椪柑用乙烯催色之效果與方法

Effects and Methods of Ethylene Degreening of 'Ponkan' Mandarin (Citrus reticulata Blanco)

早期採收只有局部轉色的椪柑（Citrus reticulata Blanco 'Ponkan'），果肉雖已成熟，外觀欠佳。本研究將椪柑放在25℃以5ppm乙烯催色48小時後轉放在15℃空氣中，獲得良好的催色效果。乙烯處理後的椪柑放在10°或20℃與放在15℃轉色速度相似，但放在20℃者色相角（h°）略大，表示橙色較少。使用連續細流通氣或間歇換氣之方法處理乙烯、乙烯濃度5或10ppm、催色箱中聚集1%或5% CO2等處理比較，催色效果相同。採收後催色前以殺菌劑克熱淨加生長素2, 4-D處理可有效防止催色後的椪柑果蒂老化及腐爛。催色處理配合15℃貯運可使椪柑在採後15日上市時有橙黃色的外觀。模擬外銷用椪柑催色後經低溫檢疫處理及15℃貯運，亦可在採後30日內完成轉色為橙黃。催色處理不僅加速椪柑褪綠，且可加深在採後30日左右測定之橙黃色澤，但不影響果實之糖、酸度。催色之效果不僅用肉眼可以看出，且能用色差儀測定及換算出CIELAB a*，a*／b*，h°，L*等數值更明確分辨。 Ponkan' mandarin (Citrus reticulata Blanco) harvested in the early maturity season often has acceptable eating quality but lacks attractive yellow orange color. We treated such fruit with 5 ppm ethylene at 25℃ for 48 hours followed by keeping the fruit in air at 15℃ and obtained good degreening effect. Ethylene-treated 'Ponkan' kept at 10° or 20℃ turned color as fast as that at 15℃, but the fruit kept at 20℃ had a slightly higher hue angle (h°) value, i. e. less orange color. Ethylene treatment by trickle or intermit air change methods, ethylene concentration at 5 or 10ppm, and CO2 accumulation of 1 or 5% in the degreening chamber made no difference in the degreening effect. Dipping the fruit in dilute fungicide Iminoctadine plus growth regulator 2, 4-Deffectively controlled ethylene-enhanced decay and preserved green button (stem plus calyx) of the fruit. Half green 'Ponkan' mandarin treated with ethylene followed by keeping at 15℃ air turned to full orange yellow in 15 days after harvest. Similar fruit treated with ethylene followed by 15 days of simulated low-temperature quarantine treatment and subsequent keeping at 15℃ in air turned to full orange yellow in 30 days after harvest. Ethylene degreening not only accelerated color change by 5 to 15 days but also improved the finish orange yellow color measured on about 30 days after harvest. The color difference between ethylene-degreened and control fruits was discernible by eyes and more accurately distinguishable by using CIELAB L(superscript *), a(superscript *), a(superscript *)/b(superscript *), and h° values. Ethylene degreening did not affect the soluble solids content or acidity of the fruit measured on about 30 days after harvest.