木醋桿菌發酵茶湯之生物活性探討

Bioactivities of Tea Broths Fermented by Acetobacter xylinum

何守雯(Shou-Wun He)

指導教授 ： 張耀南

共同指導教授 ： 劉炳嵐

國立虎尾科技大學/文理學院/生物科技研究所/碩士(2015年)

摘要

本研究利用自發酵椰子汁中篩選分離出之木醋桿菌(Acetobacter xylinum)進行紅茶和綠茶基質之發酵，並探討發酵時間(0、3、6、9、12、18、21天)對紅茶與綠茶發酵液 (分別定義為BT與GT）之抗氧化活性(DPPH 自由基清除活性、還原力與總酚含量)及α-澱粉酶抑制活性之影響。實驗結果顯示，BT與GT之pH值會隨著發酵時間增加而逐漸下降，發酵至第21天時，其pH值分別為3.28與3.30。BT與GT之DPPH自由基清除活性(RAS%)會隨著冷凍乾燥後茶基質的添加濃度增加而逐漸增加至定值後，不再有所變化，然而發酵時間對茶發酵液的RAS%似乎影響不大。維生素 C 等值(vitamin C equivalent; Vit. CE)還原力測定(RP)方面，發酵21天後的BT具有最佳還原力 (0.499 mg Vit. CE/mL) ，發酵15天後的GT則有最佳還原力(0.892 mg Vit. CE/mL)。沒食子酸等值 (gallic acid equivalent; GAE) 的總酚含量(TPC)方面，發酵21天後的BT與發酵15天後的GT分別具有最高總酚含量，其值分別為0.395 mg GAE/mL與0.385 mg GAE/mL。在α-澱粉酶(AA)抑制活性方面，發酵15天後的BT與GT對AA活性抑制率(AAi%)可達到最佳值，其值分別為75.98％與80.77％，然而僅有BT之AAi%不再隨著發酵時間而有所改變，但GT的AAi%似乎會隨著發酵時間增加而略微下降趨勢。一般而言，木醋桿菌發酵紅茶與綠茶基質之最佳發酵時間分別為21天與15天，而且綠茶基質經木醋桿菌發酵後具有較佳的抗氧化活性與對AA抑制活性。

關鍵字

木醋桿菌 ； 發酵時間 ； 抗氧化活性 ； α-澱粉酶抑制活性

並列摘要

In this study, the effects of fermentation time (0, 3, 6, 9, 12, 18, 21 days) on antioxidative activities (DPPH free radical scavenging activity, reducing power and total phenolic contents) and α-amylase (AA) inhibitory activity of tea (black tea and green tea defined as BT and GT) broths fermented by Acetobacter xylinum isolated from the fermented coconut juice were investigated. The pH values of BT and GT decreased with increasing fermentation time and were 3.28 and3.30, respectively, obtained from the 21st day fermentation. The DPPH radical scavenging activity (defined as DPPH RSA %) of BT and GT broths increased up to certain values with increasing the addition concentrations of the freeze-dried tea broths. There was no significant effect of fermentation time on DPPH RSA% of the fermented broths. The highest Vit. CE (vitamin C equivalent) values for reducing power (RP) of BT and GT obtained at the 21st day and 15th day fermentation, respectively, were 0.499 mg and 0.892 mg Vit. CE/mL, respectively. In addition, the highest GAE (gallic acid equivalent) values for total phenolic contents (TPCs) of BT and GT were 0.395 mg and 0.385 mg GAE/ml, respectively, obtained at the 21st day and 15th day fermentation, respectively. The AA inhibitory activities (AAi%) for BT and GT increased at the first 15 days fermentation, and the highest AAi% for BT and GT were 75.98% and 80.77%, respectively, obtained at the 15th day fermentation. However, the AAi% of only BT was not changed while the AAi% of GT little decreased thereafter. This study demonstrated the optimal fermentation days for BT and GT were 21 and 15 days, respectively. In comparison with BT, GT fermented by A. xylinum showed the better antioxidative activities and α-amylase inhibitory activity.

並列關鍵字

Acetobacter xylinum ； fermentation time ； antioxidative activity ； α-amylase inhibitory activity

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