| Pomegranate is delicious and nutritious.It originated in Iran,Afghanistan and other Central Asian regions.It was introduced into China in the Western Han Dynasty and has been cultivated for more than two thousand years.China is one of the largest producers of pomegranate cultivation in the world.As of 2017,the total area of pomegranate cultivation in China reached 1.4-1.5 million mu,and the total output of pomegranate in China reached 1.697 million tons.Because of the strong respiratory intensity and transpiration after harvest,pomegranate is prone to pericarp browning,grain deterioration,softening and decay after harvest,which results in short storage period,poor quality after storage and low commodity value.In this experiment,KMn04 ethylene absorbent,1-MCP and the combination of them were used to treat'Tunisian Soft Pomegranate'.The physiological indexes and nutritional quality of Tunisian Soft Pomegranate'during cold storage and shelf life were studied,and the effects of the two methods on ethylene inhibition and ethylene receptor inhibition of Tunisian Soft Pomegranate' during storage were explored.In order to provide a more effective and safe fresh-keeping method for keeping the best taste of Tunisian Soft Zi'pomegranate,the best method of fresh-keeping effect was found out through the difference of fresh-keeping effect between single and combined treatments.The results are summarized as follows:(1)Physiological Characteristics of 'Tunisian Soft'Pomegranate and Its Earlymaturing Buds at Maturity and Senescence StageRespiration rate and ethylene release before harvest of Tunisian soft seed'pomegranate and its buds showed a downward trend,and ethylene content was very low.There was no significant change in the whole experiment,which accorded with the typical characteristics of non-climacteric fruit.The variation range of respiration rate of budding grains before harvest was slightly higher than that of Tunisian soft seed',and the difference of respiration rate of budding grains was more obvious than that of whole grains after harvest.The pre-harvest respiration rate of the two materials was higher than that of the whole fruit(P<0.05).Moreover,considering the actual appearance of the fruit and the development of the grains before harvest and the Postharvest senescence,it was speculated that the development of the grains might be later than that of the whole fruit,but it might also be caused by the injury of the respiration after the placenta was removed.The ethylene release of early-maturing budding fruit was significantly higher than that of 'Tunisian soft seeds'.The difference was most obvious in early September and approached gradually in early October.At this time,the harvest time of budding was over,the maturity was higher and the hanging fruit began to rot in the field.It can be seen that early ethylene production and high ethylene production directly lead to premature budding during the ripening and development of pomegranate fruit,and the respiration rate decreases with the decrease of ethylene release.After harvest,the respiration rate of the whole fruit showed a downward trend,while the ethylene release decreased first and then increased.The appearance showed that the peel was gradually dehydrated and aged.The respiration rate and ethylene release of grains showed an upward trend,which showed that the color of grains became darker and the texture became softer.(2)Effects of 1-MCP,Potassium Permanganate and Their Compound Treatment on Physiology and Cold Storage Quality of Tunisian Soft' PomegranateThere was no significant difference in respiration rate and ethylene release between the three treatments and CK under cold storage,but they were better than CK in inhibiting respiration rate and ethylene release from grains.After 45 days of refrigeration,the appearance quality of the fruits of the three treatments showed slight browning,so the optimum refrigeration time was recommended to be 30 days.After 1-MCP treatment and 1-MCP combined with potassium permanganate treatment(MK),the fruit quality deteriorated more gently,while the fruit quality of potassium permanganate treatment(K)declined more rapidly,and it was no longer suitable for sale after 60 days of cold storage.The appearance quality of untreated fruits had deteriorated after 30 days of refrigeration,so the optimum refrigeration period was recommended to be 15 days.At room temperature,'Tunisian Soft' Pomegranatebegan to have bad flavor when stored for 14 days.Therefore,the optimum storage time is recommended to be 7 days.The soluble solids content of Tunisian Soft'pomegranate increased during cold storage,and the increasing trend of M treatment and MK treatment was gentle.The titratable acid content showed a downward trend.The titratable acid content of MK treatment was higher during the refrigeration period,from 0.61%at the beginning of refrigeration to 0.48%at the end of refrigeration,which was better than other treatments.The content of anthocyanin decreased slightly from 61.41 mg/L-1 at the beginning of refrigeration on October 5,and then began to rise gradually.The Vc content of pomegranate fruit treated with M was significantly lower than that of the other two treatments,which was basically the same as that of CK.From the changes of quality indexes of pomegranate stored in different treatments mentioned above,it shows that MK treatment maintains the flavor of Tunisian soft'pomegranate and the storage quality of pomegranate.K treatment has its own limitations in slowing down the increase of anthocyanin aging process and 1-MCP in maintaining the Vc content of pomegranate grains.The activities of PG and PE in the pericarp of pomegranate treated with MK remained at a low level,and played a good role in inhibiting the increase of PPO activity and the decrease of PAL activity in the pericarp of pomegranate.(3)Efects of 1-MCP,potassium permanganate and their combined treatments on shelf life quality of 'Tunisian soft'pomegranateAfter two months of cold storage,the pomegranate'Tunisia Soft'was stored under simulated shelf-life conditions at room temperature of 18±1? and sampled every 5 days to determine its related indicators.Sensory indicators showed that M and M K treatment had bad flavor on the shelf life of 15 days,so the optimum shelf life was recommended to be 10 days,while the preference of K treatment decreased significantly after shelf life of 5 days.The sensory quality of CK decreased significantly in all fruits.The browning index reached 41.67%and the titratable acid content decreased rapidly to 0.39%at the shelf life of 20 days,while the two indexes of M treatment and M K treatment were 16.67%,0.45%and 13.89%,0.51%,respectively.Among all treatments,MK treatment showed the best performance in sensory quality,browning index and accumulation of flavor substances. |
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