Wednesday, July 02, 2008
Posted by 醉茶生 at 10:31 PM | Comments (2) | Permalink
Categories: Tea Related

For most varieties of tea (but not all), the ideal “pick” is the topmost two leaves and a bud (一芯二葉 yīxīn èryè), because this is the part of the tea plant that is richest in flavourful compounds. This can only be achieved when tea is harvested by hand: tea that is harvested by machine will contain a larger proportion of older, less flavourful leaves.

In my previous post, I talked briefly about polyphenols and their purported health benefits. But how do these compounds benefit plants? For the tea plant, these are defensive weapons and their bitter, astringent taste prevents the leaves from being eaten by caterpillars and other pests. A friend of mine made the mistake of pouring some old tea leaves into a pot containing a cactus, thinking the leaves would compost and fertilise the plant. Two days later, the cactus was dead. I cannot think of a more vivid demonstration of the potency of tea leaves, and it is probably pure coincidence (or divine providence) that tea should have the opposite effect in humans.

The nearest parallel I can think of it chocolate, which for humans is a divine little treat, but the theobromine in two ounces of baking chocolate will kill a dog. Imagine! In the first half of the 20th century, theobromine was used in medicine to treat angina and high blood pressure. In fact we know that theobromine dilates blood vessels and can have beneficial effects on the heart; it has even be suggested that theobromine can prevent cancer. Like tea, it is the addition of sugar and milk to most chocolate confections that utterly negates any possible beneficial effects of chocolate.

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