Is 100% efficiency possible?

[vincentAlpha]

I've been getting into all grain brewing and one question arose that I didn't find already answered, is 100% mash efficiency possible?

Just to be clear, as I've seen a good number of threads where people have mistakenly thought they got >100% for various reasons and this is not the question I'm after, I'm curious if one could (with the right combination of techniques/equipment) convert and extract all the possible sugar from the grain used. I wouldn't think of this as an achievable goal, nor would I think it would result in a great beer, as I would expect to get ALL the sugar you'd wind up with a fair bit of nastiness as well and so this is a thought experiment really.

As mentioned in the sticky on efficiency I did notice about an 15-20% absolute increase in efficiency buying my own mill rather than using my LHBS's mill, and I bet if I went from my manifold to something with a bit more coverage on the bottom of my mashtun I could eek out a few more percent, but what would have to happen to get from the range most of us work in to upwards of 100%? This is mainly curiosity on my part (and on that note: if this ought to be in a different section feel free to have it re-located) and what would have to be done (in keeping within the realm of reality, no magic black-box solutions if you will, but something like hitting perfect numbers we can consider achievable) to get that high.

Discuss

tl;dr Is ~100% mash efficiency a possibility, disregarding whether the result would make drinkable beer, and what would need to be done to achieve it.

 

[b-boy]

Theoretically, yes.

In reality, I'd say no. I think anything north of 80% for a homebrewer is very, very good.

A grain mill will go a long way in getting you higher efficiency because you can play with your crush gaps. I highly recommend it. But - if your LHBS has their **** together you might not see any improvement.

 

[Braufessor]

I have been in the 91-92% range when I was still dialing in my monster mill...... virtual stuck sparge due to the large amt. of flour from the crush. I would guess it is close to possible. But, it would probably require turning your grain into powder for sure. Perhaps long mash, over sparge possibly.

I think it "could" be done, but may or may not result in something desirable. I got quite high without trying, so I am sure you could get close if you set out to do it.

 

[FatDragon]

Lab tests can achieve 100%+ efficiency, and it's possible a homebrewer could even manage it with the right grain, the right crush, a long, thin mash with well-maintained temps, and a lot of sparging. As you suggested, you might end up getting some nastiness from such a high efficiency.

One thing to remember is that mash efficiency calculations are based on the grain's potential gravity, which is a set number that doesn't necessarily reflect the actual potential gravity of the grain. Plenty of variables can lead to grain with more or less potential gravity, so if your grain's potential gravity in Beersmith is 1.036, but the actual grain has a higher potential of 1.038, Beersmith will calculate 100% efficiency when you're actually in the mid-90's. It's like apparent attenuation: a beer that ferments to 1.000 FG still has sugars in it. The apparent attenuation is 100%, even though that's not the real attenuation.

A real-world example of how potential gravity can change our perceptions of our mash efficiency:

Most of my beers are made with the most common homebrew base malt in China: feed-grade Australian 2-row imported and malted by a Chinese maltster. For my first several brews, I thought I was getting poor efficiency in the 50-65% range. Then I bought some Weyermann Pilsener malt for a Saison and got 87% efficiency. Same crush, same system, same process. It's not that my efficiency was poor with my regular malt, but rather that my Chinese malt's potential gravity is several points lower than the professionally-malted brewing-grade barley that most of you use. Now that I know that, my new Beersmith profile for my Chinese malt has my efficiency in the 80-85% range. What the actual potential of my grain is, and what my actual efficiency is, I don't know, but what I do know is that I'm getting more consistent results and hitting my numbers better than before, so that's all that really matters to me.

As for actually hitting 100% efficiency - as in getting every last bit of sugar out of your grain, I would say that's unlikely. Upper nineties could probably be reached, but 100% woud technically mean you're not leaving even a single molecule of sugar in the grain bed, which seems pretty much impossible.

 

[vincentAlpha]

I suppose I should clarify that since you mentioned it, when I mean 100% efficiency I mean as if the actual potential gravity is a known quantity and not estimated like is normally done.

 

[doug293cz]

It is theoretically not possible to achieve 100% efficiency. In order to do so you would have to remove every last sugar molecule from the grain. Dilution theory says that is not possible, but you can get infinitesimally close to 100% efficiency by using large enough quantities of water.

Let's look at an example of how dilution math works:

Assume that all of the starch in the grain has been converted to sugar (100% conversion efficiency), and that with each mash/sparge step you get perfect mixing (uniform concentration of sugar throughout all of the liquid) in the mash tun. To keep the math simple, I will use round numbers that may not be truly realistic, but the conclusions are the same if you use realistic numbers.

If we start with 10 lbs of grain mashed in 5 gallons of water, and have a grain absorption of 0.1 lb/gallon, then at initial run-off we will collect 4 gal of wort, and 1 gal will remain in the grain. So, 80% of the available sugar is in the run-off, and 20% remains in the grain.

Now we batch sparge with 4 gal of additional water, so again we have 5 gal of wort in the MLT. We then run-off 4 gals (remember the grain holds 1 gal). 80% of the 20% left in the grain after first run-off comes out with the second run-off, and 20% of the 20% remains in the grain. 20% of 20% is 4% of the original still remaining in the grain.

Sparge again with 4 more gal of water, and we remove 80% of the 4%, leaving 20% of the 4% in the grain. 20% of 4% is 0.8%.

We can keep doing additional sparges, but the remaining sugar in the grain will never become 0.

