釋迦果之後熟與貯藏

Ripening and Storage of Custard Apple Fruit (Annona squamosa L.)

釋迦果（Annona squamosa L.）為具呼吸更年性之水果（climacteric fruit）。在20℃，果實在更年上升前（Pre-climacteric）之呼吸率約60~80mg CO2/kg/hr，呼吸高峰時約在280~300mg CO2/kg/hr，屬高呼吸率之水果，亦因此，水果探收後極易熟熱變軟，不易貯藏。此水果亦屬低溫敏感性（chilling sensitive）水果，貯藏溫度低於10℃，易造成寒害（chilling injury）使果皮黑變。適當之貯藏溫度在15℃左右，溫度高加速後熟。果實含大量之澱粉；在後熱過程，澱粉大量糖化水解，總糖量相對增加，其中主要是蔗糖，果糖及葡萄糖。然蔗糖在果實後熟末期，變得極軟時，含量又減少，水解成果糖及葡萄糖，故此二單糖含量仍一直不斷增加。一般之物理或化學藥劑處理，均不易抑制或延遲果實後熟。但利用PE袋（0.03mm）密封包裝，可有效抑制後熟，然因果實高呼吸率所造成之高二氧化碳與低氧，對釋迦果造成嚴重之生理傷害，因此須在膜之厚度及透氣性上進一步研究改進，似極可能成為簡易而有效之延遲果實後熟方法。利用人工大氣貯藏（5% O2+5~10% CO2）。可有效延長釋迦果之貯藏壽命。Ethephon （1,000 ppm）處理，可促進及齊一不同熟度釋迦果之均一後熟而不影響其鮮食品質。

Custard apple (Annona squamosa L.) exhibited a climacteric pattern with high respiration rate which produced CO2 from 60-80 mg/kg/hr at preclimacteric period to 280-300, mg/kg/hr during climacteric peak at 20℃. Due to high respiration rate, the fruit softened and ripened rapidly after harvest and hard to storage at ambient temperature. Custard apple was also susceptible to chilling injury which shown black discoloration when storage temperature was below 10℃. Optimal storage temperature is 15℃. The higher the temperature the shorter the storage life. Mature hard green fruit contained high starch content but was rapidly hydrolyzed to sugars; predominanted in sucrose, fructose and glucose, during ripening. Sucrose was getting more hydrolyzed to fructose and glucose at late ripening stage. General physical and chemical treatments of fruit after harvesting, including fungicide treatment (1,000 ppm Benlate and Boltran), hot water (52℃ and 56℃) and hot water plus fungicide, disinfecting treatment (1% NaClO), costing materials (4X Bond Wax and 1.5% Prolong Treatments), and hormonal treatment (100 ppm BA), were shown ineffective to delay softening and ripening of custard apple. Fruits sealed with PE bag (0.03 mm) maintained in mature hard green state during storage, however, after PE bag was opened, the fruits appeared severe physiological disorder, such as black discoloration and unable to ripen which are resulted in too high CO2 concentration (＞15%) and low oxygen within bag. Mature hard green fruits of custard apple stored in controlled atmosphere of 5% O2+5-10% CO2 at 20℃ for 15 days, the fruits softened and ripened normally after storage. CA storage (5% O2+5-10% CO2) is therefore recommended for extending storage life and maintaining quality of custard apple fruit after harvesting. Ethephon (1,000 ppm) dipping promoted and unified ripening of custard apple fruits of different maturity without bad effect on eating duality.