first wort gravity and mash efficiency

So I'm trying to come up with a way to determine mash and lauter efficiency separately. Not because I have problems, but to provide better means of troubleshooting brewhouse efficiency. I define mash efficiency as the ratio between the extract that was dissolved into the mash and the maximum extract that was available in the grain. Lauter efficiency is the ratio between the extract that made it into the kettle and the extract that was dissolved into the mash. The product of both is the brewhouse efficiency and that is the efficiency that most of us report, brag or complain about and use to size recipes.

The motivation for this stems from the fact that both efficiencies are affected by different parameters are need to be addressed differently. If there are shortcomings in your mash efficiency, you should not make up for them by sparging more as this may lead to oversparging problems. Similar, lauter efficiency problems cannot be compensated for with increasing the mash efficiency if that is already 100%.

To measure the mash efficiency I think that taking a gravity reading of the first wort should give you an idea where you are. If there is 100% mash efficiency, the extract content (=gravity) of the first wort in Plato should be:

FW extract in Plato = (grain weight in kg * 0.8 ) / (grain weight * 0.8 + strike water volume in l)

The 0.8 multiplier for the grain weight is the laboratory extract of that grain. For most base malts its 80% or close. The water volume is the volume of all the water (including water added by batch spargers to equalize run-offs) added before stirring and taking a gravity reading. Your mash efficiency is now the measured extract vs. the calculated extract. It should be close to 100%. This works well for those of you who have a refractometer as you can actually take gravity readings fairly easily.

When I brewed my Helles this weekend, I added 17.5l of water, had 4.0kg of grain and got a FW gravity of 16 Plato. The expected FW gravity was actually 15 Plato, but I contribute this to measurement errors and try to do better next time around as you mash efficiency is unlikely to exceed 100%.

So if your brewhouse efficiency is low, or you are just curious, you may want to give this a try. And if the FW gravity/extract is significantly less than what you expected the following parameter can have something to do with that:

- pH
- crush (though I'm starting to get convinced that this should not have as big of an impact as it is reported)
- mash-out (can access starches that single infusion cannot)
- time

Kai

That makes allot of sense Kaiser.

Cheers
BeerCanuck

Kaiser said:

- crush (though I'm starting to get convinced that this should not have as big of an impact as it is reported)

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I've been suspicious of this myself. I suspect that pH is more important than convention has shown... as far as converting sugars in the malt goes. I don't think a few points finer on the crush is going to exponentially increase your efficiency, as is implied by many homebrewers. Efficiency can be broken down into 2 categories... getting the sugar from the grain and getting the sugar into the kettle. Understanding what affects each of these is what's important in efficiency. Good work Kai.

menschmaschine said:

I don't think a few points finer on the crush is going to exponentially increase your efficiency, as is implied by many homebrewers.

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Yes it shouldn’t. Malt specs show the efficiency difference between coarse and fine crush, and this is always below 2% for modern malts. I suspect that the coarser crush makes an existing problem (pH for example) worse and that that causes the big efficiency difference between fine and coarse crush that many brewers see. I plan to run a few small scale mashing experiments with different mash pH levels and I’m particular curious about this as well.

I have also read papers where the malt was crushed at a gap as large as 31 mil and their reported efficiency was just fine (90% +).

Kai

Kaiser said:

I plan to run a few small scale mashing experiments with different mash pH levels and I’m particular curious about this as well

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VERY interested to see the results of that.

I'd also be interested in seeing how different manifold types play into this equation. Maybe not at all.

I obtained 64% efficiency this weekend.

1) I mashed for 90min.
2) I did 2 equal batch sparges
3) I used PH 5.2 in the mash
4) My crush looked pretty comparable to the "good crush" pics posted in the forum.
5) I have a single bazooka screen running down the center of my MLT.

Based on all of that, I should be able to get better efficiencies. I'd be happy with 75%.

Just to add...

Is it safe to say that a longer mash time could potentially compensate for a coarser crush? Mash chemistry aside, take a single-infusion mash, for example. The typical homebrew schedule is 60 minutes. When in reality, full conversion is probably achieved in maybe 20-45 min. So, one would think that, if a longer mash time can compensate for a coarser crush, that extra 15+ minutes of mash time should compensate unless your grain is barely crushed, making the case for crush and efficiency more minimal.

