The best way to keep your coffee hot and flavorful is to use an insulated, vacuum-type coffee carafe. This will keep the coffee hot for hours without sacrificing quality. Green, oolong and black tea all come from the same evergreen bush - the camellia sinensis. Only the top leaf or two and the bud are plucked for the finest quality tea. The difference between green, oolong and black tea is the amount of fermentation each is allowed during processing.
Fermentation oxidizes the leaves and changes their chemistry.
Black tea is fully fermented. Leaves are withered then rolled to release the enzymes that cause fermentation. After careful monitoring, the tea is then fired or dried to stop the fermentation process. Green tea is unfermented. The first step in green tea processing is pan firing, where hot steam destroys the enzymes that cause fermentation.