Dulloo, Abdul G., Claudette Duret, Dorothée Rohrer, Lucien Girardier, Nouri Mensi, Marc Fathi, Philippe Chantre, and Jacques Vandermander. “Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans.” The American journal of clinical nutrition 70, no. 6 (1999): 1040-1045.
Domestic Process: This is a very simple process. It involves repeated steeping of tea in hot water and the disposal of the water (you may use this tea to serve those who don’t mind having caffeinated tea). The more you repeat the process, the less caffeine there will be left in the tea, but the same is true of the taste and flavor. Basically, don’t overdo it. Two or three steepings are probably safe. After all, you do want tea and not plain, hot water, right?
You can make African red tea much like other herbal teas, according to Teavana. Add a 1 1/2 teaspoons of loose African red tea to make an 8-ounce serving, using boiling water. Allow the tea to steep for roughly five to six minutes, longer if you wish for a stronger tasting tea. Letting the tea steep for longer will not cause the tea to become bitter. Indeed, traditionally, African red tea has been allowed to steep for several days. If you want to make chilled African red tea, you can place the hot tea in the fridge to let it cool. Alternatively, double the amount of tea used and then pour the hot tea over a glass filled with ice cubes.
Along with caffeine, which gives green tea its characteristic taste, bitterness, and stimulating effect, green tea is also rich in a group of chemicals, called catechin polyphenols (commonly known as tannins, which contribute to bitter taste and astringency). These catechin polyphenols include catechin, epicatechin, epicatechin gallate (ECG), epigallocatechin gallate (EGCG), and various proanthocyanidins. They are also known as flavonoids and are very powerful antioxidants. Flavonoids, together with some amino acids like thiamine, are responsible for the potent flavor of green tea.
One study that was published in the February 2010 issue of the Journal of Agricultural and Food Chemistry investigated the effects of catechins on eye diseases and found that consuming more catechins may help protect the eyes from oxidative damage and vision loss. Scientists involved in the study found evidence that catechins can pass from the digestive tract of rodents to the tissues of their eyes and reduce oxidative stress for up to 20 hours after ingestion. (11)

Shade grown: All matcha is made from shade-grown tea leaves—a labor-intensive process where tea bushes are protected from the sun and light is filtered to the bushes in a very controlled manor. Shading boosts the chlorophyll production in the plant, giving the leaves a rich green color. The lack of sun reduces the plant’s photosynthesis of the leaves, which in turn alters the naturally occurring levels of caffeine, flavanols, sugars, antioxidants, and theanine. By controlling the sun exposure, tea producers can significantly alter the chemical make-up and flavor of the final tea leaves.