yeast efficiency?

[FireantBrewing]

I use BeerSmith and since I started crushing my own grain I am hitting the estimated OG at 80% efficiency. Where I am pretty far off is with the FG. My last batch the estimated FG was 1.010, but it measured at 1.002... is this something beersmith is not calculating correctly or am I just getting very healthy yeast? I usually don't mind the extra alcohol but I'm tryin to stay within the style guidelines... any ideas? I am using pure oxygen to aerate, I create yeast starters, and ferment at roughly from 72 to 75 degrees. I have been using California Ale yeast for my last few brews.

Thanks for any input!
Michael

 

[Qhrumphf]

All grain or extract? What was the recipe for the last batch? Or any batch for that matter? Mash temp? How are you reading it?

For gravity that low, either your thermometer for mash temp is way off, or you've got a contamination problem somewhere.

 

[Sammy86]

I use BeerSmith and since I started crushing my own grain I am hitting the estimated OG at 80% efficiency. Where I am pretty far off is with the FG. My last batch the estimated FG was 1.010, but it measured at 1.002... is this something beersmith is not calculating correctly or am I just getting very healthy yeast? I usually don't mind the extra alcohol but I'm tryin to stay within the style guidelines... any ideas? I am using pure oxygen to aerate, I create yeast starters, and ferment at roughly from 72 to 75 degrees. I have been using California Ale yeast for my last few brews.

Thanks for any input!
Michael

72-75 is a little high IMHO...I'm in the camp of fermenting on the cooler side 62-64 degrees for two weeks...raise temp some for three days to help yeast finish up, cold crash and then keg. Haven't missed an FG yet!

 

[Bosh]

Not use about other yeasts, but the programs seem to reaaaaaaaally overestimate the FG of Belle Saison.

 

[Shawn_Brewin]

Gotta agree with the High fermentation Temp. 65-67*F is what i believe to be the norm. Is it all-grain? i know alot of people asked already but what was your mash Temp? did you hit it right on? if you mashed lower (thats what it sounds like to me) then what you put into beersmith that could be the reason.

 

[Kharnynb]

FG is mostly dependent on the mash temp, since that determines the amount of fermentable sugars.
Then it depends on the yeast and it's best fermentation temperature.

Lastly, it can depend on any critters that infected the batch.

What is your process and are there weird side flavours?

 

[castillo556]

I was using an old analog thermometer and was getting super low FG like you were. I bought a digital thermometer an discovered my old analog thermometer was 8 degrees off. I checked both in boiling water to verify. So when I thought I was mashing at 152F I was actually mashing at 144F! Had a huge impact on the beer, I am glad I corrected it.

 

[FireantBrewing]

It was an all grain recipe, mash temp was 152ish. I would love to ferment at a lower temp but all I have are Cooler Brewing bags that I swap frozen water bottles out of, tough to maintain the temps mentioned. The beer was very good,everyone that tried it loved it, so it wasn't infected.

For the mash I put the water in my 10 gallon cooler at the temp beersmith says, and add some 5.2 to adjust the PH, and then add the grain. I don't always check the temp of the actual mash, I wouldn't know how to adjust it at that point anyways.

I still don't understand how the mash could affect the FG, as I am spot on with the estimated OG?

Thanks for all the feedback!

 

[castillo556]

It was an all grain recipe, mash temp was 152ish. I would love to ferment at a lower temp but all I have are Cooler Brewing bags that I swap frozen water bottles out of, tough to maintain the temps mentioned. The beer was very good,everyone that tried it loved it, so it wasn't infected.

For the mash I put the water in my 10 gallon cooler at the temp beersmith says, and add some 5.2 to adjust the PH, and then add the grain. I don't always check the temp of the actual mash, I wouldn't know how to adjust it at that point anyways.

I still don't understand how the mash could affect the FG, as I am spot on with the estimated OG?

Thanks for all the feedback!

To give you a simple answer (because that's all I am capable of), mashing lower than 152 F will give you a more fermentable wort while mashing higher than 152 F will give you a less fermentable wort.

Cooler mash (146-152?) means lower FG and warmer mash (152-158?) means higher FG

It's all about the different sugars that are converted at those temps

You defensively need to be checking your temps through out the mash process. Cooling or heating is as simple and adding cold or hot water, though it's easier to dial in your equipment and hit your temp the first time.

Someone with more science speak will be along shortly, I hope.

 

[cannman]

Usually, the alcohol will force the yeast action to shut down WAAY before 1.002... I'd say you have a contamination issue where other critters are eating up the remaining sugars...

 

[Shawn_Brewin]

Check out John Palmers "how to brew" for the full on explanation...But in simple guy turns, your OG is how much sugar you extract from your grain through the mash. FG is how much sugar you have left that the yeast couldnt eat. Mash Temp doesnt really effect this the efficiency of your mash too much but it does change the type of molecular structure the sugar forms into. Basically there is long chain sugars (unfermentable for the most part but add body to your beer) and short Chain sugars (fermentable for the most part) See with lower temps you create short chains and with higher mash temps you create longer chains. so there for if you mashed low, i am guessing it had to be under 147* - 148*f you end up with a tons of short sugar chains and very little long chain sugars.

Just try playing with your mash temp on beersmith with this recipe up. you will notice as you change your mash temp that you FG changes with it.

