Attenuation Consistently High

[butter14]

I'm on my 4th all grain batch. I am consistently getting higher attenuation than what the recipes are predicting. I am batch sparging with a 5 gallon cooler. I've been hitting my OGs pretty close and my mashing temps have been at ~160F.

What factors could be contributing to such high attenuations?

 

[kcbeersnob]

There are a number of things that can cause higher than predicted OG. Can you provide a few more details:

• How are you calculating the predicted OG?
• What yeast strain(s) have you experience this with?
• When you say your mash temp is 160, is that the temp of your strike water before stirring it into the grain or is that the temp that is achieved for the sach. rest?
• What temp. are you fermenting at?

 

[ph0ngwh0ng]

Hi!

Have/had the same problem. Turns out the expected apparent attenuation is an estimate based on your yeast strain. Depending on the software you'll use, you'll have the choice to fiddle with those settings. What I've done is I started an excel spreadsheet where I record mash temp, mash time, yeast strain, OG and FG (not the only factors affecting attenuation, I know, but...) and have found that I get a better estimate when I enter the highest percentage of attenuation possible for a strain in my software.

https://www.homebrewtalk.com/f36/over-attenuation-440520/

 

[DrunkleJon]

My best guess would be yeast health. If you are oxygenating well, overpitching yeast, fermenting at higher temperatures, and depending on the yeast strain you can really turbocharge yeast.
Mashing - mash temperatures, is the 160 your mash temperature 10 minutes after stirring, etc? What is the mash temperature before you drain your MLT?
Do you add simple sugars (corn, table, honey, etc) to your beers? They can dry it out a fair bit. Do you add any extracts either? I have always noticed stratification when using extracts.
What are you using to measure your OG? if a hydrometer are you adjusting for temperature? That can account for many points of readings right there.

 

[kcbeersnob]

Hi!

Turns out the expected apparent attenuation is an estimate based on your yeast strain. Depending on the software you'll use, you'll have the choice to fiddle with those settings.

This is what I was getting at with my first question above. It's very possible that the estimates are just off. After using a strain a few times, I am able to determine what attenuation I should expect given my system and SOPs. Depending on other factors (such as mash temp), this is often in the upper part of the published range or even above in a few cases (e.g., Wyeast 1056). For those strains I manually adjust the "range" in Beersmith.

 

[butter14]

There are a number of things that can cause higher than predicted OG. Can you provide a few more details:

• How are you calculating the predicted OG?
• What yeast strain(s) have you experience this with?
• When you say your mash temp is 160, is that the temp of your strike water before stirring it into the grain or is that the temp that is achieved for the sach. rest?
• What temp. are you fermenting at?

• The actual OG is the final reading from the fermentor after wort aeration & cooling.
  
• The yeast strain for the most recent is Wyeast - French Saison 3711.
• Predicted FG was ~1.011 and my reading was 1.03.
• Fermentation temperature was 70F for 1 week and 80F for the next (this recipe called for very high temps).

Thanks for all of your replies. I think I've found the culprit with these high attenuations. My cellar temps can get as high as 74F this time of year. Also, for my last batch it seems that Saison yeast strains can really dry out the wort.

 

[pdxal]

Any "prediction" that 3711 will finish at 1.011 instead of low single digits is suspect. Predictions for FG are generally ballpark at best, anyway.
If you are mashing at 160 and attenuation is better than expected with other yeast strains I'd refer back to the validity of the prediction, then check the thermometer since most beers mashed that high will end up under-attenuating.