Decoction?

[Nightbiker]

I'm interested in trying out a recipe for a strong dark Belgian Ale, and it mentions that a decoction mash is required, but doesn't say how long or how much of the grain needs to be boiled. Is there a 'given' amount I could use as a rule of thumb? I've never done a decoction before, but look forward to giving it a go.

 

[helibrewer]

In an advanced brewing class I took we did a single decoction mash as follows:

60% of grist 120F
40% of grist 158F for 10 minutes, then boil for 10 minutes (this takes about 40 min total due to the heating from 158 to boiling)

Then combine the boiled portion with the 60% portion for a 1 hour sugar rest....your temp should be in the 150-158 range

Mash off for about 20 min at 165-170F

Sparge

 

[Nightbiker]

IF I'm understanding you, you took 40% of the grist (just under half) when the mash was at 120F, boiled it, then added it back? I'm a bit confused -please detail this out for me. How long did you boil it? You gave me two temps with percentages?
Also, how did you figure out how much grist you were taking out? Did you just go by taking X number of cups? I wouldn't figure you did it by weight since you would also be weighing in water, and the weights wouldn't be constant due to the grain absorbing water. Did you add water to the pot to decoct, or did you already have boiling water to put it in? Ugh. Please just dumb it down for me

 

[helibrewer]

IF I'm understanding you, you took 40% of the grist (just under half) when the mash was at 120F, boiled it, then added it back? I'm a bit confused -please detail this out for me. How long did you boil it?

The grist is split into 2 pots. The pot with 60% is heated to 120F and kept there. The pot with 40% is first raised to 158F and kept there for 10 mins, then it is heated to boiling and kept boiling for 10 minutes. At the completion of the boiling time, the 2 pots are combined into 1 batch of 100% of the grist and kept at 150-158F for 1 hour.

It's just easier to start with the grist split between 2 pots since they never really share a common temperature until they are recombined after the boil.