Trying to optimize conversion efficiency... is it my crush?

[Horseflesh]

I have a recirculating electric BIAB system, and I have always had my efficiency come in a few points lower than it seems like it should. I suspect my LHBS crush could be better optimized for my system, but I want to talk through my observations and get some feedback.

I know I can just add more grain, but because I have a lot of space under the false bottom my mash is in practice very thick regardless of the L/kg calculation. Making it even thicker will force me to reduce pump speed, which slows temperature changes. So, would like to increase my efficiency as much as is reasonably, easily possible before I start adding more grain. That will make brewing big beers easier, too.

I know I can increase time, but that changes fermentability characteristics, and also I want my brew day to be shorter where possible.

For the sake of argument (and also 'cuz I'm sure it's true) assume that glaring mash problems of dough balls and wack pH are not the issue. I also know that my refractometer reads within +/- 1 SG point for the kind of brew discussed in this example, having validated it with hydrometer readings in the past.

What did was monitor the mash conversion efficiency by referring to this chart at Braukaiser. On this brew day, I had an overall mash thickness of 6.98 L/kg. Theoretically, that might get me to a SG of 1.040.

This is what I observed during the 152F mash, which was stirred well every 10 minutes or so, and recirculated at a good clip.

+40 minutes: 1.034.
+50 minutes: 1.0345 -- (approx, obviously, but it was slightly over 1.034)
+60 minutes 1.0365 -- (again, seemed a hair over 1.036)

I called it at +60 minutes as it was close enough to the Beersmith prediction to proceed, but that's predicated on a lame 68% specified Brewhouse Efficiency. Actual values for this run were 64.9% BHE, 72.4% mash efficiency.

I know from past experience that if I let the mash go to 90 minutes, it will creep up a couple more points... so how do I accomplish that in an hour? Or less? People 'round here are doing 20 minute mashes with high efficiency and I can barely get up there in 90 minutes with recirculation and stirring it frequently.

My LHBS says their gap is 1.045, which is in the bounds recommended by the manufacturer of my rig... but I have no way of verifying what the gap actually is.

Is it the crush? Seems like it has to be but I am open to ideas.

 

[RPh_Guy]

Let's see if I get this right (I'm sure someone will correct me if I don't)...

Conversion efficiency = the percentage of starch converted to sugar during the mash. You can increase conversion efficiency by step mashing and mashing out. Conversion speed is based largely on crush (and stirring/recirc helps).

Lauter efficiency = the percentage of sugars that make it into the kettle. Some techniques extract more sugar than others: Fly sparge > batch sparge > no sparge. Also, less dead space helps.

Conversion efficiency and lauter efficiency together make the mash efficiency. To increase mash efficiency, you need to step mash, more effectively lauter, or crush tighter vs extend the time.

There's no magic wand, unfortunately.

 

[mongoose33]

It might be the crush, but I think your mash is rather XXXXX thin. My son was brewing a fairly thick mash, had recirc issues, low efficiency. He added more water and everything greatly improved.

(EDITED: I misread the liters per pound, now I'd say it's really thin. Oops. )

You can of course crush finer and that will help conversion, though you may end up stuck. A solution to this is to use some rice hulls well-mixed into the grist to help with lautering. They're actually really cheap, and I toss a couple handfuls into every grain bill now as a matter of course.

One other thing you can try is this: I do a recirc (though not BIAB, it's similar as it's a full infusion). Once the strike water is underlet and the entire mash tun full of water and grain, I give it all a good stir. Then I do another stir at about 20 minutes or so--shutting the pump off while I do this, and allowing the grist to settle for a minute or so before turning the pump back on.

It helps. If there is any channeling going on, I'm breaking it up and allowing for better conversion.

It takes about 10 minutes after stirring for the wort to clear; here's an example of what it looks like after it's had time to clear:

 

[RPh_Guy]

6.98 L/kg

=3.35qt/lb

I think your mash is rather thick

It's opposite day!

Edit: Or was that not a mistake?

 

[brewbama]

Try crushing finer

 

[mongoose33]

=3.35qt/lb

It's opposite day!

Edit: Or was that not a mistake?

No, you need to listen to what I mean, not what I say!

Just misread it. I've edited the original above.

 

[Horseflesh]

There's no magic wand, unfortunately.

No magic wand, but there are some knobs. And it seems like crush might be the next knob to turn... but I wanted to see if there was anything else I was overlooking before I bought a mill. Because that's what it will take.

A mill would be nice to have anyway so I can get bulk grain, but if I could reasonable expect to squeeze out a few more points in a 60 minute mash it would make the decision easier.

It helps. If there is any channeling going on, I'm breaking it up and allowing for better conversion.

I am as sure as I can be that there is no channeling. In this last run that I pulled the numbers from I stirred it every 10 minutes and the mash sure seemed like it was moving easily. To illustrate... my overall thickness was about 7 L/kg. If you discount the 4 gal under the false bottom, and look at the thickness of only the basket contents, it is 3.9 L/kg or 1.87 qt/lb. That will give you an idea of how soupy the actual grain is.

I do have some room to adjust thickness as I am only boiling at 55% power. I could go down a little power, or up a lot of power. But a thin mash is supposed to be more efficient, and that's what I have now.

 

[Bobby_M]

A picture of the actual crush, dry, would be informative. Have you checked your mash pH?

 

[Schlenkerla]

Try looking at step mashing. Link below. You basically add a strike and set quantities of boiling water for each step. Then decoct if necessary. Unless you have a RIMS/HERMS.

This certainly helps. As well as looking at your pH and adjust accordingly.

