Waste-derived feedstocks and industrial microwave drying influence antioxidant capacity and immune-associated protein composition in black soldier fly larvae (Hermetia illucens)

Abstract

Abstract

Abstract Black soldier fly larvae ( Hermetia illucens ) are increasingly used as a sustainable protein source in animal feeds. Beyond macronutrient value, black soldier fly larvae (BSFL) contain antioxidant compounds and immune-associated proteins that may contribute to their functional value. However, the extent to which rearing substrate and processing influence these components remains poorly understood. This study investigated the effects of feedstock and industrial microwave drying on antioxidant capacity and immune-associated protein composition in BSFL. Larvae were reared on three waste-derived feedstocks (fruit and vegetable waste, soy okara and brewer’s spent grain). Antioxidant capacity was measured using Folin-Ciocalteu, FRAP and DPPH assays. Immune-associated proteins and AMP candidates were characterised using LC-MS/MS proteomics. Industrial microwave drying was evaluated relative to freeze-drying. Antioxidant capacity differed significantly among feedstocks (ANOVA, ). Brewer’s spent grain increased total phenolic content and reducing capacity, while fruit and vegetable waste resulted in the highest radical scavenging activity. Total immune protein richness did not differ among diets; however, immune functional composition varied significantly (PERMANOVA, R 2 = 0.907, ). Larvae reared on fruit and vegetable waste showed increased representation of immune effector proteins and higher AMP candidate richness. Industrial microwave drying resulted in a 43% reduction in detectable immune-associated proteins and reduced antioxidant capacity. These findings demonstrate that feedstock and processing shape the composition and detectability of antioxidant and immune-associated components in BSFL biomass, highlighting opportunities to optimise insect-derived feed ingredients for targeted applications.