How does temperature change affect fermentation?

[gatorbeer69]

I just finished my 4th ag batch and when I pitched the yeast it was around 70 degrees and the airlock was very active. Now 2 days later it's in the 40's and everything has slowed way down. Do I have anything to worry about? Btw it's a amber ale with safale s-04 thanks


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[Dan]

Maybe. You pitched a little warm, ideally fermentation temp for S-04 is 59-68F. But 70 isn't much more than that. Agressive fermentation (airlock activity if you will) can quickly taper off after a few days of vigorous fermentation like you had. Cool temps in ales are usually recommended but 40 is to cold. Bring it into your house and let ferment a few more weeks. Then take a Final Gravity (FG) reading. Two times same reading over three days and close to what the suggested reading should be .. botttle it, keg it.

 

[fartinmartin]

Dan told you right.

 

[NTXBrauer]

As Dan has pointed out, 40 degrees is too cold for Ale yeast. Fermentation will slow to a crawl, and possibly stop all together at this point. Bring your FV back up into the mid 60s and the yeast will get going again on doing what they do best. Cheers!

 

[gatorbeer69]

Ok thanks.


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[BigFloyd]

At 40*F, I'm afraid that your S-04 has certainly dropped out and gone nighty-night before they've finished their work.

You'll want to:

1) raise the temp up into the mid-upper 60's and keep it there,

2) once it's been warmer for a day you can either swirl the bucket or very carefully (and slowly - no splashing) work the yeast up off the bottom with a sanitized metal or plastic spoon. In this situation, I'd lean toward the second option since that yeast cake has probably firmed up a bit at the colder temp making it very tough to rouse by swirling.

 

[Dan]

Just read BigFloyds' signature. True and wise words.

Good Temp Control -----> Happy Yeast ------> Tasty Brew

 

[gatorbeer69]

Once I've moved inside to a bit warmer temp will it be able to ferment out? Or have I lost the batch. Thanks


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[NTXBrauer]

It should be fine just follow the advice above and give it a little swirl to rouse the yeast

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[gatorbeer69]

Sounds good. Thanks again



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[gatorbeer69]

Sounds good. Thanks again



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[gatorbeer69]

Well after moving my amber ale inside and getting the temp up I took a gravity reading and it's at 1.024 it only been 17 days. Just wandering if it will get down closer to the target of 1.013 with more time. Thanks


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[bhanson]

... Just wandering if it will get down closer to the target of 1.013 with more time. .....

There are a number of factors that will actually determine the final gravity. Assuming you followed the advice of rousing the yeast after you raised the temperature a bit by either stirring or swirling, I'd expect that the yeast would be back in suspension and doing its thing. A brewing yeast will keep going usually until a point where the balance of quantity, alcohol levels, residual sugars and so forth basically convince the yeast to give up and begin to go dormant and drop out of suspension. These balance points are somewhat different for each yeast strain, and relative to the beer they are working on . The numbers you expect (target 1.013) to see are based on a set of calculations that numerically quantify in more concrete terms what I just described. The actual terminal gravity will differ from that target based on all the things that happen which vary from the assumptions made in the original calculations, but are in the ballpark. Experienced brewers can definitely dial in their processes to the point that they consistently get what they expect or very close.

To answer your question more directly, the only way to be certain is to measure your gravity again. Check it again in two or three days to see if it has changed at all. If it's the same in three days as it is now, and that's very possible with S-04 after 17 days, that would mean it's done.

 

[gatorbeer69]

Cool. Thanks


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[gatorbeer69]

Is there a way to have your beer judged without entering it in a contest?


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