Applicability of Black Soldier Fly and Yellow Mealworm in municipal food waste bioconversion: Assessment of efficiency, nutritional proficiency, and safety

Efficient management of municipal food waste is critical for addressing environmental concerns and meeting the growing need for sustainable protein. This study presents two case studies comparing the effectiveness and safety of Black Soldier Fly (BSF) and Yellow Mealworm (YML) larvae in bioconverting municipal food waste in Iran. In these case studies, BSF larvae achieved superior waste reduction (68.49%) and biomass conversion ratio (27.45%) compared to YML larvae (28.1% and 8.20%, respectively). Feed Conversion Efficiency was 40.1% for BSF larvae and 29.2% for YML larvae, indicating relatively similar efficiencies in converting consumed feed into biomass. YML larvae demonstrated higher crude protein content (52.63%) than BSF larvae (34.19%), while BSF larvae had significantly more crude fat (45.54%) compared to YML larvae (34.22%). The fatty acid profiles revealed that BSF larvae contained elevated levels of lauric acid (C12:0) and palmitic acid (C16:0), whereas YML larvae were richer in oleic acid (C18:1) and linoleic acid (C18:2). Mineral content analysis showed higher phosphorus levels in YML larvae and substantially more calcium in BSF larvae. Both species’ larvae and frass were found to have heavy metal levels (Arsenic, Cadmium, Cobalt, Lead, and Mercury) below the maximum permissible limits set by Iran National Standards. Microbial analysis indicated that YML larvae had higher total bacterial counts compared to BSF larvae, with a similar trend in their frass. Both larvae and frass tested negative for Escherichia coli and Salmonella spp., suggesting their microbial safety for use as feed. These case studies highlight the potential of BSF and YML larvae in sustainable food waste conversion, each with specific fatty acid and amino acid profiles, offering tailored feed sources for a variety of animal species.