[bspisak]

So I made an American Amber with an OG=1.074 and pitched a WLP002 starter. It ended up at an FG=1.016. That's an apparent attenuation of 77% which is good for this yeast (White Labs says 63-70% is typical.)  However, the beer was still too sweet on my palate. So, I pitched some WLP001 and that brought it down to 1.013, for a final attenuation of 81.5%  Tastes much better.

So, my question is, what do people see with WLP002?  Is that kind of attenuation more typical, or did I just get lucky?

I've also heard folks have good luck with rousting and even adding some extra yeast nutrient and/or simple sugar partway through fermentation.  Same question as earlier: Will WLP002 attenuate even further doing this?

Finally, I overshot my mash temp of of 154 and hit 158. I knocked a couple of degrees off that such that my mash profile was something like 158->156 for 10 minutes, then 156->155 for 50 minutes. So, my next question is, if I would have hit a lower mash temp, would WLP002 have attenuated even more?  Or should I always plan on pitching a finishing yeast

As an interesting side note, I had heard of people using beano, but the it keeps breaking down dextrins until it is done or denatured at 130F. So, as an experiment, I took two equal 1/2 gallon growlers and fermented one with straight WLP001 and the other with WLP001 plus a beano tab.  As already stated, the one with just WLP001 went to 1.013. The interesting thing is that the one with the beano finished at 1.001 and it may not yet be done!  It still had some bubbles. 

Brian

[redbeerman]

Your mash temp was pretty high for the style you were brewing.  If you had used EKGs, it looks like you would have had a pretty good bitter.  I have found that WLP002 does attenuate more in the mid 70s than the high 60s as advertised.  I think I would have gone with the 001 or S-05 in the first place for that style.  That being said, mash temps will have a pretty big influence on attenuation.

[bspisak]

I certainly agree, and perhaps I'm over analyzing this. It's just curious that if the limit to attenuation was the dextrins in the beer (as determined by the mash temp), why did the WLP001 drop it more?

Did the WLP002 finish lower simply because it flocc'ed sooner than the WLP001 did? Or, does it have more to do with the ability of a particular strain to munch on certain sugar mixes in the wort? 

I know if you have a conical, you can bubble C02 from the bottom to get the yeast back into suspension. Perhaps that would have allowed the WLP002 to attenuate more fully?

Brian

[bluesman]

Your mash temp was pretty high for the style you were brewing.  If you had used EKGs, it looks like you would have had a pretty good bitter.  I have found that WLP002 does attenuate more in the mid 70s than the high 60s as advertised.  I think I would have gone with the 001 or S-05 in the first place for that style.  That being said, mash temps will have a pretty big influence on attenuation.

+1

Keeping your mash temp down and allowing the beer to warm up after 75% of fermentation has been acheived should get you to where you would like to be.

[redbeerman]

Brian, WLP002 flocs out way faster than WLP001, so I doubt that your results were due to dextrins alone.  I also think that 001 will ferment more types of sugar more readily than 002, at least that has been my experience.

[Kaiser]

This should explain what you are seing: http://braukaiser.com/wiki/index.php?title=Understanding_Attenuation

001 and 002 can ferment the same sugars. It's just that 002's behavior in a normal fermentation keeps it from doing so. I have been able to show that 002 and a lager yeast can reach the same FG if both are roused regularily. However, leaving more residual fermentable sugars than other yeasts is part of the beer character that you get from the 002. If you don't like that you can always add another yeast later.

Kai

[bluesman]

This should explain what you are seing: http://braukaiser.com/wiki/index.php?title=Understanding_Attenuation

001 and 002 can ferment the same sugars. It's just that 002's behavior in a normal fermentation keeps it from doing so. I have been able to show that 002 and a lager yeast can reach the same FG if both are roused regularily. However, leaving more residual fermentable sugars than other yeasts is part of the beer character that you get from the 002. If you don't like that you can always add another yeast later.

Kai

Makes sense. It's exposure to sugars is limited as compared to 001 due to its high flocculation rate therefore limiting the attenuation.

[Kaiser]

I have a similar experience with WLP833 on the lager side. With about 2 Plato to go (i.e. beer was as 5 Plato and terminal gravity is 3 Plato) the beer dropped clear pretty much overnight. This makes it harder for the yeast to get the amount of residual fermentable sugars low enough for the right balance. For my current Maibock I’m planning to add some WLP830 to remove more of these residual fermentable sugars.

Different yeast have different flocculation behaviors. For most yeast the presence of maltose and glucose inhibits flocculation. Once they are consumed the yeast starts to flocculate even if there is still maltotriose, a sugar that they can ferment, present in the wort. I think some of the really heavy flocculators flocculate even in the presence of maltose.

Kai

[bspisak]

This should explain what you are seeing: http://braukaiser.com/wiki/index.php?title=Understanding_Attenuation

Excellent read, thanks!  I guess I should have done a fast ferment to see where I should be ending up! ;-)

I have been able to show that 002 and a lager yeast can reach the same FG if both are roused regularly.

So, the questions becomes, "when to start rousing, how vigorously to rouse, how long to rouse, and how regularly to do so?"

I would imagine you'd start rousing after the yeast start to floc. For WLP002, this happens in a few days. But, what happens if I wait to long? Is the viability decreasing because they are no longer actively metabolizing? Is that what Jamil's Pitching Rate Calculator is taking into account (viability based on date) and would this be an accurate model of what's really going on?

I would also imagine that you'd want to rouse as often as possible.  If I could bubble C02 up through the fermenter, I could keep the yeast in suspension for how ever long I wanted. Having to resort to rousing, then it seems like a vigorous rouse over enough time for the yeast to de-floc is required. (More than a swish, less than 5 minutes?)  Does this have any detrimental effects on the beer? Whenever I've roused before, the beer foams up (C02 coming out of solution?)  Is that bad? 

Brian