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The Art and Science of the Tea Habit

Posted: 2018-05-09 16:12 Permanent Link

Julia Fountain ND

“Better to be deprived of food for three days, than tea for one”, Chinese proverb

In the West we are finally beginning to understand, appreciate and enjoy the complexity of this very simple drink. In fact, many of the hot drinks we refer to as ‘teas’ are not teas at all. True ‘tea’ is derived from the leaves of the Camellia sinensis plant, a bush that grows in the mountains and hillsides of China, Sri Lanka, India and Japan. There are 4 varieties of true ‘tea’ – white, green, black and oolong. All others are considered to be ‘tisanes’ or ‘herbal infusions’. While all ‘true teas’ are produced form the leaves and buds of the Camellia sinensis tea plant, the differences – colour, flavor, chemical constituents – results from how the tea leaves are processed after harvesting.

White tea
Processing: white tea is the least processed of the teas. It is derived exclusively from the top 2 leaves and fresh bud of the tea plant. Once picked, the leaves and buds are immediately steamed to inhibit enzymatic fermentation, and then dried. White tea is a mild, light-bodies tea that pairs nicely with natural fruit flavours. White tea has high levels of the tea anti-oxidants known as polyphenols, or catechins more specifically.

Green tea
The anti-oxidant activity in 2 cups of green tea has been compared to 7 glasses of orange juice, four apples or 1 glass of wine.
Green tea is derived from the upper and lower leaves of the tea plant (green tea from the upper leaves is determined to be of higher quality). Once picked, the tea leaves are left to wither/dry in the sun for 1-2 days. This allows for minimal fermentation of the polyphenols prior to steaming and drying. Green tea is high in catechins including EGCg (epigallocatechin-3-gallate). Matcha green tea is powdered green tea leaves and is used in the traditional tea ceremony. Matcha has the highest concentration of EGCg and caffeine as one is not just steeping the tea leaves, but consuming them. Health effects attributed to EGCg include:
-prevention of tooth decay
-anti-bacterial vs Staph aureus
-modifies intestinal bacterial flora/anti-parasitic
-increases thermogenesis – the rate of calorie expenditure
-inhibits inflammation

Oolong tea
Known as ‘blue tea’ in China, oolong tea is derived from the upper and lower leaves of the tea plant. Once picked, the tea leaves are left to wither/dry, then gently ‘bruised’ to allow enzymes to act on the catechins, and to increase the exposure to oxygen. A partial fermentation occurs over the span of 2-3 days. The tea leaves are steamed to halt oxidation and then dried.

Black tea
Black tea is the most widely used form of tea. After the leaves are picked and withered, they are rolled and crushed to allow maximum interaction between the catechins, enzymes and oxygen. The tea leaves are allowed to ferment for weeks before being steamed and dried. The complete fermentation process will mean a lower proportion of catechins in the finished tea, and a higher proportion of theaflavins. Black tea made only from the buds is of the highest quality and is graded FTGFOP (fine tippy golden flowery orange pekoe). Black tea has a high percentage of theaflavin antioxidants, and lower percentage of catechins, compared to green tea.

Does green tea contain caffeine?
All tea leaves contain caffeine. It is generally accepted that a cup of green tea contains less caffeine than black tea, however this is not necessarily due to the processing/fermentation process. Factors affecting caffeine extraction include:
1) Temperature of the water-
Green tea is traditionally prepared with hot water; black tea is traditionally prepared with boiling water. More caffeine will be extracted from tea leaves with higher temperatures.
2) Length of steeping –
Green tea is typically steeped for a shorter length of time, compared to black tea. Again, the longer a tea steeps, the more caffeine will be extracted from the leaves.
3) Strength of the tea –
Green tea is typically made with 1 oz tea leaves in 12 oz water. Black tea is made with 1.5 oz tea leaves in 12 oz water. More tea leaves mean more caffeine.
4) The variety of the tea –
Black teas are traditionally from the Assam region of India, yielding a sub-variety of tea leaves that is higher in caffeine. Green tea is more often sourced in Japan and China, where the sub-variety of tea leaves are lower in caffeine.
5) The size of the tea leaves –
The smaller the leaf particle, the great the caffeine extraction in water. All has to do with the amount of surface area exposed. Small tea particles (ie dust) in tea bags will produce a more caffeine-concentrated beverage than whole leaf, loose tea
6) Infusion number-
The first infusion of tea leaves will have the highest caffeine extraction. The second and subsequent infusions made form the same tea leaves will have lower caffeine extraction

If loose teas are prepared according to traditional guidelines:
White tea – 5-15 mg caffeine per cup
Green tea – 8-15 mg caffeine per cup
Oolong tea – 10-20 mg caffeine per cup
Black tea – 50-100 mg caffeine per cup
For comparison: coffee averages 120-175 mg caffeine per cup

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