Bummer, first under attenuated beer.

[jaobrien6]

I checked the FG on my jubelale clone today, after 3 weeks in the primary, and it was still at 1.020, which gives me about 65% attentuation. This was wyeast 1098, which I haven't used before, but is supposed to go to 73-75% according to wyeast. I had a pretty good starter, and the fermentation was going like gangbusters early on. I fermented at about 65 to 67 degrees (varied just a little throughout fermentation). Today I moved it up to my third floor, where temps are more like mid to low 70's in hopes that might get the yeast going again and drop another 5 points. I was hoping for 1.014. We shall see, I guess.

 

[pericles]

Agitating the wort a little (gently, so as not to introduce oxygen) will help you get past 1.02. The 1.02 curse is a problem a lot of people have had, just do a search.

 

[jaobrien6]

Interesting, that does seem to be a somewhat common problem. Well, beer was agitated a little when I carried it up 2 flights of steps, and is a little warmer now. Let's hope that gets it finish off nicely.

 

[jaobrien6]

After 2 days in the low 70's, it hasn't budged. Still 1.020. Anything other than temp or gentle agitation that I can do? Or is it just done?

 

[cklages]

I would be interested to know if this is all grain or extract. Also if all grain, what temperature did you mash at?

I find extract tend to underattenuate a bit for me. High mash temps would do the same. Also, things like lactose and maltodextrin would lead to higher finishing gravities.

 

[jaobrien6]

All Grain, mashed at 153. Hit 154 at mash-in, I stirred for a little bit until it had dropped to 153. I usually lose about a degree or so an hour but I didn't bother to take the temp at the end. So it probably spent most of it's time around 152-153. I'm not an expert at this yet, but I wouldn't have thought that temp is nearly high enough to result in only 65% attenuation. However as I said, I've never used 1098 before. Maybe it doesn't behave like I expected?

 

[jaobrien6]

Looking back over the recipe, it does have quite a lot of crystal malt. Maybe that's to blame? This is the brewer's recipe for jubelale that's been posted here and other places from several years ago, so they manage to get good attenuation with this amount of crystal, but I don't know what deschutes house yeast is. I picked 1098 after reading various stuff online. Here's the recipe:

Ingredient Amount %
US 2-Row Malt 12lb 0oz 82.4 %
US Caramel 120L Malt 1lb 8oz 10.3 %
US Caramel 80L Malt 12.00 oz 5.2 %
US Carapils Malt 3.00 oz 1.3 %
US Roasted Barley 2.00 oz 0.9 %

I know that's a lot of crystal, but given that I was working from Deschutes' recipe, I thought it'd work out ok. Do you think that was the cause? If so, I wonder what yeast/mash temp they use to manage to get 75% attenuation out of this.

 

[jaobrien6]

Hmm, another thought. Came across this on Wyeast's website:

The unsaturated fatty acids found in wort trub can be utilized by yeast for membrane synthesis. If wort trub levels are low, yeast will need to synthesize more of these lipids and therefore will require more oxygen.

This is the first beer where through a combination of whirlpooling and a stainless filter, I managed to keep most of the trub out of the primary. That combined with the fact that all I do for aeration is stir vigorously sounds like maybe it could be a problem?

So anyone have any thoughts at this point on where I might have gone wrong here?

 

[cklages]

Wow, that is really interesting. So it turns out that me sucking at whirlpooling is good for my beer.

I gotta be honest, it sounds like a confluence of events that got you, not the least of which was the relatively large amount of crystal malt. I actually got suprisingly low attenuation on the beer I'm drinking now (well suprising for me at least, it went from 1.049 to 1.016). For me it was a combination of maltodextrin and using dark dme (which apparently attenuatues a little less). To be honest though, I'm learning to like it.

Thanks for this thread though, I'm definitely not going to worry about seperating trub out like I was previously.