Green tea Beverage Temperature and Caffeine

by Prof.V.G.Krishnamurthy
(Chennai, India)

I read in internet that the beverage prepared using natural green tea leaves must be taken hot and as temperature comes down, the caffeine content can increase and drinking cold beverage of green tea is harmful.

I have verified this with several articles.

Now my question is this: Is this true for a beverage prepared using green tea extract? If it is not true, then people can drink more green tea and also with comfort/ convenience.

I have asked R&D departments of a few green tea extracting companies in India to clarify this.

But their answers were very superficial. I think they have not tested the green tea beverage in hot and cold conditions for any change in caffeine and EGCG contents and simply revealing their feelings. Therefore I am in the pursuit of finding an answer.

Looking forward to your early response,

Prof.V.G.Krishnamurthy,
Chennai, India.

Answer:

Hey, I have never seen any Chinese research on this subject so I cannot comment with certainty.

The effect of temperature on tea chemistry is highly dependent on the quality of the tea leaves, as anyone who has drunk a high quality green tea will know - leave the infusion for more than 20 minutes and the color will turn from yellowish-green to brown due to oxidation.

My suspicion with green tea extract is the tea chemistry is more stable as it is artificial, and it contains less theanine and EGCG, as most supplements overstate the EGCG content.

I think it is important to consider the effect of oxidation on tea compounds. If theanine and EGCG oxidise more easily than caffeine (I think they do), then exposed tea infusion will contain a higher ratio of caffeine.

Sorry, I am not aware of any studies done on this subject.

I hope this helps.

Julian