Recirculation and decoction questions

[HOPCousin]

I have been having difficulty with my efficiency with stouts. I've added additional base malt to help. I've read that some of the big imperial stout brewers use recurculation. I've also read about decoction as a way to increase the malt profile.
Would either of these approaches help with efficiency?
Has anyone tried these methods and what did you think of the results?
? :fro:

 

[pjj2ba]

For any big beer, you are going to have a drop in efficiency. That is a hard one to correct. Typically if you want to up the efficiency, you need to sparge more and then boil longer to hit your target OG.

Now if you are doing a stout in the 5% ABV area, then I would suspect you have a too low pH problem and that is slowing down conversion. Roasted malts will lower the pH relative to the same grain bill without roasted malts.

One thing I've been messing with, to smooth our my porters and stouts a little, is to wait to add the roasted grains until the last 10 min or so of the mash. This also minimizes the affects of the roasted malt on the pH until most of the conversion is done

 

[HOPCousin]

So boiling longer and adjusting the mash. I didn't have trouble with my last porter so i didn't check the ph... but I used a touch of roasted barley and that must have been part of the issue. Why the longer boil? I have been looking for an answer to this one

 

[KuntzBrewing]

More water in the sparge will make your wort more diluted, so you need more water to evaporate = longer boil

 

[HOPCousin]

I'm aware of the longer boil more water part. My home brew books don't specify however the reasoning for a 90 minute boil vs. 60 minute boil when the hops are added in both at 60 minutes.
Why boil the wort for an additional 30 minutes when there are no hops involved?

 

[pjj2ba]

Pilsner malts have lots of DMS precursors, so grainbills with large amounts of pilsner malt are typical boiled for 90 or more minutes. Pale malt is kilned at a higher temperature such that there is very little DMS precursor left so only a 60 min. boil is used. Now the longer you boil the more caramelization you get, so that might be a reason to boil a pale malt beer longer if that is something you want in your beer