McKBrew said:

I'd also be interested in seeing how different manifold types play into this equation. Maybe not at all.

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When batch sparging, the manifold design doesn’t have any impact on the efficiency. For what it is worth, you could be lautering through a single hole. It has an impact on the flow rate though and when your mash gets stuck you may end up leaving more wort (i.e. extract) behind than intended. In batch sparging the “rinsing” of the sugars happens when you stir in the sparge water.

I obtained 64% efficiency this weekend.

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Is this number based on what was in the boil kettle or what ended up in the fermenter. If it is the latter, how much was left in the boil kettle?

What temp did you mash at and did you do a mash out? Next time you may want to keep track of the water volume added before the first run-off and measure the gravity of the first run-off. I’m curious if you are loosing efficiency in the mash.

Menschmachine,
Yes, I think a longer mash could compensate for the crush. If you have a refractometer, you can easily take a reading (after stirring the mash) every 15 min and you will see how the extract content slowly goes up. If you are not near the calculated maximum after 60 min, add another 15 and see if that changes anything.

Kai

I think the most accurate way to measure mash efficiency is to take the gravity sample directly out of the mash tun and use the strike volume in the efficiency calculation. First wort is going to be AFTER absobtion. Technically any wort locked in to the grainbed is still valid as a mash efficiency.

Bobby_M said:

I think the most accurate way to measure mash efficiency is to take the gravity sample directly out of the mash tun and use the strike volume in the efficiency calculation. First wort is going to be AFTER absobtion. Technically any wort locked in to the grainbed is still valid as a mash efficiency.

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If there is an error because of absorption, shouldn’t that affect both the first wort and the gravity in the mash? In other words, why should mash gravity be different from first wort gravity?

Or do you mean with absorption the amount of wort kept in the grains after it has been drained completely? For that reason I did say that you should take the amount of water that was added and not the volume you ran into the kettle.

Kai

In my situation I formulated the recipe in BTP at 60% efficiency. (I haven't had anything better than that since I started AG). My efficiency was calculated pre-boil and I actually used the individual calculations in How to Brew for each malt.

My thought on manifold design is that if all of the wort (carrying the sugars) has to converge on a central point, some of the said sugars that are farthest away might get trapped on their way to the center. (Stirring should take care of this). If I had a manifold that had a center point as well as two side branches, there should be a more direct route to the outlet.

Really, I probably have no clue what the hell I am talking about, but I'd really like to figure out what I can do to improve my efficiency.

Kaiser said:

If there is an error because of absorption, shouldn’t that affect both the first wort and the gravity in the mash? In other words, why should mash gravity be different from first wort gravity?

Or do you mean with absorption the amount of wort kept in the grains after it has been drained completely? For that reason I did say that you should take the amount of water that was added and not the volume you ran into the kettle.

Kai

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Yeah, I just missed that part. I just didn't want anyone to think that the first wort runnings gravity AND volume said anything about mash efficiency.

Bobby_M said:

Yeah, I just missed that part. I just didn't want anyone to think that the first wort runnings gravity AND volume said anything about mash efficiency.

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To take this a step further, given a fixed extract potential of the grains, the mash gravity/extract is directly liked to the mash thickness. At a mash thickness of 1.25 qt/lb, your theoretical mash gravity about 23 Plato or 1.093 SG.

Kai

McKBrew said:

In my situation I formulated the recipe in BTP at 60% efficiency. (I haven't had anything better than that since I started AG). My efficiency was calculated pre-boil and I actually used the individual calculations in How to Brew for each malt.

My thought on manifold design is that if all of the wort (carrying the sugars) has to converge on a central point, some of the said sugars that are farthest away might get trapped on their way to the center. (Stirring should take care of this). If I had a manifold that had a center point as well as two side branches, there should be a more direct route to the outlet.

Really, I probably have no clue what the hell I am talking about, but I'd really like to figure out what I can do to improve my efficiency.

