Few questions about yeast

Hey guys,

I had a few questions about yeast and hope someone is willing to read all this and help me out. These questions just popped into my head while I was brewing.

So there's suppose to be a "winter" storm coming here in Socal, and I think the temps will drop into the 50's. I was making a spiced Ale, and was wondering what would happen if my fermentor dropped below the 60's.

1)Will it end up killing the yeast or just making them dormant?

2)If it goes dormant, Can I just let it sit longer till temps go back up and my brew will start fermenting again? I guess if the yeast will die, I will move it upstairs or figure someway to maintain the temps.

3) Once the brew has reached the FG during fermentation, does this mean the yeast are done eating up all the simple sugars from the malts or whatever? If this is true, how does bottle conditioning make the beer taste better later.

4) Also, when you use the priming sugar for bottling, does the yeast eat the sugar to produce carbon dioxide? If the brew is left in the primary fermentor too long, will the yeast eventually die?

5) How can yeast die??

Thanks for any helpful responses.

Welcome to the forum. Do you have your fermenter outside? I would think that you would have your precious brew inside where you can keep an eye on it and enjoy the bubbling through the airlock to lull you to sleep. Temps should not get so low inside your house.Read the temp. range that your yeasts works best at and try to stay in it. A lot of people are letting their brew sit in the primary to bulk condition for up to a month with some good results.

A winter storm in the 50's? Must be nice. I just got off of work and it was -15 below.
I wouldn't worry about it too much. Ive had a few that Ive let get too cold and when the temp goes back up, the fermantation picks right back up. The yeast usually dont die very easily. When it gets too cold or they run out of suger they go dormant. Warmer temps and more food and they spring right back to life.

I'll work on the last 3 questions.

3) Yeasts eat the simple sugar and can't ferment the complex sugars. The complex sugars help give the beer its taste & mouth feel. Conditioning is like ageing, some of the unwanted byproducts convert to more pleasant tastes.

4) Yes, try about 3/4 cup for 5 gallons, just before bottling. Yes, but weeks or a few months. (depends or temp & yeast type, alcohol content, etc)

5) Too high a pitching temp.
Improper freezing, the ice crystals puncture the cell walls.
After they are dormant eventually they go though autolysis.

If you want more science, wait for someone else (to reply), or possibly check out a brew book at your local library.

don't let the fermenter get that cold. temp changes that steep can shock the yeast, and shocked yeast tend to produce off flavors.

yeast can also 'clean up' many of those off flavors after primary fermentation is complete. thats one reason bottle conditioning improves the flavor...but also the flavors melding together...hop bitterness, hop flavor, malt sweetness and flavor...

also, yeast will do a lot of clean up in primary. you may notice that primary seems to stop after 3-4 days, but you always wait at least 1 week before racking it so the yeast can clean up the diacetyl, and some other misc off flavors like acedlaldehyde.

Willy Boner said:

Welcome to the forum. Do you have your fermenter outside? I would think that you would have your precious brew inside where you can keep an eye on it and enjoy the bubbling through the airlock to lull you to sleep. Temps should not get so low inside your house.Read the temp. range that your yeasts works best at and try to stay in it. A lot of people are letting their brew sit in the primary to bulk condition for up to a month with some good results.

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I leave my fermenters in the closet downstairs. Usually there isn't much temperature change in there so I'm not too worried.

Finster4 said:

A winter storm in the 50's? Must be nice. I just got off of work and it was -15 below.

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Yeah, the weather here is pretty nice. There hasn't been any significant rain here in awhile, so this storm is a welcome. Just gotta worry about crazy drivers and slick roads when its raining here :cross:

Old_Brewer said:

Yeasts eat the simple sugar and can't ferment the complex sugars. The complex sugars help give the beer its taste & mouth feel. Conditioning is like ageing, some of the unwanted byproducts convert to more pleasant tastes.

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malkore said:

yeast can also 'clean up' many of those off flavors after primary fermentation is complete. thats one reason bottle conditioning improves the flavor...but also the flavors melding together...hop bitterness, hop flavor, malt sweetness and flavor...

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So if bottle conditioning helps improve the flavor of the beer by just letting it sit around longer, is it possible to to just leave it in a carboy during primary fermentation to improve the flavors of the beer? If the beer were to sit in the carboy longer, lets say 1 1/2 months, would it still b able to carbonate the beer w/ priming sugar later?

Thanks for the responses. Starting to understand a little bit more about how the yeast works. There seems to be a lot to learn. Any more input would be great

aliu630 said:

So if bottle conditioning helps improve the flavor of the beer by just letting it sit around longer, is it possible to to just leave it in a carboy during primary fermentation to improve the flavors of the beer? If the beer were to sit in the carboy longer, lets say 1 1/2 months, would it still b able to carbonate the beer w/ priming sugar later?

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Oh, it should carbonate just fine. But if you're going to let it sit for that long, it's recommend to rack it to a second carboy after fermentation is complete, or after about 2-3 weeks. That gets it off the yeast cake and allows the beer to clear up and condition. I usually do that for all my beers. There is some concern that if you leave the beer on the yeast cake for too long that the yeast will autolyze and produce some off-flavors. Now, there is plenty of debate on how long "too long" is- but most brewers would agree that up to 3 weeks in the primary fermenter is perfectly fine, and then months in the conditioning tank if desired.

aliu630 said:

So if bottle conditioning helps improve the flavor of the beer by just letting it sit around longer, is it possible to to just leave it in a carboy during primary fermentation to improve the flavors of the beer? If the beer were to sit in the carboy longer, lets say 1 1/2 months, would it still b able to carbonate the beer w/ priming sugar later?

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yes, but only to an extent. leave it on a large yeast cake for too long, and you'll start adding other off flavors to the beer. 5-6 weeks is your cut off for primary in almost all cases, and if you you needed to let it sit longer, I'd rack to secondary and let it sit.

people have left beer in secondary for 4 months, and it could still carbonate once bottled without any additional yeast being added...though I suspect it might take a little longer since the yeast would be fairly dormant after that time period.

its usually only the lager brewers that'll re-pitch at bottling, and even then only if they've really lagered a long time, like 5 months (plus a month in primary...total of 6 months for the yeast).