Why is a long steeping time important?

July 16, 2009

In comparison to beverage teas, which generally require only a 3-5 minute

steep for taste considerations, our recommendation of a 10-15 minute steep

may seem long. However, steeping times for Traditional Herbal Medicines

(THMs) in tea infusion form are generally set at anywhere between 10 and 30

minutes depending on the herbs in the formula. Some teas are best decocted

(simmered) for 30 minutes or longer. A longer steeping time allows for more

of the components in the herbs to dissolve into the tea water.

We tend to think that water is the extraction solvent when we prepare a cup

of tea - pour boiling water over the herbs, let them brew a few minutes and

then strain and drink. But there's more depth to this water story! While the

initial solvent is the boiling water, as soon as the plant's cell walls

begin to break down and compounds enter the water, the water changes.

It isn't just water anymore. Depending upon what compounds are first

released, the water can become a mild acid or a mild base solution, which in

turn affects the release of other compounds. The longer you let the herbs

steep, the more components you will have in your teacup.

Each new compound that is released changes the solvent's composition until

full saturation occurs or until the reaction is stopped by removing the

herbs from the solvent. This enables some compounds that are not entirely

water-soluble to still be released into the water. This is why a sufficient

steeping period is necessary to produce a complete, balanced extraction.

For instance, flavonoids are a group of plant chemicals that are only

slightly soluble in water. But testing shows that there are therapeutic

levels of flavonoids in a properly brewed cup of tea prepared from

flavonoid-containing herbs.

Another example is caffeine in black and green teas. The central nervous

system stimulant effect of caffeine is strongest when the tea is steeped

only 2-5 minutes, because caffeine dissolves quickly into hot water. Longer

steeping times of 10-20 minutes will increase the yield of catechin

polyphenols, which decreases the stimulant effect, because the catechins

bind the caffeine.

Traditional Medicinals :: Herbal Tea Preparation and Uses (16 July 2009)

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