Mash Thickness and Efficiency

[VikeMan]

So just two batch sparges then? 50-25-25 for the water?

I'd say that's a good place to start, if you don't want to go to the trouble of calculating equal runoffs.

 

[SRJHops]

I'd say that's a good place to start, if you don't want to go to the trouble of calculating equal runoffs.

I'll have to do a bit more thinking on the runoff volumes. I have never written down the totals, though the info is right in front of me as the kettle fills.

For now I think I will shoot for 60% mash water and 40% sparge. I might add a touch more mash water to get my thickness to 1.50 or 1.75. I get that it may not matter much, but my gut tells me that for my process it may help.

 

[VikeMan]

I'll have to do a bit more thinking on the runoff volumes. I have never written down the totals, though the info is right in front of me as the kettle fills.

If you want to calculate it, @dmtaylor gave an example in post #56. Basically, take your total water and subtract the wort volume that will be left behind in the mash tun (because of absorption and (if applicable) dead space). The result is your pre-boil volume. Divide that pre-boil volume by 3. That gives you the equal amount to run off at each stage.

Your strike water will be equal to: Total Water Minus pre-boil volume, plus 1st equal runoff
Your first batch sparge will be equal to the 2nd equal runoff
Your second batch sparge will be equal to the 3rd equal runoff

I think near the top of this thread you mentioned running off until you reach your pre-boil volume. But you should calculate the total water needed and use that. If you are leaving water/wort in the mash tun beyond grain absorption and any unrecoverabe dead space, you won't get an efficient batch sparge.

For now I think I will shoot for 60% mash water and 40% sparge. I might add a touch more mash water to get my thickness to 1.50 or 1.75. I get that it may not matter much, but my gut tells me that for my process it may help.

If you are getting near 100% conversion efficiency, your most efficient batch sparge strategy for any given total water volume will be equal runoffs, regardless of what your gut tells you.

 

[odie]

double sparge? why not just a bigger, longer sparge?

Or are you, closing the mash tub drain after the first run off, re-filling with sparge water, stirring it up a bunch, then drain. And then repeat again?

I've been BIAB and using less and less mash water, but then just pulling the basket and rinsing/sparging the grain longer.

 

[odie]

Does soaking the "spent" drained grain for a bit get more sugars out than just rising/sparging it after the initial drain to kettle?

Or is that what "batch sparge" vs "flysparge" is? I kinda forget the details.

 

[SRJHops]

If you want to calculate it, @dmtaylor gave an example in post #56. Basically, take your total water and subtract the wort volume that will be left behind in the mash tun (because of absorption and (if applicable) dead space). The result is your pre-boil volume. Divide that pre-boil volume by 3. That gives you the equal amount to run off at each stage.

Your strike water will be equal to: Total Water Minus pre-boil volume, plus 1st equal runoff
Your first batch sparge will be equal to the 2nd equal runoff
Your second batch sparge will be equal to the 3rd equal runoff

I think near the top of this thread you mentioned running off until you reach your pre-boil volume. But you should calculate the total water needed and use that. If you are leaving water/wort in the mash tun beyond grain absorption and any unrecoverabe dead space, you won't get an efficient batch sparge.



If you are getting near 100% conversion efficiency, your most efficient batch sparge strategy for any given total water volume will be equal runoffs, regardless of what your gut tells you.

I think I really do need to dig into the water calcs more for sure. I did increase the water for this beer, but it was just a guess. I did leave some wort in the sparge tun, maybe a quart or two. So that was clearly a mistake.

I still question If I am getting close to 100% conversion efficiency in the mash, though.

Maybe even with the 2 hour mash I might not have gotten full conversion? Or why do people do reiterated for big beers?

Perhaps reiterated isn't really a very good process improvement? I did watch one video where it didn't work....

 

[DuncB]

Have to congratulate everyone this has been a very instructive thread.
I'm going to have to read it another ten times I think to come up with a big grain bill high gravity beer plan.
Thanks to all

 

[day_trippr]

Maybe even with the 2 hour mash I might not have gotten full conversion? Or why do people do reiterated for big beers?

