How do I Caculate AAU's in my Hops

BorderBrewer said:

I can offer a method that I have used with some success that will get you close enough. This method was posted on the HBD many years ago. Buy a fresh sample with a known AA% of the same variety as your homegrown hops. Weigh out equal amounts of the known AA% hops and your HG hops. Brew two separate teas with each amount of hops using equal amounts of water. Pour equal amounts of each "hop tea" into separate tea cups. With the tea made from the known AA% hops, add measured amounts of sugar, tasting the tea with each addition of sugar until the perceived bitterness is gone. Keep track of how much sugar you add to overcome the bitterness. Repeat with the tea made from your homegrown hops, again keeping track of how much sugar you add. Determine the ratio of the amount of sugar needed to over come the bitterness in the homegrown hop tea to the amount of sugar needed to overcome the bitterness in the known AA% hop tea. For example if you make a tea with known 5% AA hops and it took 5 teaspoons of sugar to overcome the bitterness, while it only took four teaspoons of sugar to overcome the bitterness of the tea made with your homegrown hops, then the ratio is 4/5. Once this ratio is determined, simply multiply the known AA% by the ratio to determine the AA% of the home grown hops. In our example the ratio was 4/5 or 0.8, so for a known 5% AA hop the equation would be 5 * 0.8 = 4.0% AA for the homegrown hops. I hope this helps.

BorderBrewer

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cuinrearview said:

only thing I remember about the process was the use of a chemical called "toulene".

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One of the guys in my club found this. You may need access to a nice lab to do it though.


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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t-bag said:

Ooowww.... my brain. Haven't looked at math like that in years.

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StillBrew said:

yeah...thats why I w.a.g. it

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