Effects of physical sterilization on microbial safety, nutritional composition, and antioxidant activity of queen bee larva powder, a by-product of royal jelly production

Abstract

Queen bee larvae (QBL), a by-product of royal jelly production, have nutritional value and confer health benefits. The commercialization of QBL is hindered because of the lack of evidence for its nutrition and safety parameters. Thus, this study was conducted to investigate the microbial dynamics, nutritional composition, and antioxidant activity of QBL, aiming to assess its potential as a food product. Lyophilized QBL powder samples were sterilized through gamma irradiation and high-pressure processing at varying doses and pressures. Gamma irradiation at 10 and 15 kGy effectively reduced the total aerobic count to 0, whereas high-pressure processing led to no significant reduction. Regarding the microbial profile of QBL, 16S rDNA gene sequencing unveiled five bacteria—Acinetobacter pittii, Bacillus thuringiensis, Enterococcus mundtii, Enterococcus faecalis, and Fructobacillus fructosus—but no major foodborne pathogens. Lactobacillus, Bombella, and Fructobacillus emerged as the predominant genera in QBL, with low abundances of Staphylococcus and Escherichia. Proximate composition analysis indicated no significant postirradiation changes in macronutrient contents; notably, protein was the predominant component (approximately 48.0%). Sugar and amino acid analyses revealed essential nutrients meeting human dietary requirements. Upon fatty acid analysis, palmitic and oleic acids emerged as predominant fatty acids. Gamma irradiation at 10 kGy exerted no significant effect on the nutritional composition or antioxidant activity of QBL. Our study provides valuable insights into the microbial safety and nutritional value of QBL, indicating its potential as a dietary protein source with favorable microbiota.