Author Topic: The wonder of stirplates. I wonder why my fermentations now SUCK!  (Read 1513 times)

Offline andyi

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Have been using a stirplate for the last 5 batches and I cannot get the yeast to flocuate out and attenuate dry. >:(

Brewing familiar 6gal recipes (1.040 - 1.070 OG)  with same brewing process, same ingredients (sugar/no sugar),  same water, same bottling methods.  Use the same yeasts - WY3522, WL550, WY3711.  FG is not the problem with the 3522 and 3711 I  get FG's 1.006 and 1.004 but the beer is "sweet".   

Use Mister Malty calculator for starter size, light DME, 1/8 tsp of nutrient, foil on the top, stirplate vortex about 1.5 in wide and 1in deep, good yeast movement.  On stirplate for 24hrs, then into frig over night, pulled out and decanted a few hours before pitching.

Bottom line: The yeast will not flocuate out,  It will sit for three weeks and I still need to cold crash.  The last batch of 3711 left a film on the better bottle and a film in the beer bottles. It will not fully attenuate out the sweetness  like it did before the stirplate

Any ideas are appreciated.

-Cheers

Offline skyler

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Re: The wonder of stirplates. I wonder why my fermentations now SUCK!
« Reply #1 on: May 08, 2011, 10:13:15 AM »
give it 48 hours in the plate and crash it in the fridge for at least 8 hours before you decant.

Offline euge

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Re: The wonder of stirplates. I wonder why my fermentations now SUCK!
« Reply #2 on: May 08, 2011, 10:29:23 AM »
Are you positing that using a stir-plate alters the flocculation characteristics of these strains of yeast?

550 and 3711 are medium and low whereas 3522 has a "high" flocculation rating.
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Offline andyi

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Re: The wonder of stirplates. I wonder why my fermentations now SUCK!
« Reply #3 on: May 08, 2011, 04:08:23 PM »

euge

Are you positing that using a stir-plate alters the flocculation characteristics of these strains of yeast?

550 and 3711 are medium and low whereas 3522 has a "high" flocculation rating.

euge

Yes, flocuation changes as in extended time in suspension  and less attenuation for all.  Before my stir plate i found 550 med, 3711 low, and  3522 high for floc.  FGs are low but beers not dry as they were. 

Also, I use 02 to areate the wort from 60-120sec depending on the gravity

skyler,

Thanks. I have gone up to 36 hours and it sits in the fridge for 8-12hrs before decant.  48 hrs might do the trick but these are not huge beers.


Offline skyler

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Re: The wonder of stirplates. I wonder why my fermentations now SUCK!
« Reply #4 on: May 08, 2011, 04:45:47 PM »
Usually my stir-pate starters take 48 or more hours to finish.

Offline tubercle

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Re: The wonder of stirplates. I wonder why my fermentations now SUCK!
« Reply #5 on: May 08, 2011, 06:51:55 PM »

euge

Are you positing that using a stir-plate alters the flocculation characteristics of these strains of yeast?

550 and 3711 are medium and low whereas 3522 has a "high" flocculation rating.
euge

Yes, flocuation changes as in extended time in suspension  and less attenuation for all.  Before my stir plate i found 550 med, 3711 low, and  3522 high for floc.  FGs are low but beers not dry as they were. 

 Tubercle ain't no yeast scientist by no means but this don't make sense. The stir plate only increases the population of yeast before pitching (and might help the giddy-up a little bit) but nothing should change the flocculation characteristics. Not buying it. Something else is going on.
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Offline thesourkraut

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Re: The wonder of stirplates. I wonder why my fermentations now SUCK!
« Reply #6 on: May 08, 2011, 07:09:40 PM »
I can see how floc characteristics can be affected by decanting, but your results seem counter to expectations.

For example, if you decanted and ended up dumping out the yeast still in suspension, then you would be selecting for the more flocculant cells, not the other way around.

For ales and a 1000ml starter, I just stir up and dump in the whole thing, so I get the full population of yeast.  For a larger starter I would crash cool it and decant, but if you're not careful you can dump out some yeast.

The yeast stuck to the bottom of the starter is the more flocculant stuff, so if any is left behind you are selecting for less flocculation.

Offline zorch

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Re: The wonder of stirplates. I wonder why my fermentations now SUCK!
« Reply #7 on: May 08, 2011, 08:50:14 PM »

 On stirplate for 24hrs, then into frig over night, pulled out and decanted a few hours before pitching.


This procedure doesn't seem quite right to me.
   
