There’s a line for the ultimate bad cook who “can’t even boil water,” and I’ve always wondered about the issues involved.
What is the amount of O2 dissolved in NYC tap water?
At what rate is water depleted of O2 by boiling?
2a) Does less-oxygenated water boil quicker?
2b) Does it boil at a (even minutely) lower temperature?
.
Most important, practically, what about the post-boil water…
Does it taste “flat” in that it is noticeable for tea, coffee, or pasta?
I realize 3) is answerable empirically, but I’m looking for previous work ( eg I’m too lazy).
I often set water to boil for dinner, dinner is postponed, and half-a-pot of cooled down water later, when I need to crank up dinner again I toss the old water and refill completely. Is this superstitious?
I realize as an environment for living fish and other organisms the “taste” (to them) is equisitely different and important for what (to us) are minute and trivial differences in oxygenation. But with our sense organs, does the altered chemistry stimulate them differently?
When you boil water, you’re driving out essentially all of the dissolved gases, so it doesn’t matter how much it contained before. Water that’s boiled and then cooled might be detectably different from water that’s stayed cool the whole time, but water that’s brought to a boil twice will be no different from water that’s boiled once.
Which actually makes me think of Nava’s point on salts. “Soda water” differs from “seltzer water” in that the later has no added salts. So, then, how would boiled and cooled down seltzer differ from tap water?
Assuming you’ve drawn your water through a faucet with a proper aerator, then your original water will be fairly close to fully saturated, which is around 9 mg/liter of O[sub]2[/sub] @ 25ºC. Boil this water and all the O[sub]2[/sub] is driven off. What I haven’t been able to find is the rate of reabsorption as the water cools. There will be some however even without I’m not sure the small amount of O[sub]2[/sub] missing would be “tastable”, you’d also drive off all the chlorine and that won’t be reabsorbed and for some people this will make a big difference.
Also, if you scald the water it will never taste right again.
Most likely, it is the lack of dissolved CO2 (and associated carbonates) that would affect the taste more than the dissolved oxygen. Drive off the CO2, the calcium will drop out of solution.
Oh, all the books tell you this is so, but I routinely reboil water for tea and the first cup tastes no different than a reboiled second cup. The amount of oxygen in the water is too small to give it any flavor, anyway, and some is reabsorbed once the water cools down. Note, too, that some oxygen is lost when the tea is boiled the first time and is not there by the time you pour that first cup. Finally, the flavor of the tea is going to overpower any flavor change caused by the boiling.
If you boil it long enough, not at all. If you only boil it for a short enough time to still leave some “extra” dissolved CO[sub]2[/sub], with its brothers HCO[sub]3[/sub][sup]-[/sup] and CO[sub]3[/sub][sup]2-[/sup], it will taste the same as if you’d just left the glass around long enough to end up at the same composition. Why that “extra”? Because water that’s in contact with air will get some dissolved carbonic from the air - an amount so tiny that in any chemistry problem we’d just call it zero.
Leave a glass of seltzer at room temperature long enough and it will taste exactly the same as if nobody had added carbonic gas to it.
So; is my wife talking through her hat, when she insists that the water for her tea has to be freshly boiled. Re-boiled is no good; it has to be drawn fresh from the tap, bought to the boil and instantly poured on the tea.
I have always had my doubts but I don’t fight battles I can’t win
There is the possibility that the water is picking up solids from the kettle while you’re boiling it, so that leaving the same water in the kettle instead of adding new each time would lead to you consuming minute additional amounts of whatever substance the interior of the kettle is made of.
eg I’m too lazy).