Constant Stirring During Fermentation, Anyone? - Home Brew Forums
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Old 01-26-2011, 05:20 PM   #1
Triples
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I was just reading a post on another topic and the brewer mentioned that he would give his fermenter a swirl once in awhile during fermentation. That got me wondering: what if you put your fermenter on a big stir plate and constantly stirred during fermentation? (You'd probably stop stirring after primary fermentation winds down to let the yeast flocculate.) I wonder how this would change the beer. Has anyone tried it?



 
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Old 01-26-2011, 05:23 PM   #2
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I'm not sure that you'd get much of any thing out of it. The purpose of stirring when making starters is to keep introducing oxygen, but that wouldn't be desirable during fermentation. It might help keep yeast from floccing out if you're having difficulty hitting your attenuation. Under normal circumstances, though, I don't think it would help any.



 
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Old 01-26-2011, 06:45 PM   #3
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If your yeast is working, it will be stirring up the brew all on its own. It won't need your help. Make sure you aerate it before you pitch the yeast, plop the yeast in and walk away. Don't bother the yeast until its done with its job.

 
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Old 01-26-2011, 06:50 PM   #5
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Quote:
Originally Posted by Triples View Post
I was just reading a post on another topic and the brewer mentioned that he would give his fermenter a swirl once in awhile during fermentation. That got me wondering: what if you put your fermenter on a big stir plate and constantly stirred during fermentation? (You'd probably stop stirring after primary fermentation winds down to let the yeast flocculate.) I wonder how this would change the beer. Has anyone tried it?
If you get oxygen in the fermenter during fermentation while you are constantly stirring it, it will change the beer all right, more than likely make liquid cardboard. Oxygen DURING fermentation is not good.
There's several threads bringing this up, and the answer is the same, greater risk of oxydizing the beer.

The yeast are pretty adept at finding the sugars on their own, ESPECIALLY if you gave them plenty of oxygen BEFORE hand. They done need to have to ride a merry go round while they are doing their jobs.
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Old 04-10-2012, 05:39 PM   #6
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So it seems like no one who replied has tried it. I don't understand the concern about aeration - the fermenter is full of CO2 as soon as fermentation starts. The yeast keep things moving by themselves pretty well but still a yeast cake begins to form early in the process. The idea is not to aerate but to keep the yeast from settling out so soon. Perhaps we could pitch less yeast and still produce good beer if we kept it stirred up for the first few days. Perhaps it would create a cleaner tasting beer. I just might give it a whirl (so to speak).

 
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Old 04-10-2012, 06:00 PM   #7
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Quote:
Originally Posted by Triples View Post
So it seems like no one who replied has tried it. I don't understand the concern about aeration - the fermenter is full of CO2 as soon as fermentation starts. The yeast keep things moving by themselves pretty well but still a yeast cake begins to form early in the process. The idea is not to aerate but to keep the yeast from settling out so soon. Perhaps we could pitch less yeast and still produce good beer if we kept it stirred up for the first few days. Perhaps it would create a cleaner tasting beer. I just might give it a whirl (so to speak).
Go ahead and try it, get back to us with the results.

 
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Old 04-10-2012, 07:43 PM   #8
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Quote:
Originally Posted by Triples View Post
So it seems like no one who replied has tried it. I don't understand the concern about aeration - the fermenter is full of CO2 as soon as fermentation starts. The yeast keep things moving by themselves pretty well but still a yeast cake begins to form early in the process. The idea is not to aerate but to keep the yeast from settling out so soon. Perhaps we could pitch less yeast and still produce good beer if we kept it stirred up for the first few days. Perhaps it would create a cleaner tasting beer. I just might give it a whirl (so to speak).
Certainly give it a shot. I would never want to discourage someone from trying something, especially when it's something I haven't tried myself.

That said, there's a reason people are skeptical. You are correct that you won't oxidize your beer if it is sealed off. But, the idea that you'll get a more attentive yeast or cleaner beer doesn't fit with my understanding of the process. Yeast don't flocculate out for lack of mechanical agitation but because of an electrostatic change in their cell walls. This change is trigged by changes in the nutritional contents of your wort. Stirring won't stop that, and you'll just be agitating big clumps of (relatively) dormant cells.
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Old 04-10-2012, 07:47 PM   #9
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I have heard big brewers laugh about HSA, but always heard mostly the same thing about oxygenation during fementation. I believe that most apply a maxim of none, when sure some would be ok. The question is just are you adept enough to know or make sure you don't oxygenate.

There are many beers that introduce bacteria on purpose in open fermentations (lambics and such), and many Belgian, English, German, and some American breweries ferment even non lambic type beers openly. They stir sometimes depending on yeast flocculance and taste they are going for with the beer. I don't plan on stirring heavily but I do want to do a few open fermentation recipes, as some recipes for some beers I really like call for it. I like estery beers, and more Belgian styles, so we'll see, but I'm a bit afraid, so I've been waiting.

I think thats what Revvy and some of the others meant, can you and produce a great product? Sure, there are actually many breweries that do, but if you do just great without the risk, why include the risk?
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Old 04-10-2012, 10:51 PM   #10
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if its a big beer... i remember reading somewhere that some brews will need more sugar and o2 mid fermentation just to keep a healthy fermentation going. but who knows where I read that...

i just gave advice on another thread stating to shake up a stuck ferm. doing so will prob add some oxygen, but assuming the yeast are missing oxygen it should not be too much of an issue regarding oxidation.


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