Saturated fatty acid-enriched diets in Tenebrio molitor larvae: effects on growth performances and nutritional...

The nutritional composition of insects is presumed to be closely related to their diet, triggering a growing interest in investigating this aspect due to their versatility and ability to use a wide range of byproducts. The nutritional profile of Tenebrio molitor larvae (mealworm) is characterized by a high amount of fats, composed mainly of mono- and polyunsaturated fatty acids (MUFAs and PUFAs). This study aimed to investigate the effect of dietary saturated fatty acids (SFAs) on the fatty acid profile of mealworms. Six substrates were formulated by mixing different ratios of wheat bran (used as control, CTRL) and fully hydrogenated rapeseed oil (FHRO), rich in stearic acid (C18:0, 91%) in different ratios. Larvae near the last instar were fed for 2 weeks with the substrates. Mealworms were sampled at 0, 7, 11 and 14 days into the experiment. Rearing performances of mealworms along with proximate analysis and fatty acid profile were assessed.

The average weight and growth rate of CTRL larvae were lower than those of larvae fed diets with intermediate FHRO inclusion. Substrates with the highest lipid content were converted less efficiently, as highlighted by the feed conversion ratio. Augmenting the FHRO resulted in a significant increase in the total lipids and a decrease in the crude protein content. Levels of PUFAs decreased, whereas C18:0 and SFAs increased significantly. Due to the plasticity of mealworms, our results confirm that substrate is one of the main factors for obtaining feed and food products which can meet different requirements. © 2025 Society of Chemical Industry.