Effect of fruit maturity and growing location on the postharvest contents of flavonoids, phenolic acids, vitamin C and antioxidant activity of pomegranate juice (cv. Wonderful)

Pomegranate fruit (Punica granatum L.) production and consumption has increased recently due to increasing scientific evidence on its high content of health beneficial compounds. This study was conducted to investigate the phytochemical contents and antioxidant activity of pomegranates (cv. Wonderful) as affected by fruit maturation and growing location. High performance liquid chromatography (HPLC) coupled with liquid chromatography mass-spectrometry (LC-MS) and liquid chromatography mass-spectrometry electroscopy (LC-MSE) were used to analyse phenolic composition at different maturity stages. Catechin, epicatechin and naringin were the most dominant flavonoids irrespective of maturity and altitude, while gallic acid was the dominant phenolic acid. The concentrations of total phenolics and total tannins as well as radical scavenging activity (RSA) in DPPH assay declined as maturity advanced while ferric reducing antioxidant power (FRAP), total anthocyanin, total flavonoid and vitamin C increased significantly (P< 0.01). There was a significant and negative correlation (r= -0.64) between total phenolic content and antioxidant activity in the FRAP assay. Principal component analysis (PCA) showed that fruit grown in area with lower altitude were associated with higher bioactive compounds at full ripe stage. Furthermore, PCA plot also revealed that fruit growing location had a significant and prominent impact on the bioactive compounds than maturity status.