北京自来水冲泡绿茶汤颜色及抗氧化性变化因素  

Factors Affecting the Photochromism and Anti-oxidant Activity of Green Tea Infusion Brewed with Tap Water in Beijing

作　　者：陈然[1] 张季艾[1] 范志红[1] 

机构地区：[1]中国农业大学食品科学与营养工程学院,北京100083

出　　处：《食品科学》2012年第7期78-82,共5页Food Science

摘　　要：分别对北京地区弱碱性自来水及去离子水进行水质分析,并探究其中差别较大的几种离子对茶汤颜色及DPPH自由基清除能力的影响。结果表明:用北京地区弱碱性自来水冲泡绿茶得到茶汤的颜色较去离子水绿茶茶汤显著加深,DPPH自由基清除能力显著下降。Ca2+(70mg/L)、Mg2+(30mg/L)和Na+(18mg/L)能够使茶汤颜色变浅,DPPH自由基清除能力上升。提示自来水中的HCO-3在冲泡过程中将绿茶茶汤体系稳定在弱碱性环境,从而导致茶多酚的氧化降解,这是自来水绿茶茶汤颜色变深、DPPH自由基清除能力降低的主要因素。Water quality was measured on Beijing tap water with and without reverse osmosis membrane filtration and deionized water. In addition, the effect of selected ions showing a considerable difference on color parameters and DPPH free radical scavenging activity of tea infusion was discovered. Our results indicated that Beijing tap water was slightly alkaline, remarkably darkened the color of tea infusion compared with deionized water, and resulted in a distinct decrease in DPPH free radical scavenging activity. Calcium （70 mg/L）, magnesium （30 mg/L） and sodium （18 mg/L） ions in Beijing tap water could reduce the color of tea infusion and its DPPH free radical scavenging activity. This suggests that the main reason for the darker color and decreased DPPH free radical scavenging activity of tea infusion brewed with tap water is that tea infusion is kept in a weakly alkaline environment during brewing due to the presence of HCO~ in tap water, thus causing oxidative degradation of tea phenols.

关 键 词：北京自来水 绿茶茶汤 颜色 DPPH自由基清除能力 变化因素 碳酸氢盐 

分 类 号：TS201.2[轻工技术与工程—食品科学]