| 摘要： 香蕉一向為我國最大宗的外銷水果，且以華蕉類（Giant Cavendish, AAA Group）‘北蕉’為主要的栽培品種。為永續台蕉產業之競爭力及品種多樣化，台灣香蕉研究所於民國96年分別命名 ‘台蕉5號’及‘台蕉6號’，商品名為‘玉山’及‘玉豐’之改良新品種供蕉農選用栽植。惟此兩新品種與‘北蕉’在採後生理特性、後熟行為及品質之差異，仍有待進一步暸解。 因此，本研究乃針對新品種‘台蕉5號’、‘台蕉6號’與傳統 ‘北蕉’之果實採後呼吸及乙烯產生行為及後熟品質進行分析比較。期能對此二新品種之採後生理、後熟行為及品質差異，有進一步之暸解。 結果顯示，比較貯藏期間更年前期(pre-climacteric period)之呼吸率及乙烯產生率，在15℃、20及25℃時，三品種香蕉之呼吸率及乙烯產生率均隨着貯藏溫度之提高而增加，三品種在15℃貯藏環境下之呼吸率約為14.6-16.3mgCO2kg-1‧hr-1左右，乙烯產生率約在0.10-0.18μlC2H4 kg-1‧hr-1之間。在20℃貯藏環境下之呼吸率約18.3-19.3mgCO2kg-1‧hr-1左右，乙烯產生率約在0.27-0.36μlC2H4 kg-1‧hr-1左右。在25℃貯藏環境下之呼吸率約為28.3-31.2 mgCO2 kg-1‧hr-1左右，乙烯產生率約在0.73-0.97μl C2H4 kg-1‧hr-1左右。在15℃-25℃下，三品種香蕉呼吸率之Q10 值約在1.91-1.94之間。其乙烯大量產生之時間，一般比呼吸高峰產生早1-2天。香蕉達到呼吸高峰及乙烯大量產生之時間，亦隨著貯藏溫度之提高而提前，在15℃之呼吸高峰約在40-42天出現，在20℃貯藏約在33-42天出現，在25℃約在11-17天出現。一般而言，香蕉呼吸高峰以‘台蕉6號’出現的時間最早，而‘台蕉5號’ 及‘北蕉’較晚且其出現時間相近。 香蕉轉色至7級時，就果重、果肉重及果皮重，‘台蕉6號’均顯著高於‘北蕉’及‘台蕉5號’。果指之肉/果皮比則三品種間均無顯著差異。果實及果肉硬度，以‘台蕉六號’之果實硬度(含果皮)顯著高於‘北蕉’及‘台蕉五號’，但果肉(不含果皮)反以‘台蕉六號’之硬度顯著低於‘北蕉’及‘台蕉五號’，顯示‘台蕉六號’之果皮硬度顯著高於‘北蕉’及‘台蕉五號’，但果肉卻顯著較軟。就催熟後果皮顏色到達7級時之色彩亮度及濃度以‘台蕉5號’較其他二品種高，就可滴定酸及pH值之比較，北蕉之可滴定酸顯著較其他二品種高，而pH值，在三品種間並無顯著差異。就果實主要可溶性糖類，‘北蕉’、‘台蕉五號’及‘台蕉六號’均以蔗糖含量較高、葡萄糖次之、果糖較低。就果糖含量，三品種間並無顯著差異，葡萄糖及蔗糖含量，以北蕉含量較高。就轉色速率之比較，香蕉乙烯催熟後至轉色4級(果皮黃色多於綠色) ，以‘台蕉6號’轉色較快(3.2天)，‘台蕉5號’(3.8天)與‘北蕉’(3.9天)轉色時間相近。櫥架壽命以‘北蕉’(4.1天) 最長，‘台蕉五號’(3.9)次之，‘台蕉6號’最短(3.1天)。整體而言，在三個品種之同一果手不同位置(左、中、右)果指之品質、果指重、果肉重、果皮重、硬度(果指及果肉)、色澤(L值、θ值、C值)、總可溶性固形物、可滴定酸、糖酸比、pH值、糖類成分(果糖、葡萄糖、蔗糖)均無顯著差異。 香蕉經1-MCP處理24小時後，於15℃、20℃、25℃貯藏環境下，定期(每5天)觀察其保鮮效果。再由上述三種不同溫控貯藏環境逢機取樣分切之果把(3果手，每果手3果指)，並以乙烯催熟，觀察後熟轉色情形。試驗發現香蕉果實顏色轉黃程度，與貯藏溫度高低成正相關。於15℃、20℃貯藏環境下，香蕉大致呈現轉色不完全現象。香蕉若於25℃下貯藏、經15天後再催熟，則能正常轉色。此種試驗結果顯示，如果此一香蕉保鮮後熟處理方式運用在香蕉滯銷或冷藏庫不敷使用時，可達延緩香蕉出貨，調節市場供需之功能，符合商業需求。Banana has been the number one export fruit crop for many years in Taiwan, and the most widely cultivar is ‘Pei-Chiao’, in the category of Cavendish type, AAA. To sustain the competitiveness of Taiwan banana industry and to ensure the diversity of banana variety, Taiwan Banana Research Institute extended two new cultivars, ‘Tai–Chiao No.5’ and ‘Tai–Chiao No.6’, with improved traits of ‘Pei-Chiao’, for banana grower’s use in 2007 and 2008. However, the post-harvest physiology, fruit behavior after ripening and difference of fruit quality of these two new banana cultivars, when compared to‘Pei-Chiao’, still need further understanding. Therefore, the objectives of this study are to compare the postharvest behaviors of fruit respiration and ethylene production pattern, and quality of ‘Tai–Chiao No.5’ and ‘Tai–Chiao No.6’ to those of ‘Pei-Chiao’. From this study, it showed that both the pre-climacteric period respiration rate and the ethylene synthesis in fruit of all three banana cultivars mentioned above increased when the storage temperature was either risen from 15℃ to 20 ℃ or from 20℃ to 25 ℃. Under 15℃ storage temperature, the fruit respiration rate and ethylene synthesis rate of three cultivars studied each was approximately 14.6-16.3 mgCO2kg-1‧hr-1 and 0.10-0.18 μlC2H4 kg-1‧hr-1. At 20℃, the fruit