A Study On Postharvest Physiology And Storage Techniques Of Vegetable Soybean

The main physiological changes of vegetable soybean (Glycine max cv. Nannong NO.2) stored at different temperatures and the effects of chitasan coatings, 1-methylcyclopropene (1-MCP) and methyl jasmonate (MJ) treatments on postharvest senescence, decay incidence and quality changes were investigated. The results were as follows:1. The chlorophylK Vc and reducing sugar contents decreased while the weight loss, membrance permeability and MDA content increased rapidly during the first 30 days of storage, followed by a rapid increase in decay index during the later days of storage. Low temperatue inhibited the respiratory rate, weight loss and decay incidence, maintained lower levels of membrane pereability and MDA content but higher levels of chlorophylK Vc and reducing sugar contents, thereby delaying the senescence process and quality loss and prolonging the storage life of vegetable soybean.2. 1.0 % and 1.5 % chitosan coating significantly inhibited respiratory rate, weight loss, PPO and POD activities, maintained lower levels of membrane permeability, MDA content, Vc and reducing sugar content, promoted PAL activity and lignin synthesis, inhibited decay incidence, thereby prolonging the storage life of vegetable soybean.3. Treatments with 1-MCP (0.5 u 1/L, 1 |u 1/L, 2 M 1/L) significantly inhibited the senscence process of harvested vegetable soybean pods, as manifested in lower levels of ethylene production, respiratory rate, MDA and superoxide contents and higher levels of SOD, ASA-POD activities, Vc and chlorophyll contents. Moreover, 1 -MCP promoted PAL, POD activities and lignin synthesis, inhibited decay incidence. High concentration of 1-MCP (2 M 1/L) treatment, however, inhibited PAL, POD activities during the later period of storage, thereby increasing decay incidence.4. Treatments with methyl jasmonte (1 umol/L, 10nmol/L) slowed the snescence process of postharvest vegetable soybean pods, as manifested in lower levels of ethylene production, respiratory rate, MDA and superoxide contents, and higher levels of SOD activity, Vc and chlorophyll contents. MJ treatment significantly promoted PAL, POD activities and lignin contents, which might account for higher disease resistance and lower decay index in MJ treated pods.5. Vegetable soybean seeds contained 32.82%(dry base) protein, 24.55%(dry base) crude fat and 16.92mg/100g FW vitamin C. 1-MCP and MJ treatments maintained higher levels of protein, amino acid and Vc contents as well as higher value of amino acid score throughout the whole storage period, but had little effect on crude fat content.