big question about boiling water

[fracol]

ya if you have questions on this listen to chip, he is the green tea master anyways.

[Cael]

I personally find that I like to hit the point and pour it from there. I do notice a difference with many of my green teas between if I let it boil first or not. I personally tend to find that the tea tastes sweeter and has more pungent tones if I don't let it go all the way up to boiling.

What I understand from a friend of mine who is in training to become a tea master, is that the reason why it is traditional to have it boil first is so that they can learn to hit the point when the water temperature is best for brewing each type of tea.

[Xell]

I personally find that I like to hit the point and pour it from there. I do notice a difference with many of my green teas between if I let it boil first or not. I personally tend to find that the tea tastes sweeter and has more pungent tones if I don't let it go all the way up to boiling.

What I understand from a friend of mine who is in training to become a tea master, is that the reason why it is traditional to have it boil first is so that they can learn to hit the point when the water temperature is best for brewing each type of tea.

This is certainly makes most sense, that all other explanations i thought up But i use cooking thermometer, so hitting the right temperature is not a problem.

[Oni]

I believe the chinese heat their water just to the right temperature, they measure it by the size of the bubbles, if you brew green tea heat the water until fish eye size, or crab eye size if you like lower temperature, and they pour directly from the kettle to the gaiwan, there is no cooling vessel.
Brewing Japanese green tea like sencha, requires you too boil the water at least to 95 C, and pour to the kyusu and from the kyusu to the cups, this cools the water and preheats the vessels in one move.
Recently I did an experiment, I currently own gyokuro and sencha from zencha, I tried brewing gyokuro with water that was full boiled and water that was heated and cooled down, both were 55 C when they hit the leaves, and the one that wasn`t boiled full tastes better and was sweeter.
Full roaring boil is not needed to green tea nor oolong tea, when large bubbles start braking the surface of the water, switch off the boiler, take off the kettle, the water is ready, do not boil it with roaring boil too long, it will flaten the water.

[skarphedin]

I usually don't bring water to a boil, if not needed. I certainly see the point of the argument that it's easier to hit the correct temperature at falling rather than rising temp and also that it connects well with the idea that drinking tea should be a relaxing pastime, but in this day and age it's no hassle to measure the temperature of your water. Just pop a digital thermometer in it.

Since the water here is quite soft (a hardness og 3-5 mg Ca/l compared to Evian's 78 mg or 244 mg in North London), I don't want to deprive it of the last few mg if it isn't necessary. With a thermometer it's also easier to be sure that you actually are testing different brewing temperatures with the same tea consistently.

When water is boiled, depending on what vessel you use, all kinds of things happen. There is limescale and other pollutants to take into account, as well as water quality and impurities, mineral levels, what the element/vessel is made of, as well as what kinds of micro-organisms are present in the water. The more heat you use, the more taste you will draw from the impurities and pollutants.

Over time, your boiling vessel will also have a build-up of sulphates and carbonates of calcium and magnesium, and maybe other elements such as iron (mineral levels are part of how you determine the hardness of water). In most water, you will for instance have Calcium Hydrogen Carbonate dissolved in the water, which, when boiled, will decompose into liquid H₂O and CO₂ in gas form, and limestone (which will be visible as scales on the bottom and surfaces of the kettle. So the more heat you apply, the more carbonates and hydroxides are formed, which in turn get deposited in the vessel as scales. This separation is partly what deprives water it of its taste when it is boiled. Also, the reason why you should descale your vessel every now and then (the harder the water, the more ofte you should do this) is not so much because of the limestone itself, but because the limestone attracts and attaches other minerals present in the water to itself. These minerals are what can give the water an odd flavour, if left to grow.

In addition to all this, there's O₂ and N₂ loosely bonded to H₂O-molecules in the water. When you heat up water, these weak bonds break and both oxygen and nitrogen is released, and can be seen as tiny bubbles. The more heat you apply, the more gas are released, which results in a flatter taste. This may perhaps also affect the brewing of tea, as oxygen helps with extracting flavour from the tea leaves, but of this I'm not sure.

[chingwa]

I don't have anything concrete to add to this disussion, as I am not a scientist and do not pretend to understand scientific matters. However I have come under the practice the past few years of heating my water in a japanese tetsubin. I notice a difference in the flavor of the water, and it is well worth while for me to do so. But this brings up the point of what is being changed in the water, and at what point the interaction of fe2 iron and water takes place to the point of noticing the difference.

I always bring my water to the boiling point. Sometimes I'll let it boil for a couple minutes, sometimes I won't. I do notice a difference, but haven't thought so hard about it to determine what the difference is or why. (it could be put down to any of the other various "making-tea-variables" as well). I've never not boiled my water though...

[woozl]

I was told by a coffee head that boiling the water removes 02.
And the coffee made from that boiled water will taste "flat".
So I usually bring it up to temp. Might try some boiled for comparison..

[Marco]

In addition to all this, there's O₂ and N₂ loosely bonded to H₂O-molecules in the water. When you heat up water, these weak bonds break and both oxygen and nitrogen is released, and can be seen as tiny bubbles. The more heat you apply, the more gas are released, which results in a flatter taste. This may perhaps also affect the brewing of tea, as oxygen helps with extracting flavour from the tea leaves, but of this I'm not sure.

There is no N₂ in water!

[TwoPynts]

In addition to all this, there's O₂ and N₂ loosely bonded to H₂O-molecules...

There is no N₂ in water!

Sure there is! When you break the H₂ and O bonds, the horizontal cross in the H shifts and it becomes an N!

[skarphedin]

There is no N₂ in water!