respiration rate and ethylene synthesis rate of three cultivars studied each increased to 18.3-19.3 mgCO2kg-1‧hr-1 and 0.27-0.36 μlC2H4 kg-1‧hr-1. At 25℃, the fruit respiration rate and ethylene synthesis rate of three cultivars studied each increased more to 28.3-31.2 mgCO2 kg-1‧hr-1 and 0.73-0.97 μlC2H4 kg-1‧hr-1. The fruit respiration rate Q10 of these three cultivars studied at 15-25℃ was around 1.91-1.94. The time of mass production of ethylene in banana is 1-2 day earlier than that of the respiration peak. Time of banana fruit used is this study to reach the respiration peak and mass formation of ethylene was also shortened with the rise of storage temperature. At 15℃, the respiration peak of banana did not appear until 40-42 days later after low temperature storage. While it was under 20℃ storage condition, the respiration peak of banana was observed 33-42 days later. When the storage temperature was set at 25℃, only 11-17 days were need for the presence of the respiration peak of banana tested. In general, the time of banana fruit analyzed to show up its respiration peak in ‘Tai–Chiao No.6’ was much earlier than those of ‘Tai–Chiao No.5’ and ‘Pei-Chiao’. No significant difference in terms of time need to appear the respiration peak could be found between cultivar ‘Tai–Chiao No5’ and ‘Pei-Chiao’. No matter when the weight of a banana finger, pulp weight or peel weight of ‘Tai–Chiao No.6’ was concerned, all were significantly higher than those of ‘Pei-Chiao’ and ‘Tai–Chiao No.5’, respectively when the color index of banana came to level 7. When the weight ratio of pulp to peel was concerned, no significant difference could be detected among the three cultivars evaluated. Similarly, when traits including weight of finger, weight of pulp or peel, and weight ratio of pulp to peel were compared among different position of a finger, no matter whether it was located at the left, middle or right, in a same fruit hand of each studied cultivar, no significant difference could be detected either. In the respect of firmness assay for a whole fruit finger, the firmness value of ‘Tai–Chiao No.6’ finger was significantly higher than those of ‘Pei-Chiao’ and ‘Tai–Chiao No.5’. On the contrary, if only the firmness of pulp was concerned, the firmness value of ‘Tai–Chiao No.6’ pulp was obviously lower than those of ‘Pei-Chiao’ and ‘Tai–Chiao No.5’, indicative of ‘Tai–Chiao No.6’ with firm texture in the peel but soft pulp. In the aspect of brightness or tint of fruit peel at color index 7 after ripening, brightness and tint values of ‘Tai–Chiao No.5’ peel were higher than those of the other two cultivars studied. As far as the titratable acidity and pH value was concerned, the titratable acidity content in the peel of ‘Pei-Chiao’ was evidently higher than that in those two newly release cultivar. For pH measurement, no significant difference could be detected among pulps of three cultivars used in this study. From the