The Effects of Ethylene and 1 - Methycyclopropene on Pericarp Browning of Postharvest Lychee Fruit

Although ethylene treatment significantly enhanced the polyphenoloxidase (PPO) and peroxidase (POD) activity of lychee pericarp, and to some extent, enhanced the respiratory rate and ethylene production, it did not affect markedly the pericarp browning index and chemical composition of lychee fruit. 1-methycyclopropene (1-MCP) treatment did not significantly affect the PPO and POD activity, respiratory rate, ethylene production and chemical composition of lychee fruit. The results imply that the pericarp browning of postharvest lychee fruit is an unsusceptible physiological process to ethylene and cannot be simply attributed to enzymatic browning catalyzed by PPO and POD.