Brew on

 

[Talgrath]

No, it's not. First, technically even the maltster's efficiency is not really 100%, there's still sugars left in there. Secondly, in order to get that 100% efficiency the maltsters are working with extremely finely ground grain, almost flour and in very small amounts (usually measured in a few ounces). In the real world, such a fine ground mash would result in a stuck spout and wort that's almost impossible to separate from the grain. Even the commercial breweries get somewhere between 80% and 90% efficiency.

 

[beentheredrankthat]

100% efficiency is not possible, and even if it were you wouldn't want to drink the beer. Some very complex commercial systems can exceed 95%, but in order to get there without negatively impacting the beer you have to carbon filter the final runnings. High pH and high polyphenol levels of said runnings would make the beer astringent otherwise, as well as causing haze and other problems. In practice, few do go this far, it's just something brewhouse manufacturers like to compete with each other on in order to say they make the best system.

A good rule of thumb is to never extract below 1.5P from the lauter.

And to be clear, to achieve 100% efficiency you don't have to get 100% of the starch converted to sugar and 100% of that sugar separated from the grain. You just have to do as well as the lab scale Congress wort done in the laboratory on the particular malt you are using. Their results are a measure of the theoretical maximum attainable extract. Congress worts use grinds that are much, much finer than would be used in any kind of brewing (unless you are using a mash filter vs. a lauter tun) so it is very unlikely that you would achieve equal results or 100%. And again, the beer would be crappy.

 

[Cyclman]

From what I understand, you can get 100% efficiency, it is done in the laboratory to determine the extract for a grain lot- it's called doing a Congress Mash, here are some interesting links:

http://www.brewingwithbriess.com/blog/understanding-a-malt-analysis/
https://www.homebrewersassociation.org/attachments/0000/1291/JFzym03-Extracting.pdf
http://www.brewersfriend.com/2012/11/30/making-sense-of-efficiency-definitions/
www.realbeer.com/jjpalmer/NHC04_Extraction.ppt

If a lab test is done to determine extract potential, I would think it could be done by a homebrewer.

It wouldn't make wort, it wouldn't produce a beer you'd want to drink most likely, but, theoretically, if you ground the heck out of your grain and mashed it forever, you should come close enough to approximating the lab test (the challenge might be that the equipment we use doesn't have the accuracy of lab equipment).

 

[doug293cz]

From what I understand, you can get 100% efficiency, it is done in the laboratory to determine the extract for a grain lot- it's called doing a Congress Mash, here are some interesting links:

http://www.brewingwithbriess.com/blog/understanding-a-malt-analysis/
https://www.homebrewersassociation.org/attachments/0000/1291/JFzym03-Extracting.pdf
http://www.brewersfriend.com/2012/11/30/making-sense-of-efficiency-definitions/
www.realbeer.com/jjpalmer/NHC04_Extraction.ppt

If a lab test is done to determine extract potential, I would think it could be done by a homebrewer.

It wouldn't make wort, it wouldn't produce a beer you'd want to drink most likely, but, theoretically, if you ground the heck out of your grain and mashed it forever, you should come close enough to approximating the lab test (the challenge might be that the equipment we use doesn't have the accuracy of lab equipment).

Theoretically you cannot get 100%, but you can get close enough that the error no longer matters, and the Congress mash is designed to do this.

EDIT: On further thought, the answer depends on what is meant by 100% effeciency.

• If 100% means extracting all sugar from the grain, then 100% is not possible, but you can get so close it doesn't matter in practice.
• If 100% means getting the same amount of sugar from the grain as the grain datasheet says you can, then 100% is possible (cause it was done in order to generate the number on the data sheet.)

Brew on

 

[vincentAlpha]

Very interesting stuff and more than a few things to read up on. As in many things it seems much of what is discussed revolves around a question that could be phrased better (at least on my part) . Since I actually deal with quite a bit of uncertainty in work (from a maths/sciences point of view) whenever we refer to a quantity we are always saying within error usually implicitly. So yes, getting absolutely 100% is almost not even physically possible unless you start to include infinity terms, but getting within 100% in practice is what I'm interested in.

 

[Cyclman]

Very interesting stuff and more than a few things to read up on. As in many things it seems much of what is discussed revolves around a question that could be phrased better (at least on my part) . Since I actually deal with quite a bit of uncertainty in work (from a maths/sciences point of view) whenever we refer to a quantity we are always saying within error usually implicitly. So yes, getting absolutely 100% is almost not even physically possible unless you start to include infinity terms, but getting within 100% in practice is what I'm interested in.

In homebrewing practice, high efficiency is not as important a goal as consistent efficiency- consistency makes for better quality, more predictable product. It is something that can be tinkered with for an advanced brewer just to "hit the numbers" when everything else about your beer is medal winning quality, but there are many other things more directly quality related to focus on.

 

[shanecb]

I think the highest efficiency I get is 91-93%, which I only get when I do a decoction mash. For all practical homebrew purposes you're probably not going to get much higher than that.

 

[GilaMinumBeer]

If there is a will, and funding, science will find a way. So, I expect 100% efficiency is possible.

Just not practical.

 

[hawktrio]

On a recent tour of the Coopers Brewery the guide claimed that they achieve 100% efficiency. They grind to a flour and then squeeze the crap out of the mashed grain to get almost every last drop of liquid out.

 

[Natdavis777]

Chuck Norris gets 100% efficiency every time, and that's just when he uses un-milled grain...

 

[vincentAlpha]

@Cyclman I meant for this question it is what I'm interested in. I wouldn't say getting to 100% is a goal for me as a homebrewer. If I can get up a couple percent without making the brew day crazy or making nasty beer then I'm all for it but I'm not likely to go to extremes over it. I was getting 65-70% at the high end before buying my own mill and have since seen a modest boost to around 80% and that is more than enough for me. This is just curiosity on my part.