Determination and characterisation of the function of black soldier fly larva protein before and after conjugation by Maillard reaction

Abstract

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 application of making insect-based products in an unrecognised form. Nutritional value and structural properties of the BSFL flours (full fat and defatted) were assessed. The BSFL flours were obtained by freeze drying and by the removal of fat using hexane and isopropanol solvent (at ratio 3:2 v/v). The nutritional analysis (protein, fat, fiber, ash and moisture) and structural analysis (Universal Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (UATR-FTIR), Thermal gravimetry (TG) and Differential scanning calorimetry (DSC) were carried out using standard methods proposed by Association of Official Analytical Chemists (AOAC). This part of the study has shown that the defatted BSFL flour holds good nutritional value and enhanced structural properties, therefore can be incorporated into food products. Thereafter, the defatted flour was subjected to an alkaline protein extraction procedure. The protein functional properties were improved by inducing the Maillard reaction in protein-carbohydrate mixtures. An aqueous solution of the protein alone and protein:glucose (2:1 w/w, pH 9) mixtures were heated at 50, 70 and 90 °C for 30, 60, 90, and 120 min. The products obtained were then characterised and compared. The pH and zeta potential change were monitored. The protein extract displayed a good essential amino acid (EAA) profile. UATR-FTIR was able to discriminate between glycated and non-glycated proteins, when the data were analysed by the multivariate statistical method, principal component analysis (PCA). FTIR, TGA, DSC and Scanning electron microscopy (SEM) analysis indicated the formation of Maillard reaction products (MRP). The thermal stability results suggested that the Maillard reaction with the incorporation of glucose can be a promising way to improve the properties of the BSFL protein.