Late Addition affect on IBUs in recipe calculator

[MrBIP]

Is there an assumed (standard) timing for late addition in extract brewing in the calculator?
Perhaps I'm nitpicking, but wouldn't there be an effect on IBUs if say you made a the late addition at 15 minutes and then added more hops at 10 minutes (slightly higher IBU) versus hops at 15 minutes and late addition at 10 (slightly lower IBU)?

I've had a late addition in first two brews, did them both at 15 ... why 15? because the first thing I had was a recipe kit and the directions said 15.. no other reason.

 

[LarryBrewer]

In the recipe editor the late additions are not factored in the boil gravity at all - as if they are added at the very last second. So yes the IBUs would be slightly lower if you added the late additions at 15 minutes. I think the brew feature tells you to add them at 10 minutes just so they are completely mixed in and sanitized. If you want to see what that difference is, in the recipe editor temporarily set the late additions to off, and compare the IBU contribution difference from just the late additions (per line, not the total recipe since the 60 minute additions will be different too).

I recently read some debate on HBT discounting the idea that boil gravity and IBUs are even related. Someone was saying that 'Palmer got it wrong', but no reference was provided. I'd need to see some real science before doing anything different with the calculators. I personally tasted more bitterness back when I was an extract brewer when I switched to doing 50% late additions of my malt extract.

 

[Nosybear]

Make life easier on yourself. Add the malt syrup at flameout and let stand for ten minutes before chilling. That time will be enough to pasteurize the syrup and all the calculations become easier. About the only exception to this process I make is when I'm making black, malty beers and want lots of Maillard reactions. Never had an infected batch, at least from syrup additions after flameout. Pasteurization temp is 170° - as long as you keep the mix above that, it will kill off any bugs you add with the syrup.

Of course, you'll have to adjust hops for lower gravity - utilization is a function of gravity.

Cheers!

 

[chessking]

+1 on Noseybear

Add the extract late and save yourself a lot of worry.

 

[MrBIP]

.....saying that 'Palmer got it wrong', but no reference was provided. .

Thanks all for info on that....

As far as 'Palmer got it wrong' ... probably some more reading I need to do there, but seems logical to me that higher gravity would certainly diminish the input of the bitterness from the hops... I never even questioned it going into this.

 

[Nosybear]

I've seen the reference to utilization decreasing with wort density elsewhere - seems to be an issue of faith among brewers. Of course, so was geocentricity pre-Galileo. Given the complex chemistry of a wort, I'll believe it right up to the time someone has proven it doesn't matter. But pertaining to bitterness in general, our palates are so insensitive five IBU either way probably doesn't matter, except to a gas chromatograph.

 

[The Brew Mentor]

It's funny how things have changed in just the last couple of years.
According to the "pros" just a few years ago, they said that boil gravity had a large affect on utilization. Then Palmer changed his tune and said there was much less to no difference.
This has been discussed on the brewing network ( or some other podcast I listened to) and many forums(HBT).
Recently there have been discussions on just boiling hops in water to get an IBU burst if needed.( No gravity, but I promise there is utilization. Try some hop tea if you don't believe me :shock: )
I think the best judge is your own pallet. Brew it to the best of your ability and then make minor tweaks to dial it in.
As stated earlier, it is very difficult for the pallet to distinguish a difference of 5 or even more IBU in a recipe.
Think of it as education. " Honey, I really need to brew 5 more gallons of beer to determine the minute differences in hop utilization" :mrgreen:
Brian

 

[Nosybear]

Nice touch, that last.... ;-)

 

[Kaiser]

taste is a poor indicator of IBUs and since most home brewers can't measure IBUs we have to base our "IBU" numbers on the research of a few that went through the effort of measuring IBUs.

For all practical purposes, find a method that works for you and adjust your IBU targets to what the beers taste like and not the measured IBUs that commercial beers with the similar perceived bitterness list. That's one of the first things I learned in home brewing when I brewed a SNPA clone, aimed for 39 IBUs and found that the beer was way too bitter.

As for the discussion of the science behind this, I'm interested. Does someone have a link to the discussion on HBT?

Kai

 

[The Brew Mentor]

I remember Yooper stating that in a personal conversation with John Palmer that he said In his book "He got it wrong" .
Now, for what thread I read it in, good luck with that! I read and research a lot.
Sorry.
Brian

 

[LarryBrewer]

It's all just internet hearsay until we get an actual experiment with repeatable results.

Maybe we'll have to run the experiment ourselves? As I understand it, a beer sample can be sent off to a lab for IBU analysis, but it is not cheap. I thought it was around $50 per sample. Real IBU numbers would be interesting for a variety of reasons, but I'd want to take 200+ samples to build a reliable data set.

 

[chessking]

Lab measured IBU numbers can't tell the whole story. Gravity, Malt bill, Alcohol level, residual sweetness, all effect the "perceived bitterness". The pallet is the final arbitrator, and mine is the only one that is correct. To me at least.


But I could be wrong.

 

[Nosybear]

Larry, I don't think you'd need that many samples. You can get some reliable data with as little as five. In fact, there's a famous statistical test developed by a gentleman named William Gossett. He needed to compare small sample sizes, so he developed a test to do so. Since his employer would want to remain secret, he published the paper under the pseudonym "Student" and since then, we quality geeks use Student's T-test when we are comparing small (as few as five). His employer? Guinness. He was the chief experimental brewer.