Stir plate

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mtbmatt
Posts: 31
Joined: Tue Jan 27, 2015 12:23 am

Stir plate

Post by mtbmatt »

So I've got this stir plate to help make more yeast in my starters.

Can anyone think why using one on an FV wouldn't work. Say if I turned it off before fermentation finished?

I seem to never fully attenuate my beers. Looking for ways to improve the situation, and thought of that. Obviously it helps when i'm making the starter, why not when I'm making my actual beer.

The risk of oxidisation was the only problem I could foresee, but that shouldn't be a problem unless I run it after it's finished fermenting surely?
KevinS
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Joined: Wed Feb 26, 2014 5:38 pm

Re: Stir plate

Post by KevinS »

Hm an intersting idea, and in some ways not too dissimilar to recirculating the yeast - like some commercial brewers will do on occasion. But it seems like a longwinded (possibly risky) way to go - as opposed to resolving the underlying issue with attenuation

I would think your time is better spent trying to solve the underlying problem thats causing the lack of attenuation. Can you give any more details about what is happening with your brews?

Kev
Capn Ahab
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Re: Stir plate

Post by Capn Ahab »

The underlying problem is likely to be one or a combination of underpitching and underoxygenating. Get these right and your attenuation will be fine.
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PMowdes
Posts: 489
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Re: Stir plate

Post by PMowdes »

There is a good reason why stirring isn't advised but i cant remeber what it is.

for a stater stirring helps the yeast to multiply, basically it drives off the co2 keeps the yeast in suspension and allows them to multiply aerobically.

This is fine for a starter because you want to increase the cell count and you arent bothered by off flavours, but it isn't what you want in your primary fermentation.

Like Mark says there is probably another reason for underattenuation like yeast pitching rate, viability, health, fermentation temperature, mash temperature etc etc.

There are ways to fix all of the above but you need to find out where the problem is to begin with, stirring you FV sounds like a bit of an extreme solution
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EckersKlein
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Re: Stir plate

Post by EckersKlein »

mtbmatt wrote:I seem to never fully attenuate my beers. Looking for ways to improve the situation, and thought of that. Obviously it helps when i'm making the starter, why not when I'm making my actual beer.
What sort of apparent attenuation figures are you getting? I typically get ~80% mashing at 68 degC or lower for normal-ABV beers, and more like 70-75% mashing at 70 degC or above. If you're brewing all-grain, perhaps your mash is a little on the hot side.

Back when I brewed with extract, I was usually getting ~65% attenuation, despite aerating and pitching lots of yeast. I never did figure out why that was, other than to say my extracts were crap.
mtbmatt
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Joined: Tue Jan 27, 2015 12:23 am

Re: Stir plate

Post by mtbmatt »

Hmmm, i would agree that i need to look at underlying issues that may cause under-attenuation.

So for some time now i've been using an airstone and a fish tank pump, plus making 2L starters in an effort to improve things on the yeast side of fermentation.

Beyond that, i use a temp controlled fridge for the FV. I set it at around 18degC, up to 20degC, sometimes turning it up in the latter stages of fermentation to help it finish off.

However i am an extract brewer, so EckersKlein comment regarding his experience of much poorer efficiency with extracts is most interesting to me.

Perhaps that is why i never seem to get the FG down as low as i expect?

I've not written off the idea of a stirplate running for the first 12-24 hours say.

I've now done what i should have done at the start (aside from merely generating some interesting conversation anyway). I googled it.

Seems like the result is this:

1. Closed system FV = no additional O2, so no oxidation risk
2. Current system works, so why bother trying something new (crap reason obviously)
3. Start with well oxygenated wort, and correct amount of yeast, then no problem anyway.
4. Might be useful for very high gravity beers
5. Might be useful for highly flocculating yeast


So my thoughts are that it's worth a go, unlikely to harm the beer. 4 and 5 (especially 5), seem to me good reasons to give it a try.

We'll see. I'll report back if i do it.
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steve crawshaw
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Re: Stir plate

Post by steve crawshaw »

There is a school of thought that says that stir plates are unnecessary, and possibly even counterproductive, to create a healthy starter. Suggest you read all the posts by S. Cerevisae on this thread:

https://www.homebrewersassociation.org/ ... c=22055.30

he makes a cogent argument for a simpler, low cost method. I am using this approach with good results.

cheers
steve
I like to keep a bottle of stimulant handy in case I see a snake, which I also keep handy.
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