WHY TEST HOPS? - MidwestHopAnalysis.com

WHY
TEST HOPS?
Rick Cole
Proprietor
Why Test Hops?
•  Know the α-Acids, β-Acids and Essential
Oils Content for:
• 
• 
• 
Determining Peak Harvesting Time
Blending for Product Consistency
Competitive Marketing
•  Know the Moisture Content for:
• 
Preparation for Storage
•  Know the Hop Storage Index (HSI) for:
• 
Monitoring Changes (Handling & Aging)
A Little Chemistry - 1a
α-Acids:
•  Three variations
• 
Humulone
• 
• 
• 
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Cohumulone
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Major component
“Soft” bitter flavor, not “harsh”
Citra Hops
“Harsher” bitter (some argument about it)
Brewer’s Gold (US)
Adhumulone
• 
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Smallest component
Contribution to bitterness not well understood
A Little Chemistry – 1b
α-Acids (cont.):
•  Very Poorly soluble in water solutions
• 
~ 0.030% wt @ boiling temp. (270 mg/L)
•  α-acids converted into isomerized-alpha
acids (Iso-α-acids)
• 
By heat and H2O during “The Boil”
•  α-acids converted into oxidized α-acids
• 
• 
Slow but relentless reaction with oxygen
Oxidized α-acids are harshly bitter
A Little Chemistry – 2
Iso-α-Acids:
•  “Isomer” (from ancient Greek)
• 
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• 
“iso” = same, “mer” = parts,
“isomer” = same parts
Same α-acid parts, rearranged
•  Much more soluble in water solutions
• 
• 
About 100 times more soluble than α-acids
~3.0% wt @ boiling temp. (270 mg/L)
•  Iso-α-acids are actually the source of
bitterness in beer
A Little Chemistry - 3
β-Acids:
•  Also three variations
• 
• 
• 
Lupulone
Colupulone
Adlupulone
•  β-acids have little bittering capability
• 
• 
Even less soluble than the α-acids
Do not isomerize into more soluble forms
•  β-acids do convert into oxidized β-acids
• 
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Much more soluble than original β-acids
Are harshly bitter
Just for Fun!
(One of These is Not Like the Other)
Humulone
α-Acid
Lupulone
β-Acid
More Fun…
Humulone (α-Acid) in 3-D
Cross your eyes until the two black dots overlap. Focus on the overlapped dots and the
rest of the image should come into focus with the side-chains reaching out toward you.
(You may have to tilt your head slightly to get the black dots to line up correctly.)
Gray = Carbon
Red = Oxygen
Light Blue = Hydrogen
http://pubchem.ncbi.nlm.nih.gov/compound/442911
A Little Chemistry – 4a
Essential Oils:
•  Flavor is strongly influenced by aroma
• 
• 
• 
• 
Over 100 flavor/aroma compounds in hop oil
Most are at trace levels
Fresh Hop Aroma: Linalool, Geraniol,
Limonene, Terpineol, Myrcene
Noble Hop Aroma: Oxides/Epoxides of
Humulene, Caryophyllene, Farnesene
•  Oil component ratios are variety specific
• 
• 
Known component ratio can identify variety
Known variety can identify component ratio
A Little Chemistry – 4b
Taste Perceptions
Beer Brewed with “Late
Harvest” Cascade Hops
Fruit Cocktail
Orange
7.0
Beer brewed with “Typical
Harvest” Cascade Hops
Tropical Fruit
6.0
5.0
Sweaty/Onion/Garlic
Melon
4.0
Grapefruit
Apricot/Peach
Tutti Frutti (Estery)
Pine
Green Hop
“Sweaty/Onion/Garlic Floral
and Apricot/Peach Notes”
Green Apple
Rose
“Floral, Tutti Frutti
and Mellon Notes”
Chem. Summary
Brewers Choose Hop Varieties for:
•  Bitterness (Boiling Hops)
• 
• 
• 
Iso-α-acids are primary beer bittering agents
α-acids and β-acids have little beer bittering
Oxidized (old or abused) hops produce harsh
bitterness in beer
•  Aroma/Flavor (Finishing Hops)
• 
• 
• 
Oil % composition determines flavor
Each variety has a known % composition
Age and abuse affect flavor of hops & beer
Determining Harvest Timing
A Tale of Two Farms
Williamette Valley, Oregon
(MapQuest)
View Larger Map »
Apples to Apples
Williamette Sample Dates
2011
Pre-Harvest Sampling
Farm #2
Farm #1
Harvesting Samples
2010
Farm #1
Location Effect
Williamette
#2 Farm’s
Williamette harvest
is 5 days later in
both years.
Williamette
August
Farm #2
Post-Harvest Sampling
September
Seasonal Effect
Williamette
2011 harvest is
slightly earlier than
the 2010 harvest
for both farms.
Williamette
2010, 2011 Data from Ref (2)
One of These is Not Like The Other
Harvest Variables
Cascade Sample
& Harvest
Dates
Indicators?
2011
Pre-Harvest Sampling
Farm #2
Harvesting Samples
6 days
Williamette
Now, throw in…
August
2010
Post-Harvest Sampling
Cascade
Farm #2
September
Same day
Cascade
Williamette
Varietal Differences!
2010, 2011 Data from Ref (2)
Determining Harvest Readiness
Hop Alpha-Acid Development
(Content vs. Day of Year)
20
Only if you
are
harvesting
for α-acids
Harvest Dates
In Blue
Wye Challenger '02
Wye Target '02
Golding '02
15
Admiral '02
Content (wt %)
Whitbread Golding '02
Cascade '10, '11
Williamette '10, '11
10
5
Can α-acids
predict harvest
maturity?
