Green and white tea are my drinks of choice, but I've got issues with caffeine. I've always heard that white tea contains less caffeine than green tea, so I would switch to white in the afternoon, hoping to stave off a late-day caffeine high. Recently I noticed that white tea seemed to make me spikey, even more than the mild jolt I get from green tea. I wondered what was going on.
Sure enough, according to Nigel Melican, one of the world's leading tea authorities, white tea, derived from buds and young leaf tips, has a higher caffeine level—as much as black tea. Green tea does, generally, contain less caffeine, but not always. Different manufacturers, different tea plants, different continents—all affect the caffeine levels of tea.
And it's no use looking to decaf to save you. De-caffeinated tea likely has had the healthful benefits of tea, the polyphenols, stripped out. (It depends on the process, which depends on your continent, which bears more looking into.)
That's discouraging, since I really need to limit my caffeine, yet I want the health benefits of drinking tea. Plus I just like having a warm cup in my hand.
So, it's strictly green tea for me from now on.
But how to make the best cuppa green? The article mentions that 80C is the proper temperature for preparing green tea—boiling water (100C) makes a bitter cup. I've been aware of this for some time—I always add a bit of tap water to my kettle after it boils, or else I wait a while after the kettle switches off to pour my cup.
Interestingly, I'd noticed the taste difference several years ago, when I moved from the high desert of Albuquerque, which is about a mile in altitude, to spend time in Louisiana before moving here. I found the same green tea I previously drank tasted bitter. Of course, water boils at a lower temperature in Albuquerque than at near sea-level. So the taste was likely affected by geography.
Yesterday I asked my husband, who is a scientist with a background in heat transfer, just how to make a cup of 80C water conveniently. We devised an experiment, of which I'll spare you the details (it involved adding my Maldon salt to ice water to calibrate the thermometer). My inexpensive electric kettle turns off when boiling is achieved, with no option for setting a lower temperature. There are markers, however, for .5 litre and 1.5 litres. The minimum fill is .5 litre. I estimated I was adding to about .75 litre of boiling water approximately 100 millilitres of tap water (actually, reverse osmosis water from a special drinking tap), which is at room temperature, or just less than 20C. It turned out this was too little 20C water to lower the temperature of that much 100C water to 80C.
The correct proportion is 25% ambient (room temperature) water to 75% 100C (actually, it cools to around 97C when poured into a cool cup). If I add the cool water to the kettle of boiling water, the water becomes the perfect temperature. Alternatively, you could fill a cup a 1/4 full of tap water, then add boiling water, and then place the tea bag in, but I prefer pouring water over the tea bag.
The real test came when I tasted the first cup of properly brewed green tea. I placed a lid over the cup (my Laura Ashley cup came with a matching ceramic lid) and let it steep a few minutes. When I tasted the tea, I was surprised at how much better it tasted than previous cups, even though I had previously added cool water to my kettle before pouring. I just hadn't been adding enough, and that 10 degrees or so in temperature made a lot of difference. There was none of the bitter, tannic taste that many people, including me, associate with green tea. None.
It was like drinking nectar. Seriously.
But what about the CO2 consequences? Here, the water gets very muddy. Remember, filling the kettle with more water than you need is always a bad idea, carbon-wise. But even this depends a lot on where you live, and how you boil your water. In the UK, you're probably better off using a pan on a gas stove, since gas is better than the coal-powered electricity you're likely using. But if you live in France, go ahead and plug in your kettle, since your electricity likely comes from nuclear energy, which doesn't release CO2. However, if you're the kind of person who forgets they have a pan of water boiling on the hob, you're better off ignoring the environmental impacts and using the electric kettle anyway, since a major fire would have far worse environmental impacts than your kettle.
But then, I've heard green tea can improve memory, so regardless of how you heat your water, you're probably doing the right thing by drinking a cuppa green.