Right, kettle geometry is going to affect surface area (I believe some of the oils will stick to the surface area after transferring), as well as the boil off rate. Currently tinseth uses the average gravity between preboil and postboil I believe, but the boil off rate will affect this as well and adapting tinseths formula for instantaneous gravity was one of the things I was working on before my UV-VIS testing wasn’t available anymore.
I’m also curious on how fermentation affects it, testing wort IBU and fermented beer ibu. Does that impact change with attenuation, what about speed of fermentation? Does fermenting under pressure change that? How does boil pH affect it?
There are just so many variables that could play a role. :o
It’s seems to me that this IBU thing is almost an act of futility if we try to absolutely nail it down. The ingredient is biological and inconsistent by nature. So even if we found a pristine formula that worked every time, it’s still only working on the AA numbers that apply to the plug pulled for the lab, not necessarily for the ounce we have in our hands. Not to mention a big question mark on exactly how that ounce was handled. Striving for an absolute in this part of brewing, especially at our level… futile!
Then, if you send every brew to the lab for spectography, your getting a numeric value, but how are you perceiving that bitterness?
I say pick a method of estimating and stick with it then adjust in the future to taste.
Edit: sorry, I just watched 5 minutes of news and it put me in a mood. Not your fault.
Agreed, with one minor exception. When we sent the hops out for testing prior to sending them to the IGORs, they were really close to what they were listed as. Not exact, but close.
So, we know those hops were close to advertised. We still don’t know about all hops. Point being, seeking IBU absolute accuracy is kind of a fools errand. Close enough is close enough.
Absolutely. One thing that may help homebrewers get a bit closer to what they expect is the new packaging from YCH that includes HSI. But like you say, it’s still a SWAG.
I say pick a method of estimating and stick with it then adjust in the future to taste.
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This is exactly what I was thinking as I read through the thread. Beersmith is my method, and it produces consistent results to my taste in my brewery. Some of my friends have commented that my IPAs aren’t as bitter as I say they are, but they taste good to me. And, by the way, my friends aren’t exactly boycotting my taproom on the basis of science.
For home brewers, maybe even commercial, I think we’d be better served to use which ever calculation we choose (sticking with one) and then when someone who is sampling the beer wants to know “how many IBUs” don’t use numbers, just say low or medium low, or high, or very high, or whatever term best describes it. Or take the time to explain what is behind those pesky IBU numbers… good conversation piece.
On the other hand, telling them “47 IBUs” and hearing them say “hmmm, tastes more like 45 to me” tells you a lot about them lol
Oakshire had Dana (the lab person we used) come in and take reading every 10 minutes throughout their boil. That way they were able to develop a custom utilization curve so they know exactly how many IBU they’re getting. I imagine other breweries do the same.
That would be the best way. But how do you deal with the problem that most breweries don’t do that? So customers are used to the beer they drink that randomly claims X IBUs, and that beer seems different than the true numbers on the new beer. And round and round we go
You don’t taste mill gaps… I don’t taste IBU calculators
I realize that the IBU number itself is based on each brewery and a correlation to what the drinker perceives. My question pertains to calculation of that number.
When I calculate in BeerSmith I get a wildly different number that in Brewer’s Friend. I believe they both use Tinseth’s calculation but how are they 15 points apart? (I was not exact in my duplication but close enough to make the point):
Volumes – This is the biggest one. Your first entry in Brewer’s Friend says 6.5 gallons, versus BeerSmith says 5.5 gallons. That will have a huge effect.
Late hop additions in BeerSmith look way off to me. Should be much lower in single digits, not 10 IBUs each.
Are you really using whole hops? In Brewer’s Friend you specify whole hops. Not sure about what you put into BeerSmith. But make sure those are consistent between the two softwares.
If whole hops and 6.5 gallons, I calculate about 26 IBUs. Otherwise… well, it depends on all 3 of those things above.
I brew 6.5 gallon batches with whole cone hops and have evolved my own simplified method for making IBU estimates (my palate tells my my system has been dialed in to pretty darn good enough.) With your recipe I would anticipate about 22 IBU in wort, leaving about 16 IBU in beer. That’s a little lower than BF, but way closer than BS. Something just looks fishy to me with BS’s numbers. I know that doesn’t answer your question, but it might help you evaluate the results.
I agree with both of you: sumthin ain’t right. I also think at those quantities the result should be much lower than BS tells me as well which is why I poked the numbers in Brewer’s Friend to compare them.
Dave, I am using whole hops. I plan 6.5 post boil and 5.5 in the fermenter.
I want 10 IBU(s) each of the Aroma and Flavor hops.
The utilizations in BF look very plausible to me, with the caveat that you might get a little bit less with the 10 minute addition, but that’s quibbling over numbers we can’t be exact about anyway. And with whole cone, I completely ignore the contribution of a 1 minute addition. If I were you, I’d just manipulate your recipe in BF until you get the values you’re looking for. It will be closer than your palate’s ability to distinguish, I bet.
That’s still showing 5.5 gallons for the volume… or does that mean volume to the fermenter? But but on another note, your hop schedule is starting to look pretty good. I’m no longer a fan of super late additions. Maybe using whole cone and gentle boils helps, but I get more flavor and aroma pushing it back from the end.
Your batch size is clearly 6.5 gallons then, regardless of how much you actually end up with in the fermenter. Why the waste of a gallon anyway? Is that for lost wort due to using all whole hops?
Good question but it would be the other way around. I used to lose at least a gallon when using pellets. With whole cone it’s less than a quart. One (trivial) reason I went back. But what’s a gallon if you’re happy with your process and its predictable.
