- 學位論文
芭樂(Psidium guajava L.)苗抗氧化活性之探討及發酵時間對製茶之影響
Study on the Phenolic Compounds and Antioxidant Capacity of Guava Sprouts and Effect of Fermentation Time on their Tea Making
摘要
番石榴(Psidium guajava L.)是屬於桃金孃科的熱帶植物，廣泛存 在於南美、歐洲、非洲和亞洲國家。其果實和葉子中含有高量的酚類化 合物及類黃酮，並具有高抗氧化力及生物活性。更值得一提的是與其他 食用植物相比，番石榴可被歸類為功能性植物，因其具有幫助消炎、抗 咳嗽、減輕脫水、緩解腹瀉和降低血糖(減少 2 型糖尿病)之功效。此 外，在台灣、日本、中國和韓國等地區，由於番石榴葉具有獨特的香氣 和功能性成分，現今已被大量商業化為番石榴葉茶(GLT)。近年來， 關於番石榴芽苗及其芽苗茶葉研究甚少，因此本研究主要探討番石榴芽 中的酚類化合物、抗氧化成分(TPC 和 TF)及抗氧化能力(FRAP 還原 能力、DPPH 清除能力和 SOD-like)，而本次研究之目的在於探討番石 榴芽苗茶葉的發酵時間(2、4、6、8 和 10 小時)也關心相同的因素如 番石榴芽苗;並找出最適萃取條件(萃取溶劑、時間和比例)及芽苗的 最適生長時間(1W、2W、3W、4W 和 5W)。 結果顯示，番石榴芽苗之最適萃取條件為樣品和溶劑的固液比為 1:250(g / mL)，使用溶劑為 30%乙醇水溶液，萃取時間則為 35 min 會 有最好的萃取效果。此外，由於 5W 的芽苗特性可能不適用於食物感官 ，儘管其具有最高量之 TPC、FRAP 以及 SOD-like 活性，因此在不同番 石榴芽苗生長時間中選擇 4W 作為發酵茶。然而與番石榴葉相比 4W 含 有較高之 TPC 含量與 FRAP 還原能力，特別是在 SOD-like 活性。鞣花 酸，牡荊素和楊梅黃酮為番石榴葉中主要之酚類化合物，而沒食子酸， 七葉樹苷，兒茶素，牡荊素和楊梅黃酮則為番石榴芽苗主要之化合物。 然而，番石榴芽苗的主要化合物會隨生長時間的增加而提高，又以七葉 樹苷之含量增加最多。另外，沒食子酸、七葉樹苷、兒茶素和楊梅素經 由統計分析發現與 FRAP 還原能力和 SOD-like 活性呈高度正相關。根據 發酵結果顯示，又以 6h-F 為最佳發酵時間，具有高量的 TPC 含量、 FRAP 還原能力，尤其在 SOD-like 活性上也遠高於番石榴葉。而在 4、6 和 8 小時發酵後，4W 的番石榴芽苗也分別具有高量的抗氧化成分及抗 氧化能力。
並列摘要
Guava (Psidium guajava L.) is a tropical plant belonging to the Myrtaceae family, and is widely found in South America, Europe, Africa, and the Asian countries. Its fruit and leaf are known to have contained high levels of phenolic compounds, flavonoids with high antioxidant activities and bioactivities. More so, guava when compared to other edible plants it can be categorized as a functional plant since it posses functional properties that helps in anti- inflammatory, anti-cough, dehydration alleviation, diarrhea alleviation and hypoglycemic (reduction of type 2 diabetes). Furthermore, in Taiwan, Japan, China and Korea, guava leaves have been transformed and heavily commercialized into guava leaf tea (GLT) because of its unique aroma and functionalities. Recently, there are less studies about guava sprouts including guava sprout tea, thus in this research was conducted to study about phenolic compounds in guava sprouts, antioxidant composition (TPC and TF) as well as antioxidant capacity (FRAP, DPPH and SOD-like). Additionally, the fermentation time (2, 4, 6, 8, and 10 h) of guava sprout tea were also concerned in the same factors as in guava sprouts; however, the best extraction condition extraction (extraction solvents, time and ratio) were used to extract samples and also the optimum growth time (1W, 2W, 3W, 4W and 5W) of guava sprout was chosen in this study. Results showed that using 1:250 (g/mL) ratio between sample and solvent respectively and 30% Et-W as the solvent with 35 min extraction time. Moreover, 4W was chosen to make the fermentation tea among the different growth time of guava sprouts due to the characteristics of 5W might not suitable for the food sensory although it expressed the highest amount of TPC, FRAP as well as SOD-like activity. Additionally, 4W also contained the high TPC content, FRAP especially SOD-like activity which was higher than guava leaves. Ellagic acid, vitexin and myricetin were chosen to be the major phenolic compounds in guava leaves while gallic acid, esculetin, catechin, vitexin and myricetin were counted to be the guava sprouts major compounds. Moreover, these major compounds in guava sprouts were higher during growth time increase but only esculetin percentage was still raised up. Additionally, gallic acid, esculetin, catechin and myricetin were high positive correlations with FRAP and SOD-like activity. In accordance with the fermentation results, 6h- F was represented as the optimum fermentation time for the guava sprout tea due to the highest TPC content, FRAP among other fermentation times especially SOD-like activity that was higher than guava leaves and 4W with no any process and also their major phenolic compounds expressed high amount at 4, 6 and 8 h fermentation times that showed in the same trend with their antioxidant composition as well as antioxidant capacity.