If I have a 24 hour-old starter, I pitch the whole thing.

At 24 hours, that starter is probably at or near its highest level of activity.   Shocking the yeast in this state by chilling the starter is not good for the health of the yeast, I would imagine.   

If you want to decant the starter beer and pitch the yeast slurrry, my understanding is that it is best to let the starter run for several days (4-7) to allow the yeast to build up nutrient reserves, and _then_ chill to force them to floc. 

I can't say why _exactly_ what you are doing is causing that result, but I would suggest you change your procedure and see if that helps.

Online majorvices

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Re: The wonder of stirplates. I wonder why my fermentations now SUCK!
« Reply #8 on: May 09, 2011, 04:34:06 AM »
 

Use Mister Malty calculator for starter size, light DME, 1/8 tsp of nutrient, foil on the top, stirplate vortex about 1.5 in wide and 1in deep, good yeast movement.  On stirplate for 24hrs, then into frig over night, pulled out and decanted a few hours before pitching.



What OG starter are you using?
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Offline maxieboy

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Re: The wonder of stirplates. I wonder why my fermentations now SUCK!
« Reply #9 on: May 09, 2011, 08:22:47 AM »
I can see how floc characteristics can be affected by decanting, but your results seem counter to expectations.

For example, if you decanted and ended up dumping out the yeast still in suspension, then you would be selecting for the more flocculant cells, not the other way around.

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Offline andyi

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Re: The wonder of stirplates. I wonder why my fermentations now SUCK!
« Reply #10 on: May 09, 2011, 05:24:30 PM »

zorch,
I used to  shake and pitch at high kruesen, 8-12hrs.
So 24hrs is too short for good build up on a stirplate?  What do you do? Pitch a whole 2L starter at onceafter 24 hrs or wait 4-7days to fully ferment out. 

Somewhere I got it into my head that 24-36 hours is good for a stir plate then decant anything over 1 liter because possibility of off-flavors - cold crash to decant.  If the time is too short that would explain the low attenuation. 

What do you guys suggest?

majorvices,

Starter is 1.038 OG

Offline morticaixavier

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Re: The wonder of stirplates. I wonder why my fermentations now SUCK!
« Reply #11 on: May 09, 2011, 06:08:50 PM »
I know you said same ingredients but you follow it with 'sugar/no sugar' do you mean each time you have brewed it there is x pounds of two row and n pounds of munich etc? or do you mean x pounds of Great Western two row etc. If you are using a new maltsters products or a new brand of extract that could also result in a big difference in flavour. The last two batches I brewed have a distinctly similar sweetness and full mouth feel that I suspect is the result of the Gambrinus pale malt I used. It is the only ingredient that is the same between the two batches but they both have this same distinct sweetness.
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Offline narvin

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Re: The wonder of stirplates. I wonder why my fermentations now SUCK!
« Reply #12 on: May 09, 2011, 06:16:15 PM »
The only thing I can think of is that you might be prematurely cold crashing the starter.  I have no problems after 48 hours, but 24 might be cutting it close.
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Re: The wonder of stirplates. I wonder why my fermentations now SUCK!
« Reply #13 on: May 10, 2011, 04:54:24 AM »

zorch,
I used to  shake and pitch at high kruesen, 8-12hrs.
So 24hrs is too short for good build up on a stirplate?  What do you do? Pitch a whole 2L starter at onceafter 24 hrs or wait 4-7days to fully ferment out. 

Somewhere I got it into my head that 24-36 hours is good for a stir plate then decant anything over 1 liter because possibility of off-flavors - cold crash to decant.  If the time is too short that would explain the low attenuation. 

What do you guys suggest?

majorvices,

Starter is 1.038 OG


You should be running you stir plate until the fermentation is completely finished and then cold crashing and decanting the spent starter beer on top. If you are pitching at high krausen you are not taking full advantage of cell growth. Also, it may only take 24 hours or it may take 48. I usually give myself 2 or 3 days to be sure and to provide time to cold crash.
Keith Y.
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Offline SpanishCastleAle

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Re: The wonder of stirplates. I wonder why my fermentations now SUCK!
« Reply #14 on: May 10, 2011, 05:02:12 AM »
One minor suggestion (it probably made zero difference but fyi); you don't need that big of a vortex in the starter.  Just a tiny dimple in the middle is all you need.  The stirplate is more about releasing CO2 (to reduce CO2 stress) and keeping everything in suspension, it's not really about adding O2.  Very little O2 is making it into that flask with foil on top and positive CO2 pressure from the ferment.