The Nutritional Quality and Structural Analysis of Black Soldier Fly Larvae Flour before and after Defatting

SIMPLE SUMMARY: The increasing global population and consumer demand for protein will render the provision of protein a serious future challenge, thus placing substantial pressure on the food industry to provide for the human population. The lower environmental impact of insect farming makes the consumption of insects such as black soldier fly larvae (BSFL) an appealing solution, although consumers in developed countries often respond to the idea of eating insects with aversion. One approach to adapt consumers to insects as part of their diet is through the application of making insect-based products in an unrecognized form. Nutritional value and structural properties of the BSFL flours (full fat and defatted) were assessed. Defatted as well as full-fat flour both displayed good nutritional and structural characteristics for use in many food applications. ABSTRACT: This study aimed to assess the nutritional information and structural overview of the BSFL (black soldier fly larva) flours (full fat and defatted). The BSFL flours were obtained by freeze-drying the larvae and the removal of fat using hexane and isopropanol ratio of 3:2 (v/v), these solvents were used due to their defatting efficiency and because they are less toxic. Nutritional and structural analyses were conducted using standard methods. The full-fat and defatted flours had high protein content (45.82% and 56.11% respectively). Defatting significantly (p < 0.05) increases the protein content by approximately 10%, while the fat content decreased from 25.78% in full-fat larvae to 4.8% in defatted larvae. The compositional data were qualitatively confirmed with Universal Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (UATR-FTIR) mainly in the amide I and II regions. Thermal gravimetry (TG) and differential scanning calorimeter (DSC) analysis, showed the conformational physical changes induced due to removal of fat which affected protein denaturation. DSC analysis displayed curves of both endothermic and exothermic reactions. During the first heating program, both samples had wide endothermic heating peaks ranging from 42 to 112 °C, which may be attributed to the water content in the samples evaporating. The first stage of the decomposition process was important, with loss of free and loosely bound water up to 150 °C, according to TGA curves. Protein and carbohydrates volatilized during the second stage of decomposition. The third level may be linked to polypeptide decomposition. FTIR revealed that the defatting process induced structural modifications on the amide I (1650 cm(−1)) and amide II (1540 cm(−1)) regions. Defatting has a significant effect on the functional groups and nutritional value of the BSFL. Defatted as well as full-fat flour both show good nutritional and structural characteristics for use in many food applications, however the improved proximate composition of the defatted BSFL can be applied to food products using BSFL flour as an alternative ingredient.