[dannyjed]

I have used WY 2206 for five generations now and this last beer strangely got lower attenuation. The first 4 generations were at a consistent 78% attenuation, but the latest (5th) is at 73%. The first four were Helles, Dunkel, and couple of Pilsners. The latest is an IPL of sorts. All Pilsner malt with .25 lb of Special B and about 55 IBU’s of CTZ and Nugget hops. I realize that the Special B is not quite as fermentable, but at only .25 lb I didn’t think it would have played much of a role. A little puzzling considering the yeast was so consistent on the first 4 generations. I know 5 percentage points is not a really big deal, but I was hoping for a lower FG. Then again, maybe I’ll like the beer just fine after it’s carbonated because I still can’t taste numbers. Anyone know what could be the reason for this or have had some similar experience?



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[a10t2]

I routinely pitch 2206 to 5+ generations and don't typically see a drop in attenuation. I generally end up buying new because it starts to get sluggish around gen 8-10.

Although my attenuations average about 84% ADF, so take that for what it's worth.

[Robert]

I'm on a 7th generation of WLP833.  It had appeared to drop off in attenuation for at least one batch and has now jumped right back up.  I suspect there are a few of things going on in my case, maybe yours too:  One, I have had different recipes -- most were all base malt, the low one had a little honey malt, and the last high attenuator had some corn.  Can't explain it all.  Two, no matter how consistent I try to be, mashing in my homebrew system is bound to allow for slight variations in time and temperature patterns within the mash.  Still can't explain it all.  Finally -- the big one -- I'm not running a lab.  There are bound to be vagaries in measurement, and actually, though the percentage variation I've recorded in attenuation looks significant, the actual variation in °P or gravity points is probably within the margin of accuracy and resolution of my tools and calculators.  So, putting all those factors together and considering the aggrgate effects, in the end my conclusion is that there may actually be nothing to see here. So I'm telling myself:  the fermentations are proceeding identically and normally in all other ways, the beer tastes damn good, and I just need to RDWHAHB.  One apparent outlier doesn't mean anything.

[dannyjed]

I realize that there are too many variables to pinpoint a reason. I have tasted the beer today and it is fine. It doesn’t seem under attenuated, in fact it finishes dry. Thanks for the responses.


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[brewinhard]

Keep in mind, if spunding your beers then you are most likely collecting and harvesting the yeast left behind in the original primary fermenter.

These are the yeast cells that have dropped out of suspension first unlike the cells remaining into the transfer into the spunded keg where they will continue to ferment out your remaining sugars to reach FG. Just a thought...

[Robert]

Keep in mind, if spunding your beers then you are most likely collecting and harvesting the yeast left behind in the original primary fermenter.

These are the yeast cells that have dropped out of suspension first unlike the cells remaining into the transfer into the spunded keg where they will continue to ferment out your remaining sugars to reach FG. Just a thought...

The possible problem I see with this explanation is that this is conventional commercial practice -- transferring the beer off the yeast to ferment out in storage and then harvesting from the fermenter.   Furthermore, the commercial preference in this harvesting from the fermenter is to select the middle layer, neither the most nor least flocculant cells.   Just another thought...