BIAB sparge - not for me

[doug293cz]

Here's the efficiency story for no sparge BIAB. The data is for 100% conversion and 6.75 gal pre-boil volume (corrected to 68°F). Strike volume is adjusted for grain absorption to get a constant pre-boil volume. Grains are assumed to have 80% by weight conversion potential on a dry basis, and 4% moisture ("as is" conversion potential of 76.8%)



Grain absorption is affected by how long you drain and/or how well you squeeze. If your conversion percentage and your grain absorption (gal/lb) are consistent, then your efficiency will be consistent and depend only on your grain bill.

Brew on

 

[doug293cz]

The conversion may happen in any case if moisture of the right temperature can make it's way into the particle, but a finer crush will better allow those sugars to be released from the particle, rather than remain inside of it.

Actually, the rate limiting step (at least for larger grain particles) is getting the water into the particles for gelatinization to occur, not getting the sugar to "release" from the particles. Gelatinization occurs in layers from the outside of the particle towards the center. After gelatinization has occurred, the starch is soluble and goes into solution. Most of the actual conversion takes place in the liquid and gelatinized layers on the outer edges of the particles.

Brew on

 

[doug293cz]

... If there is no good reason to go with 1.25:1 ratio, then why is it taught?

...

Primarily because significantly thicker mashes are harder to stir and get good mash in, and significantly thinner mashes don't leave enough needed volume to get a good sparge. People used to think that thicker mashes converted better due to higher enzyme concentrations, but this has been debunked experimentally (and theoretically.) So, for fly spargers, ~1.25 qt/lb gave a good compromise between ease of mashing, and allowing for a large enough sparge volume for good efficiency.

The 1.25 ratio initially was carried over into batch sparging, until folks learned that thinner mashes convert more efficiently. Batch sparging recommendations are now to target strike and sparge volumes for equal run-off volumes.

Brew on

 

[doug293cz]

Although in theory this is true, in practice a 30-60 minute mash is long enough to get full conversion regardless of particle size. If I remember Braukaiser's experiments, under most "normal" conditions, one can assume near complete conversion efficiency (upwards of 90% anyway) and therefore the lauter should be targeted if you are looking for improvements in efficiency.

In short, the rate limiting step is the lauter.

I disagree. There have been several threads recently started by brewers with poor efficiencies. I have done analysis of the conversion and lauter efficiencies in for many of these brewers processes (and posted the results in their threads.) The biggest detractor is usually (but not always) low conversion efficiency. There might be some loss of lauter efficiency, but it's not the big hitter.

Brew on

 

[broadbill]

I disagree. There have been several threads recently started by brewers with poor efficiencies. I have done analysis of the conversion and lauter efficiencies in for many of these brewers processes (and posted the results in their threads.) The biggest detractor is usually (but not always) low conversion efficiency. There might be some loss of lauter efficiency, but it's not the big hitter.

Brew on

I'd be interested to see how you do this, as I don't see how this is possible without directly testing samples from that person's setup.

 

[Homercidal]

Actually, the rate limiting step (at least for larger grain particles) is getting the water into the particles for gelatinization to occur, not getting the sugar to "release" from the particles. Gelatinization occurs in layers from the outside of the particle towards the center. After gelatinization has occurred, the starch is soluble and goes into solution. Most of the actual conversion takes place in the liquid and gelatinized layers on the outer edges of the particles.

Brew on

Interesting. So does a mash stir help the starches release from the grain particle after gelatinization? I am trying to visualize this, but I can only see that the starches might still be bound up in the protein and other things that make up the part of the kernel that is converted.

I've wanted to make animated brewing videos describing how the process works, and this would be a perfect example of how an animated visual would be useful. I need to learn how to do simple animations.

 

[pricelessbrewing]

I'd be interested to see how you do this, as I don't see how this is possible without directly testing samples from that person's setup.

If you know the grain bill, and the water volumes, then you can estimate the conversion efficiency based on the run off volume and gravity. You can then estimate the lauter efficiency based on the total run off (and and subsequent sparge volumes)

Doug sent me his batch sparge simulator, and it seems to be accurate. The one time I had a higher gravity for my 2nd run off, but that was due to the grain not being drained fully before adding my sparge volumes. (it was biab so technically I lifted the grain bag and it wasn't down draining before I dunk sparged)

 

[doug293cz]

Interesting. So does a mash stir help the starches release from the grain particle after gelatinization? I am trying to visualize this, but I can only see that the starches might still be bound up in the protein and other things that make up the part of the kernel that is converted.

I've wanted to make animated brewing videos describing how the process works, and this would be a perfect example of how an animated visual would be useful. I need to learn how to do simple animations.

Yes, mash stirring or recirculation will help the swelled starch coating the particles to slough off and go into solution faster.

