Functional Chemical Components in Protaetia brevitarsis Larvae: Impact of Supplementary Feeds

The goal of this study was to evaluate the influence of various supplementary feeds on the chemical composition and production of bioactive substances in Protaetia brevitarsis larvae. The primary feed—oak-fermented sawdust—was supplemented with a variety of substances, including aloe, apple, banana, sweet persimmon (S. persimmon) and sweet pumpkin (S. pumpkin). Crude protein and fat content were the highest in the control and S. pumpkin group, respectively. Supplementary feeds increased the content of unsaturated fatty acids, except in the group receiving S. pumpkin, in which oleic acid was the most abundant (58.2%–64.5%). Free essential amino acids in larvae receiving supplementary aloe were higher compared with the control group except for Lys and His. Polyphenol and flavonoid contents and the antioxidant activities of ABTS and DPPH were higher in all treated groups compared with the control group. Although supplementary feeds led to a decreased crude protein content in the treated larvae when compared with the control group, these treatments generally improved the levels of unsaturated fatty acids and antioxidative activity. Therefore, we suggest that among the supplementary foods tested, aloe is a better resource for P. brevitarsis based on crude protein content, free amino acids and other bioactive compounds such as unsaturated fatty acids and antioxidants.