Estimating AA%

I just read the article in BYO on home hop growing and processing. Of most interest, the author claimed to have great success with drying fresh hops in a hot attic, placed in a thin layer on some spare window screens. While informative, the article still leaves a lot to be desired in determining the AA% of homegrown hops. I have read this thread, but I want an easy home/DIY approach. Here's my proposal:

Buy/acquire some small quantities of whole hops at widely varying known AA%. Make hop teas from VERY carefully measured identical amounts of the different hop varieties, including the homegrown varieties. Boil the measured hops under identical conditions and in identical quantities of water (perhaps with a small amount of DME to enhance the utilization) for at least 30 minutes. When cool, taste each tea. Compare and contrast each known AA% tea with the unknowns, and estimate the AA% of the unknowns based on perceived bitterness. Some crackers, parsley, or other palate cleansing foods may be helpful during the process.

Is there any merit to this, or do you guys think it's still just a shot in the dark?

The only suggestion I would make is to do the tests blind over several days or a week. If you can get your SWMBO to relabel all your samples every day for a week or so and then repeat your taste tests, you'd get a far more accurate result.

Do you plan on using your homegrown hops for bittering as well as aroma and flavor?

I went to an Off-flavor seminar a couple years ago and very few people could tell the difference between 20 IBU & 30 or 30 & 40, so I think your results would be no better than using the average AA% for that hop.

Yuri,

that might give an idea of the AA%

it would take one heck of a palate to notice subtle differences

I wonder if you could use a PH test strip to check acid levels

something like these

http://www.indigo.com/test-strips/pH-test-strips.html

There is a real crude procedure I read online for titrating to read AA. I have all the gear at work, so I may try this with a few different hops from the LHBS and see if I can come up with a repeatable curve. I'm thinking it won't work, but it won't cost me much to try.

Fingers said:

Do you plan on using your homegrown hops for bittering as well as aroma and flavor?

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Honestly, it's all hypothetical since I'm not growing anything this season. The article just got me thinking. Were I to grow hops, I'd like to use them just like I use commercial hops of the same varieties.

mr x said:

There is a real crude procedure I read online for titrating to read AA. I have all the gear at work, so I may try this with a few different hops from the LHBS and see if I can come up with a repeatable curve. I'm thinking it won't work, but it won't cost me much to try.

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Can you post the link to this procedure?

I think this is really the only method to get any usable information. Taste-testing a hop tea just doesn't have the precision and you could end up estimating way off (since who knows exactly how a percieved bitterness from a tea will impact the final product). This is my first season growing my own hops (both bittering and aroma/flavor) and I've decided that the first batch of beer will be the test phase (with very detailed notes and EXACT volumes during wort preparation), and then using that data to fine tune the next batch. It would be difficult for me to imagine the first beer could be undrinkable (and probably fantastic) so while the second batch should be better, that would be the least scientific method.

Even better might be to do three 1.75 gallon batches from your 5 gallon wort (5 batches just sounds like too much work). As long as you do a late extract addition with the bulk of the extract the data should be comparable enough (you all grain guys can do something similar right?). I'd also recommend using a small boil volume for the bitterness extraction and transfer the wort into a large measuring container to accurately divvy up the hop juice (maybe a pre-measured apple/orange juice container..the heavy-duty plastic ones, not glass obviously). All you would have to do would be to split up the extract evenly into 3 separate containers. After reading this over I think for the best results you should confine the hops to a bag so you don't have stray pieces getting into the containers and screwing up the results.

Now you need to decide what ratio you want test. I think you would want pretty large differences to be able to draw some conclusions so 60-30-10 would probably be the best bet. At 45-60min or so take 60% of the boiling wort and add it to container #1 (this should be the most bitter). Now add 30% to container #2, and finally 10% to container #3 (least bitter). Bring all liquid levels to equal (probably should have boiling water ready since the 10% container will probably not be too easy to dissolve the extract with cool top-off water).

Now minus the slight difference in total extract for each container (#1 has slightly more malt than #3), you have a pretty good experiment to test the AA%. You'll have to wait a bit for results (don't know if you can judge a green beer on acceptable AA% levels or whether you need to bottle condition to get an accurate picture), but it should be pretty easy to decide how to make the next batch for the perfect combination of bitterness.

HTH.

