Master Brewers Podcast BH Efficiency Discussion

[TheMadKing]

I just listened to the Master Brewers Podcast Episode 79 where Van Havoc was the guest discussing brewhouse efficiency and he said some things that really have me questioning everything I thought I knew about maximizing efficiency. I realize he's applying these to small commercial breweries, and I think at the homebrew scale these only apply to folks using the same mechanical process (i.e. 3-vessel, fly sparge) and definitely don't apply to BIAB folks. I thought I would put up a couple of my take-away's from the episode for discussion and see what all you guys thought:

1. Your mill needs to be set so that 70% of your kernels in your crush are larger than 0.055" - He said 70% should sit on top of a #14 sieve, which has a mesh size of 0.055". If you crush finer than this it will hurt your BH efficiency because of the negative impact on lautering, and that it sets up your grain bed for being too tight and uneven.
2. The majority of conversion happens INSIDE the grain kernel, not in the liquid. The starches are converted inside the grain kernel and then migrate as sugars into the liquid via osmotic pressure through the cell walls of the kernels.
3. A grain kernal that is cracked - not crushed - just cracked, enough to allow water inside will convert. Crushing finer does nothing to increase your conversion efficiency given a 60 minute mash. I speculate that it will dramatically increase the surface area of grain and speed up water access, and it will decrease the amount of distance that the sugar needs travel via osmosis so it does result in a much faster mash if you need to do it in less than 60 minutes, but if you are doing a full 60 minute mash a fine crush isn't gaining you much.
4. Because of #2 above, he advocated a lautering time of never less than 60 minutes (and never more than 90), because the sparge water has less sugars contained in it than the mash wort, it increases the osmotic pressure that draws the sugar out of the kernels, so you need to allow sufficient contact time with the ever-decreasing SG sparge water to most efficiently draw the sugar from the kernels
5. He advocated a "just right" approach to stirring saying that too much stirring results in a tighter grain bed because of removing space between larger particles and breaking up larger particles, but not enough stirring results in insufficient mixing - I never knew you could stir too much and this doesn't make intuitive sense to me.

While I automatically disliked the guy because he has a snarky and very arrogant attitude, he presented numbers that showed the effectiveness of his solutions at breweries. He called his anecdotes "case studies" which makes them more scientific too!

thoughts?

 

[Oginme]

I have listened to this podcast several times over trying to glean some understanding of his approach. I do have some very distinct impressions based upon his commentary, not expressed to respond to each of this points directly.

1. The fluid dynamics and pressures in a large mash tun or lauter tun are much different from what we encounter on a small batch home brew level. Some of the all-in-one devices with a narrower mash basket may be the closest to the head pressure and need for a fluidized bed approach to mashing. Additionally, having worked in many paper mills with some making similar products, what works in one environment can be a total disaster in another. Each process has its own 'personality' and sensitivity which makes it beneficial to treat them as different processes, even though they are basically the same in nature.

2. Starches can only be converted if they have been made soluble. If the starch has not been made soluble the enzyme cannot fit around it to do its job. While some of this can happen within the kernel, I can envision the process to be much slower. On the other hand, the enzyme concentration within the kernel may end up being higher than outside. I am reminded of a project I worked on modeling the penetration of liquor into wood chips to be able to optimize the chip size, vessel pressure, and digester time for a given process. Penetration happens pretty quick until you get to a certain thickness of the wood chip, then the rate of penetration slows down considerably. Maybe not a direct comparison, but the principles apply to a certain extent.

3. I concur that the finer crush will not affect the conversion in a 60-minute mash if you have already optimized particle size of the kernels to be converted in that time frame. Again here, we are talking about a commercial process and a 60 minute mash on top of a 60 minute lauter gives a lot of time for the conversion to be completed. Not many home brewers are going to take 60 minutes for lautering and sparging, but I could be wrong here. For my system, I crush a bit finer and get excellent conversion efficiency at a much faster than 60 minutes but I am doing BIAB and do not need to worry about lautering drainage. Again, process may be similar, but details make it much different.

4. Yes, this works with fly sparging on the home brew level also. Slower, longer sparges gives greater time for the sugars still contained within the kernels to be drawn out (move from high concentration to lower concentration) and it is this effect which potentially makes fly sparging more efficient than batch sparging where you get to a slowing of rates as the concentration of sugar in the water equilibrates to the concentration still inside the kernels.

Just my thoughts and experiences.

 

[TheMadKing]

I have listened to this podcast several times over trying to glean some understanding of his approach. I do have some very distinct impressions based upon his commentary, not expressed to respond to each of this points directly.

1. The fluid dynamics and pressures in a large mash tun or lauter tun are much different from what we encounter on a small batch home brew level. Some of the all-in-one devices with a narrower mash basket may be the closest to the head pressure and need for a fluidized bed approach to mashing. Additionally, having worked in many paper mills with some making similar products, what works in one environment can be a total disaster in another. Each process has its own 'personality' and sensitivity which makes it beneficial to treat them as different processes, even though they are basically the same in nature.

2. Starches can only be converted if they have been made soluble. If the starch has not been made soluble the enzyme cannot fit around it to do its job. While some of this can happen within the kernel, I can envision the process to be much slower. On the other hand, the enzyme concentration within the kernel may end up being higher than outside. I am reminded of a project I worked on modeling the penetration of liquor into wood chips to be able to optimize the chip size, vessel pressure, and digester time for a given process. Penetration happens pretty quick until you get to a certain thickness of the wood chip, then the rate of penetration slows down considerably. Maybe not a direct comparison, but the principles apply to a certain extent.

3. I concur that the finer crush will not affect the conversion in a 60-minute mash if you have already optimized particle size of the kernels to be converted in that time frame. Again here, we are talking about a commercial process and a 60 minute mash on top of a 60 minute lauter gives a lot of time for the conversion to be completed. Not many home brewers are going to take 60 minutes for lautering and sparging, but I could be wrong here. For my system, I crush a bit finer and get excellent conversion efficiency at a much faster than 60 minutes but I am doing BIAB and do not need to worry about lautering drainage. Again, process may be similar, but details make it much different.

4. Yes, this works with fly sparging on the home brew level also. Slower, longer sparges gives greater time for the sugars still contained within the kernels to be drawn out (move from high concentration to lower concentration) and it is this effect which potentially makes fly sparging more efficient than batch sparging where you get to a slowing of rates as the concentration of sugar in the water equilibrates to the concentration still inside the kernels.

Just my thoughts and experiences.

That all matches almost perfectly with my thoughts. Especially your points in 2-3. I think he's just flat wrong about his understanding that conversion is occurring to a significant degree inside the kernels, because of the reasoning you stated. However he did suggest putting 5 cracked (not crushed) malt kernels into a cup of 150F water for an hour and then tasting them to prove that they don't contain any sugar - how effective this taste-test is I don't know, seems a little sketchy to me.

Having switched from BIAB to a 3-vessel recirculating mash w/ HERMS, I can attest to the fact that a coarser crush will provide a benefit in these types of systems. I did several tests of crushes ranging from 0.030 (my old BIAB crush) to 0.055 and found that I got the most repeatable and highest efficiency with my mill set at 0.045" because of the benefits to recirculating and lautering. So I don't think what he says is untrue on the whole - I just think his arrogant approach, and some of his flawed reasoning is offputting.