Tea: production, sensorial and health properties

Tea is a beverage whose use has long been governed by precise rules. Its consumption predates our era, and several traditional books codify the tea ceremony both in the countries of origin and in countries where it arrived later, such as Japan and England. Its geographical spread in different cultures has given rise to a wide range of sensory products, from white tea to post-fermented tea, with green teas predominating in the Far East and black teas in the West. All these products are obtained by a variety of processes (for example, dry firing is used on the Asian continent, while steaming is used in Japan) and from different varieties and species. Its therapeutic virtues led to its inclusion in Shen Nong's first treatise on herbal medicine, dated 2800 BC. The original of this book has not been found, but more recent copies show that in Han times, tea was still the focus of attention for its health-giving properties, an attention that has not waned since. Different processes are responsible for very different compositions of bioactive compounds, but green, black, Oolong and Puerh teas are all reputed to have health benefits.

This article examines the manufacturing diagrams of the main teas and links the processes to the biochemical transformations involved in tea, their sensory properties and their effects on health. Alongside this core article, questions about tea cultivation, its impact on the environment and on workers in the industry, and trends are addressed. Boxes also deal with the history of tea and its market.

A glossary of terms is provided at the end of the article.