Contents of fluoride and tea polyphenols in brick tea at fluorosis regions in Inner Mongolia

Abstract

Objective To determine the contents of fluoride and tea polyphenols in brick-tea and to understand the utilization ratio of qualified brick-tea in fluorosis regions in Inner Mongolia. Methods The investigation was carried out in Chenbaerhuqi Country and Ewenkeqi Country. Seventy-two households of four villages in Chenbaerhuqi and 11 households of three villages in Ewenkeqi were selected as study subjects. The brick-tea in each household was sampled. The contents of fluoride and tea polyphenols were determined by using fluoride selective electrode method and Forint-Ciocalteu oxidation method, respectively. T test and linear correlation were used to analyze the data. Results The fluoride content in qualified brick tea ranged from 114.82 mg/kg to 290.23 mg/kg with an average value of 171.78 mg/kg, while tea polyphenols content was between 56.15 g/kg and 132.18 g/kg with an average value of 95.44 g/kg. In unqualified brick-tea, the average fluoride content was 459.86 mg/kg with the range from 304.71 mg/kg to 660.76 mg/kg and the average of tea polyphenols was 67.48 g/kg with the range from 36.03 g/kg to 102.15 g/kg. The content of tea polyphenols of qualified brick tea was significantly higher than that of unqualified brick tea （P 〈 0.05）. The content of tea polyphenols was negatively correlated with fluoride content（r = - 0.636, P 〈 0.05）. The content of tea polyphenols was 396 times more than that of fluoride in brick tea. The utilization ratio of qualified brick-tea in the investigation areas was 53.0% （44/83）. Conclusion The fluoride content in qualified brick-tea was less than unqualified brick-tea, and the tea polyphenols of qualified brick-tea was higher than the unqualified brick-tea. The utilization rate of qualified brick tea is not high and further actions are needed to be taken to supply more qualified brick-tea for controlling of drinking brick-tea type fluorosis. Key words: Brick tea; Fluorosis ; Tea polyphenols