A preliminary study on the variation in fluoride content in tea shoots in relation to plucking

Abstract

Fluoride (F-) is an essential micronutrient for humans but a narrow margin exists between the requirement and toxicity of F- in the human body. Adequate intake (AI) of F- collectively from all sources for adult male, female and children are 4 mg/day, 3 mg/day and 1-2 mg/day, respectively. The tea plant can selectively absorb F- from soil accumulating them in shoots in a complex form which increases with the increasing age of the tea leaves. Moreover, acidic soil is conducive to the uptake of increased amounts of fluorides. Major portions of the total fluorides stored in tea plant are in the leaves, the concentration ranging from 2.1 to 1175 mg/kg and 26-808 mg/kg in medium and young aged plantations, respectively. The aim of the present work was to determine the total F- in green tea shoots (2 leaves & bud, 3 leaves & bud, 4 leaves & bud, 5 leaves & bud) and made tea. Total fluoride in green tea shoots was found to be 78, 123, 133 and 145 mg/kg for 2 leaves & bud, 3 leaves & bud, 4 leaves & bud, 5 leaves & bud respectively while the same in brew was 0.89, 1.02, 1.40, and 2.15 mg-L-1 respectively. The release of fluoride into brew ranged between 41-74%. The results of this preliminary work thus indicated that plucking of coarse green leaf may have a detrimental role on the occurrence of fluoride in made tea.

Keywords: Green tea leaves, Fluoride, micronutrient