Study On Postharvest Storage Characteristics And Technology Of New Kiwifruit Varieties ’ruiyu’ And ’wanjin’

Kiwifruit is sensitive to ethylene after harvest,and its softening rate is fast,which seriously affects its commercial value.Low-temperature storage can effectively maintain its commercial properties.However,different varieties fruits have different adaptability to low temperature,and unsuitable low-temperature storage can easily induce chilling injury of the fruit and cause a large amount of post-harvest loss.Modified atmosphere packaging has been widely used in fruit storage and preservation,and has significant effects in delaying maturity and senescence,maintaining fruit quality,and inhibiting chilling injury.In this paper,two new kiwifruit varieties of‘Ruiyu’and‘Wanjin’were used as test materials to screen their suitable refrigeration temperature,and on this basis,the effect of combining MAP packaging on the fruit preservation effect was studied.The experimental design storage temperature gradient were（0±0.5）℃,（1±0.5）℃,（2±0.5）℃,and room temperature（20℃,CK1）storage was used as a control.After selecting the suitable storage temperature for the two varieties of kiwifruit,used PE film bags with different thicknesses were stored in sealed packaging to obtained technical methods that were conducive to actual production reference.The experimental research results were as follows:1.Compared with control（CK1）,the lower the storage temperature,the more significant the physiological metabolism of the two varieties of kiwifruit could be inhibited,and the nutrient consumption of the fruit could be reduced.At the 3 storage temperatures,the respiration rate and ethylene release rate of‘Ruiyu’and‘Wanjin’fruits reached their peaks on the 30th day of storage.Compared with the control,the peak appearance time of‘Ruiyu’and‘Wanjin’were delayed by 20 d and 15 d,respectively.2.During the storage period,the relative conductivity and the MDA content of the two varieties treated at（0±0.5）℃were significantly higher than those treated at（1±0.5）℃.Both‘Ruiyu’and‘Wanjin’had chilling injury on the 50th day of storage at（0±0.5）℃,the chilling injury index was 0.025,the pulp showed water-stained patches,and the chilling injury rate was 27.67%and 32.00%respectively upon delivery.Under（2±0.5）℃,‘Ruiyu’had no chilling injury during the whole storage period,and‘Wanjin’had slight chilling injury performance,but the fruit firmness decreased rapidly.The effective storage period of‘Ruiyu’and‘Wanjin’were 70 d and 80 d.Both‘Ruiyu’and‘Wanjin’at（1±0.5）℃showed chilling injury when stored for 60 days,the chilling injury index was 0.033 and 0.042,and the chilling injury rate was 15.00%and 12.33%when leaving the warehouse.3.Compared with the control（CK2）,0.01 mm,0.03 mm and 0.05 mm film bag fruits at（1±0.5）℃could effectively delay the decreased of the firmness,starch content and the increased of soluble solid content of the two varieties of kiwifruit.Reduced fruit respiration intensity,ethylene release and amylase activity,significantly reduced fruit chilling injury rate and chilling injury index,and prolonged fruit effective storage period.Among them,the effect of 0.03 and 0.05 mm was better than 0.01 mm.4.PE film bag packaging of different thicknesses could also inhibitted the growing in the cell membrane permeability of the fruit and the MDA content.The cell membrane permeability and MDA content of 0.03 and 0.05 mm treatments in‘Wanjin’fruits always remained low 90 days before storage.While in the later storage period,the cell membrane permeability and MDA content of‘Ruiyu’fruits at 0.05 mm treatments increased rapidly,significantly higher than that of the 0.03 mm.5.The CO₂ content in the 0.03 mm film bags of‘Ruiyu’and‘Wanjin’were maintained at 3.91%～4.51%and 3.19%～3.67%,respectively,which was the best for maintaining fruit storage quality.The CO₂ content in the 0.05 mm film bag of‘Ruiyu’was maintained at5.77%～6.44%,and the fruit rotting rate was as high as 46.67%upon delivery.The CO₂content in the bag in the early and mid-term of‘Wanjin’was maintained at 4.43%～5.46%,but the CO₂ in the bag was as high as 10.18%,and the fruit rotting rate was over 72.33%when it was out of storage（180th days）.In summary,（1±0.5）℃was the most suitable storage temperature for‘Ruiyu’and‘Wanjin’kiwifruit.At this temperature,the film bag storage had the effect of reducing the chilling injury of the fruit and had a synergistic effect on the storage and preservation of the two varieties of kiwifruit.Among them,the gas environment formed in the 0.03 mm film bag packaging had a good effect on inhibiting chilling injury,maintaining quality,reducing decay,and prolonging the storage period of the two varieties of fruits.