Hop Utilisation Formula

Stubbie · Post by **Stubbie** » Tuesday Dec 18, 2007 7:18 pm

It drives me mad when I play with someone's recipe, say one posted on this forum, in Promash only to get very different IBU results. On one occasion, I remember getting an almost twofold increase in total IBU's simply by changing the hop utilisation formula. If memory serves, it was Rager to Garetz, or vice versa. That's just crazy.

In Promash, there's a choice of Rager, Garetz, Tinseth or Generic formulas.

What's the go?

Cheers

Kevnlis · Post by **Kevnlis** » Tuesday Dec 18, 2007 7:21 pm

Tinseth is what Beersmith uses, that is why you get the different result.

Tipsy · Post by **Tipsy** » Tuesday Dec 18, 2007 7:23 pm

Most people seem to use Tinseth.

lethaldog · Post by **lethaldog** » Tuesday Dec 18, 2007 7:51 pm

Im no scientist but isnt an ibu an ibu, why do these different formulas get different results, im sure its much of a muchness once you get used to one as i am with beersmith but how are such different results found when they all claim to be rating ibu's?

Pale_Ale · Post by **Pale_Ale** » Tuesday Dec 18, 2007 8:21 pm

I don't know the distinct difference, but I believe the variations occur because of the variables involved and how that changes things, for instance how should you allow for differences in liquid volume, gravity, water composition etc.

Stubbie · Post by **Stubbie** » Tuesday Dec 18, 2007 10:03 pm

I too really expected to get similar results regardless of the formula. Y'now, plus or minus a few IBU, big deal. But I was shocked when the total IBU jumped from, say, 22 IBU to 38 IBU. That's with no change to the variables whatsover other than the formula.

OK, so Tinseth it is.

Thanks and Cheers.

blandy · Post by **blandy** » Wednesday Dec 19, 2007 8:36 am

Check out this thread for a bit more information:

http://www.homebrewandbeer.com/forum/vi ... php?t=7328
look at the second post.

anyway, Rager and Tinseth effectively conducted the same experiment, but got very different results. I've no idea why, but I'll assume that if you can be bothered you can find the answer on wikipedia.

the IBU is a unit of concentration of alpha acids (in milligrams per liter). The utilization values are where the calculations differ.

I think most people on this forum are using software that has a default setting for Tinseth, so that has become the unwritten convention, whether some people are aware of it or not

.

rwh · Post by **rwh** » Wednesday Dec 19, 2007 9:12 am

The best info I've found is this podcast from the Basic Brewing Network. They get a guy with software (on a Mac!) to predict the IBUs of various recipes, and then get a chemistry prof to run spectrographic tests to test their accuracy. Very interesting stuff, and highlights all of the unpredictable variables you're up against when trying to produce a uniform product over time.

July 5, 2007 - Measuring and Predicting IBUs
Two chemistry professors, Bradley Sturgeon and Paul Charlesworth, join BBR veterans James Spencer, Andy Sparks, Steve Wilkes and Mark Smith to share the results of an experiment putting IBU prediction formulas through their paces.

We also celebrate our 100th episode!

http://media.libsyn.com/media/basicbrew ... butest.mp3

Kevnlis · Post by **Kevnlis** » Wednesday Dec 19, 2007 11:07 am

I was going to recommend the same thing rwh, well worth a listen IMHO!

JubJub · Post by **JubJub** » Wednesday Dec 19, 2007 9:07 pm

I use the formulas in palmers book and made a spreadsheet out of it all. It's very crude and I get consistant results that seem to be true.

Jub

Cortez The Killer · Thursday Dec 20, 2007 3:46 pm

Tinseth here

Cheers

warra48 · Post by **warra48** » Thursday Dec 20, 2007 4:34 pm

Trial and error here.
That's why I'm drinking some of my batches by mixing two brews into one glass to provide some balance.
Then again, I really like hoppy beers, so I tend to err on the side of over hopping, rather than too little.

Pale_Ale · Post by **Pale_Ale** » Thursday Dec 20, 2007 10:37 pm

I use Tinseth, but I find it is not an exact science as you have perceived bitterness and of course serving temperature etc. - not all variables can be controlled.

Trial and error is still a big part of it even using calculations IMO

earle · Post by **earle** » Friday Dec 21, 2007 8:15 am

Also, won't the hop/malt balance affect the perceived bitterness as well? If two brews have the same calculated IBU the one with less malt will taste more bitter?

rwh · Post by **rwh** » Friday Dec 21, 2007 9:02 am

Absolutely. The IBU scale says nothing about perceived bitterness. It is defined as one part per million of isohumulone.

Trough Lolly · Post by **Trough Lolly** » Friday Dec 21, 2007 1:34 pm

earle wrote:Also, won't the hop/malt balance affect the perceived bitterness as well? If two brews have the same calculated IBU the one with less malt will taste more bitter?

Exactly Earle - and that's the important part to remember when you make recipes for your brews...you need balance and that isn't something that brewing software will give you. Sure, you can go crazy with hops or malt if you like one over the other, but some styles are very hard to make if you don't balance the malt and hop profiles of the final product.

I've had 70 IBU Stouts that were under-hopped....

Cheers,
TL

Pale_Ale · Post by **Pale_Ale** » Friday Dec 21, 2007 5:26 pm

I know some brewing software tries to allow for malt by reducing the IBUs when adding more malt to the recipe. However, that would be very hard to calculate accurately with predictable results each time.

earle · Post by **earle** » Saturday Dec 22, 2007 10:55 am

I know some brewing software tries to allow for malt by reducing the IBUs when adding more malt to the recipe

Is it adjusting for balance or just reducing the utilization?

The latest version of Beersmith does provide some sort of malt/hops ratio though, not sure how well it works.