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Homegrown Hops AA%

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1 Homegrown Hops AA% on Wed Jun 23, 2010 5:04 pm

Hey folks,
I got a couple of the nugget rhizomes from our friends here at BHB. I know that alpha acid ratings can't be confirmed on homegrown hops, but does anyone know if they tend to stay in the ballpark of the industrially grown hops...or does the aa% drop a bit because I'm an amateur grower/harvester?

Also, what do people do to prep their fresh hops for brewing? Dunk in some cold water like you would any other fresh veggie to get the bugs and stuff off?? Is that going to strip out some yummy hop goodness?

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2 from an old issue of Zymurgy... on Wed Jun 23, 2010 6:29 pm

This info is from a 1997 article in Zymurgy magazine. I found the article here... http://pw1.netcom.com/~dluzanp/backyard.htm

"Because homegrown hops are fresher and have suffered less handling, they are more bitter than commercial hops. Estimating their alpha as 50 percent higher than the average alpha for the same commercial cultivar is a pretty good guess. Knowing the exact alpha of your hops is less critical if you use them only for flavor and aroma additions."

If you scroll down to the section called "Estimating Hop Bitterness" there is an interesting method the author suggests for figuring out ballpark bitterness by making teas out of the homegrown hops and hops of a known alpha acid.

I plan on doing the hop tea comparison with any cones I get off my hops. If anyone has a more recent reference, please post!

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3 Re: Homegrown Hops AA% on Wed Jun 23, 2010 7:23 pm

There's a Basic Brewing Radio podcast that covers the hop tea method. Basically, you make a tea using a certain amount of hops until you perceive bitterness. Then, you make a tea using hops of known AA% until you perceive bitterness. Obviously you would need some method for determining the IBU of the tea using the hops of the known AA%. The key is you have to do this for yourself because it is based on the testers ability to perceive bitterness, which differs between us.

Good luck!

If I get lucky and get any usable hops this year, I am just going to make a "Harvest Pale Ale" and wing it. I'd rather use the hops for beer and not know the exact numbers than bother with the tests.

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4 Homegrown Hops AA% on Thu Jun 24, 2010 3:24 am

Your best bet might be to rub apart up one of the cones (after drying) and take a good whiff to see what aroma you get. I used exclusively home-harvested Cascade cones last year in a pale ale and got zero hop flavor/bitterness/aroma... very disappointing! I remember there being no huge perfume from them, but didn't think too much of it. Unless you're at year 2 or 3 with the rhizomes in full sun, I would guess on the low end for AA%.

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5 Re: Homegrown Hops AA% on Thu Jun 24, 2010 10:50 am

jquinn wrote:Your best bet might be to rub apart up one of the cones (after drying) and take a good whiff to see what aroma you get.

Maybe it's me, but I'd be nervous about not properly drying my hops.
I'm planning on just using them wet.

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6 Re: Homegrown Hops AA% on Thu Jul 01, 2010 5:01 pm

I have a spectrophotometer in my lab. I can do an extraction and calculate them.

If people want me to do it, PM me. It's easier to do several at once. However, I can't do a million. I only have 2 quarts cuvettes, and the plastic ones absorb in the UV range so they'll be worthless.

Found @ http://forums.morebeer.com/viewtopic.php?f=16&t=20673
Alpha and Beta Acids in Hops
(reference: ASBC MoA. 8th edition, 1992)
Method
1. Place 5.000 +/- .001 gr pulverized hops in an extraction bottle and add 100 mL toluene.
2. Shake for 30 min with vigorous agitation.
3. Let stand until clear or centrifuge (preferred).
4. Dilution A: Dilute 5.0 ml of this extract to 100 mL with methanol.
5. Dilution B: Dilute an aliquot of the dilution A with alkaline methanol (0.2 mL 6M NaOH per 100 mL MeOH) so that the Abs at 325 and 355 falls within the most accurate range of the instrument.
6. Immediately read dilution B (1 cm) at 275, 325 and 355 vs a toluene blank that was prepared and diluted in EXACTLY the same manner.
Notes:
? Hexane may be substituted for toluene
Calculations:
Dilution factor, d= (volume dil A x volume dil B)/ (500 x aliq extract A x aliq dil A)
% alpha acids= d x (-51.56 A355+ 73.79 A325-19.07 A275)
% beta acids= d x (55.57 A355-47.59 A325 + 5.10 A275)

-------------

Example:
1. 5 gr hops extracted with 10 mL toluene
2. 5 mL clear extract diluted to 100 mL with methanol=Dilution A
3. 3 mL Dilution A diluted to 50 mL with alkaline methanol
4. Absorbances
o A355=0.615
o A325= 0.596
o A275=0.132
d = (100 x 50) / (500 x 5 x 3) = 0.667
alpha = 0.667 x [ -(51.56 x 0.615) + (73.79 x 0.596) - (19.07 x 0.132) = 6.5
beta = 0.667 x [ (55.57 x 0.615) - (47.59 x 0.596) + (5.10 x 0.132) = 4.3

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7 Re: Homegrown Hops AA% Today at 5:00 pm

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