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Old 11-19-2011, 01:45 AM   #1
RyanWeary
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Default Stir Plate vs Intermittent Shaking Conundrum

Many months ago I brewed an 11 gallon batch of an Oktoberfest lager. I created two starters using the exact same yeast. The yeast were from the same lot as well. The only difference in the two starters was one was created on a stir plate and the other was shaken intermittently. The differences between these two beers are amazing. The beer that was fermented with the stir plate yeast came out extremely fusel-y. (If that's a word)

I can't figure out why. I have a fermentation chamber that is temperature controlled. A diacetyl rest wasn't needed and they were both lagered for roughly 3 months before kegging. Every aspect of this beer was treated the same in both fermentation vessels. The beer brewed with intermittent shaking turned out PERFECTLY. It was wonderfully malty, just slightly sweet, and an easy drinker. This one however is drinkable, but not NEARLY as good. I would have thought a larger yeast population would have benefited the beer, but it appears to have hindered it. The OG was 1.068. The FG of the stir plate beer was 1.012 and the FG of the "shaken yeast beer" was 1.016. Clearly more alcohol in the stir plate beer - but really so much more to make this much of a difference?

Anyone have any ideas?

Thanks!

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Old 11-19-2011, 02:49 AM   #2
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How did you pitch, whole starter or decant and pitch.

One thought if you pitched the whole starter there would be a fair amount of oxidized wort in the beer. The wort from the stirred starter would be more oxidized than the shaken starter could that effect the end product?

Clem

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Old 11-19-2011, 02:59 AM   #3
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Yes, I did decant before pitching the yeast. There was clearly more stir plate yeast than shaken yeast when I pitched. I know it's really hard to diagnose these yeast issues, but it's bugging me.

Thanks for the input. I'm going to keep doing research and see if I can find out anything else.

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Old 11-19-2011, 03:23 AM   #4
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I think I found the issue.... Straight from Palmer - How to Brew - By John Palmer - Common Off-Flavors

Too much yeast is bad when it will spend a lot of time in contact with the beer i.e. a lager. *sigh* Live and learn I guess.

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Old 11-19-2011, 03:36 AM   #5
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Originally Posted by RyanWeary View Post
I think I found the issue.... Straight from Palmer - How to Brew - By John Palmer - Common Off-Flavors

Too much yeast is bad when it will spend a lot of time in contact with the beer i.e. a lager. *sigh* Live and learn I guess.
Did you cold crash when building up the yeast? Cold-crashing can generate petite mutation at 2 to 10% level, which increases diacetyl.

M_C
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Old 11-19-2011, 03:50 AM   #6
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Yes, I cold crashed the night before brew day, decanted and pitched my yeast into 55 degree wort. The only difference I can see is the stir plate allowed the yeast to multiply more quickly. I wish I knew an accurate way to estimate cell count by volume, that would eliminate problems in the future.

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Old 11-19-2011, 04:01 AM   #7
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Did you cold crash when building up the yeast? Cold-crashing can generate petite mutation at 2 to 10% level, which increases diacetyl.

M_C
Where did you read this I have never heard about this? Very interested in finding out more. So if we cold crash in the yeast makes mixed up yeast how are we best to build up yeast from slants or other small stores. Do we take a longer route and let them flock regularly?

Thanks for the info

Clem
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Old 11-19-2011, 04:05 AM   #8
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Quote:
Originally Posted by RyanWeary
I think I found the issue.... Straight from Palmer - How to Brew - By John Palmer - Common Off-Flavors

Too much yeast is bad when it will spend a lot of time in contact with the beer i.e. a lager. *sigh* Live and learn I guess.
You did rack off of your yeast before you lagered right? I don't know why it makes a difference as opposed to a long primary ale fermentation, but I have heard to never lager on the yeast cake.
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Old 11-19-2011, 04:13 AM   #9
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Yes, both primaries sat for roughly 3 weeks, were racked at the same time and lagered for about 3 months. I've been brewing lagers for years, this is the first time I've ever had this result. I wonder if it was a bad yeast pack, or if it was the stir plate. I'll never really know I guess, but based on Palmer's notes I think it's safe to say I had too large of a yeast population. That's somewhat disappointing seeing as until about 30 minutes ago I had another starter going for a big ale I'm brewing Sunday lol.

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Old 11-19-2011, 04:22 AM   #10
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I know its asking a lot but will you please repeat the experiment? It just doesn't make sense another time and we'll be sure.

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