脫澀方法及溫度和平核無柿果軟化之關係

Comparative Studies of Fruit Softening in Persimmon (Diospyros kaki Thunb. cv. 'Hirataneanshi') in Relation to Different Methods for Removal of Astringency and Temperature

本試驗比較酒精脫澀法、二氧化碳脫澀法及石灰懸浮液脫澀法對‘平核無’柿果脫澀後軟化之影響。以二氧化碳脫澀法和酒精脫澀法處理之柿果在軟化速度上並無差異，但石灰懸浮液脫澀法處理者則能保持較高之硬度。‘平核無’柿果以二氧化碳脫澀時，其脫澀速率隨溫度增加而加速，在35℃下需2日才達可食用狀態，而30℃下則需3日、25℃下則需5日，而20℃者在5日內仍無法達可食狀態；在硬度方面，除35℃外，30°、25°及20℃處理者，在脫澀完成後皆有軟化之現象。此外，本試驗亦進行二氧化碳處理時間及濕度對‘平核無’柿果脫澀及軟化之影響，其中以30℃處理二氧化碳2日，再降溫至15℃放置1日，可得較佳之硬度；而以此法脫澀完後之柿果，進行貯藏溫度試驗，貯存溫度以0℃較佳，而以EVA膜逐果包裝有減輕軟化之效果，但所有貯藏後之柿果在櫥架上（25℃，2日）皆有嚴重軟化現象。

Fruit quality and softening of persimmon ('Hiratanenshi') were studied following three treatments (ethanol treatment, carbon dioxide treatment, and calcium oxide suspension dipping method) for removal of astringency. There was no significant difference in flesh softening of fruits treated with carbon dioxide and ethanol. Fruits treated with carbon dioxide softened quickly, but the firmness flesh of fruit treated with calcium oxide suspension slowly declined. The effect of temperature on 'Hiratanenshi' fruits treated with carbn dioxide was examined during deastringency at various temperature ranging from 20 to 35℃. The rate of decrease of astringency was high with higher temperature. The times required to reach under 2 of astringent index were 2, 3, 5 and more than 5 days at 35°, 30°, 25° and 20℃, respectively. A significant decrease in fresh firmness occurred when the fruits had been removed of astringency with carbon dioxide at 30°, 25° and 20℃, but except 35℃. Our results showed that carbon dioxide treatment of 'Hiratanenshi' fruits at 30℃ for 48 hr followed by storage in air at 15℃ for 24 hr produced de-astringent fruit of excellent quality without abnormal softening. However, the dc-astringent fruits could be stored at 0℃ to extend the storage life up to 1 to 2 weeks and storage of fruits wrapped individual unit with ethylene vinyl acetate film at 0℃ which improved the storage life of fruits, but the fruits appeared to became serious softening and water-logged in the flesh region when those were transferred to 25℃ for 2 day.