Resource-efficient and eco-friendly model for fruit processing industry waste valorisation using black soldier fly (Hermetia illucens) larvae under tropical conditions

Abstract

A pilot facility was developed to evaluate the digestion efficiency of mixed fruit peel waste by black soldier fly (Hermetia illucens (L.) (Diptera: Stratiomyidae); BSF) larvae in Sri Lanka. Larval biomass was characterised by proximate analysis and the techno-functional properties of BSF larvae flour protein were determined. A cost-benefit analysis was conducted to assess the feasibility of operating an onsite BSF digestion facility for a medium scale fruit juice manufacturer. The observed optimum feeding rate was 1.5 g/larva. A bioconversion rate of 15.41 was achieved. The waste reduction index was 1.73. The feed conversion rate was 3.85. The efficiency of conversion of digested food was 0.29. The highest wet and dry weight reductions were 61.72 and 55.10% respectively, indicating very efficient digestion. The crude protein content of BSF larvae was 40.87% while the crude fat content was 26.67%, proving it is a potential protein source as a feed ingredient. The protein fraction also had highly desirable techno-functional properties (water-binding capacity 3.00 g/gDM, oil binding capacity 5.22 g/gDM, emulsifying capacity 36.00 ml/g, foaming capacity 0.48, and foaming stability 0.15). The waste is currently being dumped in a non-sustainable manner at US$ 10.00 per one metric ton. The cost-benefit analysis showed a net benefit of US$ 3,963.76 per month from this valorisation, suggesting it is a highly viable, eco-friendly option for processing fruit processing industry or similar organic waste under tropical conditions in middle income countries.