low attenuation

[Graham.C]

So I brewed up a stout 10 days ago and I only have 40% attenuation so far (1.060 to 1.036). I mashed at 68C (155F) and used a 3rd or 4th gen 1056 yeast. Maybe its just a slow ferment, but it seemed healthy enough the first two days after I pitched. I was going to rack onto some ground cocao nibs but I tossed them in on top because I didn't want to lose any yeasties that might still be fermenting if I racked off the cake. It tastes great, so I don't think I have any contamination issues. Maybe its just going to be a light stout.

Does anyone know what might have happened? Maybe I shouldn't have put the cocao in, but I want it ready for M.A.L.T in a few weeks.

[NASH]

What's the recipe, XL amounts of roasted and crystal malts perhaps?

[Graham.C]

Could be.
65.24% Marris Otter
10.09% Oats
6.00% Roaster Barley
7.20% Crystal 60
4.78% Chocolate Malt
3.99% Black Patent
1.35% CaraMunich 60
1.35% Crystal 120

[mr x]

And what's your fermentation temp?

[Graham.C]

And what's your fermentation temp?

~68F

[mr x]

That's pretty good. I would have expected a healthy pitch to take care of business over 10 days at that OG...not sure what to tell you. You are using a hydrometer for measuring?

[Graham.C]

Yeah, I am using a hydrometer. I was trying out a no-sparge, but I can't see that as the cause. Perhaps the starter wasn't as healthy as I thought.

It's really weird, but it tastes good so I guess it doesn't matter. I'm just trying to get a feel for my new(ish) system, otherwise I wouldn't worry. I just hope I didn't over do the chocolate at such a low ABV, but maybe the extra gravity will balance it out. I guess I will know in a few weeks. Thanks for trying to help me problem solve.

[mr x]

I am having a hard time picturing a beer at 40% attenuation tasting good. Something doesn't seem right...???

[Graham.C]

I am having a hard time picturing a beer at 40% attenuation tasting good. Something doesn't seem right...???

Maybe there was something stuck to my hydrometer, but I doubt it. I even triple checked. I will test it again when I put it in a keg. It was sweet, but not cloying. It just seems really weird to me. I could be screwing things up somewhere, but I can't think where.

[mr x]

Usually, something stuck to the hydro will read low instead of high. So unless you made a massive beer and thought it was 1.060.....like an RIS strength, but you would think that you would taste it....

[jeffsmith]

I wonder if the paper scale in your hydrometer moved or something? At 1.036 it should be still very, very sweet.

[Graham.C]

Usually, something stuck to the hydro will read low instead of high. So unless you made a massive beer and thought it was 1.060.....like an RIS strength, but you would think that you would taste it....

I was thinking something buoyant like a bubble, but I spin the hydrometer and give it a little shake. I even triple checked. I also don't think the OG was any higher, as it was I overshot my target gravity by 6 points because it was my first time doing no sparge. It was 72% efficient at 1.060, so even if it was a couple points higher I don't think with no sparge I would be over 75%. Although I did estimate the potential using the low end of each grain potential, I would be really surprised if this was anywhere near RIS strength.

[berley]

When you say, "3rd or 4th generation yeast"... was it slurry stored in the fridge? If so, how long was it stored before you pitched it? Or was it a yeast cake from one beer that immediately was pitched into your stout wort (or stout wort racked on the cake)?

[Graham.C]

When you say, "3rd or 4th generation yeast"... was it slurry stored in the fridge? If so, how long was it stored before you pitched it? Or was it a yeast cake from one beer that immediately was pitched into your stout wort (or stout wort racked on the cake)?

It was a third gen that I harvested a while back, maybe 2-3 months, and I cleaned it and put it into sterilized jars which I kept in the fridge. I called it a fourth generation because it is technically a whole extra generation if you use a starter. It had a healthy krausen but not blow off the top of the carboy healthy.

[Graham.C]

I wonder if the paper scale in your hydrometer moved or something? At 1.036 it should be still very, very sweet.