I was thinking after writing this post that putting a couple of different size malt particles under a microscope during gelatinization would make a good video. The hard part of making the video would be devising a way to heat a small volume of water on the microscope stage to a controlled temperature. A "micro mash tun" if you will.

Brew on

 

[doug293cz]

I'd be interested to see how you do this, as I don't see how this is possible without directly testing samples from that person's setup.

With suitable data from a brew session, it's possible to model the lauter process for batch (or no) sparge with reasonable accuracy. If their batch sparging process is reasonable as far as agitation and timing, then it's difficult to get results very different from the model. Once you have an estimated lauter efficiency, you just divide the mash efficiency by the lauter efficiency to get the conversion efficiency. The data used includes:

• Grain bill (just total weight is usually enough)
• Strike water volume
• Sparge water volume
• Pre-boil volume
• Pre-boil specific gravity

Additional data on first runnings gravity, first runnings volume, etc. can aid with doing consistency checks on the model.

The efficiency calculations are based on a mass balance of all of the sugar and water thru all the run-off steps.

Here's a link to a thread where the brewer had both conversion and lauter efficiency issues: https://www.homebrewtalk.com/showpost.php?p=7171152&postcount=19

And here's a thread where the problem is mostly poor conversion efficiency: https://www.homebrewtalk.com/showpost.php?p=7161662&postcount=13

Brew on

 

[doug293cz]

Here's the efficiency story for no sparge BIAB. The data is for 100% conversion and 6.75 gal pre-boil volume (corrected to 68°F). Strike volume is adjusted for grain absorption to get a constant pre-boil volume. Grains are assumed to have 80% by weight conversion potential on a dry basis, and 4% moisture ("as is" conversion potential of 76.8%)

View attachment 312526

Grain absorption is affected by how long you drain and/or how well you squeeze. If your conversion percentage and your grain absorption (gal/lb) are consistent, then your efficiency will be consistent and depend only on your grain bill.

Brew on

Thought I'd drop the other shoe, and compare no sparge vs. single sparge with equal runnings. For the sparge process a dunk sparge with stirring is assumed, and the grain absorption is the same for initial drain and sparge drain (have to drain/squeeze both steps the same amount.) Other conditions are the same as the quoted post.



Brew on

 

[PlexVector]

Yes, mash stirring or recirculation will help the swelled starch coating the particles to slough off and go into solution faster.

I was thinking after writing this post that putting a couple of different size malt particles under a microscope during gelatinization would make a good video. The hard part of making the video would be devising a way to heat a small volume of water on the microscope stage to a controlled temperature. A "micro mash tun" if you will.

Brew on

A micro-mash tun could be made with a coil of NiChrome wire on a slide. Use silicone adhesive to keep the shape. Solder a thermister to it and create a feedback system to control the temp of the wire.

 

[doug293cz]

A micro-mash tun could be made with a coil of NiChrome wire on a slide. Use silicone adhesive to keep the shape. Solder a thermister to it and create a feedback system to control the temp of the wire.

Something like that should work. The short thermal time constant of such a micro mash tun would require a fast acting controller in order to keep a stable temperature. The kinds of PID's used by homebrewers for their macro mash tuns wouldn't cut it.

Brew on

 

[hafmpty]

More dilute mashes seem to perform numerically better all else being equal.

Contrary to common believe no attenuation difference was seen between a thick mash (2.57 l/kg or 1.21 qt/lb) and a thin mash (5 l/kg or 2.37 qt/lb).

This ratio is quite a bit lower than typical BIAB brewing though. So in actuality we are comparing thin mashes to VERY thin mashes, right?

 

[PlexVector]

Something like that should work. The short thermal time constant of such a micro mash tun would require a fast acting controller in order to keep a stable temperature. The kinds of PID's used by homebrewers for their macro mash tuns wouldn't cut it.

Brew on

A DC PWM controlled by a microcontroller driving a power mosfet would be the easiest and safest.

 

[castillo556]

I often use my fermenting bucket for the sparge dunk, easy to just drop a few gallons of water in that i boiled with an electric kettle.

I do as well, simple and effective.

 

[doug293cz]

This ratio is quite a bit lower than typical BIAB brewing though. So in actuality we are comparing thin mashes to VERY thin mashes, right?

Depends on the grain bill. Typical full volume BIAB ratios (assuming 6.75 gal pre-boil, 5.5 gal post-boil, 0.08 gal/lb grain absorption, and 95% conversion efficiency) would range from:

~4.18 qt/lb for 7 lb of malt yielding an OG of ~1.038​

to

~1.45 qt/lb for 24 lb of malt yielding an OG of ~1.100​

For a 2.37 qt/lb ratio you would use about 13 lbs of malt to yield an OG of about 1.064.

Brew on