What is the Late Extract Method?

[Schnitzengiggle]

+1 on this.

Hops utilization isn't affected by wort gravity. So late addition isn't going to help with utilization.

This is something most of the common formulas for estimating IBUs get wrong, so if your software has a flag to adjust hops utilization for late additions you're better off leaving it off even if you're doing a late addition.

I disagree about the wort gravity, the more concentrated the wort the less utilization you get from your hops, this is one reason why LA method is employed. Basically you want to have a lower gravity/less-concentrated wort to utilize the AA's in the hops more efficiently, hence increasing the IBU's. However, adding top-off water will dilute the total IBU's. Conversely, adding all of your Extract in the beginning of the boil will reduce the utilization of the AA's lowering overall IBU's, plus you will dilute further with top-off water. Of course, this is considering you are doing partial boils rather than full boils.

 

[smakudwn]

cant you boil for a shorter amount of time iif you wanted less hop utilization?

 

[homebrewer_99]

Hops utilization isn't affected by wort gravity. So late addition isn't going to help with utilization.

That's not true...wort density DOES effect hop utilization (extraction) as well as the harsh bitterness extraction from ther hops.

 

[homebrewer_99]

cant you boil for a shorter amount of time iif you wanted less hop utilization?

Yes, you can.

See the Hop Utilization Chart in Papazian's The Complete Joy of Homebrewing...

 

[SumnerH]

I disagree about the wort gravity, the more concentrated the wort the less utilization you get from your hops

That's not true...wort density DOES effect hop utilization (extraction)

No, it doesn't. This is a common myth among homebrewers that people like John Palmer are only in the past year or so working to dispel.

See, e.g. https://www.homebrewtalk.com/f128/estimating-bitterness-algorithms-state-art-109681/ for links to interviews with John Palmer and journals from the American Society of Brewing Chemists dispelling the notion that hops utilization is affected by gravity.

Common IBU algorithms do include a gravity factor, but it turns out that the actual impact on utilization is related to the total amount of break material in a boil and not to the gravity or concentration of the boil. That's an okay proxy in all-barley recipes but falls apart a bit in cases where the break increases much more than the gravity increase (e.g. wheat/rye) or much less (e.g. simple sugars). It also is a function of total amount of break, not concentration thereof, and is thus unrelated to boil size.

Now, there might be a small impact on utilization in a concentrated boil, but nothing like the gravity factors would predict (e.g. according to Tinseth you'd need about 60% more hops in a 2.5 gallon partial boil to get the same bittering as in a 5 gallon boil). If there is, it's because of volume-to-surface-area issues, not wort gravity.

 

[Schnitzengiggle]

Well then, I'll sit down and shut up. I guess the science of IBU's is finally being taken a little more seriously.

Or...we could agree to disagree...

Lets say the verdict is still out.

Having said that, does that mean in a partial boil with ALL extract and w/o any steeping grains that there would be no loss of IBU's and that the hops would be fully utilized such as in a full boil?

 

[SumnerH]

Lets say the verdict is still out.

Having said that, does that mean in a partial boil with ALL extract and w/o any steeping grains that there would be no loss of IBU's and that the hops would be fully utilized such as in a full boil?

The verdict is still out. Certainly the numbers you'd get if you believe the gravity factors used by IBU estimation algorithms (Tinseth, Rager, Daniels, Garetz, Mosher, etc) are a little out of whack; gravity correction would say that a 2.5 gallon boil needs about 60% more hops than a full boil to reach the same IBUs.

Empirical experience from home brewers seems to guess that around 10% more is a better guess, perhaps because of the lower volume to surface area ratio of the surrounding pot (exposed surfaces can pull isometerized alpha acids out), or perhaps for some other reason.

I've found a couple of places that will do real IBU measurements, so one of my goals for later in this year is to do some controlled tests of the same hopping with full and partial boils and early and late additions, as well as with grain vs. extract and see how they measure out. It's about $40/beer to test so it'll be a little while before I get the funds together to do it. I'll certainly post in the IBU thread over in brew science when I get results.

My personal guess is that there will be some relatively small difference (much closer to 10% than 60%) between full and partial boils, that there will be some difference between grain and extract, and that there won't be much difference between early and late addition. But I'm not particularly confident in any of those guesses.

And it's worth noting that perceived bitterness doesn't necessarily correlate exactly with IBUs (as Palmer's interview and other sources note). The age of the hops, the variety of hops, how much residual sweetness there is to balance things out, the aroma and flavoring, and a whole host of other factors can affect how bitter something tastes in ways that can vary differently from the IBUs.

 

[homebrewer_99]

No, it doesn't. This is a common myth among homebrewers that people like John Palmer are only in the past year or so working to dispel.

See, e.g. https://www.homebrewtalk.com/f128/estimating-bitterness-algorithms-state-art-109681/ for links to interviews with John Palmer and journals from the American Society of Brewing Chemists dispelling the notion that hops utilization is affected by gravity.

Common IBU algorithms do include a gravity factor, but it turns out that the actual impact on utilization is related to the total amount of break material in a boil and not to the gravity or concentration of the boil. That's an okay proxy in all-barley recipes but falls apart a bit in cases where the break increases much more than the gravity increase (e.g. wheat/rye) or much less (e.g. simple sugars). It also is a function of total amount of break, not concentration thereof, and is thus unrelated to boil size.

Now, there might be a small impact on utilization in a concentrated boil, but nothing like the gravity factors would predict (e.g. according to Tinseth you'd need about 60% more hops in a 2.5 gallon partial boil to get the same bittering as in a 5 gallon boil). If there is, it's because of volume-to-surface-area issues, not wort gravity.

Granted, we all learn from different sources and there is more to learn every day, but I based my statement on Papazian's TCJOHB, pages 257 and 258...which IS based on density.

...and I've been using this info since 1994...

 

[SumnerH]

Granted, we all learn from different sources and there is more to learn every day, but I based my statement on Papazian's TCJOHB, pages 257 and 258...which IS based on density.

...and I've been using this info since 1994...

Yeah, Palmer admits that he got this wrong even a decade after that (in the 2005 edition of How to Brew). It's one of those things that commercial brewers have known for a long time, but never crossed the aisle--in large part because commercial brewers never use IBU estimation algorithms, they actually measure the IBUs of their brews. And for a fairly broad spectrum of beers, using gravity as a stand-in for the amount of break material results in fairly close results.

 

[Schnitzengiggle]

Regardless of the math and the numbers, it is truly all relevant to individual perception. Almost everything can be brought down to relevance