Influence of postharvest chitosan treatment on enzymatic browning and antioxidant enzyme activity in sweet cherry fruit

• Chitosan fruit coating significantly reduced decay in sweet cherry.
• Sweet cherry fruit treated with chitosan showed high PPO and POD activities.
• Chitosan coating delayed cell membrane damage.
• Chitosan coating enhanced the activities of antioxidant enzymes.

The effectiveness of chitosan fruit coating to delay the onset of senescence in three sweet cherry (Prunus avium L.) cultivars “Ferrovia”, “Lapins”, and “Della Recca” as well as its effect on antioxidant enzymes involved in the balancing of the reactive oxygen system (ROS), were evaluated. Fruit were dipped for 60 s into a 0.5% chitosan solution, stored at 2 °C for 14 days and sampled at harvest, 7 and 14 days of cold storage. At each sampling date, subsamples were maintained for 3 days at 24 °C to assess the shelf life of the fruit. Malondialdehyde content and some enzymatic activities such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), polyphenol oxidase (PPO), guaiacol peroxidase (POD) and lipoxygenase (LOX) were evaluated. Chitosan treatment enhanced the activity of some antioxidant enzymes, including SOD and APX. The treatment inhibited PPO and POD activities, preventing flesh-browning and extending storage life of sweet cherry fruit. In addition, chitosan treatment also maintained membrane integrity by delaying LOX activity LOX and malondialdehyde accumulation. A multivariate statistical approach including a principal component analysis provided a global view of the response of the three sweet cherry cultivars to chitosan coating and storage temperature. Chitosan-coated fruit showed a lower decay both at 2 °C and 24 °C than the uncoated fruit. In “Della Recca” fruit, membrane preservation and antioxidant enzyme system resulted higher than in “Ferrovia” and “Lapins”.