I stand corrected. There is no nitrogen in H₂O, that much is true. But there will always be some air dissolved in the water. Since air is made up mostly of nitrogen, there will be some nitrogen in the water.

[Marco]

There is no N₂ in water!

I stand corrected. There is no nitrogen in H₂O, that much is true. But there will always be some air dissolved in the water. Since air is made up mostly of nitrogen, there will be some nitrogen in the water.

Okay - speaking about "some" - the solubility of nitrogen in water is very low. And nitrogen does not react with the water. So no chemical transformation and no problem with some ppm of nitrogen dissolved in water. And heating up the water does not release nitrogen - warmer water even can dissolve some more of it.
The only sources that cause some problems are nitrates (e.g. NaNO3 (sodium nitrate) and NH4NO3 (ammonium nitrate)) that come from fertilizers. But I do not think your tap water is contaminated with them.

just my little input

[edkrueger]

Nitrates, Nitrites and Ammonia are all quite common in tap water. Nitrates don't just come from fertilizer, they come from organic waste in general. Nitrites and Ammonia result from the breakdown of Nitrates.

[skarphedin]

Okay - speaking about "some" - the solubility of nitrogen in water is very low. And nitrogen does not react with the water. So no chemical transformation and no problem with some ppm of nitrogen dissolved in water. And heating up the water does not release nitrogen - warmer water even can dissolve some more of it.
The only sources that cause some problems are nitrates (e.g. NaNO3 (sodium nitrate) and NH4NO3 (ammonium nitrate)) that come from fertilizers. But I do not think your tap water is contaminated with them.

just my little input

I believe you mix up the chemistry a bit here. Air doesn't "react" with water, it gets dissolved. You're thinking of chemical reactions (i.e. when a substance is changed into one or more new substances), I'm thinking more of what would, in simplified terms, be an opposite to air humidity (no new substances occure here). It's correct as Wikipedia states that nitrogen is fairly non-reactive with H2O, but that doesn't change the fact that air will get dissolved in water. Think of it as your ground matcha suspended in a cup of hot water just after you've given it a good whisk.

And to get things clear: warmer water can NOT hold more air. Warming up water to 100˚C (212˚F) is the most efficient way of ridding water of air, and thereby of oxygen and nitrogen. In a similar way, think of a glass of soda. When cool, it will retain it's sparkling bubbles a lot longer than if you heat it up to room temperature or hotter, where it'll go flat fast. This is because when you rise the temperature of a liquid, the partial pressure of a gas dissolved in that liquid will increase, which in turn leads to decreased solubility. What is true is that water will contain a greater percentage of oxygen than you will find in the air (about 35% v. 21% in air) because the solubility of oxygen in water is greater than that of nitrogen. (For those wanting to know more about some of the chemistry behind this, read about Henry's Law)

A good way to check that water actually does hold air is to take fresh water from your spring, pour it into a pan, and heat it up. When you do this, as the temperature rises, tiny bubbles will appear and rise to the surface, long before it hits boiling point. This is air escaping water due to decreased solubility. When it starts to boil, let it do so for a couple of minutes, and then let the water cool down. Now, repeate the experiment. This time the bubbles won't appear (or at least they will not be that abundant) untill the water reaches boiling point. Why? The water has been deaerated.

I realize I have taken the discussion into a tangent, but I feel I had to defend the method of not bringing water to a boil if you don't need to. But in the end, as someone on this forum wrote a while ago: «Brew how you like. Like how you brew». True, good words which I can stand by.

[Marco]

Nitrates, Nitrites and Ammonia are all quite common in tap water. Nitrates don't just come from fertilizer, they come from organic waste in general. Nitrites and Ammonia result from the breakdown of Nitrates.

That is right, but your tapwater has a maximum allowable level of nitrates of 10 mg per liter (set by federal laws for public drinking water).
And this value should be even much lesser if not contaminated with organic waste.

I believe you mix up the chemistry a bit here. Air doesn't "react" with water, it gets dissolved.

That is correct. But earlier on you talked about breaking bonds through heat to set free Nitrogen. Molecular bonding does not occure through solution. It would need chemical reaction.

And to get things clear: warmer water can NOT hold more air.

Absolutely right. I've been wrong here.

What is true is that water will contain a greater percentage of oxygen than you will find in the air (about 35% v. 21% in air) because the solubility of oxygen in water is greater than that of nitrogen.

That is wrong. The solubility of oxygen in water is smaller than that of nitrogen. At 1 bar and 25°C solubility of O2 is about 9mg/l and solubility of N2 is about 14mg/l.

I realize I have taken the discussion into a tangent, but I feel I had to defend the method of not bringing water to a boil if you don't need to. But in the end, as someone on this forum wrote a while ago: «Brew how you like. Like how you brew». True, good words which I can stand by.

+1 on the last sentence
Yes we went slightly off topic - but it is a nice discussion I think.

[skarphedin]

I definitely agree (It must be years and years since I put my high-school chemistry knowledge to any use like this).

(Oxygen do have a higher solubility in water than nitrogen. It's expected that, initially, there is more nitrogen than oxygen in the water since air is 71% nitrogen and only 21% oxygen. The great signifier here is that in water, oxygen represents 36% of the air dissolved, which points to oxygen having a higher solubility (i.e. a greater part of the oxygen in the air gets dissolved in the water than that of nitrogen – even if more nitrogen will be dissolved in the water initially). To further my point, at 60 degrees Celsius, there will be just over 0,02 mg/l of oxygen and only 0,01 mg/l of nitrogen.)

And yes, I was wrong about the «bonds». I apologize for the unclarity.

For something related, but different: How many of you use bottled water when brewing tea, and why? Just out of curiosity.