Abstract Edible insects are key players in the alternative protein market. Alongside their high protein content, edible insects contain abundant trace minerals, including iron. Given the lack of sustainable and bioavailable iron sources, edible insects are a promising iron source in both human and livestock diets. However, little is known about how the iron concentration in edible insects can be manipulated. This study aims to investigate the impact of dietary iron at different concentrations on the growth, survival, and nutrient composition of two edible insect species larvae: black soldier fly (BSF, Hermetia illucens) and yellow mealworm (YM, Tenebrio molitor). Substrate iron content was increased using ferric ammonium citrate (FAC), ranging from 267-563 mg/kg (0 to 10 mM FAC) for YM and 323-6637 mg/kg (0 to 100 mM FAC) for BSF. Larval weight of YM was unaffected by dietary iron content, but survival rates significantly decreased by 4% at the 10 mM diet. In BSF larvae, no differences in body weight or survival were noted between dietary iron treatments, but cuticular lesions potentially indicative of iron overload appeared at 100 mM diet. When exposed to excess dietary iron, both YM and BSF showed significant increases in iron content in a dose-dependent manner, with BSF larvae exhibiting a threefold increase from 372 mg/kg to 999 mg/kg. Both species exhibited significant reductions in zinc on iron-enriched diets. Calcium levels in BSF strongly correlated with dietary iron concentration, rising by over 20% at the 100 mM diet, a phenomenon not previously reported. Finally, across all dietary iron concentrations, no significant effects on protein and fat content or soluble protein composition were observed in either species. All together data suggest that BSF larvae can act as a precious source of both iron and calcium for food and feed formulations through substrate manipulation.
Read full abstract