Author Topic: overpitching and attenuation ?  (Read 1288 times)

Offline quattlebaum

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overpitching and attenuation ?
« on: October 09, 2014, 02:18:42 PM »
Do ya think it is possible for a yeast strain to continually under-attenuate if it is over pitched?  I cont to have problems with WLP007 and Wyeast 1968 58 to 60% attenuation.  Very frustrating every time i use them. Everything is calibrated and i follow Mrmalty pitching rate calculator.

I have been wondering if i am overpitching even though i know this is rare in homebrewing because most of the time they show active signs at 6 hrs. 

Offline jeffjm

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Re: overpitching and attenuation ?
« Reply #1 on: October 09, 2014, 02:25:35 PM »
Over-pitching is pretty rare. Could it be a problem with aeration? That will cause poor attenuation.
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Offline morticaixavier

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Re: overpitching and attenuation ?
« Reply #2 on: October 09, 2014, 02:43:59 PM »
also look to your temperature. those strains are prone to early floculation if the temp drops or stays too low as fermentation starts to wind down.

Try bumping the temp up to ~68 after the first three days, 72 after another couple days.
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Offline denny

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Re: overpitching and attenuation ?
« Reply #3 on: October 09, 2014, 03:01:46 PM »
Do ya think it is possible for a yeast strain to continually under-attenuate if it is over pitched?  I cont to have problems with WLP007 and Wyeast 1968 58 to 60% attenuation.  Very frustrating every time i use them. Everything is calibrated and i follow Mrmalty pitching rate calculator.

I have been wondering if i am overpitching even though i know this is rare in homebrewing because most of the time they show active signs at 6 hrs.

Nope, I can't imagine that's happening.  Attenuation is really dependent on your wort, not just the yeast.  Underpitching might make it happen.  Since it happens repeatedly with 2 different yeasts, I'd start looking at the wort composition.
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Offline Joe Sr.

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Re: overpitching and attenuation ?
« Reply #4 on: October 09, 2014, 03:29:50 PM »
I use 1968 all the time and have no issues with attenuation.

Last batch, it was showing signs of fermentation within four hours or so and attenuated very well.  I doubt I've ever over-pitched it but I've probably under-pitched it.  I find it to be very consistent regardless.

I do as Mort suggests and raise the temp after a few days which I believe helps with attenuation and prevents the yeast from floccing out as fermentation slows down.

Are you using other strains and not having this problem?
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Offline kylekohlmorgen

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Re: overpitching and attenuation ?
« Reply #5 on: October 09, 2014, 06:30:28 PM »
Wyeast 1968 is a highly flocculant strain, which is awesome for beer clarity, but not so awesome if it clears before completing fermentation.

I had similar issues with this strain, so I started slowly increasing the temperature after high krausen (1 deg F per day) - basically a diacetyl rest.

Slowly increasing temp. after activity peaks motivates the yeast to stay in suspension and complete fermentation.

Mort's on point - if temperature isn't controlled, temp will ramp up quickly then the yeast will stall and floc as it cools.
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Offline quattlebaum

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Re: overpitching and attenuation ?
« Reply #6 on: October 09, 2014, 07:26:26 PM »
Thanks guys. i did pitch at 63 and let naturally rise to 68. Krausen started to fall after about 30 hrs (3 gallon batch, 1.052 OG wort). i raised the temp to 72 to finish and finial is 1.015. Not bad but not as predicted. I was going to mash even higher say 152 but new that i would have challenges with attenuation.   I mashed at 148F. My thermometer is calibrated.  aerated  with pure o2 60 sec. My grist was 72% otter, 12.8% Brown malt, 8.7% dark crystal and 6.5% chocolate.  Its just interesting because these are the only strains i have challenges with. Ill have to play with it a bit.   Thanks for the feedback

Offline gmac

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Re: overpitching and attenuation ?
« Reply #7 on: October 10, 2014, 09:11:07 PM »
I did an accidental overpitch/underpitch a while ago when I tried to split a re-pitch of WLP007 and ended up with 90% going into one batch and 10% into the other (imagine a big chunk of yeast paste falling out of the container....)
The dramatically overpitched batch finished faster, tasted better and seemed better attenuated (I didn't take FG at kegging but did do a de-gassed FG later and it was slightly lower).  I have never had issues with WLP007.  I went to this one after repeated stuck ferments with 1968 in the WLP002 form. 

But, for all my English beers lately I've gone to WY1469 and haven't had any regrets.  In fact, I'm about to try it in an APA next.