Attenuation Problems only with Dry Yeast

[tpaine13]

After hearing so many good things about dry yeast, I decided to try some for two of my batches. I used Nottingham for Edwort’s robust porter recipe and recently US-05 for an Ale of Three Crops Recipe and had very poor attenuation with both. The porter went from 1.064 to only 1.024 after 26 days in the primary at 68-72 degrees. I figured this was due to the maltodextrine and the fact that I used 3 pounds of extract so bottled anyway. Big mistake because this caused bottle bombs.

But that is the past. The problem at hand is that I brewed the following Ale of three crops recipe add added rehydrated US-05 yeast:

5.5 lbs 2-row
2 lbs flaked corn
14 oz minute rice
.5 lbs table sugar (added at 20 min)
.25 oz cascade (60 min)
.5 oz Willamette (60 min)

I mashed at 152 degrees for about 75 minutes (lost track of time) - my thermometer is calibrated and accurate to 2 degrees. My OG was 1.046.

I let it sit the primary for 25 days (I should note that I shook the primary about half way through because I had a fear about dry yeast) and figuring that was more than enough time, just put it into bottles last night. However after I was done bottling, I wanted to taste the sample I put aside and test the gravity. It was only at 1.018! And it had a pretty sweet aftertaste (due to the high FG). I checked the accuracy of my hydrometer, and it was spot on. I never have any problems with attenuation with my liquid yeast (both Wyeast packets and my own washed yeast), but can’t seem to get decent results with Dry yeast. Does anyone know what are some possible causes that my US-05 attenuation was only about 50%? I saved half of the yeast cake because I planned on reusing it in a few weeks, but now I’m thinking I’ll stay with liquid yeast.

Btw I tried doing a search, but kept getting posts about over-attenuation with dry yeast. And I seem to only have problems with dry.

 

[boswell]

My last two batches with 05 (mashed at 152 & 149 respectively) both had over 80% attenuation.

 

[aryoung1980]

I brewed a cream ale with rehydrated US-05 and was around 50% attenuation. I washed the yeast, made a starter, and pitched it in an APA where I got 80% attenuation.

I also heard how great dry yeast is but I don't believe the hype. I make a starter for all yeasts now even if people say not to.

 

[tpaine13]

Thanks guys! Yeah maybe it was just finished at 50%. I will reuse the yeast I harvested and hope for better results. I'll be using starters from now on and will stay clear from dry yeast. It's not much cheaper anymore anyway.

 

[NordeastBrewer77]

Thanks guys! Yeah maybe it was just finished at 50%. I will reuse the yeast I harvested and hope for better results. I'll be using starters from now on and will stay clear from dry yeast. It's not much cheaper anymore anyway.

how's your aeration? dry yeast it just as good as liquid if you give them the proper environment to work in.

 

[ksbrain]

I never had any issue with dry yeast attenuation. I'm always to FG in a week, usually less.

What about your fermentation temperature control? Temperature instability causes yeast to slow down. Since that first batch was bottle bombs, the yeast was still working.

 

[samc]

No issues at all with rehydrated dry yeast for me. I rarely do more than splash the wort into the fermenter.

Where are you buying the yeast from, is it of recent vintage and properly stored at LHBS and your house?

 

[rellot]

yeah, could be a viability or vitality or fermentation environment problem. I just used dry yeast on my last batch and it went under my expected FG

 

[tpaine13]

I always areate the same, drop the wort from a distance and do a couple heavy stirs, maybe I could have done more....

I don't think freshness was an issue. I can't remember exactly, but it wasnt more than a few months old and had been stored correctly to the best of my knowledge.

I keep everything in a closet and the temperture ranges from 68 to 72. The inconsistancy may be the problem. I have already decided to start using an ice water bath to regulate temperture better as that is an area I am lacking.

 

[NordeastBrewer77]

I always areate the same, drop the wort from a distance and do a couple heavy stirs, maybe I could have done more....

i would.

 

[tpaine13]

yeah i will make an effort to start areating the heck out of the wort. Maybe I'll give dry yeast a try again sometime and see if more areation helps.