低溫貯藏及蒸熱處理對‘帝王’番石榴果實品質之影響

Effect of Cold Storage and Vapor Heat Treatment on the Quality of 'Di-Wang' Guava (Psidium guajava L.) Fruits

本試驗調查低溫貯藏及蒸熱處理對‘帝王’番石榴冬果及夏果品質之影響。果實貯藏於1、5、10℃恆溫箱中，每週取樣調查結果，硬度隨貯藏時間增加而下降；又以貯藏於5℃之果實硬度最低。冬果之可溶性固形物高於夏果。夏果貯藏在1℃及5℃時維他命C逐漸上升但可滴定酸無明顯之變化。番石榴低溫貯藏後取出時外觀正常，但回溫25℃下3天後，表皮發生褐化。在10℃貯藏4週後褐化最嚴重；貯藏5週取出回溫3天後見腐爛及菌絲產生。適合之貯藏溫度為1℃，壽命約4週。‘帝王’番石榴果實經46.5℃蒸熱處理15、35及40分鐘後放於室溫7日，東方果實蠅蟲卵孵化率皆為0%，而對照組的蟲卵孵化率為54.1%。蒸熱檢疫處理果心溫度達46.5℃後維持15分鐘或35分鐘，皆可有效殺死東方果實蠅，但40分鐘則有熱傷害產生。蒸熱處理後再經1℃貯運7天仍可維持果實品質。 Effects of low temperature storage and vapor heat treatment on the quality of summer- and winter-season 'Di-Wang' guava fruits were investigated. Fruits stored at 1℃, 5℃, or 10℃, were examined weekly. Fruit firmness decreased with time in storage. Fruits stored at 5℃ softened most rapidly. Guavas harvested in winter had higher total soluble solids than those harvested in summer. The ascorbic acid content of the summer crop increased during storage at 1℃ and 5℃, but the titratable acidity did not change. Fruits examined immediately after the low temperature storage looked normal, but browning occurred when they were moved to 25 for 3 days. Fruits stored at 10℃ for 4 weeks had the severest browning. Fruit decay and hypha growth of molds on the skin became visible after being stored at 10℃ for 5 weeks and then kept at room temperature for 3 days. The optimum storage temperature for 'Di-Wang' guava seemed to be 1℃. None of the inoculated eggs of oriental fruit fly (Bactrocera dorsalis Hendel) survived a vapor heat treatment at 46.5℃ fruit core temperature for 15, 35 or 40 minutes, followed by 7 days at room temperature, while 54.1% of eggs in the control group hatched. The vapor heat treatment for 40 minutes caused heat injury, however. The fruits received 15 or 35 minutes of vapor heat treatment also tolerated 7 days of storage at 1℃ afterward without a loss of quality.