Flavonoids‑targeted metabolomic analysis following rice yellowing

Flavonoids are the main metabolites responsible for yellowing of rice. However, the accumulation pattern of flavonoids and the metabolic basis of flavonoid biosynthesis during rice yellowing remain unclear. Thus, flavonoid-targeted metabolomics was used to investigate the composition and concentration of flavonoids in rice during yellowing. The results indicated the differential flavonoids at Month 3 and Month 5 of storage were more in composition and concentration with higher antioxidant capacity. Accumulated flavonoids were mainly flavones, flavonols, isoflavones, and anthocyanidins, of which rutin, farrerol, naringenin, cyanidin 3-rutinoside, and diosmetin were the indicators of rice yellowing. Metabolic association among flavonoids demonstrated the formation of yellow pigments was jointly induced by flavones, flavonols, isoflavones, and anthocyanidins metabolism. Examination of flavonoid metabolism presented in this study enhanced current understanding of the relationship between flavonoid metabolites and development of rice yellowing. It also offers a theoretical basis for targeted prediction of rice yellowing in the future.