Reheating Teas
Answered by: Conrad Richter
Question from: Charlie Laborte
Posted on: December 9, 1998

I’m just curious to know if re-heating herbal teas in the microwave will lessen the potency of the herbs. Somehow, ‘radiation’ and herbs don’t seem to mix well in my mind.

Much depends on the herbs in question. Some herbs owe their medicinal or aromatic properties to constituents that are either volatile or labile. By volatile, I mean that the compounds are likely to be vapourized by heat, and reheating just adds to the chance that these compounds will be lost. Essential oils that are responsible for the aroma of many herbs are good examples of constituents that are volatile.

By labile, I mean compounds that are susceptible to breaking down in heat. Although there is much known in natural products chemistry about key compounds of many herbs, the reality is that we still don’t know much about the majority of compounds in most herbs.

Generally, the best strategy in the case of medicinal teas is to avoid reheating unless it is specifically known that the active constituents are stable in heat. In the case of aromatic teas taken for pleasure, it really comes down to taste – if the taste of reheated tea is acceptible to you then by all means go ahead and reheat it.

Is heating by microwave radiation a cause for concern? There is no evidence that suggests that microwave heating does anything to tea that might cause problems. However that statement is not the same as saying that microwave heating of herbal teas is known to be completely safe. There have been suggestions that microwave heating could cause the breakdown of chemicals in foods in ways that would not ordinarily happen when those foods are heated on a stove. Having stated that, though, there is no reason to think that microwaving herbal teas is any worse than microwaving foods; so if you have decided that microwaved foods is acceptible for you then microwaved teas should be too.

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