Keep up the good fight!

 

[RM-MN]

I use BeerSmith and since I started crushing my own grain I am hitting the estimated OG at 80% efficiency. Where I am pretty far off is with the FG. My last batch the estimated FG was 1.010, but it measured at 1.002... is this something beersmith is not calculating correctly or am I just getting very healthy yeast? I usually don't mind the extra alcohol but I'm tryin to stay within the style guidelines... any ideas? I am using pure oxygen to aerate, I create yeast starters, and ferment at roughly from 72 to 75 degrees. I have been using California Ale yeast for my last few brews.

Thanks for any input!
Michael

When you pitched your starter, you probably had the necessary yeast to ferment the beer to the intended FG. Then you added pure oxygen which will cause the yeast to multiply. That would be about the same as a large overpitch which will drive the FG lower. Fermenting warm also encourages the yeast to party in the wort and that will lead to a lower FG too. Eliminate one of the 3 factors and your final gravity will be closer to the expected. I'd skip the oxygen as an easy step.

 

[Qhrumphf]

When you pitched your starter, you probably had the necessary yeast to ferment the beer to the intended FG. Then you added pure oxygen which will cause the yeast to multiply. That would be about the same as a large overpitch which will drive the FG lower. Fermenting warm also encourages the yeast to party in the wort and that will lead to a lower FG too. Eliminate one of the 3 factors and your final gravity will be closer to the expected. I'd skip the oxygen as an easy step.

Even in a forced ferment test (overpitched and constantly aerated) Cal Ale shouldn't push that low. This is not a yeast problem. This is either recipe (too much sugar), mash (to way too low a temp), or infection. BeerSmith wouldn't be so far off for the first, so it's probably one (or both) of the other two.

Or measurement error. Warm temp plus no correction plus erroneous top of the meniscus could end up reading 6 points low.

 

[Sammy86]

It was an all grain recipe, mash temp was 152ish. I would love to ferment at a lower temp but all I have are Cooler Brewing bags that I swap frozen water bottles out of, tough to maintain the temps mentioned. The beer was very good,everyone that tried it loved it, so it wasn't infected.

For the mash I put the water in my 10 gallon cooler at the temp beersmith says, and add some 5.2 to adjust the PH, and then add the grain. I don't always check the temp of the actual mash, I wouldn't know how to adjust it at that point anyways.

I still don't understand how the mash could affect the FG, as I am spot on with the estimated OG?

Thanks for all the feedback!

I use my cool brew bag all the time and never have trouble getting down to lower temperatures. What size frozen water bottles are you using?

If I want to get down to the lower 60's I use two frozen 2 liter bottles switched out every 12 hours. If I want mid 60's it's one frozen 2 liter bottle. Hope this helps you out!

 

[Sir-Hops-A-Lot]

I wonder if you have a bacteria that is cleaning up the residual sugars in your beer, leading to the low FG reading. Does the beer taste flavourless? This is usually called a gusher infection because the bacteria produces C02 aggressively.

Judging by all the techniques you use, you're probably advanced enough in brewing to get the measures correctly.

 

[FireantBrewing]

I use my cool brew bag all the time and never have trouble getting down to lower temperatures. What size frozen water bottles are you using?

If I want to get down to the lower 60's I use two frozen 2 liter bottles switched out every 12 hours. If I want mid 60's it's one frozen 2 liter bottle. Hope this helps you out!

I will try that, what is the ambient temp of the room where your bags are?

 

[kh54s10]

Questions I didn't see asked yet. Did you use a hydrometer or a refractometer for your FG measurement. If hydrometer, was the temperature of the sample such that you need to make a correction for the temperature. If a refractometer did you use a calculator to correct for the presence of alcohol.

As others have stated, temperatures: check the calibration of your thermometer. Also check the calibration of your hydrometer and (if you use one the refractometer).

 

[Sammy86]

I will try that, what is the ambient temp of the room where your bags are?

I keep the bags in my basement...in the summer its in the low to mid 70's in the winter low to mid 60's

 

[FireantBrewing]

This is the beer that went to 1.002, doesn't look infected to me and tasted fine when we went to secondary. Kegging it today, we'll see how it is a few days...

Thanks for all your input!!

 

[Denny]

I use BeerSmith and since I started crushing my own grain I am hitting the estimated OG at 80% efficiency. Where I am pretty far off is with the FG. My last batch the estimated FG was 1.010, but it measured at 1.002... is this something beersmith is not calculating correctly or am I just getting very healthy yeast? I usually don't mind the extra alcohol but I'm tryin to stay within the style guidelines... any ideas? I am using pure oxygen to aerate, I create yeast starters, and ferment at roughly from 72 to 75 degrees. I have been using California Ale yeast for my last few brews.

Thanks for any input!
Michael

Attenuation is pretty much dependent on wort, not yeast. You can get a wide range of attenuation with the same yeast by varying the wort. Second, any software that attempts to predict FG is doing nothing more than making a WAG. Make a less fermentable wort, and mash at higher temperatures.

 

[Gavin C]

+1

On the predictive power of Beersmith regarding FG. There is a short thread on this here with some data you (OP) may find useful.

In short Beersmith's or any software's predictive power in this regard is somewhat lacking.