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I bet that by brewing on a ship and it rocking back and forth that has something to do with your eff. being low. Just kidding bro. i was a marine so i had to mention something.
anyway 60's everytime seems really low. You would think that some of the time it would fluctuate. I think your idea of manifold is good. However there has to be something else going on since you are stirring. i dunno just seems funky.

Do you guys think it would be worth putting a thread together collecting data from the HBT AG community in regards to how each of us achieves our efficiency? I'd be happy to put the data together and analyze it in excel with statistics and graphics (charts). I think it would be interesting to see what trends we might find. There could be a list of questions like:

-Mash tun construction and shape (pot, cooler (round or rectangular))
-Manifold construction (false bottom, bazooka, braid, copper w/ slits, etc.)
-Water pH (treated or not)
-Grain crusher setting
-Sparge method (1-batch, 2-batch, hybrid, fly)
-Mash time when achieving this efficiency (single infusion only, to keep it simple)
-Mash-out?
-Temperature of sparge water
-Brewhouse efficiency
-etc.

Do you think that would be useful/worth doing?... anything to add to the list?

I think the PH would be the hardest data point for me to collect. I have the crappy test strips that always read the same no matter what and hitting 92% doesn't exactly urge me to spend any money on finding out what the PH is.

The sparge temp data point should be replaced or augmented with the measured equilibrium after infusing it since that's what makes the sugar soluable.

I'd also look at sparge volume infusions as a water/grist ratio.

How about preboil-postboil ratio. Some people get higher eff by collecting and boiling off more. Not my style but it can affect numbers.

For us fly-spargers.... if I use my refractometer and measure during my vorlauf, that will be the mash gravity, correct?

My buddy has really gotten into water chemistry and the effect ph has on efficiency, attenuation anh hop brightness. He sent in the sample of our local water to a lab and we got the report back. Our ph is pretty high at 8.5, we had been using 5.2 buffering salts but it wasn't bringing the ph low enough,(5.2-5.3). The thing with water is when you start messing with it, it can get out of hand. Along with ph, you want to watch the residual alkalinity, there are some spread sheets out there that automatically adjust calcium, chloride, biocarbonates and so forth. We have found that treating the water with lactic acid and then gypsum in the mash has got us right where we want to be.

Eastside

Bobby_M said:

I think the PH would be the hardest data point for me to collect. I have the crappy test strips that always read the same no matter what and hitting 92% doesn't exactly urge me to spend any money on finding out what the PH is.

The sparge temp data point should be replaced or augmented with the measured equilibrium after infusing it since that's what makes the sugar soluable.

I'd also look at sparge volume infusions as a water/grist ratio.

How about preboil-postboil ratio. Some people get higher eff by collecting and boiling off more. Not my style but it can affect numbers.

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"Damn it Bobby" (in a hank hill voice) Everytime i read a post from you on efficiency i feel really stupid. With all your 92% and big words. Im extremely jealous. I think you my friend needed to be the sight GURU on efficiency

this is why I love kaiser, always coming up with new stuff that is just great.

and in regards to pH, me and a friend are going to do the exact same brew with almost the same equipment and same water.
One of us will adjust for pH the other won't, and I guess we can see from there. That should be somewhere to start from.

z987k said:

this is why I love kaiser, always coming up with new stuff that is just great.

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Thanks, I appreciate the support.

Efficiency is one of those things, where you can make good beer and still have problems with it. The good thing about that is that you are not really in a rush to get it fixed it would just be nice to get it fixed eventually. So brew a batch and take a few additional notes to analyze later and maybe you are one step closer to get it fixed.

Kai

Interesting thread Kaiser. How close to 100% should we expect to be at conversion for the typical system? Is 100% an ideal, or should that be typical if our procedures are sound? I'm wondering if this would be a good way to gauge conversion, particularly at low sacch. rest temps that might require variable lengths of time for conversion.

Thanks.

like everything in nature, 100% efficiency is pretty much impossible.

z987k said:

like everything in nature, 100% efficiency is pretty much impossible.

