Studies on the utilization of persimmons, Diospyros kaki Linn. F. VIII. Effect of skin injuries on fruit keeping quality.

In the previous paper, it was reported that the most desirable temperature for the storage of fruits of Fuyu variety was 0°C. The present experiment was made to investigate the practical effects of several packing materials on the weight loss and shriveling, growth of microorganisms and lengthening of storage period by maintaining a proper constitution of .atmosphere around the fruit. Post-ripening and, deterioration at room temperature after removal from cold storage were also tested. The sample fruits were obtained from the Kagawa University farm on November 13, and 27, 1958. These fruits were kept at room temperature overnight, then packed and stored on the following day at 0°C and 85_??_90 per cent relative humidity. Seven experimental items were studied: 1. control, 2. packing with excelsior in wooden boxes, 3. packing with rice hull in wooden boxes, 4. packing in sealed desiccators, 5. packing in polyethylene bags of 0.03mm, 6. packing in polyethylene bags of 0.06mm, 7. packing in polyethylene bags of 0. 08mm. The dimensions of polyethylene bags were 14×28 cm and three persimmons were packing in each bag. The results are as follows. 1. The fruits both in polyethylene bags and in desiccators lost only 1 per cent or less of weight, while in control (1), packing with excelsior (2) or with rice hull (3), the loss was 6_??_7 per cent in weight after 2_??_3 months. The fruits became visibly shriveled and spongy-like in its texture when it lost 5 per cent of weight. 2. Carbon dioxide content within the polyethylene bags and desiccators rapidly increased during the early storage period, and reached 5 per cent (in 0.03mm polyethylene bags) to 50 per cent or more (in desiccator) after I month. In the polyethylene bags of 0.08mm and desiccator, the carbon dioxide accumulated to a dangerous level and the fruit showed physiological damage in a longer storage period. 3. The advance of after-ripening and deterioration of Fuyu fruits sealed in the polyethylene bags was slower than that in open bags when moved out to room temperature from the cold storage, and the polyethylene bags of 0.06mm retarded the after-ripening most effectively. 4. On the basis of these results, a temperature of 0°C, relative humidity of almost 100 per cent and combinations of 5 per cent carbon dioxide and 5_??_8 per cent oxygen seem to be the optimum conditions for the storage of Fuyu fruits. The most successful method of storing was to pack them in polyethylene bags of 0.06mm and then to store them at 0°C.