Study On Dielectric Properties And Fresh-keeping Condition By Low Temperature And Ozone During Kiyomi Tangor Storage

Kiyomi tangor is one kind of good hybrid orange containing a lot of nutrition such as vitamin,mineral and fibrino,with high water content,sugar content and good flavor. Kiyomi tangor was used as the testing material to investigate the effect on the postharvest physiology by ozone and low temperature treatment during storage.The result shows that the fruit will rot at room temperature(25～35℃) after 2～3 weeks storage.The optimal condition for Kiyomi tangor is the content of ozone 200mg/h·m~3 with 30minutes per 24 hours,at humidity 80%and temperature 8℃.In this condition the rate of good fruit is 92.6%after 91d,however,the comparison is only 69.67%.The treatment of ozone combined with low temperature is a kind of healthy,effective method and with less environment pollution.According to the major factors affecting the dielectric property,two parallel plate electrodes are used to study the dielectric property of Kiyomi tangor and analyze the correlation between dielectric parameters and quality index.The conclusion is as follows: at frequency from 800Hz to 5MHz,the optimal measuring frequencies are 1kHz,100kHz, 5MHz.There are better correlations between impedance and Vc content,respiration intensity at F= 100kHz,capacitance and organic acid,inductance and soluble solid content, inductance and weight loss at F=5MHz,the coefficient r respectively are 0.826,0.905, 0.861,0.857,0.835.It is feasible to evaluate the quality of Kiyomi tangor by measuring the dielectric parameters in theory,and also provide the evidence for inspecting nondestructive test system at the same time.The physiology index of Kiyomi tangor is investigated at the temperatures 3℃,-2℃,-5℃,-8℃to ensure the physiology of frozen injure.The result shows that Kiyomi tangor will induce slight frozen injury at -2℃,severe frozen injury at -5℃and -8℃.When Kiyomi tangor fruit suffer from frozen injury,nearly 2/3 area of the fruit skin indicated brown disease spots,and the evidence of water-soaking appeared in the pulp,it will lose the edible value.SOD,POD,CAT and PAL behave higher activities resisting low temperature.