| Oriental melon(Cucumis melo var.makuwa Makino)is a favored fruit by consumers,but the oriental melon is climacteric fruit,it causes great economic losses in transportation because of the vigorous physiological activity during postharvest,and at present,with the improvement of consumers' requirements on fruits' qualities and food safety,which prompts us to find a effective and safe way to storage fruits.So,in this paper,the immature ‘Hongdaobian'(value of soluble solids(SSC)about 9.0)was used for experiment material,and seted two lowtemperature treatments 15? and 10? respectively,25? as control.The oriental melons in two low-temperature treatments storage after 7 d to 25? storage for 2 d(C7S2),Samples were taken on different days after storage respectively.then,the mature ‘Hongdaobian'(value of soluble solids about 12.0)were used for experiment material,according to simulating the household refrigerator were storaged in 4? for different days and transferred melons to 25?for 1 d(C5S1),0 d as control,the effects of the fruit qualities,flavor and the physiology and biochemistry were determined,looking forward to select the suit storage temperature and time,to provide the theoretical basis and technical support for improving the quality and prolonging the storage time after harvest.The results were described as follow:1.The changes of fruit peel and flesh color during low temperature starage were measured,the result show that at the later stage of storage,the L value of peel color of the two lowtemperature treatments was higher than that of the control in melon fruit,a value was lower than that of the control,and b value had no significant difference than the control,in the later stage of storage,both a values and b values of flesh color were significantly lower than the control,and L value was significantly higher than the control.During the whole storage period,the hardness,SSC,vitamin C(Vc)content and malondialdehyde(MDA)content of the melon fruits in two low-temperature treatments were all higher than that of the control.It is showed that it is better to storage oriental melon under the condition of 10? to maintain the fruit color,slow down the fruit hardness,increase the Vc content than storage at 15? and 25?.2.During the whole storage period,the glucose,sucrose and total sugar content of the melon fruit in two low-temperature treatments were higher than that of the control,and in the later storage,it was significantly higher in 10? low-temperature treatment than that of 15?.The activities of sucrose synthase(SS)and sucrose phosphate synthase(SPS),and the expression of Cm SS1 under the two low-temperature treatments were basically higher than those in the control,The expression of Cm SPS1 was only higher than that of the control at lowtemperature treatments after the recovery of room temperature storage,and lower than that of the control at two low-temperature treatments during the low temperature storage,and there were no significant changes in neutral invertase(NI)and acid invertase(AI)during the whole storage period.By on,the soluble sugar content is higher under the condition of 10? low temperature storage,fruit after low temperature storage mainly affect the SS and SPS enzyme activities,the changes of enzyme activities related to Cm SS1 and Cm SPS1 expression.3.The aroma components of melon fruit changed significantly after low-temperature treatments,the total ester,total acetate and ethyl acetate content of fruits storage in 15? lowtemperature treatment for 1~8 d were higher than those of control and 10?,and 10? lowtemperature treatment after the recovery of room temperature storage 2 d were higher than those of control and 15?.The activities of lipoxygenase(LOX)and alcohol dehydrogenase(ADH)was basically lower than that of the control,and the activity of alkyl transferase(AAT)was basically higher than that of the control.The low temperature promoted the expression of lipoxygenase genes Cm LOX08,Cm LOX16 and Cm LOX17 in melon fruits,as well as the expression of alcohol transferase genes Cm AAT1 and Cm AAT2.It is showed that under the condition of 10? low-temperature treatment can slow melon fruit esters content of lower speed,the aroma substance content changes associated with changes of mainly enzymes activity and genes expression.4.The peel color L value and b value are on the decline,a value showed a trend of increase,flesh color change trend is very small of mature melon fruit in 4 ?.The hardness,SSC and Vc content of the fruits showed a decreasing trend,MDA content showed a increasing trend,continually.The expression of Cm CBF1,which is related to the cold resistance of melon fruit,had a peak after storage for 3 d,but decreased significantly after the storage at room temperature,indicating that Cm CBF1 plays a role in the cold resistance of melon fruit.5.There was no significant change in fructose and glucose content,while sucrose content decreased in mature melon,the enzyme activities of SPS and SS-synthesis showed a decreaseing trend,while the enzyme activities of AI and NI showed no significant changes.The expression of Cm SS1 increased on the first day of storage and the first day after storage at room temperature,and the expression of Cm SPS1 showed a downward trend.Furthermore,it shows that the change of fruits' soluble sugar storage in low temperature is relate to the activities of SS and SPS,and the expression of the main genes.6.4? low temperature treatment significantly reduced the mature melon fruit aroma content,fruit aroma volatile substance,total acetate esters content and ethylene release content are presented to reduce,the rising trend after returning to room temperature storage,and is consistent with the enzyme activities change trend of LOX,ADH and AAT,Cm LOX09,Cm LOX17,Cm AAT1 and Cm AAT2 expression were significantly increased after storage at room temperature,and Cm LOX08 expression higher than control during the low temperature storage,Cm LOX16 expression at 4 d significant rise.It is known that the synthesis of esters in melon fruit is not only related to the main enzyme activities and genes expression of lipoxygenase pathway,but also closely related to ethylene release. |
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