Lab Test Hop Utilization Question

[kaz4121]

I've shifted to using a hop basket instead of loose pellets in my beers. I've noticed lower utilization, so I was hoping to get a true sense of IBUs for my beers. I've found several labs that analyze hop utilization, however my question is:

Can I brew one beer with, say, a target IBU of 50, submit for testing, and then scale my brewing software to match?

In other words, if my target IBU is 50, but lab measures 40, can I use a coefficient of 0.8 to get an accurate reading for ALL of my beers?

OR do I need multiple samples (like with pH meter) to create sort of linear (or nonlinear) function to estimate IBU via software?

I'm trying to avoid spending a few hundred on each beer I brew and would rather try to have my brewing software be a bit more accurate since many of my beers seem way under hopped now.

 

[ajdelange]

Unfortunately even a lot of data isn't going to help you much as what you can reasonably predict and what you measure can vary by quite a bit. I think this is mostly because what it says on the package and what's in the package can differ by quite a bit. You don't know, in general, which year's crop you have in hand nor the history of that shiny foil bag since it left the packer.

 

[kaz4121]

Unfortunately even a lot of data isn't going to help you much as what you can reasonably predict and what you measure can vary by quite a bit. I think this is mostly because what it says on the package and what's in the package can differ by quite a bit. You don't know, in general, which year's crop you have in hand nor the history of that shiny foil bag since it left the packer.

but do you think I can get closer than I am now?

 

[brewfun]

I've shifted to using a hop basket instead of loose pellets in my beers. I've noticed lower utilization, so I was hoping to get a true sense of IBUs for my beers. I've found several labs that analyze hop utilization, however my question is:

Can I brew one beer with, say, a target IBU of 50, submit for testing, and then scale my brewing software to match?

If your fermentation and packaging process is 100% consistent for every beer you make, then it could be close. However, if you have differing variables like yeast pitching rate, fermentation temperature, foaming and blowoff, or even total surfaced area in contact with the beer throughout the process, then all bets are off. Hop isomers are hydrophobic and look for every chance to leave the beer, including through foaming.

In other words, if my target IBU is 50, but lab measures 40, can I use a coefficient of 0.8 to get an accurate reading for ALL of my beers?

OR do I need multiple samples (like with pH meter) to create sort of linear (or nonlinear) function to estimate IBU via software?

You can do several things to get a sense of how efficient your utilization is from kettle to glass. The first is to triangle test beers you made with commercial examples that have known IBU levels similar to yours.

You could make a beer with <8 IBU at about 4 to 5% abv. Use hop isomer extract to get to a known bitterness level and both compare that to your beer and calibrate your palate.

I'm trying to avoid spending a few hundred on each beer I brew and would rather try to have my brewing software be a bit more accurate since many of my beers seem way under hopped now.

Not all IBUs are created equal.If you're bittering with Horizon, it'll be bitter, but not harsh. If you're using Chinook, that'll definitely leave a different impression.

Isocohumulone is perceived as more bitter than isohumulone. There is also apparently a difference in perception between trans and cis versions of each isomer (still being studied). University of Oregon has shown that even unhopped beer has 2 to 5 IBUs from husk tannins (well below taste threshold, but unavoidable).

The last thing is that the more calculated IBUs you have, the lower the efficiency. I don't think there's much research about bitterness above 50 IBU and nearly every brewery with a lab admits that 80-ish IBU is the upward limit of saturation.

Really just find a trustworthy hop supplier (as AJ implied) and calibrate your recipes to your palate. If the beers need more bitterness, add more hops. It's what lab analysis would point to, anyway.

 

[ajdelange]

but do you think I can get closer than I am now?

How close are you now? All you have at this point is an inclination that things don't seem right.

It has taken me a while to get back to this because I was looking for data. I finally found it. I apparently studied 24 beers whose bitterness I had measured using the ASBC method which gives an IBU number (same as EBC's) which 'adequately describes beer bitterness'. Those vague words (from the MOA) alone should convey a hint as to how iffy this is. I then took the 24 IBU readings and went back to the recipes from which I collected all the hops info (charges, times...) and stuck those numbers into the Tinseth model. Now this model comes with a couple of parameters and like the good analyst I am I tweaked the parameters to give me the best fit (mmse) of my readings to the model. Even so the results were anything but reassuring. The mean error was 3% and the rms error 17.6% with peak errors ranging from -35% to +30%.

Now were I a craft brewery that had a cooler filled with my year's contract hops buy I would expect to be able to do appreciably better than this but as a home brewer buying hops when I need them from whoever has them I guess I'm not really that surprised.