I condition my grain then crush. With about 2 oz of distilled water sprayed on and hand mixed on 10 lbs of grain. I do so because I want a slightly bigger crush and less flour like powder and more grain bits vs dust. This conditioning also let's the kernel hulls remain intact. Helps with lautering/vorloft. It's visually obvious after doing this. Large hulls, relatively small crush, very little dust before and after mashing. I no longer see accumulated grain dust on top of the mash after I drain the bed.

http://counterbrew.blogspot.com/2016/10/a-beer-geek-guide-to-step-mashing-even.html?m=1

A Step Mash for clarity and body.
100 F for 20 minutes
134 F for 20 minutes
145 F for 30 minutes
155 F for 20 minutes
168 F for 10 minutes

A Step Mash for maximum phenolic expression.
100 F for 20 minutes
113 F for 35 minutes
134 F for 10 minutes
150 F for 30 minutes
168 F for 10 minutes

A simple step mash for maximum extraction of sugar
100 F for 20 minutes
150 F for 45 minutes
168 F for 10 minutes

Step mash for dry beer - dry stout & dry lager like ales
145 F for 30 minutes
152 F for 50 minutes
158 F for 30 minutes
168 F for 10 minutes

 

[RPh_Guy]

+1 for grain conditioning.

 

[RM-MN]

I have a recirculating electric BIAB system, and I have always had my efficiency come in a few points lower than it seems like it should. I suspect my LHBS crush could be better optimized for my system, but I want to talk through my observations and get some feedback.

There are two things in this paragraph that work against high mash efficiency. First it using the LHBS crush. They have no incentive to make your mash efficiency good and they do have an two incentives to make it poorer. In order to keep most customers happy they crush a little coarse because that avoids a stuck mash/sparge. Nobody complains about having to deal with those. Then with the lower efficiency that the coarser crush causes they get to sell a little more grain.

The second item that will lead to a lower mash efficiency is the recirculating system. For those to work you must have a coarser crush. If the grain is milled too fine, the fine particles will clog up the screen which then causes the basket to overflow.

If you want the best mash efficiency, mill the grain to dust (not really but cornmeal consistency) and don't recirculate. The fine milling will let the starches be gelatinized nearly instantly and that will allow conversion to happen very quickly. You won't need to recirculate to maintain the temperature for the hour long mash because you won't need an hour long mash. You only need to maintain the temperature until conversion is complete. Once that happens you are only waiting for the flavor and color to be extracted which takes longer but is not dependent on the exact temperature.

 

[Schlenkerla]

There are two things in this paragraph that work against high mash efficiency. First it using the LHBS crush. They have no incentive to make your mash efficiency good and they do have an two incentives to make it poorer. In order to keep most customers happy they crush a little coarse because that avoids a stuck mash/sparge. Nobody complains about having to deal with those. Then with the lower efficiency that the coarser crush causes they get to sell a little more grain.

The second item that will lead to a lower mash efficiency is the recirculating system. For those to work you must have a coarser crush. If the grain is milled too fine, the fine particles will clog up the screen which then causes the basket to overflow.

If you want the best mash efficiency, mill the grain to dust (not really but cornmeal consistency) and don't recirculate. The fine milling will let the starches be gelatinized nearly instantly and that will allow conversion to happen very quickly. You won't need to recirculate to maintain the temperature for the hour long mash because you won't need an hour long mash. You only need to maintain the temperature until conversion is complete. Once that happens you are only waiting for the flavor and color to be extracted which takes longer but is not dependent on the exact temperature.

I like your post. I wouldn't say there's a conspiracy to sell more grain. To me it's just ignorance or indifference on the part of the LHBS. That said, one should have their own mill for control and freshness of the grain. I crush my grain minutes before I dough in. I'm really quick about it, maybe 2-3 minutes max.

I also subscribe to the LOB Methodology. Hence the grain conditioning comments made previously.

 

[Horseflesh]

A picture of the actual crush, dry, would be informative. Have you checked your mash pH?

I should have taken a pic but I don't have one.

My mash pH is fine. I use Bru'n Water and if it is a new recipe, I verify with a pH meter. I may not hit the pH I want to 9 decimal places but there is zero chance that the pH is out of the good range.

Try looking at step mashing. Link below.

I have an electric recirc system so it is pretty easy to change temperature. I have tried hochkurz mashes a few times and haven't seen them to help conversion efficiency more than a single temperature mash of the same duration. I'll check out that link and try some other things.

There are two things in this paragraph that work against high mash efficiency. First it using the LHBS crush.

The LHBS says their gap is .045 but even if that is true, I may just need a more fine crush anyway.

The second item that will lead to a lower mash efficiency is the recirculating system. For those to work you must have a coarser crush. If the grain is milled too fine, the fine particles will clog up the screen which then causes the basket to overflow.

This makes sense, sure. My guess from how my mash feels is that I could have a somewhat finer crush and still maintain the ability to recirculate. I do want to preserve the ability to recirculate because I want to play with easy step mashing more. This is probably the limiting factor in how fine I can crush.

It does seem to keep coming back to crush...

 

[RM-MN]

The LHBS says their gap is .045 but even if that is true, I may just need a more fine crush anyway.

.045 seems a bit coarse from what other brewers say their settings are. Many seem to set their mills at about .025.

I do want to preserve the ability to recirculate because I want to play with easy step mashing more. This is probably the limiting factor in how fine I can crush.

You're right, recirculating does limit how fine you can crush. However, I do think you can get away with finer than .045.

 

[CodeSection]

@Horseflesh FWIW, I crush at .035 and have not had any problems recirculating. Though, I brew 10 gallon batches and I regularly use .5 - 1.0 lbs of rice hulls depending upon the recipe.

 

[Horseflesh]

I usually use rice hulls too, seems to help a lot. I can't run the pump like it's a Jacuzzi but it's turning over OK.

... looks like I am shopping for a mill.