Sesame cake diet enhances the nutritional value of Tenebrio molitor (mealworm)

Mealworms (MWs) are a potentially environment-friendly, nutrient-rich, alternative food source. MWs can be fed various food by-products, including sesame cakes, a by-product of sesame oil. We studied the impact of a sesame cake diet on the nutritional value of MWs, specifically to determine the possibility of the transfer of nutritional value through feed sources. MWs were fed diets containing wheat bran-based substrates with different percentages of sesame cake (0, 10, 30, and 50%). A correlation between the nutrient composition of MWs and concentration of sesame cakes in their diets was observed. In addition, the ferric reducing antioxidant power and 2,2-diphenyl-1-picryl-hydrazyl radical scavenging activity increased by 53% and 29%, respectively, in MWs fed a 50% sesame cake diet compared with those in MWs not fed with sesame cakes. Furthermore, an increase in sesame cake concentration enhanced the biological activity of MWs fed with sesame cake, such as the inhibition of lipolysis and α-glucosidase; particularly in MWs fed with a 50% sesame cake diet, the efficacy of these processes increased by 1.2- and 1.3-fold, respectively, compared with those in MWs not fed a sesame cake diet. To assess these changes, the profiles of MW compounds were analysed using liquid chromatography-tandem mass spectrometry, where MWs fed with 50% sesame cake diets and those not fed sesame cake diets were compared. Choline content in MWs fed sesame cakes was high. Our results indicate that a sesame cake diet enhances the nutritional and economic values of MWs, validating their use as an alternative food source.