| 摘要： 本試驗目的擬探討一甲基環丙烯（1-MCP)處理對柳橙(Citrus sinensis (L.) Osbeck cv. Liucheng) 造成之負面影響，釐清造成其褐化之可能原因，並測試1-MCP對椪柑 (Citrus reticulata Blanco)、 ‘Eureka’檸檬(Citrus limon L. Burm. f.)及‘Ruby’葡萄柚(Citrus paradise Masfad cv.‘Ruby’)等不同種類柑桔，觀察是否會出現類似之褐化反應。 以不同劑量濃度1-MCP(安喜培®,有效成份為0.43%，利統公司出品)於室溫環境下燻蒸柳橙果實24小時，觀察其於室溫條件及15°C貯藏之變化，經1-MCP處理之果實乙烯釋放率及呼吸率於室溫貯藏時其迅速升高，並於出現高峰後下降，於果實外觀方面，果皮褐化情形則伴隨乙烯及呼吸率上升而出現。於15°C貯藏時，1-MCP處理之果皮於5日後開始出現褐化症狀，11日時全數果實褐化酸腐。貯藏期間之離子滲漏率隨貯藏日數增加而上升，且顯著高於對照組。當柳橙果實取出於室溫回溫時，1-MCP處理柳橙之乙烯釋放率及呼吸率迅速升高後下降，所有果實於回溫期間褐化腐爛。 以造成柳橙損害最嚴重之濃度0.5 g 1-MCP粉劑(1-MCP濃度經估算約為15960ppb)處理柳橙，並分析於15°C貯藏期間導致褐化損傷之因子，果實褐化嚴重程度隨貯藏日數增加而上升，其果皮之離子滲漏率、ACC含量皆隨貯藏天數增加而提升，乙烯生合成酵素ACO之活性於貯藏期間皆高於對照組，而褐化相關酵素PPO及POD之活性與酚類化合物之含量卻因處理1-MCP而低於對照組。由上述結果推斷，0.5 g 1-MCP粉劑處理造成柳橙處於非生物逆境之狀態，增加乙烯生合成相關物質ACC累積及相關酵素ACO活性提升，並降低膜體完整性使褐化酵素PPO及POD與酚類反應誘發果實褐化。 以0.5 g 1-MCP粉劑(15960ppb 1-MCP)於室溫下燻蒸24小時之椪柑及‘Eureka’檸檬，無論於15°C貯藏之顏色方面亦或是室溫回溫時之乙烯釋放率及呼吸率皆與對照組無顯著差異，亦無褐化之發生，但0.5 g 1-MCP粉劑處理造成‘Ruby’葡萄柚果實褐化，於15°C貯藏21日時，葡萄柚果實開始出現褐化徵狀，而貯藏28日後，果實全數褐化。此外，於7及14日取出回溫之果實，回溫期間之乙烯釋放率隨回溫日數增加持續上升，呼吸率則於回溫時皆顯著高於對照組。綜合上述結果，1-MCP處理不同種類之柑桔類造成不同反應，其中引起褐化反應者為柳橙及‘Ruby’葡萄柚，而椪柑及‘Eureka’檸檬則不會誘發果皮褐化，1-MCP引起褐化反應之機制可能與誘導大量乙烯及呼吸率之表現及破壞膜體系統有關。The purposes of this study were to investigate the negative effects of 1-MCP treatment on orange (Citrus sinensis (L.) Osbeck cv. Liucheng), to find the possible causes of 1-MCP-induced peel browning in orange, and to evaluate the effect of 1-MCP treatment on ‘Ponkan’ Mandarin (Citrus reticulata Blanco), ''Eureka'' lemon (Citrus limon L. Burm. F.), and ''Ruby'' grapefruit (Citrus paradise Masfad cv. ''Ruby'') by observing whether 1-MCP may cause the browning symptoms in different type of citrus. Different concentrations of 1-MCP (AnsiP®, 0.43% active ingredient, produced by Litong Company) were treated on orange fruit at room temperature for 24 hours to observe the changes in fruits stored at room temperature and 15°C. Our results showed that at all concentration of 1-MCP tested, the ethylene production rate and respiration rate of 1-MCP-treated fruits increased rapidly at room temperature and decreased after peak. In terms of fruit appearance, the browning of the peel occured as the ethylene production rate and respiration rate increased. Different concentrations of 1-MCP imposed no significant effect on the appearance of orange when stored at 15°C, all showed peel browning symptoms after 5 days of storage and all fruits turned brown after 11 days of storage. The electrolyte leakage rate increased during the storage with 1-MCP treated fruits significantly higher than that of control. When the orange fruit was transferred to room temperature following storage at 15°C, the ethylene production rate and respiration rate of the 1-MCP-treated orange rose rapidly and then decreased. All fruits turned brown rapidly and became rotten during the warm-up period. Application of 0.5 g 1-MCP powder (15960ppb 1-MCP) has induced the most serious damage to oranges and therefore was chosen to treat oranges to investigate the possible causes of 1-MCP-induced peel browning during storage at 15°C. The severity of browning increased with storage time. The electrolyte leakage rate and ACC content of the peel increased with storage time. The ACO activity was higher during the storage period than that of control. PPO, POD activity and total phenolic compounds were lower than the control due to 1-MCP treatment. It is inferred from the above results that 0.5 g 1-MCP powder treatment causes the abiotic stress to oranges, which may in turn induce the accumulation of ACC and the increase of ACO activity. When the membrane was damaged, PPO and POD combinded with phenolic compounds to induce browning reaction of fruits. Application of 0.5 g 1-MCP powder (15960ppb 1-MCP) on ‘Ponkan’ Mandarin and ''Eureka'' lemons for 24 hours at room temperature did not significantly affect the color of skin when stored at 15°C or the ethylene production rate and respiration rate of fruits rewarmed at room temperature after storing at 15°C compared to the control. There was no browning in the ‘Ponkan’ Mandarin and ''Eureka'' lemons after application of 0.5 g 1-MCP powder, but the ‘Ruby’ grapefruit fruit turned brown. After 21 days of storage at 15°C, the ‘Ruby’ grapefruit fruit started to show browning symptoms, and after 28 days of storage, all of the ‘Ruby’ grapefruits treated became brown. In addition, the ethylene production rate of 0.5 g 1-MCP powder treated ‘Ruby’ grapefruits stored at 15°C for 7 days and 14 days continued to increase with days durning rewarming at room temperature and the respiration rate was higher than that of control. Taken together our results indicated that treatment of 1-MCP on different type of citrus may cause different responses. Treatment of 1-MCP may induce browning of Oranges and ‘Ruby’ grapefruits, but there is no browning in peel of ‘Ponkan’ Mandarin and ''Eureka'' lemons. The browning induced by 1-MCP may be associated with the rapid increase of ethylene production and respiration rate which may in turn damage the integrity of the membrane. |
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