High Efficiency but Low Attenuation

[J8D]

I have read numerous posts concerning attenuations and efficiency. So this is not the completely uneducated question. Yet, I am still confused. I completed my 5th all grain recently and have identified a trend that I would like to correct. I hope to have all of the required info/data to get a response, but such may not be the case.

I have used recipes found within this site and brewed by others successfully. I have followed them to the letter in regards to ingredients and times. I have been following the mash temperatures pretty darn close to the T. The result is that I continue to have OGs that indicate I have high brewhouse efficiency of 79% up to 90%. This is not based on doing hydrometer readings of the first runnings but based on imputing into an online calculator to determine such. An example of this is that my last recipe (see below) should have finished up at 5 gallons at an OG of 1.054. Due to using a new brew kettle, I ended up with around 5.9 gallons yet still had an OG of 1.056. In the case of the other recipes, my final volume has been spot on and my numbers on my OG have been from .010 to .025 over that indicated by the recipe.

The next issue I have is that my attenuation seems low. My last three beers have also tasted sweet. With that in mind, I don't think my beers are fermenting down to where they should be. The end result is I am brewing beers which taste to sweet, but not cider. Yet combined with the high OG, I would think that I have more than enough sugar to have high attenuation. I realized that OG isn't only based on fermentable sugars.

I have NOT used yeast starters in the past. I have aerated by pouring into the fermentor. My fermentation is quick to start (within 24 hours if not 12. I let the fermentation continue until there is no activity in the airlock.

I am using a single infusion mash with a batch sparge. My mash temperature is as directed by the recipes. I have one at 154, one at 156, and another at 151. My sparge is heated to/around 175.

So I guess my questions are, is my constant high OG a good thing but I need to add more water or less grain to get it down to the desired level?

Next, are my high OGs related to what appears as a low attenuation trend?

Finally, any recommendations?

Thanks in advance and Happy Veterans Day!!!


Semper Fidelis,

J8D

 

[Scimmia]

Question 1 - have you calibrated your thermometer?

Question 2 - what yeasts are we talking about.

Pouring into the fermenter doesn't get much oxygen into the wort. Since you're not making a starter, you're underpitching, then not giving them the fuel they need to reproduce effectively. This could definitely lead to low attenuation. A quick start doesn't mean everything is fine, it could just means the yeast don't have enough oxygen to keep reproducing.

 

[The Pol]

High OG is relative.

Higher than forecast OG shouldnt affect % attenuation, but it will affect the FG certainly.

In your case, .010 to .025? WOW.

So that means a 1.010 beer would finish at 1.020 to 1.035?

If you are CERTAIN that your thermometers are good and accurate, then you have a fermentation problem. If you are certain of this.

This means improper pitch rate, temp. or aeration.

If your eff. is higher than the recipe is based on, yes use less grain.

 

[Yooper]

I have NOT used yeast starters in the past. I have aerated by pouring into the fermentor. My fermentation is quick to start (within 24 hours if not 12. I let the fermentation continue until there is no activity in the airlock.

There's your low attenation right there. The yeast can only do so much. Without a starter, or without pitching the proper amount of yeast, and a lack of aeration, you won't have optimum performance from your yeast.

As far as the efficiency, I find that it's easiest for me to use brewing software. I know my house efficiency, so I just tweak each recipe to give me the proper amount of grain for each recipe. So, I can take a recipe designed for 90% efficiency, or for 65% efficiency, and easily hit my OG each time.

If you're consistantly hitting 80%, for example, that makes it easy to adjust your recipe. If it's up and down, that makes it harder- so it's more important to strive for consistency than a higher number.

 

[J8D]

Yooperbrew, The Pol, Scimmia,

Thank you for the quick and informative responses. I HAVE NOT calibrated my thermometer (will do so). I will start using a yeast starter EVERYTIME. I will get myself a bottle of oxygen and get some oxygen in there. Thanks again. You guys ROCK!!!!!

Semper Fi,

J8D

 

[david_42]

The first time I calibrated my thermometers, they were +4, +6 and -2 degrees off at 172F. This is one place were a small error can really change your results.

 

[J8D]

Thank you David. I will definately be calibrating shortly.


S/F,

J8D

 

[Synovia]

The first time I calibrated my thermometers, they were +4, +6 and -2 degrees off at 172F. This is one place were a small error can really change your results.

How do you calibrate a thermometer at 172?

Do 0 and 212 and extrapolate?

 

[The Pol]

My guess is that he had a calibrated thermometer that he was comparing them to.

I just went out and bought several calibratable +/-1F thermometers this week. My old thermometers have done well, but they are not calibratable and thier precision is not as tight as the new ones.

No point in running a $2k rig with $5 thermometers stuck in it.

 

[Scimmia]

172F is the boiling point of ethanol.

 

[The Pol]

who calibrates thermometers in boiling ethanol?

Man, that sounds unsafe!

 

[boogyman]

I just went out and bought several calibratable +/-1F thermometers this week. My old thermometers have done well, but they are not calibratable and thier precision is not as tight as the new ones.

Where did you get them from?

 

[whoneedsabeer]

I have NOT used yeast starters in the past. I have aerated by pouring into the fermentor. My fermentation is quick to start (within 24 hours if not 12. I let the fermentation continue until there is no activity in the airlock.

How long is your total fermentation time before you rack?

Jay

 

[Bobby_M]

The other issue is that the higher your OG is over the recipe's expectation, the higher your GU:BU ratio. That's gravity units to bittering units. So, a recipe that expects 1.050 OG and 50 IBU would be a little off on the sweet side with 1.060 and the same 50 IBU.

That's not to say I don't think the other folks aren't already on to the other two possibilities, but you either have to nail the OG or adjust the bittering plan.

 

[Wellshooter]

I'm new here and don't have a lot of experience. I have also imdibed a little tonite, but have you calibrated your hydrometer? When I checked my original one it was high by .006.

 

[ODIN]

How long is your total fermentation time before you rack?

Jay

My fermentation is quick to start (within 24 hours if not 12. I let the fermentation continue until there is no activity in the airlock.

I know I'm new to brewing and this forum but from your statement above I can't help thinking about the many posts I have read by Revvy about using your airlock as a gauge for fermentation. I notice you have not mentioned your FG yet and just wondering if you are gauging your completion of fermentation on airlock instead of on hydrometer readings. Please don't think I'm in anyway being rude, I am just using the information provided to me to try to help.