Determining AA%

I just read yoopers smell my fingers post and among other things, it made me wonder how you can detrmine AA% when you grow ur own hops. I am considering growing some next year so was just curious.

Heineken said:

I just read yoopers smell my fingers post...

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HAHA!!!! IMO this has nothing to do with hops...

I think the concensus is that you have to send some hops away to a lab for analysis...

homebrewer_99 said:

HAHA!!!! IMO this has nothing to do with hops...

I think the concensus is that you have to send some hops away to a lab for analysis...

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Yup, lab... that is the only way an average HBer will get this figured out.

I would suggest making a tea with a known amount of your hops, as well as with a known amount of a hop with a known AA and compare. It's not exact, but it'll get you in the ballpark. I've heard the palate can only decipher IBU differences of greater than 5, so there's some intrinsic wiggle-room when it comes to how much AA your hops have when you use them anyway.

If you search around on here, there are some more complex methods which involve serial dilutions and what not.

The process is pretty complicated I think. I think if you refridgerate the hops and then dissolve the wax off of it and react it with a lead compound of some sort and the alpha acid will come out of solution and through come good old fashion centrifuging and analytical chemistry you can determine your concentrations. I wouldn't suggest doing it with less than 18megaohms/cm water though if you want really good readings. And then I believe the oils and beta acids can be determined through some form of chromatography. You could measure the pH of a boiled solution of your hops but with all the solutes it would be difficult to determine what analytes are causing such a pH. And since the alpha, and beta acids are contributing you wouldn't be able to determine which one is contributing how much hydronium ion (among all the other compounds in a plant that dissolve in boiling water). I think what I'm trying to say is that... rather than trying to wrap your head around the science just wrap your lips around that bottle and tilt it on a nice 45degree angle. The results are much more rewarding.

The simplest way is to not bother. Use a typical value for the hop and you'll be close. If exact numbers are important, you have two choices: lab tests or not using the hops to bitter.

cactusgarrett said:

I would suggest making a tea with a known amount of your hops, as well as with a known amount of a hop with a known AA and compare. It's not exact, but it'll get you in the ballpark. I've heard the palate can only decipher IBU differences of greater than 5, so there's some intrinsic wiggle-room when it comes to how much AA your hops have when you use them anyway.

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This is exactly what I am going to do with my Cascade's for this year. Seems like the palate of the end user, ME, will be adequate enuff.

david_42 said:

The simplest way is to not bother. Use a typical value for the hop and you'll be close. If exact numbers are important, you have two choices: lab tests or not using the hops to bitter.

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What he said.

I've used my home grown hops to bitter. The first batch wasn't quite bitter enough, i adjusted the % downward a bit and the next batch was spot on.

We'll see how it goes with this years hops. Hardly a tragedy having a beer a bit too sweet plus helps you get to know your own hops better.

The Soft Underbelly said:

What he said.

I've used my home grown hops to bitter. The first batch wasn't quite bitter enough, i adjusted the % downward a bit and the next batch was spot on.

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That's MY bittering intention, too. I've got some Nugget, and with a range of 12-14%, I'm going to use 13.5% in my calcs/software and call it a day.

The Pol said:

Yup, lab... that is the only way an average HBer will get this figured out.

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Sooooo, what if you have access to a lab and want to test your own hops? I have not seen a detailed procedure for doing it via mass spectrometry, photopectrometry, or titration. I need the damn details, folks.

It's all well and good if someone out there doesn't have access to the equipment, but I do... so tell me how it's done!

not sure about titration...you can use uv/vis, hplc, and im sure gc mass spec though I dont know the method for gc mass spec. http://www.realbeer.com/hops/ASBC.html you can check out the first two methods there. Gonna need to get your hands on some toluene or diethyl ether, both of which can be nasty stuff. We stock both in our research lab so access here is not issue but if you do not have access to them they may be your limiting factor.

sw341034 said:

not sure about titration...you can use uv/vis, hplc, and im sure gc mass spec though I dont know the method for gc mass spec. http://www.realbeer.com/hops/ASBC.html you can check out the first two methods there. Gonna need to get your hands on some toluene or diethyl ether, both of which can be nasty stuff. We stock both in our research lab so access here is not issue but if you do not have access to them they may be your limiting factor.

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Exactly what I was looking for! Thanks.