I think it is probably not a bad approach to try your test, Yuri, but what David said got me thinking. How does one relate bitterness? As for an analogy, I have a very hard time when I am making food for others that includes chilis because I am desensitized to them for the most part and I have to do it by experience rather than taste. It is the same with sweet, salt, bitter and sour because the more you accustom yourself to drinking them the less impact they have on you. Hence the never satisfied hop-head phenomenon. The big difference using my analogy, is that I taste the Chilis beforehand rather than going by Scoville rating.

The method I am going to use is trial and error. I think that may be the only way to home in on your locally grown hops, other than an actual lab performing an analysis.

That's a good idea in theory, but I tend to agree with David_42. Using your palate as a bitterness measurement tool isn't likely to produce accurate, dependable results.

I just plan to craft my recipes assuming my homegrown falls in the middle of the average for whatever variety I use. It's horribly innacurate but the price I'm willing to pay for relatively cheap hops.

Too complicated for most method:
http://www.realbeer.com/hops/ASBC.html

Here's a C/P from a method I have seen:

"...the titration procedure is
rather basic and you can set yourself up for almost nothing.

I use phenolphthalein as an indicator. Phenol Red (available at any
pool supply store) will work as well, just that the phenolphthalein
indicates at a bit lower pH. Household lye (NaOH or KOH) is used as
your reagent and baby medicine droppers to measure your titrant.

Dilute your reagent with distilled water to 1% solution. (10g/L) and
store it with the lid on tight. (This should last you a long time)

I boiled 1g of hops into 250ml of water for about 1 hour, strained the
cones out and further reduced to 100ml. If you go too far, just add
distilled water to get back to 100ml. That became my sample batch.

At this point you're ready to titrate.

Place 10ml of your sample into a clean container. I use Dixie cups
since their color (plain white) makes seeing the break very easy. Add
5 or 6 drops of your indicator and swirl around to mix thoroughly.
Slowly drip your reagent into the cup while swirling it around. When
the acid has been neutralized, your indicator will turn pink in
color. Continue SLOWLY dripping reagent in until the solution remains
pink for 20 or 30 seconds. Record the amount of reagent used (in
ml.) This corresponds to grams/liter of acid in your solution.

This is where I stop. I'm not sure what the hops industry uses for
their %Acid standard, but I took some hops of a known acid content and
performed the same process and use that as my standard. Like I said,
I have a spreadsheet at home with a little more detail on it, but that's
all you really need to do.

It's basic, almost crude, but it is repeatable and realistically that's
all need for my home-grown hops."

That method is pretty crude, and may be completely useless, but I can try it for nothing.

It should be fairly accurate *IF* it is only the AA's that attribute the bittering taste. If I were to do this I would use a Cascade or Fuggle (5-7%) for the low end, some 9-12% "medium" hop (Brewer's Gold or Chinook), and then say a Nugget or Zeus or the high end. That should give you a pretty good standard curve to fit your hops to.

The only other thing you'd probably need to do (to figure out the TYPE of curve) would be to take a single extract and dilute it say by 1/2 and titrate again. If you don't get a linear curve, you'd need to fit it with some more points. Shouldn't take too long.

EDIT:

Oh man after looking over the more detailed analysis I realize I could SO do the HPLC method. Not going to, but the capability is there. Method #1 with reading the absorbances just seems too inaccurate due to the precision required.

Bobby_M said:

I just plan to craft my recipes assuming my homegrown falls in the middle of the average for whatever variety I use. It's horribly innacurate but the price I'm willing to pay for relatively cheap hops.

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Now that what I like to hear! All this sciency stuff is too much for me, making my head spin.

I plan to use the same approach, though I would love to hear the results for those who delve into this a bit deeper to see how their homegrown matches up.

The Soft Underbelly said:

Now that what I like to hear! All this sciency stuff is too much for me, making my head spin.

I plan to use the same approach, though I would love to hear the results for those who delve into this a bit deeper to see how their homegrown matches up.

Click to expand...

The biggest problem I see after thinking about this some more would be what value this number actually has (assuming it's correct). The hop variability from cone to cone, plant to plant, year to year, etc. would make it pretty useless. I'm willing to bet the labs that do this for a hop farmer probably gets 50lbs of randomly sampled cones, grinds them all up, and then tests, so their analysis would be very accurate for a particular harvest.

If we only take 5 grams (or some other small amount), we may get a poor estimate if in that bunch we have under/over-ripened hops, or a poor sampling of the harvest.

Not to mention what differences there are if like me you plan to use some of the harvest fresh without drying (right off the vine and into the pot! :rockin.

With all that said, it would be cool to know the %.

And heck if the hop prices keep going skyward, you might just find 7Enigma's Cascade and Nugget hops at your LHBS.