| Kiwifruit is a typical respiratory-climacteric fruit,which will soften rapidly after harvest.At the same time,CPPU treatment is widely used in the production of kiwifruit,which accelerates the ethylene metabolism and respiration of fruits and reduces the storage quality of kiwifruit.According to the actual production,Qinmei and Hayward kiwifruit were chosen as the test material.Before harvest,they were untreated or treated with 20mg/L CPPU.After harvest they were treated with ozone.The quality of kiwifruit,the Met,SAM,ACC,MACC content in the pathway of ethylene metabolism and the activity changes of resistance enzyme of kiwifruit during cold storage were compared.The aims of this paper were to:(1)explore the effects of ozone on the quality and storage capacity of Kiwifruit;(2)provide theoretical basis for the Kiwifruit ozone preservation technology.The main conclusions are as follows:(1)The changes of fruit firmness,SSC,TA,VC and chlorophyll content in the kiwifruits during storage were studied.The results showed that the preharvest CPPU treatment reduced the quality,firmness,TA and VC content of the kiwifruits on the day of harvest.The decrease of fruit firmness,TA,VC,and chlorophyll content in the kiwifruits during the storage period was accelerated,and the quality of kiwifruits was decreased,and the softening of kiwifruits was accelerated.Ozone treatment had a good effect on the preservation of fresh kiwifruits and treated kiwifruits by CPPU.The 40mg/m~3 ozone treatment had better effect on maintaining the quality of kiwifruits,which could effectively reduce the decrease of firmness,TA,VC and chlorophyll content,inhibit the increase of SSC,delay ripening and softening,and improved the quality of the kiwifruits.Ozone treatment can not only effectively improve the storage quality of the fresh kiwifruits,but also can reduce the negative effects which were caused by the CPPU treatment.It had a better preservation effect.(2)The effects of the ozone treatment on the contents of Met,SAM,ACC,MACC and the related enzyme activities in pathways of ethylene metabolism of the kiwifruits were analyzed.The results showed that preharvest CPPU treatments accelerated the decrease of the Met and SAM contents,slowed down the accumulation of the MACC,increased the ACC contents and the enzyme activities of the SAM synthase,ACS and ACO of the Qinmei kiwifruits during the storage period,thereby increasing the amount of ethylene released.The changes of the Hayward kiwifruits after CPPU treatments before harvest were consistented with that of the Qinmei kiwifruits except that the ACC content and SAM synthase activity were less affected.Preharvest CPPU treatments had a significantly negative impact on storage.The 40mg/m~3 ozone treatment had a better inhibitory effect on the ethylene metabolism of the Qinmei and Hayward Kiwifruits,which could effectively inhibit the release of ethylene during storage,reduced the negative effects of CPPU on the Kiwifruits,such as accelerated ripening and reduced the storage capacity.(3)The effects of the ozone treatment on the activities of PAL,GLU,CHI and CAT of the kiwifruits during storage were studied.The results showed that preharvest CPPU treatment inhibited the activity of PAL,GLU,CHI and CAT and weakened the disease resistance of Qinmei kiwifruit.Preharvest CPPU treatment also inhibited PAL and CHI activity in Hayward fruits.There was no significant difference for GLU and CAT activity.Ozone treatment can effectively increase the activity of PAL,GLU,CHI and CAT of the kiwifruits,enhance disease resistance,and delay fruit ripening and aging.The 40mg/m~3 ozone treatment had better effects on the promotion and maintenance of the resistance enzyme activity of Qinmei and Hayward kiwifruit.Moreover,this treatment could effectively reduced the inhibitory effect of CPPU on the enzyme activity of kiwifruit.Postharvest 40mg/m~3 ozone treatment had good preservation effect on kiwifruit. |
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