EFFECTS OF CURING CONDITION AND STORAGE-TEMPERATURE ON POSTHARVEST QUALITY OF SQUASH FRUIT

The effects of curing treatments and storage temperatures on the keeping and flavor qualities of squash (Cucurbita maxima Duch.) cultivar 'Ebisu' were studied. Harvested squash fruits were cured at 20-degrees, 25-degrees, and 30-degrees-C for 11 and 16 days and then stored at 10-degrees-C. For comparison, a control sub-sample was stored immediately after harvest at 10-degrees-C without curing. The effects of different storage temperatures were also examined by storing fruits cured for 12 days at 25-degrees-C at 7.5-degrees, 10.0-degrees, 12.5-degrees and 15.0-degrees-C. The results are summarized as follows: 1. Starch content of the fruit decreased throughout the storage period irrespective of storage temperature. Total sugar content increased, reaching a maximum and then gradually decreased. When starch content was equal to the total sugar content, eating quality of the fruit was estimated to be most favorable. Water content of the fruit tended to increase during the storage period. After 60 days of storage, the water content increased rapidly and, simultaneously, the taste of the fruit became poor. 2. The curing treatment of fruits at higher temperature and for longer periods was more effective in promoting the conversion from starch to sugar. In addition, the curing treatment at higher temperature prevented rotting. Since the skin color of fruit cured at 30-degrees-C became yellow rapidly, the optimum temperature for curing appears to be lower than 30-degrees-C. 3. Reducing sugar content and total sugar content increased more during storage at lower temperatures than at higher temperatures. At all storage temperatures, beta-carotene content on the 43th day of storage reached a maximum, which was twice or three times the content of that at harvest. No chilling injury was observed in fruits stored at 7.5-degrees-C. The ratio of hydrochloric acid soluble pectin to total pectin content decreased much earlier during storage at 15.0-degrees-C than at lower temperatures. Furthermore, the rate of water loss was fairly constant, but it was also more rapid at 15.0-degrees-C than at the lower temperatures. The optimum temperature for storage seemed to be 10.0-degrees +/- 2.5-degrees-C.