Functionalization of Tenebrio molitor with Olive Mill Wastewater: Growth, Antioxidant Activity, and Metabolomic Insights

Olive mill wastewaters (OWWs) are a phenol-rich by-product of olive oil production, associated with high disposal costs and significant environmental impact. This study evaluated the effects of OWW supplementation on Tenebrio molitor larvae (TML) reared on standard cereal-based substrates. Larval survival was not affected, but average body weight was significantly reduced in all OWW-treated groups, indicating a measurable impact on growth. Metabolomic profiling revealed alterations in amino acid, carbohydrate, and organic acid contents, including reductions in branched-chain and aromatic amino acids, trehalose, and Krebs cycle intermediates, particularly in groups with the strongest growth reduction. Lipid analysis showed stable saturated fatty acids, a shift from polyunsaturated to monounsaturated fatty acids, and an increase in total fat in the most affected groups. Despite the lack of enhancement in polyphenol accumulation or antioxidant activity, multivariate analysis highlighted distinct metabolic signatures between OWW-treated and control larvae, with sucrose, lactate, and fumarate identified as key discriminant metabolites. These findings demonstrate that OWW, a valorized olive oil by-product, can modulate growth and metabolism in TML, opening new perspectives for its application in innovative weight management strategies.