Home Brew Forum

(inspired by Edit1now's superb sample, based on Vossy's recipe, based on Samuel Smiths Oatmeal stout as found in 'Clone brews')
I'll be roasting the Oatmeal in the oven at gas mark 5 for 45 mins, turning regularly. then I'll be mashing it with 3Kg Pale Malt & 7 Litres Liquor at 40C for 30 mins.
meanwhile, the remaining grist will be mashing at 68C.
both components of the mash will be at ph5.2 using 'ph5.2'.
after the 30 minute rest, the two components will be combined and will mash for a further hour at 66C, held by my HERMS.


you know the rest...

Gurgeh,

Is there a particular reason to split the mash and do a separate protein rest (??) at 40C for the oatmeal, as opposed to just mashing the whole lot at the same time and doing a step mash with the 40C protein rest on it all - or is it down to mash tun size or something else entirely?

He said something like:

but I reckon I could shave a significant amount of time off the process by doing the cereal mash and main mash simultaneously. I don't really see a down side so long as I give the goods in the cereal mash sufficiently long at 66C to do the main conversion.

Aaaahhh.......now I get it!

I do the same thing, Its a great recipe, i've had the pleasure of tasting Vossy's version - cracking beer, very smooth.

never got the chance to brew this on Friday - hopefully tomorrow.

The water calculations seem quite interesting, so I thought I'd share them:

I'm after 42L (~9 gallons) so...

during a 90 minute boil (and hops) I will expect to lose 7L. So must collect 49L from my two runnings (call it 50).

2 equal runnings, so each batch to be 25L

2nd batch is easy enough, 25 in 25 out.

1st batch however...

cereal mash in coolbox: 7L liquor, 3.5Kg grist (40c)
main mash in tun: 11L liquor, 5.25Kg grist (68c)
total liquor 18L, total grist 8.75Kg (call it 9Kg)

I'd only get 9L wort out of that, once combined, so have 16L to add to it which will help me gain my 66C final mash temp. I'll have at least that volume standing by at temp.

questions is, what temp should that 16L be at? i.e. how can i find out the temp of the resulting mash when the two parts are combined and how do I calculate the required temp of that final liquor addition?

My HERMS will ultimately sort this out, but I'd like a more elegant solution to this!
fun huh!

T=(M1T1 + M2T2)/(M1+M2) should work...

(10.5*40 + 16.25*68)/(10.5+16.25)=57C

which makes sense

and tomorrow I'll work it backwards to find the desired temp of that 16L addition.

zonk.

(T(M1+M2)-M1T1)/M2 = T2

(66(26.75+16)-26.75*57)/16= 81C

which seems reasonable...

Aha! Somebody who could help us with our Maths homework