椪柑採後模擬低溫檢疫處理、貯放溫度及提早採收對轉色之影響

Effects of Simulated Low-temperature Quarantine Treatment, Storage Temperature, and Early Harvest on Coloration of 'Ponkan' Mandarin (Citrus reticulata Blanco)

早期採收的椪柑（Citrus reticulata Blanco 'Ponkan'）果皮常帶綠色，較不受消費者喜愛。本研究調查模擬低溫檢疫處理、採後貯放不同溫度，以及提早採收後之適溫貯放對椪柑果皮轉色之影響。果皮顏色除以目測轉色率表示外，並以色差儀量測CIELAB L*、a*及b*值。試驗結果，椪柑在模擬低溫檢疫處理（0℃、15日）期間轉色幅度甚小，而此低溫處理不影響後續的轉色速率。果皮帶綠色的椪柑不論是否經過此低溫處理，在15℃最快轉成橙黃色，放在10℃或20℃各三次試驗中有兩次轉色略慢，在25℃則三次都轉色最慢。提早14日採收帶綠色的椪柑存放於15℃比不提早採收者加速轉色，但早採的果實有糖度較低和酸度較高之趨勢。椪柑在半轉色的適熟期採收後，除低溫檢疫外皆以15℃貯運，最有利於後續的轉色。 Early harvested 'Ponkan' mandarin (Citrus reticulata Blanco) with greenish peel has less appeal than the fullycolored for consumers. We studied the effects of simulated lowtemperature quarantine treatment, storage temperature, and early harvest on the rate of coloration. In addition to visual evaluation on coloration of the fruit, a Hunter color difference meter was used to measure CIELAB a(superscript *), b(superscript *), and L(superscript *) values of color. We found that simulated lowtemperature quarantine treatment at 0℃ for 15 days changed the peel color very slightly and this treatment had no effect on the subsequent coloration. Greenish 'Ponkan' stored at 15℃ turned to full yellow color fastest regardless of prior simulated lowtemperature quarantine treatment or not. Fruits stored at 10℃ or 20℃ turned color slower than those at 15℃ in two of three experiments. Fruits turned color slowest at 25℃ in all three experiments. Greenish 'Ponkan' harvested twoweeks earlier and stored at 15℃ accelerated coloring compared to similar fruit left on the tree two weeks longer. However, earlier harvest caused lower soluble solids content of the fruit in one experiment and higher acidity in another. Harvesting halfcolored 'Ponkan' mandarin and using 15℃ for shipping and storage is favorable for rapid and good coloration.