All teas come from the same plant, Camellia sinesis, which is indigenous to an area encompassing northern India, Myanmar, and southeastern China. Tea leaves contain hundreds of chemicals, but a few are particularly important to consumers: catechins, caffeine, and tannins.
Catechins are antioxidants responsible for many of tea’s reputed health benefits. White teas contain the most catechins, due to the minimal processing involved in making white tea. Green tea has slightly less catechins, Oolongs varying degrees less, and black teas have the lowest content of catechnins and thus the least known health benefits. Numerous scientific studies claim tea can be helpful for such conditions as cancer, atherosclerosis, and cognitive impairment. Tea also is helpful in promoting weight loss and preventing age-related cognitive impairment.
Caffeine is the primary stimulant in tea. Many conflicting statistics exist regarding the caffeine content of tea. Due to discrepancies in tea to water ratio, brew strength, extraction rates, temperature, etc. it is very difficult to know how to interpret the reported caffeine content of a “cup of tea”. What can be said confidently is that a cup of black tea of a given size has between 25-50% of the caffeine content of a cup of coffee of the same size brewed from Arabica beans. It is also true that a cup of black tea contains the most caffeine, and next is oolong, which in turn has more caffeine than green tea, and white tea has the lowest caffeine content.
Tannins are the chemicals responsible for the astringent, bitter taste of tea when it has been steeped for too long. When steeping whole leaf tea the tannins start extracting sometime between 1-3 minutes. Our recommended steeping times are based on keeping the leaves in the water just until the tannins start to extract. (One of the reasons tea from tea bags is so bitter is the tannins start extracting almost immediately.)
We recommend using 1 gram of tea leaves per 3 ounces of water, or 1 teaspoon of leaves per 8oz. water. (about 2 teaspoons per 8oz for white teas, which are lower density).
Steeping times are mostly determined by leaf size. Smaller leaves have more surface area per unit volume and therefore steep faster. Larger leaves need more time, and tightly rolled large leaves need the most time.
Ideal water temperature varies as well; black teas taste best when made from water at or ear boiling. Oolongs taste best steeped at 180-190F, greens steep best at 160-170F and white teas steep best at 150-160F.
It is best to use a prewarmed teapot and a coarse mesh strainer large enough to allow the tea leaves to fully expand.