Study On Postharvest Quality And Physiological Effect Of "Winter- Jujube" By Ozone Ice Coating Film

With the winter-jujubes as the research object, this thesis dealt with impacts on the quality, physical change, protective enzyme and shelf life in the condition that the winter-jujubes were processed with ozone ice coating film. What is more, the thesis furthered the discussion of the ozone ice film control over the physiological mechanism of the horticultural products in the ageing process. The research provided new approaches and theories for the storage and fresh-keeping of winter-jujubes. The main research results are as follow:1. Ozone ice film treatment kept winter-jujubes with high firmness. Stored for 100d, their rigidity reached 7.3×105Pa and 5.55×105Pa respectively. The differences of the two processions were obvious(P<0.01)This procession kept the winter jujubes in better appearance. Stored for 40d, a value of the two processions were -1.7and -3.1 respectively. The differences were obvious (P<0.05). Stored for 100d, a value of the two processions were 4.3and 0.3 respectively. The differences were obvious (P<0.01).Meanwhile, it effectively prevented the quantity decrease of titration acid and Vc in winter-jujubes to maintain their quality in the storage period, and delayed the ageing rate without any damage. Ozone ice film procession could prevent the increase of reducing sugar content of the winter jujubes. Stored for 100d, the quantity of Vc of the two processions are 188.23 mg/100g and 233.33mg/100g respectively,the difference between them were obvious(P<0.01).2. Ozone ice coating film preservation could effectively protect the cell membrane system from being hurt; reduced the accumulation of the MDA. The MDA quantity in the two processions were 4.1178mmol·100g-1FW-1 an88d 5.87mmol·100g-1FW-1 respectively. The difference were obvious (P<0.05). This procession effectively inhibited the activity of CAT and PPO, obviously delayed the fruits'ageing process, reduced the active peak of PPO, postponed their peak time, and kept their activity in a high level. Ozone ice coating film also could maintain POD and CAT's activity in a high level, and reduce the film's over-oxygenation effect to provide a better protection to winter-jujubes and delay their aging process.3. Ozone ice film procession reduced dehydration quantity of the winter jujubes, delayed their softening rate, effectively prevented their ethanol accumulation, partly cleared the wax piece in the cracks and lenticels, which was helpful for the release of the inner produced CO2, and delayed its accumulation to keep the accumulation of pyruvate low. It also reduced the activity of PDC and ADH, delayed the pyruvate's transformation to acetaldehyde and the formation of ehtanol, which effectively prevented their ethanol accumulation, kept their commodity value, and prolonged their storage time.4. The best fresh keeping method with ozone was: get the winter-jujubes cold below 0℃for 24h on the harvest day, then put them into the wet refrigerator for 24h---48h(temperature -2℃~ -3℃, relative humidity >95%). Then soak them into the 0℃ozone water (2.00~3.00mg/L)for 2 min, and deposit them to the wet refrigerator (-2-3℃) to form ice films on the surface of the winter-jujubes. Finally, deposit them in a condition with low temperature.5. The shelf life of the harvest winter-jujubes which were processed with the ozone ice filming method could be increased effectively. After 15d's storage, the fresh ones accounted for 89.55%. The winter-jujubes'commercial value was well kept. The ozone water procession also worked well on winter-jujubes'soften process. Winter-jujubes, freshened for a long time and exposed to a room temperature, turned to be easily rotten. Their storage period became extremely short. However, with the ozone ice coating procession, winter-jujubes'shelf fresh keeping time was significantly prolonged.