柿子後熟與脫澀後軟化之研究

Studies on Fruit Ripening and Softening after Deastringency in Persimmon

柿子在未熟期採收者，呈現更年型果實之呼吸型態，成熟期採收者則呈現「後期呼吸上升型」之非更年型呼吸型態。已成熟但未後熟的柿子，貯藏性較佳。柿葉抑制乙烯生成，秋季延緩果樹落葉之栽培技術，不只改善果實品質，也延長其貯藏期限。乙烯的生成路徑中，因為柿果的ACC（1-aminocyclopropane-1-carboxylic acid）氧化酵素基因先大量表現，隨後ACC合成酵素基因才大量表現。故柿果之乙烯生成後，ACC方才蓄積。乙烯生成後，柿子即開始軟化，顯示乙烯是扮演柿子軟化之關鍵角色。利用基因轉殖技術顯示，果實中果膠質的分解與果實軟化，沒有直接關係。以打孔PE袋包裝柿子，經二氧化碳短期（CTSD，constant temperature short duration）脫澀，可有效防止柿子軟化。乙烯作用阻礙劑1-MCP（1-methyl cyclopropene）對‘蓮台寺’、‘西条’柿子效果不錯，至少可延長‘西条’品種貯藏期限10日以上。 Persimmons harvested at different maturity reveal different respiration patterns. For maximum storage life, the fruit must be picked when mature but not fully ripe. The fruit produced by healthy trees has longer storage life than those from trees with early fallen leaves. During the biosynthesis of ethylene encoding ACC (1-Aminocyclopropane-1-carboxylic acid) oxidase were first highly expressed in persimmon, and then the expression of genes encoding ACC synthase were followed. Therefore, the ethylene was produced before ACC was accumulated in persimmon fruit. It was found that ethylene played an important role on the softening of persimmon. However, the pectin may not be only softening factor of fruit. Packing the fruits in perforated polyethylene bag was an efficient method to retard softening of persimmon, and CTSD (Constant Temperature Short Duration) method could efficiently remove the astringency of persimmon. It was found that the storage life of several persimmon cultivars treated with the ethylene inhibitor, such as 'Lentaisu' and 'Sitiau', could be extended significantly.