Reiterated mash...anyone done it?

[hoppyscotty]

Fancy brewing an imperial stout and tuck it away for a good 12 months or so. Watched a David Heath video on YouTube who brewed an Imperial Stout using the Reiterated mash method. My understanding is you mash and spare as normal once, then dump the grain, refill with fresh grain and mash again in the wort you already have. Obviously a good method to get high gravities from a large malt bill with a limited mash volume. I fancy giving it a go but I usually use Brewfather for my water volume calls and wondering how to work out the strike water and spare water x 2 volumes. Anyone done this before or got any ideas how to work out the water volumes for a Brewzilla 35ltr? Aiming for a 20litre or more if possible batch?

Thanks.

 

[RoomWithABrew]

You might get some clues in this thread

https://www.homebrewtalk.com/threads/partigyle-water-adjustment.694185/#post-9141184

 

[Slid]

Early in 2018 I watched the same video and did some calcs for one of my own. In the end I never did do one, but have done a couple of Partigyle brews, in which you use a fairly big grain bill and mash in the normal way, but only take the first runnings (i.e. no sparge) for the boil of your strong beer, which could be in a pot on the stove?

Then you add more water at mash temp to the grain (underletting works well) and add a "cap" of grains that don't require mashing and then do a shorter "mash" and sparge as normal for a full length brew as well as your strong beer.

Here is a thread I did some time ago:

https://www.thehomebrewforum.co.uk/threads/parti-gyle-brewing.68729/

 

[Richard_H]

I have done something similar once before for a Belgian tripel as my current BIAB isn't one I would trust with a 8kg+ grain bill.

My method was extremely simple to stop me overcomplicating things and making a mistake.
-mash in 4kg for 60 mins in your normal water volume.
-rinse and remove spent grain.
-replace with new grain(3.5kg in my case) for a further 60 mins in the wort you just removed the grains from.

From this stage just carry on as normal, this got me 23L of tripel and I intend on doing the same for an Imperial stout

 

[PhilBrew]

Hi @hoppyscotty

I combined a recirculated mash and a parti-gyle approach earlier this year to end up with 12 lts of Impy Stout and 23 lts of a more sessionable stout all from my (35lts) BrewDevil, so it can be done.

For 20lts of stronger beer your approach should be as @Richard_H describes above ... but then the "complicated" bit will be how much liquor to use at each stage, as you recognised in your original post ...

I usually use Brewfather for my water volume calls and wondering how to work out the strike water and spare water x 2 volumes.

... if Brewfather is generally accurate for you, if it usually gets you there-or-thereabouts in terms of predictions of volumes and gravities out, then I'd suggest you do your calculations initially with that (for the full grain volume, but perhaps with a slightly lower efficiency assumed, just to give you more chance of getting what you want). That will give you a volume for mashing and another for sparging, and if you add those together a total volume. Basically, you need to then make some assumptions to turn those two numbers (mash and sparge volumes) into three (mash ,1st sparge and 2nd sparge) that still add up to the same total volume.

Taking 2.5lts per kg of grain that you don't include in the first mash out of the calculated mash liquor and adding that into the 1st sparge volume would give you a starting point ... but then you might want to do some more "refining" from there. Without see what the numbers come out as, it would be hard to explain what I mean by "refining", but generally I'd suggest you want to end up sparging with a greater volume for the 2nd mash (to rinse off the higher gravity wort) than for the 1st mash, so just keep "borrowing from Peter to pay Paul" until the numbers look about in the right proportions to you

Cheers, PhilB

 

[hoppyscotty]

finally got around to brewing this today. Was a bit of a grueller of a brewday but on the whole reasonably successful but not without its challenges. The first mash went swimmingly. Had to sparge a couple of litres to make upto strike volume for second mash then things started to go a bit array. Basically a major stuck mash and sparge. Managed to get through it with alot of faffing around. All culminated in the pump completely blocking up making for a challenging transfer to the fermenter. Wasn't until clean up after transfer that we discovered the Brewzilla false bottom was all bent and twisted with a load of grain having got past which was what blocked the pump and loads of grain between the bottom plate of the malt pipe and the thin mesh, so it seem as some point during the second mash the bottom plates became dislodged letting loads of grain past. Have no idea how that happened. Any way ended up with an OG of 1.110 to 1.115 vs a target of 1.125, but with a couple of extra litres of wort, so about as good as we could have expected with our equipment.

