|關鍵字： 鳳梨；內部褐化；低溫貯藏；pineapple；internal browning；low temperature storage
|摘要： 鳳梨果實經低溫貯藏後易發生寒害，導致內部褐化 (internal browning)，造成果實品質降低，且因無法由外觀判斷，而影響商品信譽並造成經濟損失。本研究主要目的為調查‘台農17號’金鑽鳳梨果肉銅含量增加是否會增加鳳梨果實內部褐化發生率，以及使用不同溫度貯藏對果實內部褐化發生之影響，探討鳳梨果實發生內部褐化之關鍵因子。 ‘台農17號’鳳梨果實於田間噴施硫酸銅，果皮銅含量顯著高於果肉，而採收後以低溫貯藏並移至室溫2天，鳳梨果肉銅含量上升會伴隨鳳梨果實內部褐化發生。當果實於採收後處理硫酸銅，並以低溫貯藏並移至室溫2天，果肉銅含量有上升之情形，且銅含量上升會伴隨果實內部褐化指數之上昇。 低溫貯藏能延緩果皮轉色。不同低溫貯藏之果實，貯藏1週後皆無發生內部褐化，但移至室溫4天後皆發生褐化，且以4℃貯藏最為嚴重，12℃次之，8℃最輕微。低溫貯藏2週後，果實皆發生果實內部褐化，並在移至室溫後內部褐化更為嚴重。而與4℃及8℃之處理比較，內部褐化程度以12℃貯藏最為嚴重。 鈣離子於貯藏期間由內部果肉往外部移動，可能影響‘台農17號’鳳梨內部果肉細胞對低溫逆境的耐受性，內部褐化嚴重之鳳梨果實，果肉銅含量也明顯較高。 本研究之貯藏溫度試驗結果顯示，4℃貯藏2周並移至室溫4天的‘台農17號’鳳梨果實內部褐化程度輕微，但果實剖面經PPO基質處理後褐化嚴重。果實低溫貯藏時間越長，移至室溫後果肉PPO活性越高，總蛋白質含量在果實低溫貯藏期間有下降之趨勢，移至室溫後則上升。而低溫貯藏期間鳳梨酵素活性有增加之趨勢，而移至室溫後鳳梨酵素活性則下降，並伴隨內部褐化之發生，鳳梨酵素活性與內部褐化之關係值得更進一步探討。 綜合上述，‘台農17號’鳳梨並不是貯藏溫度越低越容易發生內部褐化，本研究結果顯示8℃貯藏之果實內部褐化比4℃與12℃貯藏之果實輕微，若搭配上蠟或溫湯等貯藏前處理，可能有較佳的貯藏後果實品質。Pineapple fruits stored at low temperature are easy to develop chilling symptoms, leading to internal browning and fruits quality decreasing. Because there are no external symptoms on affected fruits, it may cause losses of business reputation and profits. The main objective of this study was to investigate whether an increase of copper level in ‘TN17’ pineapples pulp will cause an increase in internal browning incidence, and to analyze the occurrence of internal browning of ‘TN17’ pineapple fruits which were stored at different low temperatures to provide information about the key factor to internal browning development. After spraying copper sulfate on‘TN17’ pineapple fruits in the field, copper concentrations in the shell were significantly higher than in the pulp. After stored at 8℃ for 1 week and followed at room temperature for 2 days, copper level of flesh slighity increased with internal browning symptom occurrence. Both copper level and internal browning index increased in ‘TN17’ pineapple fruits which were dipped in copper sulfate solution and stored at 8℃ for 1 week followed at room temperature for 2 day. Low temperature storage can delay ‘TN17’ pineapple skin color development. No internal browning appeared in fruits stored at low temperature for 1 week, however, it occurred in fruits stored at low temperature for 1 week followed by 4 days at room temperature. Internal browning index was significantly increased in fruits stored at 4℃, followed by fruits stored at 12℃ and only slightly increased in fruits stored at 8℃. More severe internal browning was found in fruits stored at low temperature for 2 week, followed at room temperature for 4 days. Fruits stored at 12 ℃ for 2 weeks followed by 4 days at room temperature had the highest internal browning index, compared with 4℃ and 8℃ treatments. Calcium ions moved from inner pulp to outer pulp during storage may affect the tolerance of the ‘TN17’ pineapple inner pulp cells to low temperature stress. The copper level was significantly higher in pineapple fruits with more severe internal browning. In this study, ‘TN17’ pineapples stored at 4℃ for 2 weeks followed by 4 days at room temperature had slightly internal browning, but fruit section was seriously turned brown after treated with PPO substrate. The longer low temperature storage period, the higher PPO activity was found after 4 days at room temperature. The total protein content of fruits decreased during low temperature storage, and then increased after stored at room temperature. The bromelain activity increased after stored at low temperature, then decreased after moved to room temperature with internal browning occurrence. The relationship between bromelain activity and internal browning is worthy of further study. Taken together, for ‘TN17’ pineapples, it is not that the lower storage temperature, the more internal browning occurrence. In this study, the results showed that 8℃ storage had lower internal browning incidence than 4℃ and 12℃ storage. In combination with waxing or hot water dipping before storage, pineapples may have better storage quality.