I go back and forth on this a lot - recently, I pitched a helles with yeast that sat in a jar for 3 weeks since racking pils off the top and collecting. I pitched about 50% more than mrmalty.com recommended and although it took about 36-48 hours to show airlock activity, it fell from 1.050 to 1.012 in less than 2 weeks. I did not have a chance to do FFT on this one.
point is, sometimes it seems extended dormancy is a major factor, other times its irrelevant.
[quote=“blatz, post:21, topic:5063, username:blatz”]
I agree that this is a subject that may warrant more investigation. In the end it is not just about how fast and how well the beer attenuates but it is also important how the final product tastes. My recommendations are largely based on what I have observed. Records of measured values, like gravity and attenuation, are always better than recollection of taste.
Kai
OK, its Friday now and I racked both carboys to secondary carboys, 6.5 days after pitching (I pitched the yeast last Saturday morning). Gravity data is this:
Old yeast:1.014
New yeast: 1.013
Both were in the same fridge held at 50F. While it’s tempting to say the new yeast did better, I’d say 0.001 difference in gravity after 6.5 days is really, in practical terms, pretty much the same. The taste between the two was very similar. I’d say the old yeast was a tad sweater but I think that is just because I knew the gravity was higher. In a blind test, I don’t think I could tell the difference. There was nothing funky with the old yeast. Now I’ll drop the temp a couple degrees each day down to 36 or so and lager until the gravity levels out. This is a new recipe so I’m not sure where it will end up but I’m hoping for 1.008 or so. I’ll post the final results when I have then.
I think the conditions in the white labs or wyeast package are a bit more optimal but yes it is similar to stored slurry. That’s one reason I wouldn’t ask these companies to package large quantities of yeast. If I can’t get it within a couple of days (I sometimes can but I cannot count on that) I would want to use a smaller quantity and a starter anyway.
OK, here are the final numbers. To remind everybody, on February 18, I brewed an 11 gal batch of wheat beer. OG = 1.044. I had some old yeast slurry saved from a previous lager batch that was brewed on Thanksgiving (Wyeast 2035). I had periodically been “feeding” this yeast with shots of DME wort. On brewday, I took this old yeast and made a new starter from a 1/2 gal of my new wheat beer. I also did the same thing with a brand new smack pack of 2035. I let the starters do their thing over night while I let the remaining 10 gal of wort chill and settle in the fridge. The next morning, I racked the work of the trub into new carboys and pitched each starter into the wort at 50F.
Both took off pretty quickly. 7 days later on 2/25 the gravities were:
New yeast = 1.013
Old yeast = 1.014
Today (3/21/2011), after lagering at 33F since 2/25 the gravities are:
New yeast = 1.010-
Old yeast = 1.010
I put the minus sign after the 1.010 for the new yeast because it was a slightly lower reading than the 1.010 for the old yeast.
I can’t say that I can detect any real flavor difference between the two half batches. The “old yeast” may be a little sweater but it is barely perceptible, I may even be imagining it. Both taste really good. I am certain that any taste difference could only be noticed by tasting each beer side by side. Tasted months apart, with different batches, you could never tell, there are many more other factors that could cause “identical” homebrew batches to be different (that is part of the fun).
My conclusion is that the “old yeast” was just fine to use and conversley, the “new yeast” provided no real advantage in the end product. The only advantage I see for the “new yeast” would be a higher chance of success and and lower chance of something bad happening.