Refrigerating Technique And Antibacterial Research Of Gannan Navel Orange

In present study, effects of harvest time, fruit size, storage temperature and individual film wrapping on the quality, rotting rate, weight loss rate and aberration in the fruit of ‘Newhall’ navel orange(C.sinensis Osbeck) were investigated. The aim of research was to reveal the optimal parameter of storage and therefore to provide theoretical basis for the commercialization of postharvest citrus fruit stored by low temperature. The effects of different traditional Chinese medicine on Newhall storage quality were also investigated. The main results were as follows:1. The postharvest quality and storage property of fruit were apparent influenced by temperature. The storage time was long and quality was maintained well when fruit in lower temperature storage, but when the temperature was too low,chilling injury was took place. The contents of TSS, TA, total sugar and VC of fruit storing in 4℃ in 150 days period were high, and the rotting and weight loss rate of the same fruit were least, the color of peel was always orange-yellow, and chilling injury was not took place, therefore, the optimum temperature for ‘Newhall’ navel orange long-term storage was 4℃.2. The effect of high RH on navel orange stored in low temperature was investigated, the results showed that the quality of navel orange stored in low RH was not better than navel orange stored in high RH, the significant effect of RH on the weight loss of navel orange, the high RH environment decreases the weight loss rate of navel orange evidently, but compared to high RH condition, individual film wrapping can significantly reduce the weight loss. Therefore, individual film wrapping showed to replace high RH method for navel orange under low temperature.3. The wrapping of fruit can reduce the water loss of peel and cross-infection.the rates of decay and weight loss of fruit wrapped in non-woven fabric in 4 ℃ in 150 days were 4.22% and 4.36%, the rates were least. The postharvest quality and storage property of fruit wrapped in polyethylene plastic bag was similar to fruit wrapped in heat-shrinkable film, but was better than non-woven fabric wrapped fruit. The best wrapping of storage of naval orange was double layer polyethylene plastic bag.4. By the end of the experiment, an increase in total sugar/TA was observed in fruit from all harvest dates, whereas the total sugar, TA and VC decreased significantly during the same period. The content of TA decreased sharply and chilling injury index was high in fruit harvested before early November. The quality of fruit harvested between the middle of November and early December was maintained well. Conversely, harvest date had a clear influence on decay with 9.7%of decay in fruit harvested at middle of December versus 0.67% in fruit harvested in late October. These results indicated that a period between the middle of November and early December was the optimal harvest stage of Newhall navel orange.5. The size of naval orange had a greater effect on the postharvest quality and storage property. During the whole storage, the contents of TSS, TA and VC of small fruits were always higher than the big fruit and middle fruit, the rotting rate and weight loss rate of big fruit were always higher than small and middle fruit, the hue angle of different fruit had no significant difference, the peel color was always orange-yellow. At 60 days in storage, the contents of total sugar and total sugar/TA of big and middle fruits were reached the maximum, and the rotting and weight loss were low. During the later period of storage, the postharvest quality and storage property of small fruits was better than big and middle fruits. Therefore, the big fruits are adequate to short storage, the middle and small fruits are suit for middle and long storage.6. The effect of antifungal substance on the development of P. italicum Wehmer was investigated, the experimental results show that IMZ, bellkute, potassium sorbate, propylparaben have apparent inhibition to penicillium. IMZ, bellkute,potassium sorbate, propylparaben were applied to navel orange storage using as preservative, through the comparison with control, we find the navel orange quality can maintain well and the rotting rate was low at the end of 120 d storage by handle with IMZ and bellkute, the potassium sorbate and propylparaben of preservative effect is not apparent.The pesticide residue of navel orange storage soak by 1 and0.5g/L IMZ and bellkute is not exceed the max line of national standard.