With sufficient enzymes (check the net Lintner => 40), fluidity, endosperm availability and reasonable temperatures, a mash will likely have fully converted within the first 40 minutes or less. That said, "conversion" just means transformation from the base starches to compounds which may or may not be fully fermentable. Prolonging the mash duration can allow time for unfermentable dextrins to be degraded into fermentable sugars.

Iterative mashing is often used to produce the wort density desired when working with a "too small" mash tun...

Cheers!

 

[SRJHops]

With sufficient enzymes (check the net Lintner => 40), fluidity, endosperm availability and reasonable temperatures, a mash will likely have fully converted within the first 40 minutes or less. That said, "conversion" just means transformation from the base starches to compounds which may or may not be fully fermentable. Prolonging the mash duration can allow time for unfermentable dextrins to be degraded into fermentable sugars.

Iterative mashing is often used to produce the wort density desired when working with a "too small" mash tun...

Cheers!

So if I can fit all my grain in my tun, there is no real point of reiterated mashing, correct?

 

[day_trippr]

Well, that and fitting enough wort in your kettle.
As an example, if you wanted to brew 5 gallons of a 110 point stout and your gear will mash, lauter and boil enough grain to hit those numbers there'd be no reason for iteration...

Cheers!

 

[SRJHops]

Well, that and fitting enough wort in your kettle.
As an example, if you wanted to brew 5 gallons of a 110 point stout and your gear will mash, lauter and boil enough grain to hit those numbers there'd be no reason for iteration...

Cheers!

So a reiterated mash doesn't help with mash conversion efficiency. It's for folks who can't fit all their grain in their tun.

My grain did all fit, and I could add more wort to my kettle for the boil off. I have been in the habit of boiling 7 gallons, which has worked for every beer but the Quad. But I could fit at least another gallon in my 10 gallon kettle.

Going forward I am going to calculate my water volumes better. I will also do a double sparge for all my beers!

Great advice all - thank you!

 

[doug293cz]

So if I can fit all my grain in my tun, there is no real point of reiterated mashing, correct?

Correct. There is no efficiency benefit to doing a reiterated mash (there is actually a slight penalty.)

Brew on

 

[PCABrewing]

I think as the mash gets "thicker", the enzymes have to work harder to convert all starch to sugar, or it hits a "wall" and stops short.

I believe a thinner mash helps achieve full conversion, but then you will have a greater volume/lower SG wort to deal with (boil down).

Once you drain off the mash and start sparging...it's all the same "thickness" I would think

I think that sounds right.
EDIT: I don't believe the enzymes "work" harder, it just becomes a question can they be as effective in a more viscous liquid.
But I will add that if you have multiple grains in the mash and you are relying on a particular grain with a high diastatic value to help convert perhaps a larger volume of grain with a low diastatic value, there is a balance to be struck in-order to ensure the enzymes from the higher diastatic grain get distributed to where they are needed. So it seems like sufficient water and sufficient motion would help.
Just a theory

 

[bracconiere]

hey @doug293cz , is there a therorectical limit to grain water? i know you did the batch sparge itteration chart before? maybe be handy for this thread....

maybe something similar for fly sparging? if i've seen it already and forgotten sorry.....

 

[doug293cz]

As I digest it all, could I ask if this sentence you wrote is accurate? I've read it a few times and I'm still processing it: "The effect can be calculated with high accuracy for batch sparging, and estimated with reasonable accuracy for fly sparging (by using many small batch sparges to simulate a fly sparge.)"

Yes, I was very careful about how I worded that sentence. For batch sparging, the calculations are more accurate than the measurements that we can make as typical homebrewers. For fly sparging, the calculations appear, based on limited data, to be about as accurate as the measurements that we make. There are a few conditions that must be met for the calculations to be accurate:

1. The wort must be completely homogenized throughout the mash volume prior to each run-off. An aggressive stir before each run-off will assure this condition is met.
2. Conversion of starch to sugar must be complete (or stopped via a mash out) prior to the first run-off, otherwise you will get conversion continuing during the sparge process, and that will mess up the calcs.
3. Apparent grain absorption must be the same for each run-off. The calculations could be modified to remove this pre-condition, if absorption data were available for each run-off step.

