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Stirplate For Fermenter?

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lael

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Hi,

looking at building a stirplate soon. I saw this one on youtube:
which got me wondering.

Is it possible to build a stirplate that will run in the fermenter? as per in a yeast starter would it lead to higher growth rates and therefore better fermentation?

physically it would just need a platform that could hold the fermenter - a platform on bolts as per the video should be able to do it I would imagine?
 
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barls

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would also lead to massive oxidation in the final beer
 

lael

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would also lead to massive oxidation in the final beer
only if it was running fast enough to pull air into the wort?

edit:

what about if it was only run for the first six hours (during yeast ramp-up)
I read on the maltose falcons site that HG beers can need the yeast cake stirred up (http://www.maltosefalcons.com/tech/thinking-big-getting-handle-brewing-big-beers see Yeast 2:Babysitting your yeast three paragraphs down) and they have 'walked barrels to do this. Could a stirbar do the same thing more gently? though I'm guessing the bar would not be able to shift the trub unless it had been going the entire time...
 

lael

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would also lead to massive oxidation in the final beer
just looked up oxidation as I'm new to this - howtobrew says no to splashing hot wort into the fermenter - no splashing when hot, cool then aerate is his recommedation - other books I've read recommend it, as they say oxygenation is helpful.

all say post ferment - as little splashing as possible to prevent oxidation.

Which is right for pre-fermentation?
 

barls

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you want controlled oxygenation up to a point after that it forms harsh flavours in the final beer. it is possible to over oxygenate. there is a difference in oxygenation and oxidation
personally if you pitch the right amount of yeast at the right temp and oxygen level it will lead to a better beer.
think of it this way if it produced a better beer wouldnt the big breweries do it as a continuous oxidation rather than just as they transfer to the fermentation vessel.
 

katzke

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would also lead to massive oxidation in the final beer
How? A fermentor should be a closed vessel. Once the yeast use up the O2 and start pooping CO2 where is the risk of oxidation coming from.

As to stirring fermenting wort. One advantage to using glass fermentors is being able to see what happens. Have a video clip of a beer fermenting. Looks like a cyclone in there. The yeast do enough stirring on their own.

But why not try it and see if it is worth the effort. Wine makers do some kind of agitation to break up the top crust and something to do with distributing the skins.
 

barls

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How? A fermentor should be a closed vessel. Once the yeast use up the O2 and start pooping CO2 where is the risk of oxidation coming from.

As to stirring fermenting wort. One advantage to using glass fermentors is being able to see what happens. Have a video clip of a beer fermenting. Looks like a cyclone in there. The yeast do enough stirring on their own.

But why not try it and see if it is worth the effort. Wine makers do some kind of agitation to break up the top crust and something to do with distributing the skins.
the fermentation vessel isnt actually 100% closed ie you have gas transfer both ways. ie it vents co2 pressure when too high and you can also have gas transferring back the other direction. ive run an air lock on a starter on the stirplate a few times and ive seen the gas go both ways. as ive also said its been covered at least a dozen time have a read of some of the links ive included, at least once every 8 months this comes up and more educated people than me have answered this.
 

lael

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thanks barls

http://www.aussiehomebrewer.com/forum/inde...st&p=831550 was really helpful in understanding it. I didn't realise that there was more to it. So the difference is that in a yeast starter you aren't looking for a full fermentation I guess?
 

djar007

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Just researching the topic. I know this is an old thread. I dug up an interesting picture of Samuel Smiths the old brewery of them recirculating the wort to keep the yeast from flocculating before it had competed fermentation. Was only a problem with certain yeasts, but it leads me to a few questions about agitation during the first 24hrs .
http://www.brewinfo.org/samsmiths/samsmth5.html

Questions. If I was to agitate or recirculate the wort over the first twenty four hours would this increase my o2 saturation?
At this early stage would it still oxidise the wort?
Because of an increase in diacetyl, would a d rest at the end of fermentation need to be a lot longer in order for the yeast to remove the taste and aroma of the extra diacetyl produced using this method.

I was looking at the idea of stepping up the starter to full volume of my wort in order to keep the yeast happy and working. And then leaving it alone when it is at its best.




edit: just around the eight month mark barls. So thought it appropriate.
 

Black n Tan

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Have a taste of your yeast starter and decide if that is how you would like you beer to taste. I suspect not. A yeast starter is all about maximising yeast growth. Wort fermentation is all about the taste of the beer. Oxygen after the first 24 hours is detrimental and a stirrer will only oxidise your beer.
 

yum beer

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I normally 'double-drop' my English beers, especially anything with a higher starting gravity.
12-24 hours after pitching I transfer via the tap from one fermenter to another, gives a big stir up and the ferment goes pretty hard after.
Have read of a few British breweries that still double drop. Sam Smith's is one and also Innes & Gunn. I think Wychwood may have mentioned dropping Hobgoblin.

I just dropped a Samuel's Smiths India Ale clone this afternoon. Pitch around 1/2 cup of rinsed Wyeast 1028 London Ale yesterday afternoon, today SG has not moved but a 2 inch high Krausen had formed with an amount of yeast sitting on top here and there.
Dropped into second fermenter whilst stirring both batches to get as much oxygen in as possible. Locked it up and back in the fridge.
 

lael

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I'm not actually completely convinced of the oxidation argument. I think starters are often run by some at high rpms which beats everything up, but in a fermenter I would think the aim would be only to get movement and res-suspend yeast - which doesn't introduce oxygen and the wort is sitting under a layer of CO2 at that point anyway. It doesn't seem that different to breweries that used to 'walk' the fermenter around the brewery to keep the yeast suspended and working...
 

barls

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ill put it this way, if there was any advantage to constantly stirring the ferment big breweries would do it.
last time i checked none of them do it. they may drop it to help with the clarity but thats it.
 

billygoat

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I've posted this link before. Its what they do at Black Sheep brewery in Yorkshire. Saw the same set up in other English breweries as well but this was the only time I got a chance to film it.
 
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gap

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I've posted this link before. Its what they do at Black Sheep brewery in Yorkshire. Saw the same set up in other English breweries as well but this was the only time I got a chance to film it.
Did you do the Brewery tour at Black Sheep?

I did and I can veryfy that they pump the wort from the bottom of the fermenter and spray the wort back into the top of the fermenter.
This is done for 15 minutes every few hours for the first 36 hours after pitching the yeast.
The fermenters are also open to the environment, but the fermentation room is a separate, closed room.
This works for their processes and yeast but may not necessarily work for mine or your processes , environment or yeast.
 
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Alex.Tas

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It would be good to help with stalled fermentation. I agree that there would be very little oxygenation and consequential oxidation of the brew is the velocity of the stir 'bead' or whatever its called is relatively low. the agitation on the surface of the wort would the half a bee's penis.
 

lael

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I'm thinking good for high gravity to resuspend the yeast partway through the ferment, and for the first 24hrs during yeast growth...

Looking at getting barbell stir bars to allow better movement in the trub. No idea if it will work :)
 

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