Saturday 12 July 2008

The Bohemian method of decoction mashing

This is more like it. Jumping over the Bayerischer Wald into Bohemia. Exciting, isn't it? Well, I'm excited, even if you aren't. This is taken from "Schule der Bierbrauerei" pages 306-308.

In Bohemia decoction mashing is carried out differently to in Bavaria and provides an interesting practical example of dispensing with the last starch rest.

Before discussing this method in more detail we first need to learn more about the division of the brewing water. For 100 kg of malt 750 kg of water is required. Of this amount, a quarter is used for the Nachguß (sparge) and the rest for mashing, except for one thirtieth, which is used to dilute the first wort. Of the remaining mash water, four fifths is used for Ausschütten (pouring) and one fifth for the following temperature rises (Zubrühen). The 750 kg are divided like this:

435 kg pouring
108 kg warming
19 kg diluting the first wort
188 kg Nachguß

The water required for pouring [Ausschütten] is boiled in the kettle (a highly wasteful and unnecessary practice; rational brewers heat just a little water and put cold water into the mash tun) and put into the mash tun where it is allowed to cool (to 33º C in summer, 40º C in winter). The warming [Zubrühen] water is now put into the kettle and brought to the boil.

The ground malt is added to the cooled water in the mash tun and mashed well for 5 or 6 minutes, after which the boiling Zubrühen water is added and stirred in well. Then about a third of the mashed grains are moved to one side of the mash tun and transferred to the kettle as Dickmaische. There it is careful brought to the boil (to prevent burning or boiling over) and simmered for 30 minutes. The foam that accompanies saccharification then appears. As soon as this foam starts to disappear and the pale colour of the wort starts to turn brownish-yellow (as a result of the transformation of proteins) the Dickmaische is considered to have boiled long enough and is returned to the mash tun. There it is mixed in well. Now another Dickmaische is assembled, but from another side of the mash tun (why "from another side?" Hasn't it been mashed properly?) put into the kettle, boiled for 20 to 24 minutes (why not again until the appearance of signs of saccharification, as with the first Dickmaische?) and returned to the mash tun. Finally there is a third Dickmaische which is boiled for 20 minutes.

Through the three boils, the temperature in the mash tun is raised to 71-75º C. The remaining one thirtieth of the mashing water is now put into the kettle.

The wort is run off into the underback until it becomes clear. The cloudy wort (which is full of starch) is added to the boiling water in the kettle and boiled for several minutes (whereby the starch is gelatinised). It is returned to the mash tun, but without disturbing the sediment which has already settled. Then the saccharification is left to complete.

If, however, the intended complete saccharification can ever take place is doubtful, since, as Balling has shown, the temperature in the mash tun is already over 75º C after the third Dickmaische and is now raised even further.

It's pretty obvious from the snide comments that the author isn't too impressed with this method. I wonder if this is how they mashed at Pilsner Urquell 150 years ago? As some of the wort is boiled four times, I suppose this is a quadrupel decoction.

2 comments:

Jim Johanssen said...

Very funny to see the sharp remarks for a process that he does not understand. One reason for boiling the water and letting it cool is to have the carbonates solidify and fall out of solution, acidifying the water. Yes, evan in the old days good brewers were smart lot. There was usually a good reason for everything they did we just have figure out why

Kristen England said...

Jim, the water in Bohemia, specifically pils urq and budvar breweries, is nearly entirely void of all minerals. Its damn near distilled and nearly void of all carbonates. This is one of the main reasons for the hugely long acid rests (5-6hours).