View Full Version : Halting a Fermentation?

Brego Brew
01-09-2011, 12:23 AM
Alright guys, I have a question for you all. My mead is currently in the secondary fermentor and the fermentation will not stop. It has gone WAY over the yeasts 14% ABV tolerance and is starting to produce some off flavors and aromas. Is it safe to cold crash it, wait for it to clear, and rack the clear mead onto some sorbate? I believe I'm going to proceed with this plan either way, but has anyone ever had problems with this technique?


01-09-2011, 02:43 AM
Well, as you've seen first hand, yeast are anything but predictable. While the cold crashing will get most of the yeast out of suspension, there is no guarantee that you'll get them all out. Then when they warm back up, they could keep right on going.

If you do plan to go this route, you'll need to use sulfite in conjunction with sorbate to have any chance of stopping the fermentation. Sorbate alone won't cut it, it just prevents new growth, which the yeast aren't doing at this point any more.

Another option would be sterile filtration, which you can find more on using the search tool. This question seems to get asked frequently, and it could be answered in a few minutes of searching.

01-09-2011, 05:08 AM
Well, most people asking about halting a ferment are trying to halt it lower or around the yeast's tolerance. If the yeast is past it's tolerance cold crashing should slow it waaaaay down or stop it. It might start up again later, so don't bottle before extended aging (years IMO) or chemically stabilizing to finish the job once and for all - but I think if you cool it down it should stop.

That said, it should stop anyways. Could you expand on "way past" 14%? What was your starting SG and what is the SG now?

01-09-2011, 06:00 AM
It's quite unlikely that it's gone "way over" it's alcohol tolerance. Some yeasts are known for 1 or 2 % extra, but it depends on your definition of "way over" really.

Either way, if you have the space in a fridge or the weather in your part of the world is close to zero C/32 F, and you can leave it long enough, then cold crash is the best way, then as the others don't seem to have noticed, if, after cold crashing, you can let it clear at the cold temperature, or at least drop a sediment, you can then rack it onto sulphite and sorbate, which in theory, should stun and still living yeasties and at the same time, prevent them from multiplying as well.

It's about the best way of stopping a ferment and not having to try chem's etc that might affect the flavour of the brew.

In fact, because of the alcohol content, you can even crash it a little below zero C/32 F, say something like -1 or -2 C/30 or 28 F. It's not going to freeze as the alcohol content prevents that and as you'd be thinking on time periods of a week or two, a little below freezing won't hurt it (if you're somewhere that the temp drops to stupidly low levels, then you might need to insulate to retain the right temp as it would freeze solid in a couple of days or so).

Dunno if any of that's of help?



Brego Brew
01-09-2011, 11:16 AM
HAHAHA!!! Well, everyone must excuse my over enthusiastic thread. :p I had a number of glasses of Pink Catawba at the time of writing this thread, from the local Meadery/Winery last night, Pretty good stuff!

Alright, now the WAY OVER is an ABV of @ 15.5%, over the 14% stated tolerance. It's only 1.5% over, but with wine in your gut, that's like 50% Over!;D

After the diminished Blood Alcohol Limit, I think I'm going to just let it finish out.

Don't flame me! It was just the wine ;D