ABSTRACT
The leaves of many plant species are used in the preparation of potable infusions, but the tea of commerce is derived from Camellia sinensis. Black tea is produced by an enzymic fermentation of the leaves. The harvested leafy shoots are first rapidly withered and then passed through rollers to release the sap containing the enzymes which break down the polyphenols by an oxidation process. Green tea is not subjected to a fermentation process, but is prepared by rapidly inactivating the enzymes by steam or heat treatment, so that dark condensation products are not formed. Coffee is used as the roasted product of the beans (endosperm of seeds) which when ground and brewed gives a stimulating beverage containing caffeine. Cocoa and chocolate are derived from the roasted cotyledons of the seeds of the highly variable species T. cacao.
