Cold Crashing Not Working

[krizo96]

I have miscalculated up to how much abv the yeast I am using can go so I tried cold crashing it by putting it in the fridge.
The first day after it look like the fermentation completely stopped, but the day after it cintuined going at the same pace as it was before I put it in the fridge.
I'm stunned, shouldn't yeast go dormant at low temperatures? Any tips? Am I just doing something wrong?

 

[Yooper]

I have miscalculated up to how much abv the yeast I am using can go so I tried cold crashing it by putting it in the fridge.
The first day after it look like the fermentation completely stopped, but the day after it cintuined going at the same pace as it was before I put it in the fridge.
I'm stunned, shouldn't yeast go dormant at low temperatures? Any tips? Am I just doing something wrong?

It's tough to stop an active fermentation- it's like stopping a freight train. I've never had any luck with cold crashing to stop a fermentation, and I've been making wine for 25+ years. I don't have the proper sized fermentation temperature to get it cold enough for long enough, I think.

The only way to get it to work is to cold crash, rack off of the dormant yeast, repeat. Even then, it may not really work well. Keep it colder, and maybe that will help. If you can hold it at 30 degrees or so, it might work. The idea is to get it as cold as possible without freezing.

Next time, feed the yeast incrementally and stop when you reach the desired ABV. It's really hard to get it to reliably stop where you want it otherwise.

 

[krizo96]

The problem is that in the yeast didn't go dormant for long it enough and it didn't separate at all, so it's kind of impossible to rack it off. Currently it's probably around 3° C (so around 37° F), it surprised me that it basically didn't slow down at all.

Never thought of that, thanks for the advice. Just wondering, does the yeast rely that much on the nutrients that it would stop if it ran out? Wouldn't it keep going on the sugar from the honey?

I guess there's not much I can really do now, so if it doesn't slow down I'll just let it finish and see approximately how much abv can this yeast really handle.

I was going for a small 5 liter (1.3 gallon) batch of sweet mead, and it's probably gonna end up medium or dry. Might be a good learning opportunity to try back sweetening if nothing else.

 

[Yooper]

The problem is that in the yeast didn't go dormant for long it enough and it didn't separate at all, so it's kind of impossible to rack it off. Currently it's probably around 3° C (so around 37° F), it surprised me that it basically didn't slow down at all.

Never thought of that, thanks for the advice. Just wondering, does the yeast rely that much on the nutrients that it would stop if it ran out? Wouldn't it keep going on the sugar from the honey?

I guess there's not much I can really do now, so if it doesn't slow down I'll just let it finish and see approximately how much abv can this yeast really handle.

I was going for a small 5 liter (1.3 gallon) batch of sweet mead, and it's probably gonna end up medium or dry. Might be a good learning opportunity to try back sweetening if nothing else.

When you cold crash, it's important to get the mead/wine/cider/beer as cold as possible as soon as possible. (That's what cold crash means, after all).

Putting it in a 37 degree fridge would mean a fairly gradual cool down, and yeast are hardy little organisms and would try to adapt to that temperature change. By getting it colder (near freezing) faster, it can shock the yeast and they sometimes will drop out.

Like I said, during a very active fermentation it's not likely to work. It can work when fermentation is slowing and when the ABV tolerance is close-ish, because the yeast aren't as active at that point.

But one of things that can happen by stressing the yeast isn't just that they quit- they can put out off flavors under stress.

 

[bernardsmith]

Some strains of yeast are perfectly comfortable fermenting at lower temperatures and there may be enough cells active at 37 F for that temperature to be too high to be considered as "cold crashing". I think you want to cold crash closer to 32 F

 

[krizo96]

When you cold crash, it's important to get the mead/wine/cider/beer as cold as possible as soon as possible. (That's what cold crash means, after all).

Putting it in a 37 degree fridge would mean a fairly gradual cool down, and yeast are hardy little organisms and would try to adapt to that temperature change. By getting it colder (near freezing) faster, it can shock the yeast and they sometimes will drop out.

Like I said, during a very active fermentation it's not likely to work. It can work when fermentation is slowing and when the ABV tolerance is close-ish, because the yeast aren't as active at that point.

But one of things that can happen by stressing the yeast isn't just that they quit- they can put out off flavors under stress.

Interesting, thank you. I don't have a freezer big/empty enough to do it then. I'll just leave it to finish and try back sweetening if it ends up too dry, won't risk getting the off flavors.

Some strains of yeast are perfectly comfortable fermenting at lower temperatures and there may be enough cells active at 37 F for that temperature to be too high to be considered as "cold crashing". I think you want to cold crash closer to 32 F

I got that, don't have anyplace to store it at the temperature. Is tricky since there are almost no brands of yeast I read about online available here (and buying online with shipping it ridiculously expensive) and the ones that are available don't have any properties like temperature and alcohol tolerance clearly stated or known from experience of others.