Over achieving yeast

[jeffpn]

My batches are consistently hitting final gravity at less than the expected gravity. For example, my Holiday Ale, which started at the expected 1.079, should've stopped at 1.021. I just racked it, and it's at 1.011 and probably will lose another point or two. It tastes fine. Should I be concerned? Any ideas what may be happening? My mash for this one was 153°

 

[GernBlanston]

It tastes fine.

There is your answer.

 

[The Brew Mentor]

Are you mashing out?

 

[jeffpn]

Unless I'm accidentally doing that, I don't know. I'm a BIABer. I pull my bag out and set it on top of an upside down colander in a 6 gallon bucket. I pour 170°water over the grains after they've drained.

 

[EbonHawk]

What do your ferment temps look like? If you're over the yeast's optimal range, you might be getting extra fermentation activity from them.

Just curious.. You're taking your grains out and then rinsing them? For what purpose? If you were to add, say, 200 degree water to your mash tun to bring the temp up to around 170, the increased temp would stop the enzymatic activity in the grains, but rinsing them after removal doesn't do anything except give you cleaner grains (for disposal, maybe?). Just trying to get a better picture of what's maybe going on.

What about other mash temps? Do you record those as well? Such as mashing-in, steeping, times, etc...

 

[jeffpn]

I ferment in my basement, which is upper 60°s at best. My method is BIAB, so I only use one vessel, not 3. I don't have a mash tun, lauter tun, etc.

 

[Nosybear]

If you're mashing out, you know it. I don't think that's the issue, though. I generally get higher attenuation than the calculator uses and my beer tastes fine. But I religiously control fermentation temperature so the yeast aren't exposed to temperature swings, I oxygenate and generally use starters. Healthy yeast will eat more than sickly ones so that may be your "problem." I don't see it as one.

 

[jeffpn]

My lagers are very carefully temperature controlled, using a small chest freezer, of which I have two. My ales generally are not temperature controlled. In the winter, when the basement temp is low to mid 60s, I'll use ferm wrap. I use dry yeast for everything except when I make Kölsch. That ale is temperature controlled. I don't mind chalking this up as a non-problem. It did pique my curiosity, though.

 

[EbonHawk]

Yeah I would like to know as well; might be important one day.

 

[The Brew Mentor]

I'll stick with my original thought that it has to do with your mash.
Check accuracy of your thermometers, make sure you're mashing at your desired temp, check for conversion and mash out by adding hotter sparge water.
When I'm messing around with BIAB, I'll use my 10 gallon brew pot, mash the grains with 1.25 qts./lbs., then after conversion, I'll add hotter water to fill the pot to about 8 gallons total. Stir to evenly dilute the sugar and then pull the bag to drain.
This will raise the temperature in the mash and stop conversion, locking in the mash profile.
I also agree that healthier yeast attenuate more but it's not usually day and night difference.
Give it a try and let us know your results.
Brian

 

[jeffpn]

My BIAB method is based on a company called Brewer's Best. I bought one of their BIAB kits first time I tried BIAB. I mash with 7.25 gallons of water regardless of the grain bill. Then I rinse the grains with 170° water to bring the volume back to 7.25 gallons. At the end of the boil, I have 6.5 gallons in the boil pot, which is my goal in order to fill 29 twenty two ounce bottles. You've intrigued me to try lowering my mash water volume to 1.25 qt/lb. then I'll add 170° water to result in 7.25 gallons after the bag gets pulled. Of course, the grains will drain when I pull it. Might as well add that back in. Seems like it's anywhere from a half to a full gallon.

 

[The Brew Mentor]

Brewer's Best BIAB kits are made to produce 5 gallons of finished beer.
Maybe i'm misunderstanding you when you say you end the boil with 6.5 gallons and then yield 29-22 oz. bottles.
Do you lose 1.5 gallons to your fermentor?
Lowering your mash water volume helps keep your PH in check and using hotter sparge water (~180+) will get you to your mash out temperatures.
Brian

 

[jeffpn]

My method is based on their instructions. I've adjusted my recipe to yield 5 gallons worth of bottled product. Even with their extract kits, you really can't get 5 gallons.

 

[The Brew Mentor]

When I brew their kits in my brewing clinics, I'll strain my wort through a paint strainer bag to remove the hop and break debris. I'll then top up the fermentor to 5.25 gallons and after fermentation is complete, I end up with exactly 5 gallons going in the bottling bucket. 53-12 oz. bottles every time.
:mrgreen:
Brian

 

[Brew Cat]

My batches are consistently hitting final gravity at less than the expected gravity. For example, my Holiday Ale, which started at the expected 1.079, should've stopped at 1.021. I just racked it, and it's at 1.011 and probably will lose another point or two. It tastes fine. Should I be concerned? Any ideas what may be happening? My mash for this one was 153°

I don't know if you are reusing your yeast but i seem to get better attenuation from ritched slurry, others have said the same. If you Ike the results no problem.

What do your ferment temps look like? If you're over the yeast's optimal range, you might be getting extra fermentation activity from them.

Just curious.. You're taking your grains out and then rinsing them? For what purpose? If you were to add, say, 200 degree water to your mash tun to bring the temp up to around 170, the increased temp would stop the enzymatic activity in the grains, but rinsing them after removal doesn't do anything except give you cleaner grains (for disposal, maybe?). Just trying to get a better picture of what's maybe going on.

What about other mash temps? Do you record those as well? Such as mashing-in, steeping, times, etc...

Wouldn't you be also rinsing some sugar off the grain? I've done full volume biab and also the rinse method. I get better efficiency with the rinse pretty close to what I get with my tun.

 

[jeffpn]

I don't know if you are reusing your yeast but i seem to get better attenuation from ritched slurry, others have said the same. If you Ike the results no problem.

I'm not understanding your reply. My actual final gravity is consistently less than the target final gravity. I'm getting significantly more attenuation than I should be getting. I don't need better attenuation.