Development of a post-processing method to reduce the unique off-flavor of Allomyrina dichotoma: Yeast fermentation

Allomyrina dichotoma larva is an edible insect that has been consumed in East Asia for centuries. A. dichotoma is suitable for insect farming due to its numerous health benefits and advantages in industrial production. However, its market share is very poor due to their unique off-flavor, which negatively affects consumer preferences. So far, only one study has reported an effective method for reducing the unique off-flavor of A. dichotoma larvae. In this study, to reduce the off-flavor without increasing larval mortality, we inoculated Saccharomyces cerevisiae W-3, which is a wine fermentation yeast strain, in processed larva powder and investigated changes in volatiles. In the fermented larva powder, the intensity of indole, which has a strong fecal odor, decreased to 1/12. In addition, fruit-flavored volatiles such as ethyl acetate, isopentyl acetate, and 2-butanone increased by 17, 13, and 4 times, respectively. To provide clues for understanding the mechanisms by which volatiles change, we performed network analyses. Our yeast fermentation method can be used as a post process to reduce the off-flavor and improve the overall flavor of A. dichotoma larvae.