Boil size vs. hop efficiency

[david_42]

"[Pardon the science to all of the opinionated folks out there]"

That graph certainly doesn't show anything about utilization being independent of gravity. All that shows is a saturation effect. ie the more hops you add, the less of an impact the next addition will have.

And this, which shows smooth curves dependent only on available AA without any impact of wort density (which would increase during the boil).

 

[NordeastBrewer77]

I am a little confused (OK a lot confused). My recipe only has 2# of grains, the rest is all extract. Does that mean I should only steep the grains in 3 Qt of water?

Would I then add the extra water when I start the boil?

The instructions that I have say to steep in 1.5 gallons, add the LME and then bring to a boil.

No, that's the ratio for mashing, for steeping volume isn't as important. You'll be fine steeping in the ~1.5 gal.

 

[kevinb]

So for an extract kit does that mean I should:
-Steep grains in 1.5 gallons.
-Add the extract
-Add addatiional water (example bring it up to a total of three gallons)
-Then start the oil, add hops, etc

 

[BronxBrew]

So for an extract kit does that mean I should:
-Steep grains in 1.5 gallons.
-Add the extract
-Add addatiional water (example bring it up to a total of three gallons)
-Then start the oil, add hops, etc

That's what I've been doing. Although I'm going to start to only add some of the extract in the beginning and the rest at flame out.

 

[NordeastBrewer77]

So for an extract kit does that mean I should:
-Steep grains in 1.5 gallons.
-Add the extract
-Add addatiional water (example bring it up to a total of three gallons)
-Then start the oil, add hops, etc

That'll work just fine. You might consider looking into adding some or all of the extract late in the boil or at flameout.

 

[billl]

"And this, which shows smooth curves dependent only on available AA without any impact of wort density (which would increase during the boil). "

That still doesn't show what you are claiming. The graph shows the rate of absorption going DOWN with time/gravity. Just because the graph is "smooth" doesn't mean it is independent. You can't tease apart those variables from the data shown.

What you need is a test of numerous different starting gravities with equal hops additions to show that the utilization curves are the same.

 

[ludomonster]

There are many factors at play that can affect IBU's. Here are some:
hop bags; whether the hops are pellets, plugs, or whole; hop age; boil vessel geometry; boil vigor; altitude; finings; fermenentation; filtering; finings; water hardness.

My advice is to brew using the utilization from some table or software. If your beers are coming out more or less bitter than you want, then you should determine your system's utilization. You may need to tweak this for beer that have very different ingredients or gravities.

There's a lot of chemistry that goes into brewing that is still poorly understood. This includes calculating IBU's for a given beer. It's similar to Maillard Reactions. We know a lot about them, but many things related to them are still a mystery. The good news for IBU's is that a lot of our estimates are good enough. You should be able to tweak your system to repeatably get the beer you want.

 

[TooGoodToCheck]

One time I was experimenting with late boil addition of DME, as I was trying to make my pale ale more pale. The unintended consequence was that my beer ended up with quite a bit more hop bitterness than what I had really been planning, because the first 40 minutes of the boil were done with a significantly reduced specific gravity.

Anyway, if you are using malt extract, adding it later in the boil will increase hop utilization

 

[Streeter]

I have always just filled to 4 gallons, and used that to steep, then boil, adding all the extract right after the boil starts. My beers have been tasting great so I don't know that steeping in less water is really going to make a big difference. Also it seems like it may screw things up more by suddenly dropping the 170 temp of a gal or 1.5 by then adding in 3 more gallons of cold water and having to start the boil over. Thoughts?

 

[KiwiBruce]

I suggest you use the opportunity to do two brews. One at 1.5gal and one at three plus. Not only will this allow you to test each batch boil size, taste and hoppiness, you'll have twice as much brew to enjoy! Then keep us posted on the results.

 

[ncbrewer]

Weird, because he told me that "it could be related to break material" instead of wort gravity. Palmer told me the same thing.

I’ve been looking through my notes, and I think the confusion is in terminology. From some podcasts with both Palmer and Tinseth, I think they agree that hop utilization is affected by break material rather than dissolved sugar. But break material is also related to wort boil gravity, so hop utilization is related indirectly to wort boil gravity. The formulas were developed empirically, and are still valid, but not for the reasons that were once thought.

Podcasts:
http://www.beersmith.com/blog/2011/02/10/beer-bitterness-and-ibus-with-glenn-tinseth-bshb-podcast-9/

http://hw.libsyn.com/p/3/0/4/30433c...31834041&hwt=a1babd357d2d091bbf481fb8c715d1b4

http://beersmith.com/blog/2012/02/2...-beers-with-john-palmer-beersmith-podcast-33/

http://s125483039.onlinehome.us/archive/bs_020711.mp3