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I was just curious about the lab extract figures. If they are calculated in real world conditions with some margin, then 100% efficiency should be attainable on the mash level. I suppose that's what this experiment is all about.

korndog said:

I was just curious about the lab extract figures. If they are calculated in real world conditions with some margin, then 100% efficiency should be attainable on the mash level. I suppose that's what this experiment is all about.

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Yes, 100% mash efficiency, as I define it, should be possible. The lab extract is done with a step infusion mash and a very fine grind. Your actual grind is not going to be as fine, but that should have only very little effect with modern malts. The efficiency losses come with the lautering step where you have to strike a compromise between getting the most of the converted of the mash and the amount of water needed/wort quality.

Kai

Kaiser said:

Yes, 100% mash efficiency, as I define it, should be possible. The lab extract is done with a step infusion mash and a very fine grind. Your actual grind is not going to be as fine, but that should have only very little effect with modern malts. The efficiency losses come with the lautering step where you have to strike a compromise between getting the most of the converted of the mash and the amount of water needed/wort quality.

Kai

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That's what I was looking for Kaiser. I suspected as much.

Kaiser said:

Yes, 100% mash efficiency, as I define it, should be possible. The lab extract is done with a step infusion mash and a very fine grind. Your actual grind is not going to be as fine, but that should have only very little effect with modern malts. The efficiency losses come with the lautering step where you have to strike a compromise between getting the most of the converted of the mash and the amount of water needed/wort quality.

Kai

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I have enjoyed reading many of your posts on this forum, it would seem you are a brewer with much experience. However, as I read the above post I am left wondering if you are really trying to make excellent tasting beer, or are you simply trying to create a "lab" experiment. Last time I checked, many great beers never even approached 100% mash efficiecy, and even if they did, isn"t fermenting it properly the key?! The more I hear people talk about mashing efficiencies and the less I hear about fermenting, it really tells me where the homebrewing really is!! With all due respect sir, I don't think
100 % efficiency is relevant in homebrewing!! You lost credibility with me on this one!

Peace

Eastside.............

Even great brewers should strive to do better, the best strive for perfection.

Great thread... last weekend I broke out my new refractometer and measured my mash efficiency... 100%! :rockin: That's with a good BC crush, and carefully adjusting the mash pH to 5.2 (for me that means 5.2 + Gypsum and/or Phosphoric Acid.. my water is farkin' hard!!).

Prost Kaiser.

Eastside Brewer said:

I have enjoyed reading many of your posts on this forum, it would seem you are a brewer with much experience. However, as I read the above post I am left wondering if you are really trying to make excellent tasting beer, or are you simply trying to create a "lab" experiment. Last time I checked, many great beers never even approached 100% mash efficiecy, and even if they did, isn"t fermenting it properly the key?! The more I hear people talk about mashing efficiencies and the less I hear about fermenting, it really tells me where the homebrewing really is!! With all due respect sir, I don't think
100 % efficiency is relevant in homebrewing!! You lost credibility with me on this one!

Peace

Eastside.............

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I think there is some confusion Eastside. He was talking about extraction efficiency at 100%, not brewhouse efficiency. Clearly, this should be attainable given that the published number is derived under normal conditions.

I certainly am not an efficiency nut since I do plenty of no-sparge brewing. I am primarily interested in this for on-the-fly calculations.

Fair enough, my words were not meant to be harsh, I am always interested in improving techniques and getting better overall efficiency. That being said, fermentation seems to be my weakness so I am currently dialing in my process so as to get a better finished product. Forums like this one can be very helpfull.

Peace

Eastside

Great thread. Have to do my conversion out of metric sober in the morning. I think mash efficiency is where my problem is. Our water is very hard. Doing 50/50 tap/distilled tomorrow, + 5.2

Yep quickerNu mine too. Once I started correcting the water, my eff. jumped up to 78-82% brewhouse.

Here's an improvement on Kai's method that takes into account differences in the grain bill such as highly kilned malts which have a low extract potential:

- Plug your recipe into your favorite tool at 100% brewhouse efficiency. Note the target OG.
- Multiply the OG by your post-boil volume. This gives you the total extract points available in your grain bill.
- Divide the total points available by the total pounds of grain.
- Divide the result by 45 to get the extract coefficient (% of grain mass convertable to sugar).

