medium, namely, raw coconut endosperm waste. The impact of different solvents employed for BSFL lipid extraction was as well unveiled using harvested larvae fed with limited raw coconut endosperm waste. The results showed that the BSFL supplied with limited feed medium had gained only 0.7 g of weight from 100 BSFL. A slow growth rate of 0.018 g/day and long rearing duration of about 5 weeks were also recorded. In terms of overall degradation, the coconut endosperm waste was reduced to the tune of 0.7 with a waste reduction index of around 0.2 g/day. However, the ingested coconut endosperm waste that had been digested and assimilated into BSFL biomass was only 9.3%. This could be due to the nature of coconut endosperm waste containing high in fibres; therefore, hard to be broken down and assimilated by BSFL. Besides, the choice of solvents for lipid extraction also played a role as different solvents were capable of extracting different classes of lipid. By using petroleum ether as the extraction solvent, the extracted lipid from BSFL biomass was found to be around 31%. Meanwhile, by using Bligh & Dyer method, i.e., a methanol and chloroform mixture as the extraction solvent, the lipid obtained was found to be 41%. This was plausibly due to that the difference in solvent polarities that impacted the efficiencies and classes of lipid extracted. In short, the choice of solvents used for lipid extraction is vital and must be taken into consideration prior to the subsequent sample processing.