I know I usually go on about coffee, but right now I’m enjoying a wonderful cup of loose-leaf green tea and it made me think a little bit about, well, hot water.
Most people just boil water and then throw a tea bag in it; and honestly, if you’re drinking tea-bag tea then it probably won’t make much of a difference. That’s not necessarily a barb against tea-bag tea; I have two pouches of loose-leaf in my pantry, but three different boxes of bag tea. I enjoy an herbal chamomile before bed most nights, and it comes out of a bag.
But loose-leaf tea is like the fresh-roasted, unground coffee bean of the tea world. It contains more of the natural flavors and properties of the tea leaf, but as a tradeoff it is much more delicate.
Boiling water burns tea leaves. It’s true. But, excess dissolved oxygen left behind in the steeping water can inhibit the release of some of the anti-oxidizing agents in teas that so many tout for their health benefits1. The best way to evaporate these dissolved oxygen molecules is to boil the water first. WHAT TO DO?!?!
Darker teas are usually less delicate, and need higher temperatures to develop all of their characteristics; an English black tea or an Oolong tea does well at temperatures between 194° F and 204° F. Green and white teas need cooler water.
So we know what temperature we want our water to be at. And we know we want it to boil first. But waiting for water to come down to temperature from boiling can take a while, and we want our tea now, dammit!
And so, I give you: The high altitude pour.
This works best with a gooseneck kettle or some other narrow spout, both for control and for physics. The technique is simple: pour your tea water in to a cup from really high up. Like, a foot or two.
There is a very large temperature gradient between room-temperature air and boiling water. In addition, heat transference across a temperature gradient has a direct correlation with the radius or distance from the center of the object demonstrating a temperature gradient. A large volume of water will be less willing to give up its energy to the outside air than a thin stream of water, and so will take longer to cool down. By pouring a narrow stream of water, the volume of water becomes spread out and has a much smaller radius, so the energy near the center can reach the surface of the stream and in turn transfer energy to the air much more readily.
But why the high altitude? The longer that the water stays in this form where it is willing to give up its energy, the more time it has to give up its energy to the air. By pouring the water from high up and in a thin stream, you can use elementary thermal conductance to manage the temperature of your water.
If you’re obsessive like me, you can even use a cheap instant read thermometer to get your water to the perfect temperature; pour from up high while watching the temperature, and if the water is too cool then pour from lower down to bring the temperature back up.
It sounds really fiddly, but once you get the hang of it, it’s about as simple as breathing. I poured my green tea water to a perfect 185° F from right off the boil using this technique. And yes, I do use a thermometer and a gooseneck kettle, so it’s definitely very easy for me to do.
A trick that I used to use before I got my gooseneck kettle, though, was to simply boil the water on the stove top and then pour from the kettle from fairly high in to a measuring cup, then from the measuring cup in to the mug that I’d be putting the tea in. I’d toss back and forth from the mug to the measuring cup until I got to about 5° F too hot, then dump the water back in the cup and put my tea leaves in.
Yes, I really do care about my food and drink this much.
I think the jury is mostly still out on just how useful antioxidants are, but I’d like to think that it can’t hurt.↩