Parti gyle: russian imperial stout and porter

[Surgicalbrews]

I am planning to make a Russian Imperial Stout and with the second Runnings make a porter. Here is the grist for the Russian imperial stout:

17.00 lb Pale Malt (2 Row) UK Grain 81.93 %
1.50 lb Roasted Barley Grain 7.23 %
1.00 lb Special B Malt Grain 4.82 %
0.75 lb Chocolate Malt Grain 3.61 %
0.50 lb Cara-Pils/Dextrine Grain 2.41 %

I plan on making a 6 gallon batch, I will drain 7.5 gallons pre boil to end up with 6 gallons after a 90-minute boil.

With the second Runnings I would like to make it Porter.

My first question is what should I add to the mash during the second Runnings to end up with a porter?

My second question is once I add new grain should I mash for a full hour, I recirculate throughout the mash. Or should I mash for less time? Not entirely sure on the process.

Thanks

 

[Kent88]

I don't think a parti-gyle brewer typically adds more base malt in order to start the mash process again. I think I have heard of steeping grains being added for color.

There is an episode of brewingTV on youtube from the original run with Chip W and Mike D, I think it is called "Big Beer Brewing", that does a good job explaining the process. You aren't mashing twice, you're just playing with the sparges/runnings/gyles.

You could do a separate mini-mash with some base malt and/or specialty/steeping grains if you need to and blend it with the later running "porter" wort. Porter has been one of those styles that I just don't get, so I can't really help you with what specialty/steeping grains you might need.

Here is a link you might find useful from MoreBeer.
Here is another link from BeerSmith.

I think a lot of parti-gyle brewers look at what the beer would be (OG) if you attained your usual efficiency for the full volume you will be sparging to. Then use tables or equations like these to predict the gravity of certain splits.

 

[McKnuckle]

The whole point of a partigyle is to make 2 beers from one mash. As such, you don't add more grain or mash twice.

Basically, the second/weak beer is produced by sparging the mash that you just lautered once to make the first/strong beer. This effectively makes the first beer a full volume/no sparge mash. People tend not to describe it that way, but nonetheless that's the concept. Instead of combining the first lauter and a single sparge of equal volume, the two runnings are separated into distinct batches.

 

[John Eberly]

I have done some parti-gyle beers in the past. The rule of thumb is that you'll get about 2/3 of the extract in the first 50% of the runnings.

Your proportions look OK for the flavor profiles of the two beers. What gravity are you going for with the Imperial? I calculate you'd have an OG of about 1.089 if you used all of the available extract (37 gravity points per pound of grain estimated, 70% mash efficiency estimated). That is about right for an imperial stout but would not leave any extract for the porter.

You have to make sure there is enough extract in the mash for both beers. Assuming you want about 1.090 for the stout and 1.045 for the porter, you would need about 31 pounds total grain to make a 6 gallon batch of each.

Math is ((90 points of gravity x 6 gallons)/.70 eff + (45 points of gravity x 6 gallons)/.70 eff))/37 points/pound = 31.27 lb of grain.

If you can handle this size mash there's no reason you could not make these beers.

 

[John Eberly]

Sorry, I thought of this afterward -

If your goal is 6 gallons at 1.090 OG you will need to draw off first runnings until you hit the total gravity points required, or six gallons x 90 points = 540 gravity points.

You will have to monitor your runoff gravity and volume until you hit this target. So you might stop when you have 7 gallons at 1.077, or 7.5 gallons at 1.072, or so on and so forth. This can vary with your actual mash efficiency - the good news is you'll always have enough extract to hit your first beer's gravity target. If you hit a super efficient mash you might even have to add water to the boil to account for evaporation because you get your gravity units with a smaller volume of wort.

The second beer is more like your usual process - sparge until you get down around 1.012 and see what volume you end up with.

Hope it's not confusing, best of luck.