This extract coefficient replaces the 0.8 in Kai's formula with a more accurate extract potential of your grain bill.

A quick example, I'll use Bee Cave Brewery Haus Pale Ale. For 5.5 gal after boil I get 1.068 out of the Tasty Brew recipe calculator. That's 374 extract points, or 35.6 points per pound. DME is 45 points per pound so that's a coefficient of 0.791.

Google Calculator says 10.5# is 4.76 kilos and (10.5# * 1.25 quarts/#) is 12.4 liters, which gives the equation:

FW extract in Plato = (4.76 * .791) / ((4.76 * .791) + 12.4) = 23.3* Plato ~= 1.091

Does this seem reasonable?

z987k said:

like everything in nature, 100% efficiency is pretty much impossible.

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although after reading and watching Bobby_M's stuff, 125% efficiency from him wouldn't surprise me!

Eastside Brewer said:

Last time I checked, many great beers never even approached 100% mash efficiecy,

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As already answered, I used another definition of mash efficiency. But yes, I would rate fermentation as more important for the quality of the beer as the brewhouse efficiency.

The idea of this test is not to make brewing more complicated, but give brewers yet another tool to isolate problems. Whenever someone complains about efficiency problems there is a host of suggestions that are made. But isn’t it nicer if we can isolate the efficiency problem to the calculation part, mash part or the sparge part. While this requires some more measurent and diligence reduces the trial and error necessary. And for the brewer who is happy with the brewhouse efficiency it gives the nice confirmation that there is nothing he/she can improve in the efficiency of mashing and that any additional brewhouse eff improvement would have to come from the sparging process. But we all need that this is not always good for the quality of the beer.

Saccharomyces said:

This extract coefficient replaces the 0.8 in Kai's formula with a more accurate extract potential of your grain bill.

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Yes, that seems about right, though the process seems complicate. The idea is that you get a weighted average of the extract potential in your girst. 0.8 or 80% is a good starting point if you have only little amounts (<5%) of crystal/roasted grains in the grist.

Kai

Kaiser said:

Yes, that seems about right, though the process seems complicate. The idea is that you get a weighted average of the extract potential in your girst. 0.8 or 80% is a good starting point if you have only little amounts (<5%) of crystal/roasted grains in the grist.

Kai

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Sure, 0.8 seems close for most brews, so it's a good start unless you're trying to analyze a RIS or something.

I just brewed a RIS and tried the FW efficiency formula Kaiser provided. I hit it dead on at 100% so I guess there's nothing wrong with my mashing process. BTW, what is the definition of a FW sample? Is it any sample taken within the first couple of quarts of runoff or what? I assume that it is as the gravity should be fairly constant for at least that duration. I'm still not clear on how the formula works exactly, but it does. I seldom achieve really high brewhouse efficiency numbers, but that doesn't bother me in the least. I do OK at something usually between 70 & 85% depending on the target OG. It's always lower for higher gravity brews and I'm OK with that so long as I know what to expect and can adjust the grain bill accordingly. Not calling anyone a liar or anything, but I just don't believe it when I hear claims of brewhouse efficiencies much above 85%.

Catt22 said:

BTW, what is the definition of a FW sample? Is it any sample taken within the first couple of quarts of runoff or what?

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Anything after recirculating and before the sparge starts should be fine.

I'm still not clear on how the formula works exactly, but it does. I seldom achieve really high brewhouse efficiency numbers, but that doesn't bother me in the least. I

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It works by calculating the wort strength as % sugar (which is Plato) and then converting it to SG.

What was the efficiency into the kettle and how did you sparge?

Kai

Thanks for the reply Kaiser. I have a better grip on it now. My lauter efficiency was 75% which is about what I expected for this high gravity (1.100) recipe. I fly sparge on my direct fired RIMS setup. I do a mash out and sparge slowly and I use a false bottom. I don't remember what the gravity of the runoff was when I reached my pre-boil volume, but it was still fairly high. Again, that was expected for this high gravity recipe.