Think we were pushing the limits of the BZ 35. was a recipe for a 50 litre + system so which is why we split it into a reiterated mash - just over 10kg of grain split in two. Wont know the results for another year yet.

All in all an interesting experiment but a bit of a faff so not sure its something I'll be repeating regularly.

Anyway thanks for the advice above. Will let you know in a year if it was a success or not !!

 

[Slid]

I would also suggest doing a large-ish grain bill in the A-I-O system and adding DME at the transfer to the FV. The drop off in efficiencies with super large grain bills is huge, unless you do the Parti-gyle approach.

 

[Brewnaldo]

I did one of these a few weeks ago to make an imperial style stout as that, plus just the experiment of the iterated mash was on my to do list. The day obviously takes a wee bit longer, with a full extra mash but on the whole I tohught it was a good way to hit high gravity and I have the grains in hand to do it again......

 

[moto748]

Having read Richard's comments upthread, it strikes me that that method would actually be quite suited to my low-tech procedure, it would literally be a case of lifting one bag of grain out of the boiler, sparging, and then replacing it with a fresh bag of new grains. I don't normally go much above a 3.5 kg (dry) grain bill anyway, largely for H&S reasons, so should I want to brew a high-strength beer at some point in the future (never have so far), this might be the way to go.

 

[hoppyscotty]

I got no where near the sugar extraction from the second mash. Achieved 1.080 in the first Mach then a bit over 1.100 after the second so maybe if I did it again I’d not split the batch evenly and have a larger grain bill in the second mash or just add more grain for the second mash assuming a lower efficiency at that stage. Or could have been due to the issue I had with the false bottom. Then recipe called for DME so I added that with another 50% to bump up. I did yield more volume than intended so could have extended boil, but day was already getting long enough.

 

[IainM]

I did one of these last March, and it was great. For the first mash I did an overnight mash, which helped get a bit more efficiency, as well as dry out the first part a bit so the end beer wasn't too sweet without resorting to dextrose. I had 4kg pale in each batch, plus some cararye, dark munich and special W in each batch, then some chocolate, dark crystal and black in the second mash, as a I didn't want to extract too much out of the darker malts in an overnight mash and get astringency. To calculate volumes, I wanted to do a mash and sparge on both batches, so just did the grain-absorption/boil-off/dead-space calcs by hand. Ended up doing a 15L mash and 8L sparge on mash 1, then 10 L sparge on mash 2. Got 18L bottled, with OG of 1.118 and FG of 1.029, so about 12%. Pitching on a yeast cake of a low abv ale fermented with MJ New World Strong Ale, plus adding three packs of US-05, and it fermented quickly and very clean.

I need to get another one of these on soon. Splitting up the otherwise long brew day with a nice nights sleep was nice.

 

[moto748]

That's interesting, Iain. It did strike me that it might be better to put darker malts mostly (entirely?) in the second batch, which I see you have done.

That;s a whole lotta yeast, though!

 

[IainM]

That's interesting, Iain. It did strike me that it might be better to put darker malts mostly (entirely?) in the second batch, which I see you have done.

That;s a whole lotta yeast, though!

Yup, a lot of yeast, but if you want a 12% stout bottled, carbed and ready to drink in 2 weeks, it's the way to go.

 

[moto748]

That's probably a bit rich for my blood!

 

[private4587]

I did one of these last March, and it was great. For the first mash I did an overnight mash, which helped get a bit more efficiency, as well as dry out the first part a bit so the end beer wasn't too sweet without resorting to dextrose. I had 4kg pale in each batch, plus some cararye, dark munich and special W in each batch, then some chocolate, dark crystal and black in the second mash, as a I didn't want to extract too much out of the darker malts in an overnight mash and get astringency. To calculate volumes, I wanted to do a mash and sparge on both batches, so just did the grain-absorption/boil-off/dead-space calcs by hand. Ended up doing a 15L mash and 8L sparge on mash 1, then 10 L sparge on mash 2. Got 18L bottled, with OG of 1.118 and FG of 1.029, so about 12%. Pitching on a yeast cake of a low abv ale fermented with MJ New World Strong Ale, plus adding three packs of US-05, and it fermented quickly and very clean.

I need to get another one of these on soon. Splitting up the otherwise long brew day with a nice nights sleep was nice.

Hi Iain I am looking to do a RIS for Christmas coming could you explain an example of the calculations used