Germination-induced changes in anthocyanins and proanthocyanidins: A pathway to boost bioactive compounds in red rice

This study aimed to investigate the specific changes in the anthocyanins and proanthocyanidins content of red rice during germination. Different methods including chemical detection, UPLC-QToF/MS, and metabolite analysis were used to examine these changes. The findings showed a significant increase in the overall levels of polyphenols and pigments in red rice as the germination period advanced. Specifically, the proanthocyanidins being the predominant pigments showed a significant increase during later stages of germination. Whereas, the anthocyanin levels reached their peak after 12 h of germination and subsequently declined. Furthermore, six anthocyanins and three proanthocyanidins were identified among the pigment constituents. Additionally, several significant precursor substances associated with pigments were identified, and their contents showed a significant increase, indicating that the proanthocyanidin synthesis pathway is activated by germination. These dynamic changes suggest that germination effectively stimulated the synthesis and accumulation of both anthocyanins and proanthocyanidins, thereby improving the nutritional value of red rice.