2017-2019年石家庄市市售茶叶浸出液中氟含量调查分析

Analysis of fluoride level in tea leachate from Shijiazhuang City from 2017 to 2019

目的对石家庄市市售茶叶浸出液中氟含量进行调查分析。方法2017-2019年,将石家庄市茶叶市场抽取的销量较高的茶叶(包括绿茶、花茶、黑茶、乌龙茶、红茶、白茶、黄茶7大类),经不同的浸泡时间(5、10、15、20 min)、浸泡次数(1、2、3次)处理后,使用氟离子选择电极法测定茶叶中氟含量。结果本研究共检测82个茶叶样品,其中绿茶25个(30.49%),花茶5个(6.10%),黑茶11个(13.41%),乌龙茶17个(20.73%),红茶15个(18.29%),白茶7个(8.54%),黄茶2个(2.44%)。绿茶、乌龙茶、红茶、黑茶浸泡20 min后茶叶浸出液中氟含量(中位数,40.63、65.43、26.39、58.90 mg/kg)显著高于5 min(23.09、32.24、15.77、32.00 mg/kg,P均<0.05)。以浸泡20 min浸出液氟含量为总氟量计,乌龙茶最高,中位数为65.43 mg/kg;红茶最低,中位数为26.39 mg/kg;且乌龙茶、黑茶、花茶的氟含量显著高于红茶(P均<0.05)。绿茶、乌龙茶、红茶、黑茶、白茶随冲泡次数的增加,茶叶浸出液中的氟含量显著减少(P均<0.05)。结论石家庄市市售茶叶浸出液中氟含量最高为乌龙茶,最低为红茶,建议石家庄市本地居民宜饮用红茶。

Objective To understand the content of fluorine in tea leachate in Shijiazhuang City.Methods From 2017 to 2019,different varieties of tea(including 7 varieties of green tea,scented tea,dark tea,oolong tea,black tea,white tea,and yellow tea)with high sales volume were purchased at the Shijiazhuang Tea Market.The fluoride content in tea was determined by fluoride ion selective electrode method through different soaking time(5,10,15,20 min)and soaking times(1,2,3 times).Results A total of 82 tea samples were detected,including 25 kinds of green tea(30.49%),5 kinds of scented tea(6.10%),11 kinds of dark tea(13.41%),17 kinds of oolong tea(20.73%),15 kinds of black tea(18.29%),7 kinds of white tea(8.54%)and 2 kinds of yellow tea(2.44%).After soaking for 20 min,the fluorine contents in tea leachate of green tea,oolong tea,black tea,and dark tea(40.63,65.43,26.39,58.90 mg/kg)were significantly higher than those in 5 min(23.09,32.24,15.77,32.00 mg/kg,P<0.05).Taking the fluorine content of the tea leachate soaking for 20 min as the total fluorine content,oolong tea was the highest,with a median of 65.43 mg/kg;black tea was the lowest,with a median of 26.39 mg/kg;The fluorine contents of oolong tea,dark tea and scented tea were significantly higher than that of black tea(P<0.05).With the increase of soaking times of green tea,oolong tea,black tea,dark tea and white tea,the fluorine contents in tea leachate decreased significantly(P<0.05).Conclusions In this study,the content of fluorine in the oolong tea is the highest,and the lowest is black tea.It is suggested that local residents in Shijiazhuang should drink black tea.