冷泡烏龍茶抗氧化能力分析與感官品評

Antioxidative Ability Analysis and Sensory Evaluation of Low-temperature Steeping Oolong Tea

冷泡烏龍茶在市場上越來越受消費者歡迎，有別於傳統熱水沖泡方式，冷泡法使用冷水浸泡茶葉，除了口感上會有差異，茶液中機能性成份的含量也會因低溫萃取而有所不同。浸泡溫度與浸泡時間是影響茶液特性的2個獨立變數，本研究使用反應曲面設計法(RSM)，同時分析此2個變數對冷泡烏龍茶DPPH自由基清除能力的影響，根據反應曲面設計法所建立的兩變數二次迴歸方程式，成功地預測冷泡烏龍茶的DPPH自由基清除能力。當進行冷泡烏龍茶感官品評時，共邀請53位年輕的大學生擔任品評員，品評滿意度項目共分成7項，包括「茶湯色澤」、「香氣」、「第一口甘甜度」、「回甘甜度」、「順口度」、「苦澀度」與「整體感受」，品評表使用1到14分的給分方式，數字越低代表接受度越低而數字越高則代表接受度越高，使用4、15和25°C三種不同溫度處理的冷泡茶進行相關性分析，以了解各品評項目間的關聯性，結果顯示以25°C處理的冷泡烏龍茶所獲得的滿意度較高，而且處理溫度較高的冷泡烏龍茶，所獲得的整體滿意程度也較高。

Low-temperature steeping oolong tea is getting more popular recently. Different from the traditional hotwater steeping method, the low-temperature steeping method use cold water to soak tea leaves. The active ingredient contents and sensory characteristics of oolong tea were affected by the low-temperature process. Two independent factors, including soaking temperature and time, were evaluated in this study by using the response surface methodology (RSM). Based on the second-order regression model, the DPPH radical scavenging activity of low-temperature steeping oolong tea was successfully predicted. The sensory evaluation of the low-temperature steeping oolong tea involved 53 young college students as the panelists. Seven sensory items were evaluated including color, odor, sweetness after first taste, sweetness after taste, ease of swallow, bitterness, and overall acceptability. The evaluation score for each item ranged from 1 (extremely unacceptable) to 14 (extremelyacceptable). Three low-temperature (4, 15, and 25°C) steeping oolong tea samples were prepared for sensory evaluation. Based on the correlation analysis results, the oolong tea prepared at 25°C had the highest overall acceptability. In addition, the oolong tea with higher steeping temperature had higher overall acceptability.