Effects of postharvest storage conditions on phytochemical and radical-scavenging activity of pomegranate fruit (cv. Wonderful)

Abstract

This study was conducted to investigate the effects of storage temperature and duration on phytochemical and antioxidant properties of pomegranate fruit (cv. Wonderful). Commercially ripe fruit were stored at 5±0.7°C, 7.5±0.3°C, 10±0.5°C with 92±2% relative humidity (RH) and 21±3°C with 65±6% RH for 5 months. Fresh pomegranate juice was assessed for concentrations of total phenolic compounds (TP), total anthocyanin (Acy) ascorbic acid. The radical-scavenging activity of fruit juice was tested against 2, 2-diphenyl-1-picryl hydrazyl (DPPH). The investigated parameters differed significantly (p<0.05) at different temperatures and duration. Results showed that TP increased with storage temperatures and duration with the maximum levels measured at 10°C (364.47mg/100ml) for 3 months storage period. However, the concentration declined thereafter at all storage regimes, the lowest concentration was 196mg/100ml in fruit stored at 7.5°C for 5 months. Similarly, Acy concentration increased with storage temperatures in the first month, and gradually declined thereafter. Furthermore, ascorbic acid concentration gradually declined with storage period, with the lowest concentration (12.69mg/100ml) measured at 7.5°C after 5 month storage. For antioxidant activity, storage of fruit at 5°C, 7.5°C, and 10°C significantly (p<0.05) reduced the radical scavenging activity of juice by more than 56% when stored beyond 2 months. This study highlights the need to consider the effects of different temperatures and duration on health promoting compounds in pomegranate fruit, especially where fruit are stored for long term and primarily used for health-promoting purposes.