EFFECT OF FLUORIDE ON THE AMINO ACID COMPOSITION OF TEA LEAVES

Hydroponic solution culture experiments were carried out on seedlings of the Fu ding da bai variety of tea (Camellia sinensis, L.) for 30 days in order to investigate the influence on the leaf amino acid composition of the fluoride ion (F) in concentrations of 0-16 mg F/L. The results indicated that, as the F ion concentration increased, the total amino acid content and the contents of the individual amino acids, apart from Tyr and Cys, generally increased initially and then decreased. In contrast, as the F concentration increased, the Tyr content decreased significantly while the Cys content fluctuated with an initial increase followed by a decline and then a further increase. With increasing F concentrations, the bitter amino acid content generally decreased, while the sweet, delicious, and flowery amino acid contents initially increased, reaching a maximum at 4 mg F/L, and then declined. In conclusion, low concentrations of F, up to 4 mg F/L, can promote the synthesis of the amino acids with sweet, delicious, and flowery tastes, without increasing the bitter amino acid content, resulting in an improved tea quality, while higher F concentrations, 6-16 mg F/L, tend to reduce amino acid synthesis and lower the tea quality.