Effect of Postharvest Calcium and Hot-water Dip Treatments on Catalase, Peroxidase and Superoxide Dismutase in Chilled Lisbon Lemon Fruit

摘要

Lisbon lemons [ Citrus limon (L.) Brum.] harvested early in the season (green stage) were treated with hot-water dip (HWD, 53?°C, 3 min) or vacuum infiltration with 1.5% CaCl2 (15?°C, -33 kPa, 10 min) prior to storage at 1.5?°C for up to 8 weeks, to determine the effect of these treatments on the Chilling Injury (CI) and activities of Catalase (CAT; EC 1.11.1.6.), superoxide dismutase (SOD; EC 1.15.1.1.) and Peroxidase (POD; EC 1.11.1.7.), as well as Malondialdehyde (MDA) content. The decrease of CAT and SOD, accompanied with the increase in POD activities during cold storage, might contribute to the development of CI in lemon fruits. HWD and Ca treatments similarly reduced CI and delayed the reduction of CAT, SOD and suppressed the increase in POD activities as well as MDA content compared to the control. CAT activity in fruits exposed to these treatments before cold storage increased and remained higher in the treated fruits than in the non-treated fruits over the storage period. The data indicate that CAT may be a major antioxidant enzyme involved in the defense of lemon fruits against chilling stress. Lemons harvested at the late maturity (yellow) stage had significant higher CAT, SOD and lower POD activities compared to the early maturity (green) stage. Collectively, results indicate that the chilling-tolerant property of lemon fruits may be related to the higher ability of fruits to have or maintain high CAT, SOD and low POD activities during low temperature storage.