How Does Temperature Affect Yeast?

How much effect does temperature have on actively working yeast?

Will a lower temperature produce slow non-agressive fermentation with an ale yeast?

For example, I pitched Pacman at 60 degrees, and maintaining a 60-63 temperature range by placing the carboy in a water bath with ice packs.

While I did under-pitch, fermentation has begun but has not exploded into a fast and furious vigor. After 36 hours, the airlock off-gasing every second but krausen hasn't formed and there is only a thin layer of bubbles on the surface of the wort.

I am more curious than woried. This is the first time fermenting at 60 degrees and not sure what to expect.

Temperature is probably the most important factor in controlling your yeast. Cooler temps will lead to relatively slower metabolisms, and thus less rapid fermentations.

Yeast and Temperature


name Alyssaaum
status student
age 8

Question - How does temperature affect yeast?
------------------------------------------------
Dear Alyssa,
At low temperatures (0-10 C) yeast will not grow, but
not die either. At temperatures 10-37 C yeast will
grow and multiply, faster at higher temperatures with
an optimal growth at 30 or 37 C (that depends on the
species). At higher temperature the cells become
stressed, meaning that their content becomes damaged
and which can be repaired to some degree. At high
temperatures (>50 C) the cells die. The bacteria can
survive freezing under certain conditions.

http://www.newton.dep.anl.gov/askasci/bio99/bio99693.htm

That "ask a scientist" page is nearly useless for understanding brewer's yeast. And it is not encouraging that the answer refers to yeast as bacteria at one point.

Might want to check this out: http://www.mrmalty.com/

After 48 hours, the fermentation has starting picking up speed. What was 1 gurgle per second this morning with little or no krausen is not 2 gurgles per second with a near 1/2 inch krausen.

The fermenting wort is in the 60 to 62 range.

If fermenting 10 degrees warmer, what do you think the outcome would be?

Fermentation temperature is one of the most inportant things to monitor and can have a profound impact on the beer.

Like stated previous yeast grow best from 10-37 degrees celcius with 37 being the optimal growth temperature for some strains however it is not usually a good temperature for brewing and will often produce off flavours due to the yeasts shift in metabolism to focus on reproduction. Fermenting in the low 10`s for any beer will slow the process but will usually result in a cleaner beer.

When brewing high gravity beers you really need to watch temperature since the excessive metabolism by the yeast can cause a drarmatic elevation in temperature which will stress the yeast usualy producing a solvent like flavour. However, raising the temperature of a fermentation after 3 or so days can cause a drier beer and does not tend to impair flavour since most of the fermentation has already occured; the higher temp makes it easier for the yeast to consume the small amounts of sugar left in solution.

lol and YEAST ARE NOT BACTERIA, THEY AND FUNGI! Single celled Eukaryotic fungi

I am a newb and just did my second brew (IPA). I pitched at 70 degrees. For the first

Oops, I hit send before I was finished. Anyway, for the first 48 hrs. The temp. was 65 F to 70 F. I had it stored in a closet. The house got a little warm today (3rd day) so I checked it and it was way up above 75 close to 79 F. Is this batch doomed?

pitching at too low a temperature makes it not perform. Pitching at too higher temperature kills it. 70 is a good temp to pitch at for most beers. Yeast is a magical creature that is alive and does the super important job of converting sugars to alcohol. Once you pitch, keep it around this 70 degree rate on the low end. i.e. mine ferment at 62-68 depending on when i brew.

Some yeasts need lower temperatures like lagers which need to be stored considerably lower than ale yeasts. For lagers you typically need a temperature controlled environment for lower temps. Then there are some yeasts that are hybrid like Kolsch and California Common that are lager yeasts that act like ale yeasts and don't need the typical lager temp controls.

For specificities on yeast for what you are brewing, check out the website of your yeast, they usually have a lot of info there. Otherwise, let us know and we'll try to help as much as we can.