採收時果實性狀對‘黑美人’及‘紅嬌’酪梨 後熟品質之影響

Abstract

酪梨果實為典型的更年性類型，且需要完全後熟才具有食用價值，然而果實採收狀態會影響果實的後熟品質，因此本研究欲探討臺灣本地早生種‘黑美人’和中生種‘紅嬌’酪梨果實於不同採收時期的性狀差異，而後進一步了解果實採收時性狀對果實後熟期間品質的影響。早生種‘黑美人’於2022年5月7日開始調查果實的生長發育情形，並於6月20日開始採收果實進行後熟試驗; 中生種‘紅嬌’於2022年5月30日起調查果實生長發育情形，並於9月12日起採收果實進行後熟試驗。兩品種果實於發育期間果長、果寬及果肉粗脂肪含量皆有顯著提升，然而‘黑美人’的果肉乾物質含量維持在12%上下，‘紅嬌’果肉乾物質含量則在10月3日後累積至16%以上。‘黑美人’果實採收後約在5到7天內完成後熟，其中最早採收的果實後熟所需天數最長，果皮轉色和蒂頭萎凋的速度也最慢，但完熟後果肉生理障礙與病害的發生情形最為嚴重，可能與其果肉總酚含量最高有關。‘紅嬌’果實約在8到10天內完成後熟，各批次果實的後熟所需天數、果皮轉色及蒂頭萎凋速度並無明顯差異，完熟後同樣屬最早採收的果實果肉生理障礙與病害的發生最為嚴重，應為其果肉總酚含量及多酚氧化酵素活性最高所造成。果實採收時的性狀，‘黑美人’的果長、果寬、重量和果肉率與果肉生理障礙嚴重程度呈現中度負相關，表示該品種較大的果實採收後品質較佳; ‘紅嬌’果實各性狀與果肉後熟品質之關係則較不顯著。而透過DPPH和ABTS兩種抗氧化力分析，‘黑美人’與‘紅嬌’的果實，皆以最早採收的果實果肉抗氧化力最高，‘紅嬌’果實果肉的過氧化酵素和過氧化氫酵素活性，亦以最早採收的果實最高。本研究結果初步建立了‘黑美人’與‘紅嬌’採收時果實性狀與內容物之關係，並持續追蹤果實後熟過程的表現，兩品種的表現差異，說明以果實性狀作為採收判斷指標時，需更一步考慮各品種的果實發育特性，以建立更適合的參考依據。

Avocado is a climacteric fruit renowned for consumption upon reaching full ripeness. However, the harvest date significantly influences fruit ripening quality. Therefore, this study aims to examine the fruit characteristics of the early-season cultivar ‘Black Beauty’ and the mid-season cultivar ‘Red Fairy’ on different harvest date. Furthermore, it seeks to comprehend how these fruit characteristics impact fruit quality during the ripening. Growth measurements for ‘Black Beauty’ began on May 7, 2022, with the ripening experiment starting on June 12. As for the ‘Red Fairy’ cultivar, growth measurements and ripening experiments commenced on May 30 and September 12, respectively. Both cultivars exhibited substantial increases in fruit length, diameter, and oil content during the fruit development. However, while the dry matter content of ‘Black Beauty’ remained consistent at around 12%, that of ‘Red Fairy’ notably increased to over 16% after October 3. The ‘Black Beauty’ fruits ripened within 5 to 7 days. The initial harvest of ‘Black Beauty’ took the longest time to ripen, displaying slower changes in peel color and pedicel wilting. Nevertheless, this harvest exhibited the severest occurrence of physiological disorders and rots. This phenomenon could be attributed to the highest polyphenol content in the mesocarp. Similarly, the ‘Red Fairy’ fruits ripened within 8 to 10 days. While the days to ripen, color changes, and pedicel wilting speeds did not significantly differ between harvests, the earliest harvest displayed the most pronounced physiological disorders and rots, also likely due to elevated polyphenol content. Among the harvested fruit characteristics, the fruit length, diameter, weight, and flesh ratio of ‘Black Beauty’ displayed a low-to-medium correlation with the degree of physiological disorders, indicating that larger fruits generally exhibited better quality. Conversely, the fruit characteristics of ‘Red Fairy,’ excluding days to ripen, did not exhibit a significant correlation with fruit quality. Using the DPPH and ABTS assays, it was determined that the earliest harvests of both ‘Black Beauty’ and ‘Red Fairy’ possessed the highest antioxidant capacity in the mesocarp. Notably, the ‘Red Fairy’ fruits exhibited the highest peroxidase and catalase activity in the earliest harvests. This study established the relationship between the fruit characteristics at harvest and the chemical contents of ‘Black Beauty’ and ‘Red Fairy’ avocado. Through tracking the fruit ripening performance, the different ripening patterns of these two cultivars showed that it was necessary to consider the feature of fruit development of each avocado cultivar before using fruit charateristics as harvest maturity indices.