Decoction mash

[Powell Royall]

Years ago when I was reading about Decoction mashes, I must admit I was mesmerized by the idea. I certainly loved a nice Pilsner Urquel on a hot day with a nice balance in a hop and malt profile but I also felt a little intimidated about doing it. Finally after a few years thinking about it, I asked my buddy Jim if he was interested in coming over for a long brew day to give it a try to try and make a Pilsner Urquel clone. Nice thing about a decoction mash is you don’t need tons of special equipment as odds are you have most of what you need already in you house if you are already brewing. Whether you are cooking on you stove top, using a cooler system or have a nice fancy pilot system.

Basically decoction mash came about before the advent of thermometers as a way to try and find a consistent way to make the same beer over and over again. Now, I personally use a thermometer, not because it breaks from convention, but because science has given me this little advantage.

The classic triple decoction started out with warming up water to about your body temperature (97-100) and adding in your grains for a rest of about 20 minutes. For a light beer you are going to use more water than you would with a traditional single infusion mash about 2Q per lb of grain. For a darker beer, you are going to be at about 1.5Q per lb of grain. the Then take about 1/3 of you grist mash out and taking as little water as I you can and put it into another pot and warming it up. They would bring it up to about 150 -155 degrees, stirring constantly to not burn anything on the bottom and then rest it in this range for about 15 minutes for a lighter beer, 30 minutes for a darker beer. I have gathered that historically this is about the point they would start seeing the first bit of steam since they lacked temp probes. After the rest was complete, they would bring the decoction up to a boil. For a light colored beer this only lasts a few minutes (10-15 minutes) and for a darker beer, it could last 30-40 minutes. Remember again to stir so you don’t burn the bottom. This boiling creates a Melanoidin in the grains which gives a nice malty flavor in beer and can slightly adjust the color darker the longer you boil.

Once this is done, you return the decoction to the main mash and stir in to help even the temperature out which would bring the mash temp up to about 120-125 for a good protein rest. If using classic floor malts, you will want this to rest here for about 20 minutes before moving on to the next decoction but most of what we get here in the US is modern modified malts so you do not have to let the whole thing sit, you can jump right to the second decoction. Same process as the first time, pull a 1/3 , bring it up to 150 for 15 minutes then up to boiling for the same amount as the first.

Returning the decoction to the main mash and stirring in will bring us to our familiar mash temp of around 150 degrees. Repeating the decoction one more time (hence the term triple decoction) will help you up get up to the mash out temperature of 168. From there, go on with your brew day as you normally would and you will probably find the vorlauf a bit easier to get clear.

Be prepared that this is going to be a longer brew day than you are used to and I generally make sure to stretch before I do this brew as I still remember how sore my muscles were after the last time I did this but the taste was always worth it later on.

If this is something that you are interested in but really don’t want to spend all day brewing, you can try a single decoction. Just get your grain up to you Single infusion temp you would normally rest at and at about 40 minutes and pull 1/3 of your mash grist and put it straight in another pot and bring it up to a boil. When your timer goes off to do mash out, put the decoction back in your main mash and stir. Ready to be on with the rest of your brew day but with with a bit of the Melanoidin’s to go along with your brew.

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