analysis of soluble sugar content in the banana fruit at color index stage 7, a similar composition of soluble sugar content in three banana cultivars studied was found, i.e. glucose in major, glucose intermediate, and fructose with low proportion. No significant difference of fructose content could be verified among three banana cultivars studied but higher content of glucose and sucrose was found in ‘Pei-Chiao’. When the degreening rate of banana was compared among three cultivars studied, the number of days needed for each cultivar to reach color index stage 4（more yellow than green on the peel）after ethylene ripening treatment was 3.2 days for ‘Tai–Chiao No.6’, 3.8 days for ‘Tai–Chiao No.5’, and 3.9 days for ‘Pei-Chiao’, illustrating that ‘Tai–Chiao No.6’ had a much shorter time need to be ripen when compared to that of ‘Tai–Chiao No.5’ and ‘ Pei-Chiao’ From the shelf life study, it showed that ‘Pei-Chiao’ fruit had the longest shelf, 4.l day. Fruits of ‘Tai–Chiao No.5’and ‘Pei-Chiao’ both lasted similarly for 3.8-3.9 days whereas fruit of ‘Tai–Chiao No.6’ could only be kept on the shelf for only 3.2 days with commercial value. For three banana cultivars studied, in overall no significant difference could be detected for traits including fruit quality of finger, finger weight, weight of peel, weight of peel, firmness (finger and pulp), color (L value, θ value, C value), total soluble solid, titratable acidity, ratio of sugar to acid, pH value, carbohydrate composition (fructose, glucose, sucrose) for banana fingers no matter whether they were in the left or middle or right side of a same fruit hand. In 1-MCP experiment, banana which was treated by I-MCP for 24 hours, then ripen immediately by ethylene under storage temperature of 15℃ or 20℃ or 25℃ was observed regularly with a 5-day interval for fruit refresh. Colorization of 1-MCP treated banana stored at three different temperature environment was also ripen by ethylene gas, respectively, with three random sampled clusters, which all were composed of 3 fingers per cluster. It was found that the extent of colorization of 1-MCP treated banana was positively correlated with the storage temperature set-up. Generally, colorization of 1-MCP treated banana could not ripen evenly when they were kept under either 15℃ or 20℃. On the other hand, if banana was stored under 25℃ and ripen again by ethylene 15 days later, banana treated by I-MCP all could be ripened evenly. From this study, it indicates that if the approach of treating banana first with 1-MCP for 1 day, storing them under 25℃ temperature atmosphere for 15 days, and then apply ethylene again to enhance the colorization of banana could be adopted, it should be able to function in the sense of postponing the time for delivering banana under overproduction pressure to the market or when storage spaces available for storing banana are not possible. |
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