I've had a look through my books and on the net but can't find any reference to an even approximate figure. They all say...it has surplus diastatic power, so it can convert 'an ammount' but they don't say how much more!
Aaaarrgh!
I liked the flavour of Seveneer's porter and it reminded me how much I like dark beers, even though I've brewed mainly bitters and pale ales. So, I'm going to have a crack at a porter of my own, but along more historical lines which means OG 1050+ and the inclusion of substantial quantites of brown and amber malt.
What I need to know is..how much brown I can get away with? I can use a lighter grade of amber which has diastatic power together with darker non diastatic amber. I'll also use a percentage of Rauchmalt to get some of the smokiness of old brown malt, and a small percentage of black malt for colour adjustment.
Preliminary grist make up aiming at OG 1060 in 24L :-
Maris Otter Pale 30% 2.3kg
Diastatic Amber 30% 2.3kg
Brown 20% 1.5kg
Rauchmalt 10% 800g
Amber 8% 600g
Black 2% 150g
If it looks like a lot of grain, I'm working on a basis of 65-70% efficiency, so rather than sparging down to 1006 I'm going to stop short and discard the thin stuff at the end of the sparge.
Hops? Who cares. The porter brewers of old used whatever they could get cheap, and rarely first-quality. I've got some goldings in the freezer, I'll copper hop to about 35-40EBU. None late/steep/dry.
If it's sufficiently ready in time I'll bring some along to the next beer club meet.
Just need to know wether the grist as made up will convert fully in the mashtun.
