採後殺菌劑處理和氣變包裝延長‘大目’釋迦貯藏壽命之研究

Abstract

‘大目’釋迦(Annona squamosa L.)由於採後快速軟熟、對寒害敏感且經長時間貯藏後易受採後病害發展嚴重等因素，很少外銷。但其產期調節技術成熟，採收期由7月到翌年5月中旬，若能研發長程貯運技術，可填補鳳梨釋迦產期12至4月以外的番荔枝屬果品外銷空窗期。本研究旨在探討氣變包裝作為‘大目’釋迦保鮮技術的可行性，同時嘗試結合貯前溫湯與殺菌劑抑病處理，以期延長採後壽命，俾利外銷拓展。‘大目’釋迦在12°C對照組採後壽命不足2週；若將6 kg果實經微孔內襯袋+Ca(OH)2包裝貯藏3週，袋內O2平衡濃度約3%，CO2平衡濃度維持<0.3%，貯藏期間無果實後熟軟化，20°C回溫>96%果實可以正常後熟，可溶性固形物20.1°Brix，果皮色相角值90°，惟後熟期間病害嚴重發展。‘大目’釋迦貯前以8.3 μg L-1三氟得克利45°C溫湯處理25~30分鐘，病害發展明顯降低，但該處理結合氣調貯藏，果皮貯藏期間褐變嚴重，不具商品價值。另以2500 μg L-1三氟得克利、9600 μg L-1普克利、4800 μg L-1撲克拉、4800 μg L-1亞托待克利4種含G1殺菌劑農藥浸漬‘大目’釋迦果梗端，再進行氣變包裝貯藏3週，貯前0.48%撲克拉浸漬處理抑病效果最佳，外觀與內部病害嚴重程度1.09與1.3，71.4%果實回溫後熟具有商品價值。結合貯前藥劑浸漬與氣變包裝技術，‘大目’釋迦於12°C貯運壽命可由<2週延長為3週。

The ‘Ta Mu’ sugar apple (Annona squamosa L.) is not widely exported due to its rapid softening after harvest, sensitivity to chilling injury, and susceptibility to postharvest diseases during prolonged storage. However, with the maturity of production season regulation techniques, the harvest season can be extended from July to mid-May of the following year. If long distance transportation techniques can be developed, sugar apples may fill the gap that outside the atemoya production period for the export. This study aims to investigate the feasibility of modified atmosphere packaging as a preservation technique for ‘Ta Mu’ sugar apples. Additionally, the combination of pre-storage hot water dip and fungicide treatments was investigated in order to extend the postharvest life and facilitate export expansion. Packaging 6 kg ‘Ta Mu’ sugar apples in a 35 microperforated liner bag with 6% Ca(OH)2 at 12°C maintained 2.4-3% oxygen and <0.3% carbon dioxide inside the bag for 3~21 days of the storage, which alleviated physiological disorders caused by high CO2 and prevented fruit ripening during storage. After 3-week storage, the fruit did not ripen but ripens normally after transferring to 20°C. The soluble solids content was 20.1°Brix, the hue angle of the fruit peel was 90°, and over 96% of the fruit could ripen successfully. In contrast, the control group without modified atmosphere packaging (MAP) had a postharvest life of less than 2 weeks, while MAP retarded the onset of ripening in ‘Ta Mu’ sugar apples for 3 weeks. However, disease development was severe during rewarming period. Before storage, treating ‘Ta Mu’ sugar apples with 8.3 μg L-1 trifloxystrobin + tebuconazole in 45°C hot water for 25~30 minutes significantly reduced disease development. However, when this treatment was combined with controlled atmosphere storage, the fruit underwent severe peel browning during storage, leading to a loss of marketability. Additionally, four commercially fungicides containing G1 fungicides, namely 0.25% trifloxystrobin + tebuconazole, 0.96% propiconazole, 0.48% prochloraz, and 0.48% azoxystrobin + difenoconazole, were used to dip the stem end of ‘Ta Mu’ sugar apples. After 3 weeks of MAP storage, the best treatment was observed with 0.48% prochloraz dipping, which resulted in slight appearance and internal disease index of 1.09 and 1.3, respectively. Furthermore, 71.4% of the fruit were salable after ripening at ambient temperature. By combining pre-storage fungicide dip and MAP techniques, the postharvest life of ‘Ta Mu’ sugar apples was extended from less than 2 weeks to 3 weeks at 12°C. This information can be useful for export industry.