My big take-away is that I need to do more than one sparge, at least for beers over 1.080 OG. I will try the 50-25-25, splitting the sparge water in half and doing two. But it looks you do 15 small ones? There must be diminishing returns, but you have determined that 15 is about right?

Yes, there are diminishing returns for each additional batch sparge step. When doing an actual batch sparge, more that two or three sparge steps doesn't seem worth the effort. As @VikeMan said, the 15 sparge steps is just a way to approximate a continuous (fly) sparge in order to make the calculations tractable. I settled on 15, because with the diminishing returns, the results don't change significantly if I use more than that, so it's "good enough", and better than anything else I know of. You would never actually use that many batch sparge steps.

Brew on

 

[doug293cz]

hey @doug293cz , is there a therorectical limit to grain water? i know you did the batch sparge itteration chart before? maybe be handy for this thread....

maybe something similar for fly sparging? if i've seen it already and forgotten sorry.....

There is no theoretical limit to the amount of water you can use for mashing and sparging. But there are practical limits based on vessel size, boil time, and energy cost.

Brew on

 

[doug293cz]

Just to add... if we do the volumes and concentrations math, we find that the highest lauter efficiency when batch sparging is obtained when all of the runnings volumes are equal to each other, and not where each of the sparge volumes equals the strike volume, because grain absorption matters. @doug293cz's rule of thumb will typically yield something pretty close to that, given reasonable (i.e. "real life" recipe/brewhouse) inputs.

This is correct. Thanks for the clarification; I was not this clear in my initial response. The grains soak up a lot of wort permanently, so for highest efficiency, with a batch sparge, the volume that matters for the first part out of the mash is the runnings, not the entire volume of the mash.

For more of a real-world example, for 5 to 6 gallons of final wort, if you were to use say 20 lbs of grain for a monstrous gravity beer AND wanted excellent efficiency close to 80%...

Well first of all, the 20 lb grain will soak up about 2 gallons of water permanently. So if you wanted, say, 9 gallons pre-boil (maybe you're planning to boil for 3 hours), and wanted to divide that 9 gallons 3 ways for optimal double-sparge after the mash, you would actually need about 11 gallons of pre-mash water total, using 5 gallons strike water in the mash (approx 1.0 qt/lb!), and 3 gallons for each sparge (times 2 for double sparge). This will maximize the efficiency you can get from a double sparge in a big beer. This is precisely the method I use for monster beers. I have gotten brewhouse efficiency in the 80s with big beers before. It IS possible, with a big sparge volume and very long boil to concentrate it down.

Looks like Doug's percentages of 50/25/25 are reasonable approximations, maybe a little swaggy, but would put you into a decent ballpark. You can get pretty darn good efficiency with that ratio.

Here's a chart by Kai Troester (aka Braukaiser) that shows how lauter efficiency varies with the ratio of initial run-off volume to sparge run-off volume for a single batch sparge. As stated many times already in this thread, the maximum occurs when the volume ratio is 50:50. However, the efficiency difference between 60:40 up to 40:60 is only about 0.5% (which is too small for us to measure given the typical accuracy of our measurements.) So, you don't have to geek out (unless you want to) about getting exactly 50:50 or 33.3:33.3:33.3 run-off ratios. My 60:40 and 50:25:25 rules of thumb are designed to keep you on the flat portion of the efficiency curve over a wide range of grain bill sizes.

Brew on

 

[sibelman]

There is no theoretical limit to the amount of water you can use for mashing and sparging. But there are practical limits based on vessel size, boil time, and energy cost.

Brew on

Maybe what @bracconiere was trying to ask was about a point after which it's silly to keep sparging just to get a tiny additional amount of sugar into the kettle. Not a theoretical limit exactly... but what is a silliness limit?

Brewing in a more intuitive way with less regard for "hitting numbers," I have sometimes continued sparging until the liquid going into the kettle has no apparent sweetness -- i.e., before it becomes astringent tasting.

