Membrane deterioration, enzymatic browning and oxidative stress in fresh fruits of three litchi cultivars during six-day storage

A comparative study of membrane deterioration, enzymatic browning and oxidative stress of three litchi cultivars, namely ‘Feizixiao’, ‘Heiye’ and ‘Xiangli’, was carried out. During 6-d storage at room temperature, pericarp browning index and disease rate of ‘Feizixiao’ were highest. The increasing rate of relative electrolyte leakage of ‘Feizixiao’ rose most rapidly. The relative phospholipase D activity significantly increased for ‘Feizixiao’ but insignificantly changed for ‘Heiye’ and ‘Xiangli’. The relative acid phosphatase activity increased for ‘Feizixiao’ but decreased for ‘Heiye’ and ‘Xiangli’. On day 6, ‘Feizixiao’ exhibited the lowest relative contents of browning substrates (−)-epicatechin and procyanidin A2. Furthermore, on day 6, ‘Heiye’ presented the highest relative activities of peroxidase, ascorbate peroxidase and superoxidase dismutase, but ‘Feizixiao’ possessed weak activities of antioxidant enzymes (especially ascorbate peroxidase). Thus, among three cultivars, membrane integrity of ‘Feizixiao’ broke down most seriously because of its increasing PLD and ACP activity during 6-d storage. The most browning substrates in ‘Feizixiao’ were consumed due to conversion into quinones by polyphenoloxidase catalysis. Senescence and deterioration of ‘Feizixiao’ were most grave under postharvest oxidative stress.

► Postharvest biochemical differences of three litchi cultivars were compared.
► Pericarp browning and disease development of ‘Feizixiao’ were rapidest.
► ‘Feizixiao’ exhibited highest phospholipase D activity.
► Most substrates in ‘Feizixiao’ were consumed by polyphenoloxidase catalysis.
► ‘Feizixiao’ possessed weak activities of antioxidant enzymes.