Effect of different extraction conditions on the quality of Yushan oolong tea drink

• Main Authors: Wen-Cheng Liao, 廖文誠
• Other Authors: Lih-Shiuh Lai
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/48950636998394056235

碩士 === 國立中興大學 === 食品暨應用生物科技學系所 === 97 === Abstract Tea is the most general and popular healthy drink in recent years. As changing of the social environment, consumer drinking habits of tea have been changed from the traditional way in the past with a hot pot of tea to a modern style with cold bottle ones. Thus, how to make a tasty and delectable bottle tea drink has become one of the most important issues among all drinking venders. The objective of this research is to understand the effect of extraction conditions on the physicochemical properties of bottled tea drinks. By taking Yushan oolong tea as the experiment material, the following extraction conditions were investigated: 1. pH value of water: 5, 7 and 9. 2. Temperature of water: 50°C, 70°C and 90°C. 3. Extraction duration: 5 minutes, 10 minutes and 20 minutes. The physicochemical of various tea extracts were analyzed by different physical and chemical analysis. In addition, both descriptive and consumer sensory evaluation were investigated as well for selecting suitable control factors and conditions for future tea drinks product research and development. The result shows the brix, total polyphenol, caffeine, catechins in Yushan oolong tea generally increased by increasing the extraction temperature , and extraction duration, but decreased by increasing pH value. Sensory evaluation results showed that Yushan oolong tea will have a better aroma, taste and overall acceptance to customers under a lower pH value (pH5) extraction. Furthermore the color of tea infusions is bright and lighter. In contrast, the overall acceptance of tea infusions is worse under a higher pH value (pH9) extraction. In addition, the color of tea infusions is darker, redder with higher extent of browning accompanied with higher total flavonoids . The pH value of water also showed a pronounced influence on the compositions of catechins and aroma compounds of Yushan oolong tea.