Water Loss And Its Control Of Postharvest Gannan ’Newhall’ Navel Orange

Fruits of Gannan ’Newhall’ navel orange(Citrus sinensis Osbeck cv.Newhall)were used as experimental material to explore the occurrence patterns of water loss and weight loss during storage,and reduced the occurrence of water loss and weight loss through post harvest treatment with polyethylene oxide(PEO)to maintain fruit quality and improve economic benefits.The main research findings were as follows:(1)During the low temperature(5 ℃)and room temperature(26 ℃)storage of Gannan’Newhall’ navel orange,the initial storage phenotype of the fruit and the decay of the fruit after being refrigerated at 5℃ for half a year were observed.The research results indicated that fruit decay was mainly caused by green mold,and bagging can effectively prevent cross contamination of mold.Gannan navel oranges began to rot after 20 days of storage at 26℃,but began to develop diseases after 90 days of storage at a low temperature of 5℃,indicating that low temperature can effectively inhibit the growth and reproduction of pathogenic microorganisms,thereby reducing fruit decay.In the early stage of storage(0–45 days),the daily average water loss rate of Gannan ’Newhall’ navel orange stored at 26℃ was 8.09 times that of 5℃.In the later stage of storage(60–105 days),the daily average water loss rate of navel orange stored at 26℃ was 3.36 times that of 5℃;At 105 days,thecumulative water loss rate per fruit of navel oranges stored at 26℃,which is the proportion of cumulative water loss per fruit to the original fruit weight,reached about 12.8%,while the water loss rate per fruit of navel oranges stored at 5 ℃ was only about 2.3%,indicating that lowtemperature storage can effectively slow down the water loss of navel oranges.(2)Using low field nuclear magnetic resonance technology to measure the moisture characteristics of the peel of Gannan ’Newhall’ navel orange during storage.With the extension of fruit storage time,the relaxation time of free water,non-flowing water,and bound water continuously shifts to the left,and it was found that the content of bound water and non-flowing water continues to increase,but the content of free water tended to decrease.The research results indicated that with the extension of storage time,there was a trend of free water migration towards non-flowing water and bound water in the peel of Gannan ’Newhall’ navel orange,and the water mobility continuously decreased.When stored for 40 days,the relaxation time T21 of the bound water shifted to the right,which may be due to the gradual conversion of weaker neighboring water and multiple layers of water to less easily flowing water through partial bonding in the bound water.(3)Polyethylene oxide is a water-soluble polymer with crystallinity and thermoplastic properties.0.6% PEO was used to coat the fruit of Gannan ’Newhall’ navel orange after harvest,and the changes in quality characteristics of the fruit during storage were analyzed.The results showed that 0.6% PEO treatment could effectively reduce the respiration rate of Gannan ’Newhall’ navel orange fruit,delay the decline of peel brightness and hue angle,and help maintain the appearance of the fruit,but had no significant effect on the content of soluble solids and titratable acid in the pulp.