Fatty acids profile of black soldier fly (Hermetia illucens): Influence of feeding substrate based on coffee-waste silverskin enriched with microalgae

The aim of this work was to find alternative low-cost and environmentally friendly rearingsubstrates for the growth of Hermetia illucens (HI) (Diptera, Stratiomydae), used as feed. At thispurpose, insect feeding substrates based on the re-use of coffee silverskin, the main waste productof the coffee-roasting industry, enriched with various percentages of microalgae (i.e.,Schizochytrium sp. or Isochrysis sp.), were tested. The fatty acid profile, as well as the relativeamount of lipids, proteins and carbohydrates (these latter calculated as ratio to the total biomassof the sample) of ingredients, insect feeding substrates and HI prepupae, were determined for thefirst-time coupling Gas Chromatography-Mass Spectrometry and Fourier Transform InfraredSpectroscopy. A multivariate statistical analysis (Principal Component Analysis) was performedto better read into results. In general, the inclusion of microalgae caused in both feeding substratesand in HI prepupae an increase in the relative amount of lipids and proteins, improvingtheir nutritional value. Higher amounts of unsaturated fatty acids, particularly of omega-3, andgood nutritional indices were detected in HI prepupae reared on substrates enriched with 10%,20% or 25% of Schizochytrium sp. with respect to HI prepupae fed with coffee silverskin enrichedwith Isochrysis sp., suggesting them as new nutraceutical ingredients for future functional feedand food. In addition, the substrate enriched with a 10% inclusion level of Schizochytrium sp. hasto be considered the most convenient one since a greater inclusion of microalgae did not promoteadditional benefits in terms of nutritional value of HI prepupae.