Effect Of Different Preservation Treatments On Postharvest Physiology And Quality Of Sponge Gourd And Bitter Melon

Sponge gourd and bitter melon are all of gourd vegetables, and they are the main vegetable varieties in summer and fall in China. However, they are perishable and have a relative short shelf life after harvest. In ambient temperature, sponge gourd losses water severely and the deterioration of fruit quality associated with yellowing and wilting in skin and fibrosis in pulp makes the loss of commodity values; Bitter melon turns yellow in postharvest2-3days, and the deterioration of fruit quality associated with turning red of seed coat makes the loss of edible values. Low temperature storage can suppress respiration, reduce decay rate and disease incidence, and prolong storage period of fruits and vegetables. However, sponge gourd and bitter melon are chilling sensitive and low temperature storage easily lead to chilling injury. This study was designed on the causes of quality deterioration of sponge gourd and bitter melon. Sponge gourds were treated with chitosan in ambient temperature and salicylic acid (SA) in low temperature, while bitter melons were treated with1-MCP in room temperature. The objectives of this study were to examine the effects of chitosan on postharvest preservation of sponge gourd in ambient temperature, the effects of salicylic acid on chilling injury of sponge gourd in low temperature, and the effects of1-MCP on ripening and senescence of bitter melon. The main results were as follows:(1) Chitosan coating could reduce respiration rate and weight loss, decrease the increase of firmness and cellulose content, and delay the decomposition of chlorophyll and the loss of ascorbic acid (AsA) content of sponge gourd.(2) Chitosan coating could spppress the increase of PAL, PPO and POD activities and thereby delay the fibrosis of sponge gourd, we obtained that1.0%chitosan was the best for preservation of sponge gourd..(3) The1.5mmol/L SA treatment significantly reduced postharvest chilling injury of sponge gourd, suppressed the increasing trend of relative electrolytic leakage MDA content, retarded the membrane lipid peroxidation, and enhanced membrane integrity.(4) The1.5mmol/L SA treatment significantly increased the activities of CAT and APX, inhibited the increase of total phenolics content, retarded the increase of PPO and PAL activities, and thereby inhibited the enzymatic browning of sponge gourd.(5) Decay and yellowing of bitter melon were inhibited when the does of1-MCP reached5.0uL/L, and the application of1-MCP significantly delayed the decrease of firmness, AsA and soluble protein contents, prolonged the storage period and maintained the nutrition and flavor of bitter melon.(6) Although the peak of ethylene production and respiration rate could not be delayed, their contents were markedly decreased by1-MCP.