Going above 212*F/100*C during boil

pmicka · 02-03-2012, 05:31 PM

I recently started my first brew, a Bavarian Weissbier kit from my local HBS, and had a question regarding the temperature at which I boiled my wort. I used a 23-Quart Aluminum canning pot, which in and of itself isn't notworthy. However, the range in my apartment is quite small and it was a challenge getting the water to a rolling boil. To speed things up I put the lid on the pot and it was boiling in no time, I ended up repeating this for a few minutes to get the wort back to a boil after I had thoroughly mixed in the first tub of LME. With the lid on the temps easily surpass 212 degrees fahrenheit and I'm wondering what impact this might have on the beer.

The beer has been fermenting at a steady 68-70 degrees and after about 6 days I'm still seeing a bubble in the airlock every minute or so.

I'm not really too concerned that I've negatively influenced the taste in such a way as to make it undrinkable, just curious.

atom · 02-03-2012, 05:35 PM

your wort did not go above boiling temp (212ish)...once you do it evaporates.

Zixxer10R · 02-03-2012, 05:36 PM

Well, your boiling wort didn't actually surpass boiling temps (205-215 depending on sea level and humidity). Your lid surely did, but that's because aluminum's boiling point is MUCH higher than 212°.

You did ferment a little high though, how are you controlling your ferm temps? either way, it's going to beer that you will drink.

spokaniac · 02-03-2012, 05:37 PM

There may be a degree plus or minus difference due to the specific gravity or your altitude above sea level, but unless you seal the lid and pressurize it, you aren't going to get significantly hotter than 212 in the wort itself.

pmicka · 02-03-2012, 05:48 PM

@atom, a canning pot, aka a pressure cooker, enables temps above 212 degrees.

@Zixxer, due to a mild winter and my aversion to turning on the heat the temp is kept stable at 68/70 degrees without any action taken by me. Not optimal, but it will do for now.

The lid was "on" but not sealed, so it was essentially just the weight of the lid keeping any pressure in. I estimate that at the low end of the PSI/Temp scale it reached 220 degrees for no less than 5 minutes.

**DeafSmith** · 02-03-2012, 07:23 PM

Quote:

Originally Posted by pmicka

The lid was "on" but not sealed, so it was essentially just the weight of the lid keeping any pressure in. I estimate that at the low end of the PSI/Temp scale it reached 220 degrees for no less than 5 minutes.

For the temperature to reach 220º F, you would have to have a total pressure of a little over 17 psi, or over 2.3 psi above sea level atmosphere:

http://www.engineeringtoolbox.com/boiling-point-water-d_926.html

If your pot or kettle is, for example, 10 inches in diameter, with an area of 78.5 square inches, then it would take a force of (2.3)(78.5) = 180.6 pounds to hold the lid closed and maintain the wort at 220ºF. Unless your lid weighs 180 pounds (assuming 10 inch diameter), your wort did not reach 220º. Even the fact that this is a sugar solution and not pure water doesn't significantly raise the boiling point.

http://chestofbooks.com/food/science/Experimental-Cookery/The-Boiling-Point-Of-Water-And-Solutions.html

From the above, you can see that even with a 30% sugar solution, the boiling point is only increased by 1º C, or less than 2º F.

If you measured the temperature of the vapor inside the closed pot, maybe it could have been at 220º F, but it's more likely that your thermometer is not accurate.

pmicka · 02-03-2012, 07:31 PM

@DeafSmith The 220 was just an estimate. Like I said, I'm not really worried about having ruined the beer. I'm mostly interested in knowing what impact this raised temperature would have on the wort (sugars, enzymes, etc). I'm not really interested in knowing the exact temperature my wort coulda/woulda/shoulda been at if it were travelling on a train going 100mph at sea level on a leap year.

atom · 02-03-2012, 07:36 PM

in that case, it had no impact.

**mcarb** · 02-03-2012, 07:56 PM

It sounds like you know the answer you are looking for and don't really want input.

It destroyed your wort by breaking down enzymes normally used by yeast.

Is that the answer you want?

Well if so, it's not true.

pmicka · 02-03-2012, 08:10 PM

@mcarb If had known the answer I wouldn't have asked the question. I'm not sure what I've said to make you assume otherwise, but I digress and what's done is done. Maybe if I rephrase my question in purely theoretical terms I won't give off the impression that I'm a jackass by asking a completely reasonable question.

Theoretically speaking, what effect would temperatures in excess of 212 degrees fahrenheit have on wort?