Studies On The Physiological Effect Of The Cold Treatment In Citrus Gonggan

Citrus Gonggan is a variety of difficult to store, of which the flavor and quality will be changed after 7 to 8 days of storage. Cold treatment is a kind of scientific fresh-preservation technology having such characteristics as energy saving, safety, sanitation, and etc, and will have a wide application prospects in storage and fresh preservation of fruits and vegetables. The Citrus Gonggan of DeQing was picked for experimental material in this research, and treated by cold storage with the temperature of 0℃ and the humidity of 90%. Then, the reaction of Citrus Gonggan's conductivity to the above storage condition was measured by the critical cold damage temperature methods, consequently the time of Citrus Gonggan suffering cold damage is concluded. Moreover, the Citrus Gonggan was stored respectively in preservation bag at ambient temperature after cold treated of 1 day and 3 days. Not only the sense effect was evaluated, but also the changes of many physiological and chemical index such as respiration intensity, SOD,MDA, membrane permeability, content of ethanol,the rate of weight loss, soluble solid content, acidity, total sugar ,titrable acid ,peroxydase and isoenzyme were measured during storage period. Combined with the comprehensive analyses of experimental data, the experimental results shows:(1) The conductivity of the Citrus Gonggan increased continuously when it stored with the temperature of 0 ℃ and the humidity of 90%, and changed abruptly at the sixth day of cold storage, which shows that the membrane permeability of the sarcocarp tissue increases sharply after 6 days and that the Citrus Gonggan was already damaged by cold. Therefore, the following conclusion could be drawn: the fruit can't be damaged with cold treatment of 1 or 3 days at the temperature of 0 °C and the humidity of 90%.(2) The cold treatment of the Citrus Gonggan was benefit for its storage at normal temperature, thus the storage life of the Citrus Gonggan was prolonged. Through measuring and analyzing many physiological and biochemical parameters of the Citrus Gonggan such as the sense effect, membrane permeability, content of ethanol,the rate of weight loss, respiration intensity, SOD ,MDA ,soluble solid content, acidity, total,, sugar ,titrable acid of three treatments of Citrus Gonggan which was stored at normal temperature without cold treatment, or cold treatment of 1 day, 3 days respectively. It was founded that the storage effect of the Citrus Gonggan with cold treatment was better than that of the Citrus Gonggan stored at normal temperature without cold treatment, The storage effect of the Citrus Gonggan with 3 days cold treatment with the temperature of 0°C and the humidity of 90% was the best among three treatments.(3)The Citrus Gonggan with cold treatment at the temperature of 0°C and the humidity of 90%, of which peroxydase and isoenzyme content increased compared with normal temperature tyeatment, but also the amount of iosenzyme of the Citrus Gonggan increased in the period of cold treatment. The peroxydase and isoenzyme of the fruit experienced complicated 'readjustment and reorganization process' to adapt the change of environment. Finally, the isoenzyme amount after readjustment was positive relative with preservation effects. ( correlative coefficient 0.99, correlative degree 98%)...