Accounting for dilution in an extract IPA

It's an interesting question because I suspect there is not just one answer - compounds that we appreciate for bitterness vs. aroma likely have different extract efficiencies in relationship to sugar concentration and may require different tweaks. Just speculating. The common wisdom, which is modeled in some brewing software programs, is that you need more hops for bitterness in a concentrated extract* There was at last one experiment on the Basic Brewing Radio Podcast that seemed to debunk this idea; but that's one experiment, so who knows?

*If I construct an extract Pale Ale using Beersmith (OG 1.051, 5 gallon batch, 1 oz of centennial at 60, 15, and 5 mi), the program tells me I have 38IBUs if I do a concentrated 3 gallon boil. If I double the boil volume, 59 IBUS.

As Vikeman has thought about this stuff to program his own brewing recipe calculator, wait for him to chime in to get more details on how programs tend to treat this issue.

I suggest you use some software as a guide and adjust according to personal tastes over several batches. Or else start doing full boils, which might save you money on hops, but you'll still have to adjust taste.

 

I would recommend taking whatever program you're using and populate a version of the recipe pretending it's a small, high gravity batch. i.e. batch size consistent with your size before adding the topoff water. And gravity of the wort before topping off. (The latter should be automatic when you decrease the batch volume input.) In this version, you'll also need to target higher IBUs that are...

Real IBUs You Want in Final Beer X (Final Batch Size / Pre-Topoff Batch Size)

i.e. target IBUs that are roughly double (in the smaller batch size). You'll find the total hops needed are more than with a full boil. With an IPA, it may be very hard to get the IBU level you are looking for (if it's relatively high), even if the calculation says you can. That's because solubility of iso-alpha-acids decreases as you get into the upper end of theoretical IBUs.

Will this result in a final beer that's exactly the same as if you had done a full boil? No. But it's the way to get in the ballpark.

 

As Peter (@pweis909) made mention, there was an experiment by BYO/BBR in 2010 on whether a partial boil affects hop utilization. The results of the experiment were that there was no effect.

You can listen to the podcast of March 4, 2010 and hear for yourself:http://www.basicbrewing.com/index.php?page=basic-brewing-radio-2010

Cheers!

 

IIRC, I think there were some flaws in that experiment, which I can't quite remember. I may have to listen to it again.

 

Even if that experiment was squeaky clean within its parameters, do you think it's possible to prouduce a 70 IBU IPA with a partial (say half) boil? That would mean getting 140 IBUs into the boiled wort.

 

I can't recall finding flaws in the experiment when I listened, but it was some time ago. It is a controversial result, given that it flies in the face of the common wisdom. While it is hip to debunk "common wisdom," I think this wisdom about sugar concentrations and hop utilization exists because it reflects experiences of homebrewers and professional brewers. I don't think people should dismiss that wisdom based on one study. I guess I brought it up to stir the pot a little bit. Shame on me.

I think the most important point I can make on the topic (and maybe the only one that counts) is that the brewer should taste the beer and make adjustments accordingly. This should be my default response to all questions relating to hop utilization. Also in a Basic Brewing episode, Glen Tinseth more or less said hop utilization is unique to every homebrewery. Numerical calculation of the IBUs is only of use for internal consistency (paraphrasing both Tinseth and Zainasheff on this, I think). You still need to calibrate your beers with your taste buds.

 

“Also in a Basic Brewing episode, Glen Tinseth more or less said hop utilization is unique to every homebrewery.” I have heard Glenn Tinseth in a podcast state relative to his hop utilization estimator: “This is a great formula for my 10 gallon home brewery.”

Cheers!

 

FWIW, the highest laboratory measured IBU level in a commercial beer that I can recall ever hearing is 113. That's pretty much it as far as testable evidence has shown for the actual physical IBU ceiling.

So I'd say no, you're not going to get 140 IBUs into a partial boil, and I'd be very skeptical of any experiment that claimed you could derive 5 gallons of 70 IBU beer by diluting 2.5 gallons of concentrated wort.

 

One tool that might help the partial boil brewer is those hop extracts, e.g., hopshots.
http://www.northernbrewer.com/shop/hopshot.html --1 mL of this CO2 extracted resin can add 10 IBUs to a 5 gallon batch. That's pretty concentrated stuff. So if you are brewing a double IPA that calls for 70 IBUs of bitterness and you are not tasting 70 ibus of bitterness because of your concentrated boil and/or the fact that you are diluting, this could help get you where you need to go.

 

I'm not sure I see how that helps when it still needs to be boiled to yield IBUs and you still have the issue of the IBU concentration ceiling.

 

My bad. I was thinking of isoextract, which doesn't require boiling. So you make 50 ibu concentrated wort that you dilute to 25 ibus. You add the ISO to get it back to 50 ibus. You might also be able to isomerize the hopshot with a small volume boil and essentially do the same thing. I don't know that these extracts could get you through the ceiling but they should help with dilution issues at lower ibus.

 

I've been wondering about this.... My experience is that my beers seem to be under-hopped... given the IBU's Beersmith is calculating for me. Methinks I need to investigate this... I could be in for some interesting brews in the future...
Ahhh... the bitterness of failure!

 

It's your beer, so if 50 ibus as calculated by beer smith doesn't seem bitter enough, brew the same batch at 60 ibus and see if that helps. I'd ramp up 10 ibus at a time. I've read that people have difficulty detecting 5 ibu differences. That likely depends on the absolute ibus (10 vs 15 might be more noticeable than 50 vs 55) and of course, the individual taster.

 

Peter, on a podcast I heard somebody (John Palmer?) state that the typical beer drinker cannot discern a difference of 7 IBUs.

Cheers!

 

I heard it was 6.

 

I use Co2 extract to bitter my IPAs and this won't really fix the issue. It's based on volume, and how long you plan to boil. Similar to what would happen with leaf and pellets, but I honestly think you get a better bang at the estimated IBU's with extract than you would otherwise.

 

I thought the same as well. Couple that with a lupulin threshold shift, and you'll find your IPAs being a bit weak. I started using extract to bitter my IPAs, and giving them a longer boil. Laid off the heavy bitter IPAs for a week or so, and I noticed the beers starting to stand up bitterness wise with the beers like Sculpin and Pliny, Ruination, etc.

 

If it is isoextract, as I suggested in my followup post, the alphas are already isomerized, so there should be no issues with volume and boil length.