 

[doug293cz]

Maybe what @bracconiere was trying to ask was about a point after which it's silly to keep sparging just to get a tiny additional amount of sugar into the kettle. Not a theoretical limit exactly... but what is a silliness limit?

Brewing in a more intuitive way with less regard for "hitting numbers," I have sometimes continued sparging until the liquid going into the kettle has no apparent sweetness -- i.e., before it becomes astringent tasting.

If you ignore vessel volume limits, then this is really an engineering question that must include costs. When the cost of the additional boil time (both time cost and energy cost) becomes more than the cost of additional grain to make up for the efficiency loss, you have gone too far.

Brew on

 

[PCABrewing]

There are a few conditions that must be met for the calculations to be accurate:

1. The wort must be completely homogenized throughout the mash volume prior to each run-off. An aggressive stir before each run-off will assure this condition is met.
2. Conversion of starch to sugar must be complete (or stopped via a mash out) prior to the first run-off, otherwise you will get conversion continuing during the sparge process, and that will mess up the calcs.
3. Apparent grain absorption must be the same for each run-off. The calculations could be modified to remove this pre-condition, if absorption data were available for each run-off step.

Aren't most Mash done with conversion in ~30 minutes, at least with today's highly modified grains?
Given that, and it seems true when I test for conversion midway through the mash, if you mash-out at say 60 minutes, you aren't really stopping the conversion are you? Because the modern grains are done long before then.
Don't the equations tend to be aiming for as close to full conversion as is possible with a given grain bill. And in that case they set the mash time based on that time requirement.
Or are they just shotgunning it and saying 60 minutes?

 

[doug293cz]

Aren't most Mash done with conversion in ~30 minutes, at least with today's highly modified grains?
Given that, and it seems true when I test for conversion midway through the mash, if you mash-out at say 60 minutes, you aren't really stopping the conversion are you? Because the modern grains are done long before then.
Don't the equations tend to be aiming for as close to full conversion as is possible with a given grain bill. And in that case they set the mash time based on that time requirement.
Or are they just shotgunning it and saying 60 minutes?

Time to complete conversion in the mash is highly dependent on the crush coarseness or fineness. Fine crushes can achieve complete conversion in 20-30 minutes, but coarse crushes (most supplier crushes are coarse) may take significantly longer than an hour to complete conversion.

Conversion is a two step process. Before the enzymes can act on the starch chains, the starch must be gelatinized (swollen by the absorption of water - this is what happens when you cook rice or oatmeal.) Once (at least the surface of) a starch grain is gelatinized, then the enzymes can come in contact with the starch molecules, in the presence of water to cleave chain bonds. Each bond that is cleaved requires one water molecule to complete the reaction. You have to cleave lots of bonds to convert starch to fermentable sugar.

The gelatinization step is the rate controlling step. Actual hydrolysis (the bond cleaving) happens quite quickly. Gelatinization starts at the surface of grain grits, and proceeds towards the center. The larger the grit, the longer it takes to completely gelatinize. And, you cannot have complete conversion without complete gelatinization.

There are many threads on HBT asking "why is my efficiency so low?" When enough data is available for diagnosis, it often turns out that conversion efficiency is much lower than 100%, and this is almost always because the mash was too short for the coarseness of the grain crush. I have seen one case where the mash pH was way out of whack (much less than 5.0) that had almost no conversion, but that is a rare case.

Conversion can be monitored quantitatively by measuring the SG of the wort during the mash. For accurate results the wort must be well homogenized (aggressive stirring or recirculation) before taking SG samples. Take a sample every 15 minutes (you can start after 30 or 45 minutes if you wish), and when the SG doesn't increase between samples, the mash is done. A refractometer is very handy for this kind of sampling. Turns out the maximum SG of the mash wort is only a function of the weighted average grain potential and the mash thickness (water to grain ratio.) Since most typical mashes have weighted potentials of about 37 points/lb (or 80% max extract) it's possible to create a table that shows max mash SG vs. mash thickness (in qt/lb.) When you hit max SG, your mash is done. Here is such a table:

