An Ode to the Humble Tannin

June, 2014

A short stroll in any of Ottawa’s trendier markets will confirm what is already common knowledge among tea aficionados: the world’s second most consumed beverage is experiencing an unprecedented explosion of popularity in the western world. Although tea is best known as a herbal tonic, opportunistic businesspeople have been adding tea extracts to everything from nutritional supplements to shampoos in order to market their products.

The important question Ottawa’s tea community should be asking itself is this: why pay for something you already own? The used leaves in the bottom of your teapot or gaiwan have hardly outlived their usefulness.

While tea’s stimulating and antioxidant properties have been well publicized, the myriad utilities of a diverse group of large molecule, weak organic acids called tannins are less well known.

 

In The Kitchen

One needn’t be a biochemist to appreciate the textural nuances of a round, full-bodied glass of red wine at one of Ottawa’s fine-dining establishments. The tannins responsible for this feeling in tea and wine bind to the surface of the tongue, making a cup of tea which is more than 99% water give the sensation of a much more viscous fluid.*

After finishing a tea session, chop up a few of the leaves (discarding the stems) and add them to savoury dishes to lend the meal extra depth. When making quiche, I often let my tea leaves steep overnight in cool water, then use the liquor to deglaze the pan used to fry onions. (I’ve found roasted oolongs to be particularly well-suited to this dish.) Deglazing provides a quick shot of flavour, and the added tannins from the long infusion give the dish a rounder aspect.

 

In The Medicine Cabinet

All tannins possess the ability to slightly constrict biological membranes, including the skin. This makes tannin solutions particularly useful in skincare regimens, due to their ability to decrease redness and inflammation, and reduce the appearance of wrinkles. This, coupled with their ability to stop bleeding, makes a cup of oversteeped tea (or a strong infusion made from no-longer-flavourful leaves) an excellent aftershave.

Additionally, tannin molecules are able to bind to microbial membranes and interfere with their function. Coupled with their mild acidity, this property gives tannin solutions a mild antifungal and antibacterial effect. Even better for those of us with oily skin! (Note that although tannins are safe to drink in tea, it’s always a good idea to do a test patch with any skin product before applying to a larger area.)

 

In The Garden

Last, but not least, tea can be used as a fertile top-dressing. Old tea leaves that would have ended up in the compost or Ottawa’s Green Bin program can be scattered across the soil at the base of acid-loving plants, such as azaleas and rhododendrons. The tannins, being slightly acidic, will gradually leach out of the leaves and slightly lower the pH of the soil below without having to use chemical fertilizers.

By using the above-mentioned Ottawa’s tea community can reap the benefits of their tea—long after they’ve drain the last dregs from their mug.

 

 

*This is the same reason an over-steeped tea can make the mouth feel dry; the tannins cover the surface of the tongue and form a layer which water cannot penetrate, making the tongue dry at the molecular level.

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