I just checked with well water and got 1.002. It was sweet, but not terribly. Tasted like a milk stout on the sweetness scale. My hydro is probably messed up or I screwed up a measurement somewhere. I shouldn't have put the chocolate in it and just kept it as is for experimental sake. I used the same amount of nibs as I did last time I made it, but last time I put them in the boil for 10min. I think it was too much to put strait into the secondary after reading some treads on that website that should not be named. Now it might taste sweeter from the cocao nibs. Oh well, it will be beer. If its too sweet I'll give it away at a lab party or something.

[berley]

When you say, "3rd or 4th generation yeast"... was it slurry stored in the fridge? If so, how long was it stored before you pitched it? Or was it a yeast cake from one beer that immediately was pitched into your stout wort (or stout wort racked on the cake)?

It was a third gen that I harvested a while back, maybe 2-3 months, and I cleaned it and put it into sterilized jars which I kept in the fridge. I called it a fourth generation because it is technically a whole extra generation if you use a starter. It had a healthy krausen but not blow off the top of the carboy healthy.

Did you make a small starter before brew day to "wake up" the slurry? How much slurry (roughly) did you pitch?

I'm not asking to bug you, I'm asking b/c I had something similar happen last year, and it frustrated the hell out of me!

[Graham.C]

It was probably 200ml or more of slurry. I put it into a starter of 4.5oz of DME in 1.5L of water aprox. 36 hour prior (probably should have been a bit more). Your not bugging me. I am really curious about why this has happened, so if it happened to you I would love to hear your experience.

[berley]

It's probably a good old-fashioned yeast health issue; starting fairly active sounds encouraging, but if it pooped out after a couple of days with no real drops in your fermentation temperature, it's likely just that the yeast wasn't super-healthy.

With about 200 mL of slurry that was at most 3 months old, your 1.5 L starter is pretty close to what you'd want (and if you have a stir plate, even better). I imagine you did exactly everything right; maybe the yeast just couldn't quite come back after 3-4 generations this time.

I had done a SNPA clone, also with 1056. I think it was 2nd or 3rd generation as well... pitched lots of slurry, but it just couldn't get the job done. I also had visible fermentation for the first couple of days, but my FG came out at 1.030 (from 1.055, for an extract-APA, pretty bad). I tried everything to get it to go down more - pitched more slurry, pitched rehydrated dry yeast, but it didn't budge.

[berley]

Something else I just thought of... maybe a 1.5 L starter made to about 1.035-1.040 OG was a little too much for 3-month old slurry? At 3 months it would have about 10% viability (according to the mrmalty.com calculator)... so, instead of ~750 billion cells in 200 mL, you'd have about 75 billion - possibly tired - yeast cells. Maybe a starter at 1.020 to wake them up, then your typical ~1.040 OG starter to grow them, would have worked better?

Just guessing here. I don't really have the experience to say for sure!

[mr x]

I wouldn't think that starter size was the issue, i've done some pretty drastic stuff in regards to not stepping up with no problems. But, who knows....

[amartin]

That seems like a high mash temperature for that amount of specialty malt. I'd still expect it to ferment further than that though. If it was me, I might pitch another yeast strain, just in case that was the problem.

[jeffsmith]

That seems like a high mash temperature for that amount of specialty malt. I'd still expect it to ferment further than that though. If it was me, I might pitch another yeast strain, just in case that was the problem.

Agreed, a packet of US-05 would get you down to where you expected.

[berley]

I wouldn't think that starter size was the issue, i've done some pretty drastic stuff in regards to not stepping up with no problems. But, who knows....

Yeah, same here, but I figure sometimes there's no other explanation. I really don't know for sure.

[CartoonCod]

If your going to pitch more yeast, I would recommend you put the yeast into a small starter first and pitch at high krausen. With the presence of alcohol and most of the more accessible sugars taken up by the previous fermentation, yeast at high krausen will preform better than yeast not already fermenting.

[mr x]

Yup. Dumping in a fresh pack of yeast on beer that's already fermented generally = fail. One exception is racking onto a fresh yeastcake. I also agree with the mash temp being too high. Maybe some alpha amalzye would be the best choice.....