| Xinjiang Hami melon is favoured by lots of consumers because of its tender and juicy flesh, sweet fragrance and excellent quality. For the reason of high temperature and short-term in harvest season, Hami melon will be perishable and soft in storage and transportation, which has seriously affected the commodity value of Hami melon. In this manuscript, xizhoumi No.25 was used as the test material, and the effects of different window period of 1-MCP treatment and 1-MCP treatment on postharvest fruit physiology and quality in different time were studied. The softening mechanism of melon fruit was researched, at the same time, the effect of 1-MCP treatment on volatile composition of Hami melon at different storage time was studied. And the theoretical basis for the application of 1-MCP in the postharvest Hami Melon during storage could be provided. The results are as follows:1. Effect of 1-MCP treatment on suitable window period and treatment time on the melon storage quality and physiology was studied. 1-MCP treatment in picked 12 h could effect on storage quality and physiological of melon fruit very well, and 1-MCP treatment for 12 h hours made melon fruit maintaining good quality and physiological characters. At the end of storage, the decay rate of Hami melon fruit treated after 12 h is 52.07%, lower than the control fruit, postharvest 6h treatment fruit, postharvest 24 h treatment 41.03%, 7.93%, 34.6% respectively. The fruit decay rate that treated 1-MCP for 12 h is 37%, which is only 2/5 of the control fruit, lower than fruit treated 1-MCP for 6h, 24 h respectively23% and 16.33%. Different window treated fruits reached respiration peak and ethylene release peak at 6 day. The respiration peak and ethylene release peak of fruit 1-MCP treated after 12 h is 6.97mgCO2·Kg-1·h-1and 41.36μL·Kg-1·h-1, compaired with fruit 1-MCP treated after 12 h, respiration peak and ethylene peak of 1-MCP treatment after 6h,24 h and the control fruit reach at 95.61%, 73.44%; 92.81%, 89.45%; 87.89%, 64.76%. Fruit of different 1-MCP treated time reach respiration peak on 9 day, which delayed 3 day compaired with control fruit. Respiration peak of 1-MCP treated for 6h is 6.39mgCO2·Kg-1·h-1, and treated for 12 h, 24 h appear 5.47mgCO2·Kg-1·h-1, 5.74mgCO2·Kg-1·h-1.2. Effect of 1-MCP treatment on cell wall metabolism of Postharvest Hami melon was studied. Treatment of 1-MCP reduced the falling of total fruit pectin relative content, protopectin content, covalent pectin, hardness and degradation of hemicellulose, cellulose. It also inhibited the increasing content of soluble pectin, ion binding pectin to a certain extent. Thus it inhibits the softening of Hami melon fruit, and it proved the same thing throught FRIT spectral analysis of fruit cell wall material.It can be learned that 1-MCP significantly inhibited enzymes activity of PG, CX, PME, β-glucosidase, α-glucosidase, β-galactosidase that related with fruit softening. It can be shown that in early storage stage PG, CX enzyme made the fruit soft and PME, β-glucosidase, α-glucosidase, β-galactosidase played a role in the mid and the end storage time.3. Effect of 1-MCP treatment on reactive oxygen species metabolism of Hami melon fruit was studied. Treatment of 1-MCP promoted fruit POD, SOD activity. On the contrary it inhibited LOX activity, relative conductivity and MDA content. The conclusion is that treatment of 1-MCP maintained the integrity of cell membrane and it delayed senescence of the fruit.4. Change of 1-MCP treatment on Volatile composition of Hami melon fruit at different storage period was studied. Treatment of 1-MCP decreased the types of fruit volatile composition during storage. Along with the extension of storage, volatile esters produced by the fruit increased. But the relative content of esters of 1-MCP treated fruit were lower than the control fruit, and benzyl acetate got the highest content. |
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