Effects Of Cold Shock And Heat Shock Treatments On Senescence Physiological Properties Of Fresh-cut Vegetables

Preservation effects and antioxidative mechanisms of cold shock and heat shocktreatments on different fresh-cut vegetables were investigated to promote theirpractical application. Four kinds of vegetables with different physiological andecological characters (pepper, cabbage, onion and carrot) were fresh-cut and treatedby different cold shock and heat shock treatments, then stored at20°C. Sensoryquality of different treatments was compared. Senescence physiological indicators(weight loss, soluble sugar, soluble protein, membrane permeability andmalondialdehyde (MDA) content) and antioxidative enzymes system activities(superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD)) were analyzedduring storage.Experimental results show that moderate cold shock and heat shock treatmentscan keep fresh-cut vegetables’ sensory quality and prolong the self-life. Instead, highintensity cold shock and heat shock treatments may accelerate deterioration offresh-cut vegetables. For the difference in physiological and ecological characters,different fresh-cut vegetables react differently to cold shock and heat shock treatmentsand suitable treatments for them have significant difference.0°C·30min and45°C·1min for fresh-cut pepper,0°C·10min and35°C·1min for fresh-cut cabbage,0°C·10min and55°C·1min for fresh-cut onion,0°C·30min and50°C·1min for fresh-cutcarrot are the best treatments respectively.Moderate cold shock and heat shock treatments can inhibit the increase of weightloss, keep the content of soluble sugar and soluble protein, and inhibit the augment ofcell membrane permeability and the accumulation of MDA. High intensity cold shockand heat shock treatments show the adverse effects on fresh-cut vegetables storage.Moderate cold shock and heat shock treatments can induce and regulateantioxidative enzymes system activities, increase the SOD and CAT activities andinhibit POD activity to regulate the balance of reactive oxygen species metabolism,inhibit the loss of water, soluble sugar, soluble protein, protect cell membranestructure, postpone senescence physiology process and keep good sensory quality.High intensity cold shock treatments can inhibit SOD and CAT activities, enhancePOD activity, and result in reactive oxygen species accumulation and tissue oxidative damage, accelerate senescence process; High intensity heat shock also can inhibitSOD and CAT activities, but inactivate POD partly, induce physiological disorder ofreactive oxygen species metabolism, destroy cell membrane structure and acceleratesenescence.