Specific Gravity at 100% conversion for various mash thicknesses​
​	​	​
Mash Thickness (qt/lb)​	Max °Plato​	Max SG​
0.75​	33.0​	1.1436​
0.80​	31.6​	1.1367​
0.85​	30.3​	1.1304​
0.90​	29.1​	1.1247​
0.95​	28.0​	1.1195​
1.00​	26.9​	1.1147​
1.05​	26.0​	1.1103​
1.10​	25.1​	1.1062​
1.15​	24.3​	1.1023​
1.20​	23.5​	1.0988​
1.25​	22.8​	1.0955​
1.30​	22.1​	1.0924​
1.35​	21.5​	1.0895​
1.40​	20.8​	1.0868​
1.45​	20.3​	1.0842​
1.50​	19.7​	1.0818​
1.55​	19.2​	1.0795​
1.60​	18.7​	1.0774​
1.65​	18.3​	1.0753​
1.70​	17.8​	1.0734​
1.75​	17.4​	1.0715​
1.80​	17.0​	1.0698​
1.85​	16.6​	1.0681​
1.90​	16.3​	1.0665​
1.95​	15.9​	1.0650​
2.00​	15.6​	1.0636​
2.05​	15.2​	1.0622​
2.10​	14.9​	1.0609​
2.15​	14.6​	1.0596​
2.20​	14.4​	1.0584​
2.25​	14.1​	1.0572​
2.30​	13.8​	1.0561​
2.35​	13.6​	1.0550​
2.40​	13.3​	1.0539​
2.45​	13.1​	1.0529​
2.50​	12.9​	1.0520​
2.55​	12.6​	1.0511​
2.60​	12.4​	1.0502​
2.65​	12.2​	1.0493​
2.70​	12.0​	1.0484​
2.75​	11.8​	1.0476​
2.80​	11.6​	1.0469​
2.85​	11.5​	1.0461​
2.90​	11.3​	1.0454​
2.95​	11.1​	1.0447​
3.00​	10.9​	1.0440​
3.05​	10.8​	1.0433​
3.10​	10.6​	1.0427​
3.15​	10.5​	1.0420​
3.20​	10.3​	1.0414​
3.25​	10.2​	1.0408​
3.30​	10.1​	1.0402​
3.35​	9.9​	1.0397​
3.40​	9.8​	1.0391​
3.45​	9.7​	1.0386​
3.50​	9.5​	1.0381​
3.55​	9.4​	1.0376​
3.60​	9.3​	1.0371​
3.65​	9.2​	1.0366​
3.70​	9.1​	1.0362​
3.75​	9.0​	1.0357​
3.80​	8.8​	1.0353​
3.85​	8.7​	1.0348​
3.90​	8.6​	1.0344​
3.95​	8.5​	1.0340​
4.00​	8.4​	1.0336​

Brew on

 

[bracconiere]

Maybe what @bracconiere was trying to ask was about a point after which it's silly to keep sparging just to get a tiny additional amount of sugar into the kettle. Not a theoretical limit exactly... but what is a silliness limit?

Brewing in a more intuitive way with less regard for "hitting numbers," I have sometimes continued sparging until the liquid going into the kettle has no apparent sweetness -- i.e., before it becomes astringent tasting.

damn, you reminded me of what i was trying remember! sparge until the run off hits ~1.010....if you're doing a BIG beer you'll probably hit it after you thought you would, thus end up with more wort in the kettle.....

 

[doug293cz]

Perhaps it's time to plug my Mash and Lauter Simulator spreadsheet again. You can use this sheet to make predictions of your efficiency based on recipe and process, or even (using "Goal Seek") to tell you how much grain you need to hit a given OG! To use the spreadsheet, you need to download a copy as either an Excel or LibreOffice format sheet, and work with the local copy.

