Leftover bread as a potential feed additive: Impact on growth, fatty acid content, and antioxidant properties in Tenebrio molitor larvae

Bread waste in Saudi Arabia is a significant environmental issue that has caused significant losses. Insects, specifically Tenebrio molitor larvae, offer potential bioconversion solutions for food waste. Larvae were fed diets comprising different proportions of leftover bread (LB) powder mixed with wheat bran (WB), and feeding trials were conducted over 50 days. Results indicated that including LB powder did not significantly affect larval survival, affirming its safety. The larvae fed the diets LB100, LB75WB25, LB50WB50, LB25WB75, and WB reached the final weights of 27.64, 95.27, 105.012, 98.74, and 67.64 mg. Similarly, the highest mean pupal weight, at 0.133 mg, was observed when larvae were reared on LB75WB25, while the lowest mean pupal weight, at 0.107 mg, was recorded on the WB diet. Protein content varied significantly among diets, with mixed diets exhibiting protein content ranging from 16.98 % to 55.26 %. The primary fatty acid found in mealworm oil was oleic acid (C18:9), which made up 54.11 % of the total fatty acid content for larvae raised on 75LB:25WB, 52.01 % for LB, and 46.942 % for WB, with LB incorporation positively impacting growth, pupal weight, protein content, and antioxidant properties. Utilizing LB powder highlights its potential for sustainable insect farming, addressing environmental concerns, and enhancing resource sustainability.