Evaluation of inherent fructose, glucose and sucrose concentrations in tea leaves (Camellia sinensis L.) and in black tea

Tea is the most popular beverage consumed in the world after water. In the present study, evaluation of inherent sugars viz. sucrose, glucose, and fructose in fresh tea leaves and in black tea were quantified using High Performance Liquid Chromatography. Fructose, glucose, and sucrose concentrations in the third and fourth tea leaves were significantly higher (P ≤0.05) than that of the bud, first, and second leaves. The significantly lowest (P ≤0.05) concentrations of glucose, sucrose, and fructose were observed in black tea manufactured using the bud and the first two leaves. There was no significant effect of time of plucking on glucose, sucrose, and fructose concentrations in fresh leaves and in black tea. There were significant (P ≤ 0.05) changes in the concentrations of sucrose, glucose, and fructose that took place during the black tea manufacturing process. As sucrose and glucose have been allegedly used for the purpose of altering the appearance and heaviness of green and black teas, the results of this study would provide useful information for the tea industry in Sri Lanka and other countries to detect the adulterations of black and green teas with sucrose and glucose.