Here's what the input section looks like:

You can select either imperial or metric units using a drop down in the "Units" input box. Grain bill potential can be entered as either points per pound (often called ppg), or in percent extract. Percent extract takes precedence if both are entered. You can specify up to 3 sparge steps, and the sheet will determine the strike and sparge volumes for equal run-off volumes. It will reduce sparge volumes if needed to maintain your minimum mash water to grain ratio (maximum mash thickness.) You can override the sheet selected strike and sparge volumes by entering values in the blue boxes shown here:

To determine how much grain you need to hit a given OG based on your process profile data that you input, you need to use the "Goal Seek" functionality of your spreadsheet. The LibreOffice Goal Seek drop down menu looks like this (Excel is similar but the terminology is slightly different):

For "Formula cell:" enter "K59" (it can be a little more accurate than K55, but K55 works too.) In "Target value:" enter your target OG. For "Variable cell:" enter "B5" (Total Grain Weight). When you have made all three entries, click the "OK" button.

Brew on

 

[VikeMan]

Conversion can be monitored quantitatively by measuring the SG of the wort during the mash. For accurate results the wort must be well homogenized (aggressive stirring or recirculation) before taking SG samples. Take a sample every 15 minutes (you can start after 30 or 45 minutes if you wish), and when the SG doesn't increase between samples, the mash is done.

When the SG stabilizes, conversion is complete. But I'll add that fermentability, OTOH, may still be increasing. This is the reason I rarely do iodine tests or SG monitoring during the mash to determine when to stop. I use mash length as a knob to target fermentability.

 

[bracconiere]

that spreadsheet is private only?

 

[doug293cz]

When the SG stabilizes, conversion is complete. But I'll add that fermentability, OTOH, may still be increasing. This is the reason I rarely do iodine tests or SG monitoring during the mash to determine when to stop. I use mash length as a knob to target fermentability.

If you determine SG stability by samples 15 min apart, then conversion was complete by the second to last sample. You then gave it 15 more minutes for hydrolysis to continue increasing fermentability. I would say you are pretty much done after that extra 15 minutes.

On the other hand, if you are working from a max obtainable mash SG table, and stop the mash when you think you are "close enough" to 100% conversion, then you may still have some fermentability to gain by waiting longer.

Brew on

 

[doug293cz]

that spreadsheet is private only?

You should be able to download a copy ("File -> Download -> {format option}".) Giving random people the ability to edit the on-line version would lead to chaos.

Brew on

 

[VikeMan]

If you determine SG stability by samples 15 min apart, then conversion was complete by the second to last sample. You then gave it 15 more minutes for hydrolysis to continue increasing fermentability. I would say you are pretty much done after that extra 15 minutes.

I hear you. But I'll point out that Greg Doss' (Wyeast) fermentability study saw an increase in fermentability at each step from 45 to 60 to 75 minutes. And Kai Troester saw increases from 15 to 30 to 45 to 60 to 90 to 280 minutes. Of course these observations were under their specific experimental conditions, but they are consisent in broad strokes with my own experience. Also, it's unfortunate that neither (afair) determined when conversion was complete. But in my own batches, I've done mashes ranging from as short as 30 minutes (with full conversion) to as long as 90 under essentially the same conditions, and for the most part I do see the attenuability differences I'm expecting with various mash times (per BrewCipher's predictions).

I'm of the opinion that amylase enzymes are generally laboring away for longer than they are usually given credit (in BYO Articles, etc.). And I believe it's because of the tendency to denature in a half-life-like fashion. It's like walking the proverbial half the distance to a wall, then half again, ad infinitum. (The difference of course being that mashes have a limited substrate.)

 

[dmtaylor]

When you say that's the process you use, do you really use a mash thickness of 1.0 qt/lb? That's really getting low...

Could I ask your opinion about the reiterated mash? Maybe it's not really necessary if I do the 50-25-25 with the double batch sparge?

Yes, I have gone down as low as 0.9 qt/lb. It is thick but doable.

Reiterated mash seems like a good process. I have not tried it myself but maybe someday.

 

[InspectorJon]

I did some research and came to the conclusion that 1 qt/lb of grain was kind of the limit with diminishing returns if one goes thicker. There is a thread here that discusses this and a big stout I did pushing my system to its limits if you are interested.