Critical taste substances and regulatory pathways of fresh lotus seed pulps at different ripeness stages

Abstract

Previous reports about measuring flavor substances in lotus seeds focus on the nutritional quality. Currently, no research is devoted to the taste quality of lotus seeds. In this study, fresh lotus seeds' pulp at different ripeness stages was used to explore the critical taste substances and related regulatory pathways affecting the suitability of lotus seeds for fresh eating. Sweetness and umami were the basic flavors of low maturity, and astringency mainly existed in high maturity fresh lotus seeds. Fructose is a crucial factor affecting the suitability of fresh lotus seeds. During the ripening of lotus seeds, the increase of fructokinase (FRK) activity and related gene expression caused the decrease in fructose content. In contrast, the decrease in phosphoenolpyruvate carboxylase (PEPC) and NAD-malate dehydrogenase (NAD-MDH) activity was related to the decline of malic acid content in low maturity lotus seeds. The present study revealed the crucial taste substances and regulatory pathways of lotus seeds, which laid a theoretical foundation for the study of the taste formation mechanism of fresh lotus seeds.