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Brew Like A Pro: Low Oxygen Brewing

The next evolution for homebrewers: prepare to revisit all your old recipes and modify new ones: Low Oxygen beer brewing yields an exciting new palate to work with new enhanced malt flavors, and better hop flavors and aromas.

The Dissolved Oxygen (DO) Problem In Beer Brewing

Controlling Dissolved Oxygen (DO) levels in the mash preserves fresh malt flavors by reducing oxidation. In fact, controlling DO levels is important throughout the entire process up to bottling/kegging and has a significant impact on flavour and shelf life. This is especially true with lightly hopped beers, where the hops won't conceal off flavors introduced by oxidation. 

To give an indication of what we are after, here are the ideal levels of DO at various stages in the brewing process:
- less than 0.5 ppm DO during hot side, and
- less than 0.15 ppm DO during bottling/kegging.

And here are some DO saturation numbers worth considering: 
- tap water: 8 to 12 ppm. 
- mash: 4 to 5 ppm. 
This doesn't mean that these are the actual levels, but they could be depending on your brewing process.

So, how de we get these numbers down?

Here are a number of techniques used by professionals, but none of them on their own is sufficent: 
- pre-boiling the mash water, 
- adding oxygen scavengers to the mash: sulphites or other chemicals,
- avoiding copper wort chillers which can cause oxidation chemical reactions. 

Unfortunalely, adding chemicals can introduce other undesirable reactions which can affect beer flavour. But we can pre-boil mash water and use all stainless steel equipment.

Next up, we need to look at our brewing process. We need to reduce splashing and any other means of aeration (loose connectors, leaking syphons etc). When mashing in, stir the malt in very gently. And avoid sparging completely (not a big deal with modern all-in-one brewing system efficiencies).

Finally, select a brewing system that is designed for low DO. Speidel have just launched new attachments for the 20 and 50 litre Braumeisters that will significantly reduce DO during mashing; see: 
Low-Oxygen-Brewing-Kit for 50-litre Braumeister
Even before this innovation, Braumeisters worked differently that other all-in-one brewing systems: most use a pump to feed wort on top of the grain bed, the Braumeister gently pumps wort up through the grain bed which then overflows over the malt pipe and eventually back down to the pump. This new innovation consists of a plate which better secures the grain in the malt pipe and allows the brewer to then add more water (and also more grain if desired) so that there is essentially no overflow falling down over the outside of the malt pipe, and thus less oxidation. It also comes with a "swimming lid" which keeps air off the wort during cooling (only applies to the newer Braumeisters with built in cooling jackets). The floating lid can't be deployed while using a wort chiller with an older Speidel Braumeister since the chiller gets in the way but the system will still result in lower dissolved oxygen with the older models, just be careful to avoid splashing during cooling.

Here is a web site devoted to low DO brewing: and here is another one showing the Braumeister is low DO mode (scroll down for the English version):