Low-concentration ascorbic acid dips to prevent pericarp browning of ‘Daw’ longan fruit during storage

Abstract

Ascorbic acid (AsA) plays an important role in protection against oxidative stress in plants. It either directly detoxifies reactive oxidative species or indirectly stimulates antioxidant defence systems. This study evaluated the potential of AsA at low concentrations to reduce oxidative membrane damage and prevent pericarp browning of 'Daw' longan fruit. Fresh fruit were dipped in 0 (control), 1, 2.5 and 5 mM AsA for 5 min and stored at 25±1°C and 82±5% relative humidity for 6 days. All concentrations of AsA reduced pericarp browning (browning index, L* and b* values), polyphenol oxidase (PPO) and peroxidase (POD) activities during 5 days of storage. Membrane integrity (electrolyte leakage (EL) and malondialdehyde content) of longan was retained for 4 days. AsA at concentrations of 1 and 2.5 mM were most effective in reducing pericarp browning and extending shelf-life from 1 to 4 days compared with the control. Thus postharvest application of low-concentrations of AsA could be an effective method for protecting pericarp browning by reducing the activities of PPO and POD and maintaining membrane integrity of 'Daw' longan fruit during storage at 25±1°C.