Evaluation of the contribution of trichomes to metabolite compositions of tea (Camellia sinensis) leaves and their products

Tea is processed from the postharvest tender leaves from tea plants (Camellia sinensis). Leaves containing more trichomes are considered to produce higher quality tea, but no evidence is available to support this opinion. In the present study, morphological and metabolic analyses of trichomes showed that tea trichomes were unicellular, simple, and rich in many water-soluble metabolites, including free catechins, caffeine, and amino acids. Furthermore, the analysis of known quality-related and non-targeted metabolites in fresh tea leaves and tea products showed that the presence of trichomes did not change the overall metabolite profiles of fresh tea leaves, white tea, and black tea, but might affect the non-targeted metabolites in green tea. Overall, more trichomes might only indicate higher quality tea leaves, while metabolites in the leaf might be the key factor. This study provides the first determination of the contribution of trichomes to tea quality.