Optimizing slaughter and drying methods to improve the quality of <i>Tenebrio molitor</i> and <i>Zophobas morio</i> powder

Purpose Acknowledging the critical role of processing in determining the final quality of T. molitor and Z. morio flours, this study aimed to assess the effects of different slaughtering methods (boiling, steaming, freezing, nitrogen, microwave and dehydrator) and drying methods (dehydrator and oven) on the nutritional composition, yield and colour characteristics of these insect-based products. Design/methodology/approach This study investigated the combined effects of six slaughtering methods (boiling, steaming, freezing, nitrogen, microwave and dehydrator) and two drying methods (dehydrator and oven) on the yield, nutritional composition and colour attributes of flours produced from Tenebrio molitor (Coleoptera: Tenebrionidae) and Zophobas morio (Coleoptera: Tenebrionidae). Larvae were processed in a factorial arrangement (6 × 2) and analysed for dry matter, crude protein, ether extract, ash, mineral content and colour parameters. Findings The slaughter and drying methods significantly influenced T. molitor and Z. morio larvae flours. In T. molitor, interactions affected dry weight, flour yield, dry matter, minerals and colour, with boiling + stove and steaming dehydrator being the most efficient combinations. Nutrient and mineral retention varied depending on treatment, highlighting the potential for tailored nutritional profiles. For Z. morio, slaughter methods had stronger effects than drying, with thermal processes yielding higher quality flours. Stove drying enhanced protein and micronutrient retention, while the dehydrator favoured macronutrients. Colour was markedly influenced, with thermal methods producing lighter, more appealing flours. Originality/value The innovation of this work lies in the integrated evaluation of slaughter and drying combinations, using a factorial design that allows the identification of optimal processing routes for each species. Our results have direct application in the edible insect industry, offering sustainable and cost-effective processing alternatives, especially relevant for producers in regions where high-energy processing methods (e.g., freeze-drying) are economically unviable. This is the first comprehensive study to systematically compare multiple slaughter and drying combinations for these two commercially important species, linking technological parameters with market-relevant quality characteristics.