Small Grain Bill = High Effcy. Why?

[Dhack61]

I've done about 10 AG batches now and I am starting to see a pattern I don't understand. The batches I make where the grain bill is under 10lbs my efficiency rockets up to 80-85% I use the same equipment same process for all batches I have done. 40qt Coleman cooler, Home built PVC manifold. I always double pass my grain through my pasta mill on every batch to get a fine crush. I mash at the given Temp for beer style with 1.5 qts/lb for 60 minutes and Mash out at 168-170 then batch sparge with a single volume of 170 degree water.

Most all of my other batches have been in the 73-75% range. I know I will probably just have to start adjusting for the added Effcy. so I stop screwing up my lower gravity beers but I would really like to know.

Is this Nornal? and Why does it happen?

 

[DMartin]

I have heard that high gravity brews produce lower efficiency, I believe this is natural.

 

[passedpawn]

It's all about sparging, which is essentially a dilution problem.

Using the same amount of sparge water in two batches, the batch with less sugars will get rinsed better; a greater percentage of the sugars will get rinsed out, and the efficiency will be better.

 

[brewmonk]

something about extraction, and parts per million.

 

[stux]

The higher your liquor to grain ratio, the higher the first runnings efficiency into kettle will be.

Efficiency of First Runnings will roughly be

(Liquor:Grain Ratio - Real Absorption Ratio) / Liquor:Grain Ratio

Then the sparging will dilute the remaining sugars in your mash further increasing effciciency

An example with BIAB and Metric numbers

(7.5L/KG - 1.3L/KG) / 7.5L/KG
=(7.5-1.3)/7.5
=6.2/7.5
= 82.66% first runnings efficiency

Note: actual efficiency will be a bit lower unless you get 100% conversion efficiency.

 

[smizak]

What these guys said. I sparge with a set rate per pounds of grain in my grain bill to maintain a consistent efficiency and then top up post boil to hit my volume.

 

[Yooper]

It's all about sparging, which is essentially a dilution problem.

Using the same amount of sparge water in two batches, the batch with less sugars will get rinsed better; a greater percentage of the sugars will get rinsed out, and the efficiency will be better.

Yep. As was mentioned, in a lower grainbill, you sparge more per pound if you're sparing up to your boil volume.

If you used the same amount of sparge water per pound of grain in the batch with more grain, you'd get the same efficiency. But you'd have to boil all day to get down to your boil volume!

 

[Dhack61]

It's all about sparging, which is essentially a dilution problem.

Using the same amount of sparge water in two batches, the batch with less sugars will get rinsed better; a greater percentage of the sugars will get rinsed out, and the efficiency will be better.

So what you are telling me, is that the extra gallon or two of water that does not go into mashing and is used to sparge the small grain bills is giving me a better rinse. ie better effcy numbers. So..with larger grain bills I should mash at a lower volume of water per lb and mash out at a lower water per lb rate and then sparge in several batches with the remaining water to get the best rinse. I'll give it a try on the next batch...Thanks

 

[smizak]

Don't get crazy about chasing efficiency. You ideally want consistency. Like I alluded to in my previous post, I keep my mash and spare water ratios constant for all batches, if I need to boil off more for a higher gravity batch, no problem. If I need to add some top off water on a smaller beer, no problem. Better to keep most things constant and tweak as few variables as possible.

 

[passedpawn]

So what you are telling me, is that the extra gallon or two of water that does not go into mashing and is used to sparge the small grain bills is giving me a better rinse. ie better effcy numbers. So..with larger grain bills I should mash at a lower volume of water per lb and mash out at a lower water per lb rate and then sparge in several batches with the remaining water to get the best rinse. I'll give it a try on the next batch...Thanks

Not exactly.

Analogy time: if you put a drop of shampoo in your hair, then rinse in the shower, you'll pretty much get 100% of it out in 5 seconds. Put a MOUND of shampoo in your hair, and you'll get about 10% out in 5 seconds.

It takes a lot more water to effectively rinse all the sugars out of a thicker batch. Most people don't use more water, though, and end up with lower efficiency. Now, if you wanted to use a lot more water, you could, but then you'd have to boil all that water down to get back to your batch size (I've done this a few times - not too painful if you brew outdoors with an electric system).

 

[Yooper]

Don't get crazy about chasing efficiency. You ideally want consistency. Like I alluded to in my previous post, I keep my mash and spare water ratios constant for all batches, if I need to boil off more for a higher gravity batch, no problem. If I need to add some top off water on a smaller beer, no problem. Better to keep most things constant and tweak as few variables as possible.

Right- I agree totally!

You don't want to skimp on mash volume- that's not the point. Let me phrase it another way. You can use up to 3 quarts of water per pound of grain total, without risking oversparging.

In an 8 gallon batch, that's easy. You mash with 1.5 quarts of water per pound of grain, then sparge, and you pretty much get everything the grain has in it.

But if you've got a 20 pound batch, you could put 60 quarts of liquid through that grain without risking tanin extraction. That would maximize your effiency for sure. But do you want to stand outside all day, boiling 13 gallons of runnings down to 5 gallons, just to maximize the efficiency? That's what it would take to simulate the same amount of liquid through the grainbed to make a 5 gallon batch.

Most of us just accept it. We get 80%+ for a small grain bill and 72% (or whatever) for a super large grain bill. The difference is $2 worth of grain vs the 6 hour boil.

 

[Dhack61]

Right- I agree totally!
Most of us just accept it. We get 80%+ for a small grain bill and 72% (or whatever) for a super large grain bill. The difference is $2 worth of grain vs the 6 hour boil.

OK..it all makes sense mow. Thanks for all the input. I'm Not about chasing efficiency more about consistency. So I'll just have to adjust my grain bills on my small batches to hit my OG's ..Thanks

 

[rjschroed]

Most of us just accept it. We get 80%+ for a small grain bill and 72% (or whatever) for a super large grain bill. The difference is $2 worth of grain vs the 6 hour boil.

$2 of grain, or $20 of propane. . . no brainer. I think everyone has pointed you in the right direction of the answer to your question here. As you continue to brew you'll learn your system and process better and have an idea of what to expect from a recipe and be able to adjust it before brew day so that everything works out well.

 

[Bsquared]

http://www.ahaconference.org/wp-con.../A_Closer_Look_at_Efficiency-Kai_Troester.pdf

Kai does a great job at explaining how mash efficiency is impacted by the size of the grain bill.

 

[BrewMU]

As gravity rises your water is more and more saturated - a higher % of the polar ends of the water molecules are occupied with an oppositely polarized sugar molecule end. As the water gets closer and closer to complete saturation it gets harder and harder to dissolve more sugar in it, until it finally can accept no more - in other words at some point virtually every neg. oxygen pole and pos. hydrogen pole is attached electrostatically to an opposite number.

 

[stux]

I really don't think it has to do with saturation. It has to do with absorption and dilution.