Abstract:Harvested longan is susceptible to pericarp browning, which is the most important factor affecting the quality and shelf-life of harvested longan. Heat treatment is an environment-friendly postharvest physical treatment, which can delay senescence and maintain quality of harvested fruits and vegetables. Effects of heat treatment on browning and phenolics metabolism in pericarp of harvested longan (Dimocarpus longan Lour.) were investigated in this paper. The harvested ‘Fuyan’ longans were treated with hot water at 50 ℃ for 10 minutes. Then they were dried, packaged and stored at (15?1) ℃. During storage, browning index, total phenolics content, activities of phenylalanine ammonialyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD) in pericarp of harvested longan were determined. The results showed that as compared to the control fruits, the treatment with hot-water effectively reduced browning index, decreased PPO and POD activity, increased PAL activity, and remained higher total phenolics content in pericarp of harvested longan. Therefore, hot water treatment at 50 ℃ for 10 minutes can effectively reduce phenolics metabolism, thereby delaying the occurrence of browning in pericarp of harvested longan.
