Insight into the chemical and nutritional fat profile of Tenebrio molitor larvae reared on different Agri-food by-products

Insects are capable of feeding with a variety of substrates, being possible obtaining products rich in protein using by-products from agri-food industry. Hence, the aim of this work was evaluating the effect of different diets based on three agri-food industry by-products of Tenebrio molitor larvae's total fat contents and fatty acid profiles. Stabilized Alperujo (ALP), Pleorotus ostreatus spent substrate (POS) and olive leaf flour (OLF) were used mixed with wheat bran, control diet, at different percentages (20-100 %). All substrates studied modified the parameter analysed respect to the control diet. OLF subtract led to the greatest effects on the total fat content at percentage higher than 40 %. Respect to fatty acid profile, the most relevant changes were the increases of total MUFA content in samples from all T. molitor larvae fed with ALP and in most of those fed with POS, due to the specific increases of oleic acid content. On the contrary, total PUFA content decreased in most cases except for OLF substrate when the addition percentages were lower than 100 %. Moreover, OLF substrate enhanced the presence of ω-3. Finally, according to European regulations on nutritional claims, this fat fraction could be labelled as "source of ω-3", "high in monounsaturated fat" and "high in unsaturated fats". We can therefore conclude that feeding T. molitor with these agri-food by-products, especially from olive oil industry, enhanced the fatty acids profile of their fat fraction.