Valorization of Former Foodstuffs and Heat-Treated Post-Consumer Catering Waste through Black Soldier Fly Larvae

Former foodstuffs are promising substrates for black soldier fly larvae (BSFL; Hermetia illucens ), but evidence from heterogeneous, industrially collected waste streams remains limited. This pilot experiment evaluated larval growth, bioconversion performance, composition, and heavy-metal transfer using four diets from an industrial waste handler: one post-consumer catering waste stream and three pre-consumer expired foodstuff streams differing in meat content and packaging removal. A moisture-matched broiler starter diet served as the control. The control produced the fastest growth and best feed conversion ratio (FCR 3.94; bioconversion rate 25.4%; harvest at 14 days). Pre-consumer streams most closely matched the control, yielding 1.84–2.08 kg per tray, FCRs 4.81–5.42, waste reduction 47.8–52.8%, survival 53.7–60.0%, and harvest at 16 days. Post-consumer catering waste performed poorest (survival 42.4%; waste reduction 26.8%; FCR 6.39; harvest at 33 days). Comparing identical substrate streams with and without packaging removal showed that compliance-driven packaging removal improved waste reduction (52.8% vs. 48.9%) and survival (60.0% vs. 56.8%) but slightly reduced yield, highlighting trade-offs between regulatory compliance and substrate aeration. BSFL biomass composition shifted with diet, notably fat and ash, while protein remained relatively stable. Cadmium, lead, zinc, and manganese concentrations in substrates and BSFL biomass were below EU feed limits, although cadmium showed the clearest transfer to biomass. Results indicate that pre-consumer former foodstuffs can be viable BSFL substrates under practical conditions, provided sorting, regulatory compliance, and batch variability are managed. Given the pilot scale (two trays per diet), outcomes are presented as indicative performance ranges rather than definitive estimates.