Decoction Mashing....

[Mark Farrall]

Heard a fascinating other way of thinking of decoction mashing the other day. German Berliner Weisse nerd was asked about whether to do decoction for a 'historically accurate' Berliner Weisse. He didn't think it was that important, but then went on to explain the genesis of decoction mashing as he sees it...

Brewers in the 18th century couldn't afford anything more than a small copper kettle, but they new if you wanted bitterness from your hops you had to boil the water. So to get decent bitterness in a big batch that you're mashing in a wooden tun you take out a thin part of the mash, add the hops to that and boil it. So for him decoction is an old approach to getting isomerisation when you couldn't afford a metal boil kettle. He didn't really see the caramalisation/maillard reaction stuff as part of the reason for decoction.

This was on the latest milk the funk podcast.

 

[Nosybear]

Interesting.... I thought it was much older than that and that the purpose was twofold, first off, to mash the under-modified malts of the time. Imagine trying to mash uncooked corn grits, an analog of the steely parts of the undermodified barley. Second, as you say, you can't directly heat a wooden kettle and metal was valuable so you take part of the mash out, boil it and add it back. One other very important function was controlling temperatures when no one had any idea what a thermometer was: The brewer could gauge the first rest temperature by sticking his thumb (or other digit) in the mash. When it was just hot enough he couldn't leave his thumb in there any longer, it was ready to go. By using volumes from that point, the brewer was able to hit rest temperatures within a couple of degrees.

I recently acquired a book on historic German styles and some of the mash regimes were convoluted, to say the least. And the method you mention was used for some of the northern German Weissbiers - they pulled a decoction and boiled their hops in it, added it back to the mash and lautered.