Can too high of efficiency be a problem?

I have heard that if your efficiency is too high you'll pull out tannins and that you never want to hit 100% efficiency. Is that true?

I have a series of questions and if they have all been answered before I apologize in advance.

First the set up: This is my third all grain brew. The first two had very low efficiencies 50's and 60's. I came to the conclusion that my crush was off so this time I cranked the grain mill way down. To add to that the recipe I was brewing called for a 90 min mash. I mashed a little higher than the target (154 degrees instead of 152). When I went to go batch sparge I got a phone call during my second sparge and I was tied up for about 20 minutes. So the second sparge sat at about 152 degrees for about 20 minutes.

I pulled 14 gallons. Split them into two kettles and boiled them down t 12 gallons.

The efficiency going in the boiler was 95%. The efficiency going into my fermentor was 99%.

My math may be a little off because I used flaked maize and minute rice and I am not 100% that I used the correct numbers for the minute rice.

Am I in trouble for getting off flavors? Should I worry? Which efficiency matters into boiler or into fermentor?

There was likely a compounding series of measurement errors there because your efficiency never goes UP from "into the boiler" to "into the fermenter". It has to be either equal or less.

I think conventional wisdom states that tannin extraction is due to high temperature and high pH. Although hotly debated, it appears that a fine crush does not lead to tannin extraction. It may lead to a stuck sparge however.

That being said, I'm guessing your numbers are way off here. Although maybe not....people have reported 95% efficiencies in the past.

Another hotly debated topic is intentionally lowering your efficiency (mostly by altering the sparge schedule) to obtain a richer, more concentrated wort.

The main reason I can think of where a too high efficiency could be a problem would be if your recipe was not adjusted for it. If you formulated a recipe at 70%, and ended up with 90% efficiency, it could through the recipe out of balance - BU:GU ratio (bittering unit to gravity unit).

If your recipe is formulated for 90%, and you hit 90%, than no problems

I'll be honest. I wouldn't be all that suprised if my second number is off because i lost the gravity reading when cleaning up. The gravity into the boiler should be accurate. My question on the numbers would be for the max potential gravity for the minute rice. I went off of flaked rice at 1.032. Any idea what the potential of minute rice is?

pjj2ba said:

The main reason I can think of where a too high efficiency could be a problem would be if your recipe was not adjusted for it. If you formulated a recipe at 70%, and ended up with 90% efficiency, it could through the recipe out of balance - BU:GU ratio (bittering unit to gravity unit).

If your recipe is formulated for 90%, and you hit 90%, than no problems

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Oh it definetly is going to whack out my recipe. I only set it up for 60% efficiency. I overshot the gravity by a ton. I was figuring I would maybe bump up the efficiency by 10% on 20%+

I just brewed a pale ale yesterday using the 2 cooler fly sparge method for the first time and hit 91% efficiency per-boil, while my recipe was set for 73%. Doing batch sparging, I was getting 55-60%, so did not know what to expect this time. Original gravity gave me a brewhouse efficiency of 84.5%.

Its impossible to a small homebrewer to get 100 %. Even the big brewery dosent achieved this. Maybe you miscalculated something or your final volume is way lower than espected?

Beerbuck said:

Its impossible to a small homebrewer to get 100 %. Even the big brewery dosent achieved this. Maybe you miscalculated something or your final volume is way lower than espected?

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I can't find a link but there is a company which does hammer milling under water that claims greater than 100%. Percent is based on doing a mini-mash under 'ideal' conditions. This usually involves a different crushing procedure.

I would check your pre-boil and post-boil volumes and compare to your calculated volumes, even a 1/4 gallon off can throw off your numbers.

I'm confused on efficiency here and i bet others are too. THis is what I brewed last night and i'm trying to figure out what might have happened.

6.5 lbs. 2-row
.375 lbs amber malt

After the mashout, i had 4 gallons of wort and a gravity of 1.055 which shows a 87% efficiency

After the 60 minute boil, i had 2.5 gallons an a gravity of 1.076 which shows an efficiency of 75%.

What efficiency is correct? Why would it change so much just from a boil?

D_Nyholm said:

I'm confused on efficiency here and i bet others are too. THis is what I brewed last night and i'm trying to figure out what might have happened.

6.5 lbs. 2-row
.375 lbs amber malt

After the mashout, i had 4 gallons of wort and a gravity of 1.055 which shows a 87% efficiency

After the 60 minute boil, i had 2.5 gallons an a gravity of 1.076 which shows an efficiency of 75%.

What efficiency is correct? Why would it change so much just from a boil?

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Something doesnt add up. Unless there were losses when you transfered between the two measurements. If all you did was boil 4 gallons of 1.055 wort down to 2.5 gallons then you should have 2.5 gallons of 1.088 wort (55 * 4)/2.5 = 88 Since sugar is not lost in the boil. So maybe one of the gravity readings are not corrected for temperature? Or there were some losses somewhere? Or when you measured pre-boil the wort wasn't mixed properly? Or the volume measurement of one of the readings is off?

zeekage said:

Something doesnt add up. Unless there were losses when you transfered between the two measurements. If all you did was boil 4 gallons of 1.055 wort down to 2.5 gallons then you should have 2.5 gallons of 1.088 wort (55 * 4)/2.5 = 88 Since sugar is not lost in the boil. So maybe one of the gravity readings are not corrected for temperature? Or there were some losses somewhere? Or when you measured pre-boil the wort wasn't mixed properly? Or the volume measurement of one of the readings is off?

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Yup, I'm still learning. I added 4 gallons to the pot, then BIAB, then too gravity after mashout. There definitely was not 4 gallons still in there...

At least I got the efficiency calc right, now I just have to learn how to plug in the right numbers!

D_Nyholm said:

Yup, I'm still learning. I added 4 gallons to the pot, then BIAB, then too gravity after mashout. There definitely was not 4 gallons still in there...

At least I got the efficiency calc right, now I just have to learn how to plug in the right numbers!

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Ah, you didn't account for grain absorption. I believe it's usually a pint/lb of grain. so for your grain bill thats .85 gallons lost there. Which would give you an estimated 3.15 gallons of 1.055 wort not 4. That will make the numbers a bit closer for sure. Take an actual volume measurement pre boil if you want to know pre boil efficiency. In your case, the actual efficiency would be your post boil one. So the 75%

What is the significance of pre-boil gravity? I have been more focused on post boil, as that is what is going into the fermenter.

sfrisby said:

What is the significance of pre-boil gravity? I have been more focused on post boil, as that is what is going into the fermenter.

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Pre-boil gives you a chance to adjust your hops if you are off or you can add DME or water to compensate.

That makes a lot of sense. I should start paying more attention to that.