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Home Brew Forums > Home Brewing Beer > Brew Science > Meaning of oil percentages in the hop wiki
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Old 09-28-2009, 06:21 PM   #1
jdc2
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Default Meaning of oil percentages in the hop wiki

Hello everyone, new member here.
I want to ask if anyone knows what the meaning of the oil
percentages given on the wiki pages for various hops (such as Perle)
is. If you add up the percentages for alpha acids, myrcene etc
the number is greater than 100%.
Thanks
Jim

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Old 09-28-2009, 07:26 PM   #2
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Hop oils are rarely more than 2% of the total weight. The numbers for other components are ranges and if you have a lot of one thing, you have less of something else.

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Old 09-28-2009, 07:36 PM   #3
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Right. But for instance, in the American Perle page at the wiki, even
if you exclude the alpha and beta acids and farnesene, the minimum
percentage for cohumulone, myrcene, humulene, and caryophyllene
add up to 110%:

Alpha Acids: 7-11 %
Beta Acids: 4-5 %
Cohumulone: 27-32 %
Myrcene: 45-55 %
Humulene: 28-33 %
Caryophyllene: 10-12 %
Farnesene: less than 1 %
Total Oil: 0.7-0.9 %

So it can't be a question of less of something if more of something
else, because even the least amount of everything is too much.
I wonder what the source of this information is.
Jim

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Old 08-23-2010, 09:47 PM   #4
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I had the same question myself. It looks like the numbers in
the wiki are taken from the data sheet at hopunion.com. For
example, for Ahtanum the wiki has:

Alpha Acids: 5.7-6.3 %
Beta Acids: 5-6.5 %
Cohumulone: 30-35 %
Myrcene: 50-55 %
Humulene: 16-20 %
Caryophyllene: 9-12 %
Farnesene: less than 1 %
Total Oil: 0.8-1.2 %

So if you add the lowest percentages of cohumulone through
Farnesene, you get a number greater than 100%. But the original
data says that the cohumulone is expressed as a percentage of
the total alpha acids, while the remaining oils are percentages of
total oil content, so they are completely different quantities, which
makes sense because cohumulone is one of the acids while the
components like myrcene are fragrant oils.

Ray

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Old 08-24-2010, 01:34 AM   #5
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It was my understanding that hop chemistry is split into 2 distinct parts, bittering and flavoring/aroma.

Bittering is described by Alpha and Beta acids, the most important being the percentage that is made up Cohumulone. Higher Cohumulone supposedly has "harsher" bittering. (I don't think "harsher" is meant as a negative description, ie - Columbus @ 33% Cohumulone vs. Simcoe @ 17% Cohumulone)

Flavoring/aroma is comprised of the essential oils, mainly Myrcene, Humulene, Caryophylene and Farnesene. Their percentage listed is their portion of the essential oils in the hops and should add up to less than 100% because there are a whole bunch of other lesser known essential oils in hops also.

The example of Ahtanum:
Cohumulone 30-35% is the percentage of Alpha Acids comprised of Cohumulone. It affects bittering

Myrcene 50-55% is the percentage of essential oils comprised of Myrcene. It affects flavor/aroma
Myrcene+Humulene+Caryophyllene+Farnesene = 75%, so 25% are other lesser known essential oils.

Rules of thumb -
total Alpha Acid percentage indicates potential bittering power.
Cohumulone percentage indicates the type of bittering flavor.
Total essential oils indicates the potential flavoring/aroma power.
Ratios of each of Myrcene, Humulene, Caryophyllene, Farnesene to the total essential oils determines the flavor/aroma profile.

check these references for some more insight:
My understanding of HOPS need-help!
HBT Wiki - Hop Chemistry

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Old 08-25-2010, 12:37 AM   #6
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I was always of the impression that AA are given as a percentage by mass of the total hop mass, not the total oil. What particularly gives me this impression is the treatment of it in Tinseth's formula...

mg/L of added alpha acids = (decimal AA rating * milligrams hops) / (L finished beer)

It is obvious that the numerator represents mg of hop oil, which is directly calculated from the total hop mass. Is this right?

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Old 08-25-2010, 12:41 AM   #7
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Quote:
Right. But for instance, in the American Perle page at the wiki, even
if you exclude the alpha and beta acids and farnesene, the minimum
percentage for cohumulone, myrcene, humulene, and caryophyllene
add up to 110%:

Alpha Acids: 7-11 %
Beta Acids: 4-5 %
Cohumulone: 27-32 %
Myrcene: 45-55 %
Humulene: 28-33 %
Caryophyllene: 10-12 %
Farnesene: less than 1 %
Total Oil: 0.7-0.9 %
Take a look at the stats from usahops.org...
Code:
Alpha Acids
12.0 - 14.5%
Beta Acids
8.5 - 9.8%
Alpha-Beta Ratio
1.4 - 1.5
Cohumulone (% of alpha acids):
33 - 35%
Total Oils (Mls. per 100 grams dried hops)
1.50-01.9
Myrcene (as % of total oils)
45 - 55%
Caryophyllene (as % of total oils)
9 - 12%
Humulene (as % of total oils)
12 - 15%
Farnesene (as % of total oils)
<1%
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