Composition and biological activity of edible insects biomasses: effect of rearing conditions, processing, and gastrointestinal digestion on black soldier fly raw materials

Abstract

By exploiting and adequately orienting what insects normally do in nature ¬– i.e., growing on organic waste and using the available compounds for their metabolic needs and for their development – it is possible to design systems to recycle and reuse organic residuals. To date, one of the most studied species, due to its potential in bio converting organic by-products and waste, is the Black Soldier Fly (BSF, Hermetia illucens L.). With particular attention to this species, the present PhD thesis is aimed to better understand the potentiality of insects as food and feed ingredients, and to provide improved tools to fully exploit this potential. With the purpose of optimizing bioconversion performances of black soldier fly by minimizing wastes, we tested different seasonality mixes of agri-food by-products as growing substrates for insects’ development, and we evaluated the effect on their nutritional composition with a focus on protein fraction. Black soldier fly species proved to be suitable in growing on basically all low-value agri-food wastes tested, simultaneously reducing waste, and producing valuable protein biomass that can be employed for numerous purposes. The most effective substrates that were identified were those belonging to the Autumn group. Furthermore, to fully achieve the sustainability objective, the composition of biomasses obtained from lactobacillus fermentation of black soldier fly wastes was determined. The nutritionally improved composition after fermentation proved that this process can be a way to valorize insect residual biomasses otherwise unused. This PhD thesis also presents a technical solution to the problem of chitin quantification in insect biomasses. An optimized UPLC-ESI/MS method for the simultaneous quantification of chitin and proteins was validated, providing a quicker and more accurate method to fully characterize insect biomass. The investigation on the effects on human health when insects are used as a high-quality and sustainable protein source was also another important issue that was addressed. As a result of in-vitro experiments, black soldier fly prepupa showed the ability at the intestinal level to inhibit the DPPIV enzyme and stimulate GLP-1 hormone release, suggesting an antidiabetic potential. In conclusion, the results obtained from this thesis improve knowledge on black soldier fly as a tool to re-use agri-food wastes and highlight the high nutritional quality and potential beneficial effects on human health of insect-derived biomasses.