| Decay,drop and rachis browning are major problems that limit the shelf life of fresh table grapes and are often combated by application of sulfur dioxide (SO2) to maintain quality. However, SO2 is dangerous to people who are allergic to sulfites and its applications have been restricted in many countries.In this paper, with the'Red Globe','Kyoto'and'Crimson seedless'as material, grape was lightly processed according to fresh cut principle and technology, followed by heat treatment as a non-chemical residual, nonpoisonous, simple and efficient physical treating method. The objectives of this research were to investigate the effects of heat treatment on the storage quality, the changing of physiological and chemistry, phytohormone, together with the composition, hydrolase activity and ultrastructure of cell wall. Furthermore, a combination of mild heat treatment, modified atmosphere package (MAP) and sanitizer technologies was conducted, and its effect on the quality and microbial growth of fresh-cut grapes was investigated. The pathogen growing during storage was isolated and identified. All the results are showed below:1.Hot water and hot air treatment were employed for minimally processed grapes, and the optimum conditions were at 45℃for 8min and 55℃for 5min, respectively. Heat treatment too high temperature or too long exposure time caused heat injury. Grapes exposed to 50℃hot water for 4min resulted in heat injury that was harmful to fruits. The results showed that decay rate of minimally processed grapes was significantly declined slowly in cold storage after heat treatment compared to control, and the Vc and firmness in minimally processed grapes were also delayed by heat treatment. There were no significant differences on SSC and TA between heat treatment and control.2.Hot water treatment (45°C, 8 min) and hot air (55℃, 5min)could suppress both the accumulation of MDA and the relative conductivity membrane permeability significantly, inhibit the decline of POD, CAT and SOD activities, significantly retard the decline of soluble protein content and keep soluble protein content of grape at high level during the storage, and significantly inhibit the increase of PAL and PPO activity, therefore, the senescence and softening of lightly-processed grape were delayed.3.Lightly processed grape belong to non-climacteric fruit, so heat treatment had significant effects on the respiration rate of grapes during storage, therefore the senescence of lightly processed grape were delayed. There were negative relation between IAA content, GA3 content and decay rate of lightly processed grape, and the correlation coefficient are 0.9035 and 0.8416, respectively. The ABA content of lightly processed grape during the storage was characterized by a parabolic-shaped curve developing from lower to higher and then to lower. Heat treatment can delay the appearance of peak and decline the peak value. ZR content was not significantly affected by heat treatment. There was no obvious changes rule of ZR content during the lightly processed storage.4.Heat treatment could inhibit both the accumulation of PE and PG activity significantly during the end of storage. There was negative relation between PE activity and firmness, and the correlation coefficient is -0.7573. There was no relativity between PG activity and firmness. Heat treatment could significantly suppress the accumulation of Cx activity. There was negative relation between Cx activity and firmness, and the correlation coefficient is -0.9289.The pectin content of grapes were not significantly affected by heat treatment.5.Transmission electron microscope was used to observe the ultrastructure of the grape. The results showed that in the beginning of storage, there was no significant difference between heat treated grape and control one. After ninety days, the middle lamella of heat-treated grape was not completely dissolved, leaving a lot of small microfibrils, and the primary cell wall was integrated. Chloroplast and mitochondria of heat-treated grape were integrated. But the cell wall structure of control grape swell and flab, the primary cell became crooked and thicker; most of the middle lamella was dissolved and disappear. Chloroplast gradually became disorganization, the brink of membrane and grana lamella were unclear. Mitochondria remained numerous, mitochohdrial crista disappeared.6.The effects of heat treatment combined with MAP package and sanitizer usage on two kinds of lightly processed grape were analyzed. The results showed that grapes keeping 1-2 mm of cap stem maintained significantly better quality than those without stems. Hot water treatment (45°C 8 min)and hot air treatment(55°C 5 min)significantly reduced the decay rate for grapes both with and without stems. Heat-treated grapes retaining 1-2 mm cap stems maintained high quality for 14 days with no decay, and had the lowest population of yeast and mold, lactic acid bacteria and total mesophilic aerobic bacteria in comparison to all other treatments. Heat treatment combined with close stem cutting is an effective process to control decay and retain quality of grape.7. The effects of heat treatment combined MAP and sanitizer usage on lightly processed grape and cluster grape were analyzed and compared. Hot water treated (45℃8min) grapes significantly enhanced the firmness and visual quality, and reduced the decay rate and microbial growth of grapes. Although heat treatment also kept the good quality of cluster grapes, the rachises became brown, dry and drop and decreased the visual quality. Chlorine- pre-washing treatments significantly reduced microbial populations and maintained better overall quality. Cut grapes treated by hot water maintained the highest quality for 4 weeks with least decay among all treatments. Commercially packaged grapes developed dark decay and unacceptable product quality at the end of storage.8.In order to research pathogen during preservation as well as makes a comparison based on the statistics of main diseases that takes the samples of lightly processed fresh grape. The separating, cultivating, and re- inoculating of the pathogen has been tested; the diseases could be concluded as a mix- infection. Finally the species of the pathogen has been identified. The pathogen of the diseases are A. tenuis Nees , P. simplicissimum(Oud.)Thom, F. avenaceum( Fr.) Sacc and B. cinerea Pers.ex Fr. The percentage of Botrytis cinerea was not higher, so it indicated heat treatment could inhibit Botrytis cinerea.
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