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I'm just getting started, so in my first couple batches I realized I had a problem cooling the wort all the way down to 60°F/16°C recommended by my instructions. I boil all of my water, but I don't have all day to let it cool before introducing the wort, which also needs to cool. Please let me know if I'm doing anything totally wrong or can be done better.

The best I've been able to do in the shortest amount of time is boil my water, let cool for 15 minutes and dump into my sterilized plastic fermenter pail. I place the pail in a utility tub full of cold water to cool while I start the wort. After the wort is done boiling, I place that vessel in a bath of ice water in the sink. I bring it down to 90°F/32°C before racking into the pail. By this time, the entire mixture is about 90°F/32°C. When I take my original gravity reading, it's always way off the mark from recommended due to temperature. I adjust my reading to 60°F/16°C reference temperature.

Pail is then pitched with yeast, sealed, placed in basement, and airlocked.

1) Is there any harm to start fermentation while warm? Will this affect the beer quality?

2) Is there any harm to let the wort sit longer to cool before going into the fermenter?

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7 Answers 7

Pitching yeast into wort that is too warm can cause a number of problems. At the very worst, you'll shock the yeast and/or kill it, and you'll have a stuck fermentation. Another problem with pitching too warm (and maintaining fermentation too warm) is that it can cause the yeast to produce unwanted off-flavors in the beer.

Letting the wort sit longer to cool isn't desirable; the wort needs to be chilled quickly for two main reasons:

  1. Allowing the wort to cool on its own gives bacteria a chance to take hold. There are bacteria that thrive at high temperatures, and leaving the wort too hot increases the chance of infection (not to mention anything that might find its way into the wort during the long cooling time).

  2. Chilling the wort quickly causes what is called the "cold break", where proteins in the wort clump together due to the rapid temperature change and flocculate out. Without the cold break, these proteins remain suspended in the wort (and subsequent beer), and lead to chill haze.

Having said that, I usually chill my wort down to about 70-75°F/21-24°C and pitch. Aeration before pitching (pouring from high above the fermenter, shaking, etc.) usually helps bring the temp down a few more degrees as well. 90°F/32°C is too warm to pitch IMO, but 60°F/16°C is probably lower than necessary.

If boiling/cooling water for topping off is a problem, you might want to consider purchasing bottled water or boiling/chilling your top-off water the day before. As for the wort, I did the "ice bath in the sink" method when I did extract batches, and while it works ok to an extent, I recommend building/buying a wort chiller when you have the time and money, because it will save you both.

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1  
Palmer recommends against aerating the wort when it's hot (see answer)- haven't had a chance to check other sources yet, but he generally knows his stuff. –  Fishtoaster Nov 9 '10 at 4:33
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I completely agree, but I wouldn't consider 75F to be "hot". –  Jeff L Nov 9 '10 at 4:45

Regarding (1): Yes, there is harm. Even if the yeast holds up well, with most yeasts, you will get lots more estery flavors than you want if you're pitching at 90 F. With some styles (e.g,.Scottish Ale, Altbier, Kölsch) the aroma profile will be completely wrong.

Regarding (2): There's not too much problem letting wort sit a bit longer once you get down to 90 F -- if it is in a sealed, sanitary container. That's a big if for a partially-open pot. Keep in mind that some retailers have sold "wort in a bag" before, room temp storage. But it went into the bag higher than pasteurization temp when it was sealed. So the theory works, but the practice might not, not with a home kitchen.

A wort chiller is really the way to go, but that's $60 up. If you're on a budget I'd look to snag a cheap 25-foot (minimum) immersion chiller off of Craigslist or even from one of the brew shops on an occasional sale. Copper is pricey, yes, but you save a lot of your own time and remove potential for problems from the aforementioned points (1) and (2).

Calvin Perilloux, Middletown, Maryland, USA

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Wort chiller was the best investment I ever made. Saves so much time. –  Jeshii Nov 19 '10 at 18:21

If you do pitch hot, keep an eye on your airlock. I've gotten impatient during hot summer brew sessions and pitched at 80+, and occasionally the vacuum created as the wort cools will suck most of the sanitizer out of the airlock.

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One thing to consider is that you generally want to aerate the wort before pitching the yeast, and you don't want to aerate wort above 80 degrees, according to Palmer. The reasoning is that the oxygen will bind to various wort compounds, which later break down, freeing the oxygen, which then oxidizes fatty acids + alcohols, causing off-flavors.

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I think you are probably fine as long as you pitch below 80 degrees. That should be low enough for the yeast to remain viable until the temperature comes down. Depending on how much yeast you pitch the first few hours will probably be more important for yeast multiplication than fermentation. That said, fermentation temperature is pretty important for your flavor profile and controlling it will help your beer. The more delicate the beer flavor you are aiming for the more careful you will need to be. In time as you get more into brewing I would definitely recommend a wort chiller (it speeds things up considerably and gives you a nice cold break)and something to control your fermentation temperature (it will help with stuck fermentation and help you get the flavors you want).

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When I've done partial mashes and extract kits I haven't boiled my water (I know, bacteria and chlorine etc...).

I trust my water source and I have not had any infections from this (YMMV). So it is a possible change in your current process which may speed up your brew day significantly.

You may also look into a Immersion Chiller they're relatively inexpensive and this would allow you to have the best of both worlds (speed and sterile)

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Both questions resolve to the same issue - there's a chance of something other than your yeast taking over the nice environment you've made for microbes. By not letting it cool sufficiently, you risk killing off enough yeast that something else can muscle in. Unfortunately, the longer you let the wort sit before pitching your yeast, the more likely that something else can take hold as well.

That said, proper sterilization and sanitation can help prevent the second problem. I've made a whole lot of beer that I didn't pitch the yeast for a good 8 hours without problems. Eventually, I figured that the risk wasn't worth it and made a counter-flow wort chiller (see this for info on wort chillers). It was much cheaper than buying one, and pretty easy to build. The only precaution is that you must carefully filter your wort before it goes through the chiller, as it clogs easily enough on hops, etc.

This article has a pretty good description of building a counter-flow cooler from scratch, although it occurs to me that I bought a set of fittings for about $20. The rest is the same - 50 feet of copper tubing, and 50 feet of garden hose. The nice part is that it's insanely easy to get wort into your primary fermenter at whatever temperature you want, given sufficient flow of cold water.

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