Decoction Question

[stef]

This probably has a very obviously answer. I understand the process behind decoctions, but have 1 question.

Obviously mash temps are important- liquor temp when 'steeping' grains is also important- too hot and you extract astringency etc.

So how does the decoction work then? Sure the same undesirable characteristics are extracted when boiling the buggery out of the portion of grain & liquor used for decoction?

Cheers

Stef

 

[argon]

Have a read here and all will be revealed...

Decoction Mashing

basically it's a pH thing... tannin extraction is a function of pH as well as temperature, and that tannins are only a problem when the pH rises to 6+. In a decoction only a small amount of mash water is taken with the grains to be boiled, so the pH stays at around 5.2, which prevents tannins forming despite the decoction being taken to boiling temperatures.

 

[stef]

Ah, sweet. Thanks Argon. I assume, therefore, that the decoction needs to be really thick (mainly grain)?

 

[argon]

Nope not always... Rule of thumb; Cooler you take the decoction, the thicker it needs to be. All the way up to a no grain decoction* when boiling for ramp to mash out.


*discussion continues as to whether this is considered a decoction or just a boiled portion of wort for ramping.

 

[stef]

Cool. I also found a slideshow that some bloke made that was pretty helpful. Explained the chemistry/theory behind how it works, but i gotta admit it went a bit over my head. I might give it a shot on one of my next brews!

 

[Nick JD]

I've read in a few places that some of the colour change and flavour change can actually be attributed to some tannin extraction. So a little part of the decoction flavour is actually tannins, but to a small degree - and probably hidden somewhat by the melanoidins, as their sweetness and mouthfeel probably overrides the slight increase in astringency.

I wouldn't be surprised if there are other "brown" things in the husk that contribute to the colour change too.

 

[Dave70]

Check this out.
It's a little long winded, as is the American way, but really shows you what its all about.

 

[felten]

The vid from braukaiser helped me out before doing a decoction. http://youtu.be/_V1zt0mW084