Influence of Dietary Protein Content on the Nutritional Composition of Mealworm Larvae (Tenebrio molitor L.)

Abstract

The use of insects as livestock feed is becoming increasingly accepted because they provide an important source of protein. The purpose of this study was to investigate the chemical composition of mealworm larvae (Tenebrio molitor L.) reared on a range of diets that differed in nutritional composition. Focus was placed on the influence of dietary protein content on larval protein and amino acid composition. For the experimental diets, wheat bran was chosen as the control substrate. The following types of flour-pea protein, rice protein, sweet lupine, and cassava, as well as potato flakes, were mixed with wheat bran and used as the experimental diets. An analysis of the moisture, protein, and fat content was then carried out for all diets and larvae. Furthermore, the amino acid profile was determined. It was shown that supplementing the feed with pea and rice protein was most suitable in terms of high protein yield in larvae (70.9–74.1% dry weight) with low fat content (20.3–22.8% dry weight). The total amino acid content was highest in larvae that were fed with a mixture of cassava flour and wheat bran (51.7 ± 0.5% dry weight), as well as the highest content of essential amino acids (30.4 ± 0.2% dry weight). Moreover, a weak correlation between larval protein content and diet was identified, yet a stronger influence of dietary fats and carbohydrates on larval composition was found. This research could result in improved formulations of artificial diets for Tenebrio molitor larvae in the future.

Innovative Applications of Tenebrio molitor Larvae in the Production of Sustainable Meat Sausages: Quality and Safety Aspects

“…Kröncke et al study results have shown that freeze-drying mealworms leads to significantly higher oxidation compared to other drying methods [117]. Contrarily, our findings did not show a statistical difference; however, sausages containing dried larvae exhibited a higher peroxide level than those with lyophilized larvae.…”

Fatty Acid Profile and Escherichia coli and Salmonella sp. Load of Wild-Caught Seaweed Fly Fucellia maritima (Haliday, 1838) (Diptera: Anthomyiidae)

“…The lower levels of fats in F. maritima might be an indication of high protein content, as it occurs in other insects species [ 21 ]. For instance, when supplemented with a diet rich in protein, T. molitor shows a higher protein content with a lower fat content than when supplied with a control diet [ 22 ].…”

Exploiting Agri-Food Waste as Feed for Tenebrio molitor Larvae Rearing: A Review

“…In addition, the growth, development, and subsequent nutritional value of the feed substrate are of great importance. TM larvae are recommended to be reared on starchy substrates, mainly flour and wheat bran [28,[70][71][72]. However, many studies have been carried out recently that examined the inclusion of other products as constituents in the rearing of TM larvae.…”

“…In particular, its protein content ranges from 13.7 to 60.2% [19,20], whereas its fat content fluctuates from 17.0 to 40.0% [21,22]. Furthermore, it boasts all of the EAAs (histidine (His), isoleucine (Iso), leucine (Leu), lysine (Lys), methionine (Met), phenylalanine (Phe), threonine (Thr), tryptophan (Trp), and valine (Val)) [23][24][25][26][27][28] and EFAs (myristic acid (C14:0), palmitic acid (C16:0), palmitoleic acid (C16:1), and omega-9 oleic acid (C18:1)) [29][30][31][32][33][34][35]. Last but not least, the following minerals have been identified and quantified in TM: 1.0% phosphorus (P) [36], 0.5% calcium (Ca) [20], 0.4% sodium (Na) [37], 1.6% magnesium (Mg) [20], 1.0% potassium (K) [37], 100.02 mg/kg of iron (Fe), 117.4 mg/kg of zinc (Zn), and 20.0 mg/kg of copper (Cu) [36].…”