Nutritional Composition of Tenebrio molitor Larvae Reared on Substrates Derived from By-Products

Abstract

The larvae of Tenebio molitor are increasingly recognized as a sustainable protein source, offering a potential solution to the challenges of food waste, essential amino acids, omega acids, and unsaturated fatty acids [1]. In pursuit of economic, safe, and sustainable practices, there is a growing interest in rearing mealworms using by-products from production and agriculture. The impact of these by-products on mealworms varies based on the chosen raw materials and their proportions [3]. Our study aims to identify local by-products or food residues suitable for mass larval production, specifically focusing on sprouted and green potatoes, wheat bran, and by-products from brewers' production as a comprehensive substrate for rearing mealworms. Conducted at the "DIVAKS" company in Lithuania, the larvae were grown, lyophilized, and subjected to tests in an accredited laboratory. The results showed that the highest protein content (59.18 ± 0.07 %) was observed in samples grown on brewers' spent grain, while wheat bran yielded the highest fat content (34.22 ± 0.491 %). The amount of FAs in the larvae was influenced by the substrate used, with variations in monounsaturated, omega-3, and oleic acids. Notably, wheat bran showed the highest content of total polyunsaturated FAs (36.23 %). In the analysis of 16 distinct amino acids, a sample with brewers' spent grain, consistently demonstrated the highest content in 11 instances. This adaptation renders the larvae suitable for diverse purposes, including animal or human nutrition and health enhancement. In conclusion, our study underscores the significance of substrate optimization in harnessing the full potential of Tenebio molitor larvae for targeted applications.