Phytochemicals accumulation in Sanhua plum ( Prunus salicina L.) during fruit development and their potential use as antioxidants.

This study followed the flesh reddening of Sanhua plum from the surface to the center during fruit development. Five key stages were identified based on colour changes during fruit ripening full-green (FG), red-appeared (RA), half-red (HR), full-red (FR) and purple-red (PR). Fruits were collected and analyzed for phytochemicals and antioxidant properties. Concurrently, the transcript levels of genes associated with phenolic, flavonoid and anthocyanin production were investigated. The titratable acid (TA) content of Sanhua plum decreased during development, while total soluble sugar (TSS) content increased. In addition, both the total phenolic content (TPC) and total flavonoid content (TFC) decreased during development, while anthocyanin content increased. The polyphenol oxidase (PPO) activity peaked at PR stage. The maximum antioxidant activity in vitro was observed at FG stage, while cellular antioxidant activity peaked at PR stage.