Ideal fermentation temp given a yeast's viable range

I recently completed the build out of my fermentation chamber and temp controller, so I now have the capacity to control to a much better degree the temperature I'm fermenting at.

I've noticed, looking at info on several yeast strains, that many of them tend to be rated for pretty wide temperature ranges - but if I can keep a batch at a temperature +/- 1C (or less), I'm struggling a little bit to figure out where in a range to set my chamber.

I know that many yeasts can create fruity esters and other off-flavors at higher temperatures. But is that only when the fermentation happens at a higher than rated temperature, or can it also occur when fermentation happens towards the upper end of the yeast's range?

And what, other than slower fermentation, kind of effects can be attributed to fermenting at the low end of a yeast's range?

I guess what I'm mostly looking for here is any rules of thumb that would help in determining where in a yeast's range I should be setting my chamber.

Thanks in advance!

The colder the cleaner, my friend. This applies to the entire spectrum.

I like fermenting @ 64 for most ales, so I like ambient temp around 61. I do a bunch of belgians, so temperature fluctuation doesn't scare me much.

General rules of thumb:

1) Lower tempertures result in cleaner beers. "Lower" here means the low end of the rated scale. Below the low end of the rated scale and you risk the yeast going dormant before completing fermentation.

2)Higher temperatures result in more fruity/estery/fusel beers. "Higher" here means the high end of the rated scale (and above). Above the scale will give you undesirable results most of the time.

Other than those two general rules of thumb, it's really up to you and what you're going for. Adjusting the temp anywhere between the low and high end of the range will result in a blend of clean/estery flavors, depending on what temp you pick.

Keep in mind that fermentation will raise the temp by 5 or 10 F (so what, 2-4 C?).

It's nice to play around with fermentation temps. I brewed a great quad last March with the Westmalle strain that I started out about 55 F, and then slowly raised it up to about 80, and then cold conditioned/lagered at 55 for ~2 months. Beer turned out great. Very fruity, low fusels.

Plus most of the undesirable byproducts are produce when fermentation is at it's most active stage. Once the gravity has dropped significantly you can raise the temp to speed fermentation. There are not as many fermentables so the yeast aren't giving off fusels and esters at the same rate. You also don't have the additional heat being generated by the active fermentation so raising ambient temp toward the end really just keeps the fermentation temp stable.
For instance I'll ferment my ales at 60F until I get about 80% of my expected attenuation(say around 1.020), then I start warming the chamber up by a degree or 2 per day until it hits 65, then I leave it there a week or more.

JoePro said:

The colder the cleaner, my friend. This applies to the entire spectrum.

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This simply ins't the case. With hefe yeasts, and all other yeasts, the colder you ferment you can still cause stress on the yeast and cause undesirable or desirable off flavors or esters. This is an advanced technique that is used when brewing hefes (to ferment cold to stress teh yeast out).

Too hot or too cold stresses the yeast. clean ferments are typically the result of steady middle of the road temps. i.e. for ales 68F constant for the entire ferment.


for most of your pale ales, IPAs browns, stouts porters I would try to hold 68F for ferment. For hefes, lambics, lagers and belgians those are different animals.

Belgians in particular have odd yeast strains. I made a belgium quad recently and kept the ferment temp at 83F for 5 days - worked fantastic and no crazy smells or undesirable esters. Try that with a cream ale or other and you might get some funky tasting brew.