Proximate composition and lipid nutritional indices of larvae and pupae of the edible Huhu beetle (Prionoplus reticularis) endemic to New Zealand

Abstract

The proximate composition, fatty acid profile, and lipid nutritional indices of the edible Huhu grub development stages (small, medium, large larvae, and pupae) of the New Zealand endemic beetle (Prionoplus reticularis), were investigated. Ash (1.5–3.2%, dry weight (DW)) and crude protein (26.2 – 30.5%, DW) contents were similar across the development stages. Lipid content was highest in pupae (58.4%, DW). Between 10 and 13 fatty acids were found in each of the four development stages. Palmitic acid (7.45 – 13.95 g/100 g DW), oleic acid (22.04 – 40.54 g/100 g DW), and linoleic acid (0.82 – 1.47 g/100 g DW) were the most abundant saturated fatty acid (SFA), monounsaturated fatty acid (MUFA), and polyunsaturated fatty (PUFA) acid, respectively. The PUFA/SFA ratio ranged from 0.07 to 0.09, while the ω6/ω3 ratio ranged between 16.23 and 29.54. The hypocholesterolemic/hypercholesterolemic acid ratio ranged from 2.89 to 3.15. The atherogenicity indices ranged between 0.32 and 0.37, the thrombogenicity index range was 1.63 – 1.99, and the health-promoting index range was 0.07 – 0.11. Overall, the results of this study indicate that Huhu grub larvae and pupae contain relatively high levels of lipids, but they differ in their fatty acid profile and lipid nutritional indices.