Commercial low o2 mashing

[Natebriscoe]

Does anyone have a good understanding of how the larger commercial guys are are achieving low o2 worts? Or is that equipment and process proprietary? I see some names of products, but not real specific on how it works.

[Weizenberg]

Obviously this is high-end engineering know-how and very system specific. This is chemical engineering at it's best.

However, there are some generally accepted principles that are adhered to.

I may sound like a broken record, but I recommended the English translations of the Kunze book to our initial group and everybody found it quite useful.

Here is the again (no, I am not affiliated with the VLB)

It's a beautiful book and has a plethora of illustrations, graphs, pictures and exploded diagrams of equipment. Apart from mentioning to avoid oxygen ingress in almost every chapter, he also lists best practices like connecting hoses correctly, cleaning equipment, use of pumps and a plethora of other things. Never mind various mill, kettle, boiler designs etc... etc.. It is quite likely that many a question you have will most likely be covered in there.

It is very comprehensive and contains all one needs to know as professional brewer and I highly recommend you invest in it before investing in anything else.

[Natebriscoe]

[Weizenberg]

A lot of the equipment is explained in lovely detail in there. I keep going back to Kunze over and over again

[Techbrau]

Here is the simple version of what it boils down to:

All water is degassed to 0.01 ppm DO using packed columns that bubble co2 or n2 up from the bottom

Milling is done in a closed environment under inert gas inside the malt delivery pipe itself. Immediately after milling, degassed water is mixed into the grist in the delivery pipe. There is no atmospheric air present at this point, so they dough in with zero oxygen uptake.

All of the vessels are closed, filled from the bottom, and often times purged before filling with N2 or steam. Many modern tuns are steam heated anyway, so all you have to do to purge them is run the steam jets to preheat the tun for a bit.

The commercial sized volumes (think 500-1000 hl) involved have vastly smaller surface area to volume ratios than a homebrew system thanks to the Square-Cube Law. This is approximately on the order of a 20x difference. This means that atmospheric oxygen diffuses into a homebrew mash 20 times faster than a commercial mash. In the time it takes for 0.1 ppm to diffuse into a commercial mash, your homebrew mash picks up 2 ppm just sitting there exposed to the air.

In summary, the three biggest sources of oxygen pickup are

1) oxygen already in the strike water

2) oxygen mixed in during dough in

3) diffusion

They solve o2 in the strike water by degassing

They solve dough-in by milling in-line with the delivery pipe under inert gas and using a vormaischer to mix the water in

They solve diffusion by scaling up the batch size to take advantage of the Square Cube Law. Closed vessels, bottom filling (no splashing) and inert gas blankets when necessary are all helpful additions here.

You can find pages upon pages of detailed description of each one of these points in Kunze, along with pictures and diagrams of the equipment.

[Bilsch]

Very eloquent explanation. Thank you for taking the time.

[Natebriscoe]

Thank you, as well! I really have to get that book!

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[Natebriscoe]

So if one could pressurize a mash vessel (with grist) and purge with inert Gas, then underlet with degased liquor, one could possibly get away with little to no smb and good DO#?

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[Weizenberg]

As the vessel size increases, the surface area in contact with oxygen decreases. Bigger is better in this respect.

I once looked into one of these mash tuns. It's impressively big and deep. It's the height of a 2 stories house.

The ingress from doughing in is very high. Using a regular mill it's in the order of 24-36 mgl IIRC.

Ideally you want to mill under inert gas. This also protects from explosions. Your grist already enters the mash tun in a virtually lodo state. Kunze has some very interesting pitures of such machinery in his book.

Then there is the engineering issue. Safety is paramount. The relief and safety valves are regularly inspected.

You also need to flush all the pipework and ensure your pumps don't have cavitation issues (you'll most probably need a frequency inverter to control motor speed)

The list goes on....

[Natebriscoe]

This does explain why some of the bigger craft guys get pretty close. My local large craft brewery (Boulevard) gets the lodo flavor in most of their beers, but they don't make many/any German style beers.

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