Brew question - double batch of two different styles with single mash & boil.

Hey,

planning to brew again soon. Want to do a version of Biermuncher's "OktoberFast Ale".
I want to re-use some fruit from secondary sour beer fermentation for a second sour beer from the same mash. I don't want to have to do two mashes if I can avoid and would like to try this just to have some fun and do things a little differently.

I was planning to brew a 20 gallon batch, and brew 10.5 gallons (post boil volume) concentrated wort, diluting in fermenter to desired gravity with about 9.5 gallons of water. This is nearing my maximum capacity.

Here is the wrinkle though - I want the Oktoberfest style beer to have about 20 ibu, and the soured version, to have less ibu.

I don't think that Beersmith accurately reflects the IBU of finished beer when you go into the top off water under the VOL tab and add water to the fermenter/bottling section.

Also, my sparge water is only like 5.5 gallons, and wonder if that'll be enough to achieve similar extraction of sugars without adding DME to the BK.

I could always adjust bitterness with the iso alpha stuff in sold by hoptech, but would rather not have to if I can avoid.

It seems that I should probably make my wort, and split it like 70/30 or 60/40 - more wort going into the oktoberfast and less into the soured half - and the higher attenuation of the soured half will give it a similar % ABV even though there is a smaller OG. I know based on the first sour beer that its going to be getting close to 1.000 FG.

Once I decide how strong to make the wort and what fraction to split off to the OktoberFast to achieve desired volume and OG with dilution water I can get an estimated ABV for both beers.

What I don't want is problems with too many IBUs in the soured portion of the wort, and I don't really have a handle on how to calculate and plan it out.

Seeking advice. Another option I could do is a parti-gyle but don't know how to determine OG for first and second runnings. That would solve the IBU problem but I'd have to do a double boil which I'm not too crazy about.

Thanks

TD

Ok,

Well I think I have a pretty good handle on this after some late night tinkering around in beersmith.

Gonna brew up about 11 - 10.5 gallons of wort, est at 1.092 OG and dilute to working strength in fermenter.
I'll need to keep IBUs low, but can add ISO alpha extract to adjust bitterness in the keg. I don't see any other way around it.
I am assuming IBU dilution works the same way as alcohol dilution. I assume also that beersmith correctly will deal with the high OG in estimating IBUs.

One other thought I had was taking a secondary pot and draw off a 1-1.5 quarts from the main boil kettle, and diluting a little to get SG down to 1.055 or so, then boiling a high alpha hop like magnum in this wort, maybe like 2 ounces even, and then fermenting separately and blending back into the Oktoberfest beer to achieve desired bitterness, rather than use the extract.

TD


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Well continuing the one man thread...

Scaling the oktoberFast ale recipe into a high gravity, estimated 1.092 post boil wort.
Beersmith for Mac seems to puke on the numbers and dilutions in the recipe design part.
Estimated post boil volume 11.18 gallon, so let's say 10.5 gallons accounting for losses in equipment.
So by my math, the Saflager 34/70 seems will hit 83% AE. The sour blend will hit 100% for all practical purposes. If anyone can comment on the performance of the Saflager, I've not used it before. Planning to ferment at 50°.

If I want to hit approx 5% ABV on the lager half, I would dilute an appropriate volume of wort to about 1.046 OG. That works out to exactly 5 gallons water to 5 gallons wort. I might tweak this a bit to end up with 10.5 gallons at the same gravity or 5.25 gallons of each to account for losses during fermentation.

For the soured half, I also want to keep a low-ish ABV. Target OG in the neighborhood of 1.040, expecting near 100% AE to end up with 5.2% ABV. This would require the remaining 5.25 gallons wort at 1.092 plus 6.75 gallons water for total of 12 gallons. The fermenter I'm planning to use for this is a 13.3 gallon conical. That leaves some room for the fruit leftover, but probably not enough room- I think there is a good 3-3.5 gallons of fruit. I suppose I could homogenize the fruit all together and split six gallons of the diluted wort in with all the fruit and ferment the other half without any fruit, or split fruit equally among two smaller fermentation vessels. The residual sugars and adsorbed beer in the second-use fruit does add an unknown element. I'm planning that the fruit will inoculate the wort without adding any additional yeast.

What I am most concerned with though is the IBUs in the beer. My target IBU for the oktoberfast is 21. If I dilute the wort 50:50 with water I think the IBU are proportionally diluted as well, so I would need to brew a 42 IBU wort. The math for the resultant IBU for the sour half is 18.4. That's much more than I would like. Half that value would be best, but not ideal for the oktoberFast.
I think that I will resort to "cheating" and add an appropriate dose of ISO alpha extract from hop tech. I have discovered that my boil intensity is often insufficient to achieve appropriate bitterness levels, though have since corrected this problem. To adjust a couple of beers I gave this stuff a try, and it seems to work as advertised, though is a little intimidating to use the first time.

Comments?

TD




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Well at least the homebrew mags can address the issues.....

Update.

Brewed this 13 days ago. Ended up splitting wort into two kettles for different hop schedule. Immersion chilled to below 100 then racked to cooled fermenters to attain desired pitch temps for each half:48 for the lager, and 78 for the sour. Screwed up though, I realize that I must not have reset my mash tun temp controller after heating mash water to strike temp to 161, I think I left it there, and I ended up mashing too high. Wanted to mash at 152. What a dummy!! Very upset with myself on that. Will see what happens.

Half was an oktoberfest. 1.049 OG, down to 1.016 and possibly stuck there probably because of the too high mash temp. Target was 1.009. Using 34/70 dry lager yeast appropriately hydrated before pitching. Tastes pretty good, but would like to shed as many more points as possible. Allowing to rise for a Diacetyl rest, so will see if that coaxes out any more points.

Other half was for a sour beer on remnant fruit from previous sour batches (rhubarb, blueberries, and guava). I filled that fermenter to nearly the top with 1.047 OG wort and it's down to 1.004 now, nicely souring and developing some funk. No additional yeast or bugs pitched.

Overall, it was a great way to pull off two different brews. I imagine that it might be possible to include steeped grains, or mini-mash of darker or roasted malts to have even more variety out of the brew day. I think there was a timely article in BYO about some creative ways to do this in several, slightly different ways.

TD


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