2002 Data from Ref (1)
2010, 2011 Data from Ref (2)
0
215
220
225
230
235
240
Day of Year (days)
245
250
255
260
Monitoring Cone Maturity
Hop Alpha-Acid Development
(Content vs. Day of Year)
20
Wye Challenger '02
Wye Target '02
15
Golding '02
Content (wt %)
Admiral '02
Whitbread Golding '02
10
Date Harvested
In Dark Blue
Notice the
considerable
variation
between
varieties.
…does not
predict the
later behavior
of others.
The early
behavior of
one…
5
2002 Data from Ref (1)
2010, 2011 Data from Ref (2)
0
215
220
225
230
235
240
Day of Year (days)
245
250
255
260
Getting it Right?
Hop Alpha-Acid Development
(Content vs. Day of Year)
20
Date Harvested
In Dark Blue
Content (wt %)
Peak
Harvest?
Wye Challenger '02
15
How do
you
know?
10
5
2002 Data from Ref (1)
2010, 2011 Data from Ref (2)
0
215
220
225
230
235
240
Day of Year (days)
245
250
255
260
One Harvest Fits All?
Hop Alpha-Acid Development
(Content vs. Day of Year)
20
Date Harvested
In Dark Blue
Golding '02
15
What do you think
those early
maturing cones
look like at harvest,
15 days later?
Content (wt %)
Admiral '02
10
Larger, more
mature
cones picked
and tested
early.
5
2002 Data from Ref (1)
2010, 2011 Data from Ref (2)
0
215
220
225
230
235
240
Day of Year (days)
245
250
255
260
Two-Farm Cascade Study
Cascade α-Acid, β-Acid and Hop Oil Development
(Content vs. Day of Year)
Harvest Dates
In Blue
10
Content (wt %)
α-acid
Properly
chosen harvest
date?
β-acid
Oil (x40)
5
Looks Good
a-Acid (g/100g)
b-Acid (g/100g)
2002 Data from Ref (1)
Oil (g/4000g)
2010, 2011 Data from Ref (2)
0
215
220
225
230
235
240
Day of Year (days)
245
250
255
260
Two-Farm Williamette Study
Williamette α-Acid, β-Acid and Hop Oil Development
(Content vs. Day of Year)
a-Acid (g/100g)
Harvest Dates
In Blue
b-Acid (g/100g)
10
Properly chosen
harvest date?
Content (wt %)
Oil (g/4000g)
β-acid
α-acid
5
Oil (x40)
Hmm…
2002 Data from Ref (1)
2010, 2011 Data from Ref (2)
0
215
220
225
230
235
240
Day of Year (days)
245
250
255
260
What About
Appearance and Oils?
?Test Characteristics vs. Days to Harvest
Later harvest is
better for Oils
Data from Ref (3)
2)
Pre-Harvest Testing
Maturation Summary:
•  Know what the brewer wants:
• 
• 
α-Acids for bittering
Essential Oils for aroma & flavor (finishing)
•  Determine approach to harvest date
• 
Peak harvest varies
• 
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• 
Field to field
Season to season
Variety to variety
Appearance can be deceptive
Later is better for finishing hops
Drying Hops
Moisture Content
Fresh Hops:
•  Fresh hop cones contain 70-80%
moisture by weight
•  Quickly turns to mush: think of “bagged
Lilly blossoms”
•  Drying heat oxidizes α-acids and
vaporizes oils
• 
• 
• 
Good: <140 °F
Better: <120 °F
Best: <100 °F
Moisture Content
Dried Hops:
•  Not good - Less than 6% moisture:
• 
• 
• 
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Cones become brittle,
Crumble with handling,
Lose resins as “shake-out” and
Don’t pelletize as well
•  Goal Moisture Content: 8-10%
•  Not good - More than 12% moisture:
• 
• 
Prone to spoilage by mold and mildew
Potential risk of…
Fire!
Spontaneous Combustion: Ironically, in
2006, moist hops
caused this fire
in a Yakima, WA,
warehouse
destroying or
ruining two
million pounds of
baled hops, and
the 40,000 ft2
warehouse that
contained them.
Hop Storage Index & Aging
The Hop Storage Index (HSI)
(Absorption vs Wavelength)
275 nm
HSI =
A275
0% Oxidized
HSI = 0.20
A325
40
50% Oxidized
HSI = 0.78
80% O
xidize
d
20
325 nm
Specific Absorption Coeeficient (l/g cm)
60
0
265
275
285
295
305
315
Wavelength (nm)
325
HSI =
1.5
100%
Oxidiz
ed
HSI =
2.4
335
345
355
365
HSI & Freshness
The Hop Storage Index (HSI)
(HSI vs Degradation)
3
Completely Oxidized
HSI A275/A325 (log scale)
2
1
0.8
0.6
0.4
Fresh Hops
0.2
0
20
40
60
80
Hop Acids (α-Acids and β-Acids) Lost (%)
100
Why Monitor HSI?
KNOW Your Product:
•  HSI as indicator of quality
• 
• 
• 
• 
• 
• 
Vine Fresh Hops – 0.20 to 0.30
Fresh Dried Hops – 0.20 to 0.40
Moderately Abused Hops – 0.40 to 0.60
Abused Hops – 0.60 to 0.80
Poor Quality, Oxidized Hops – 0.80 to 1.2
Garden Compost Hops – 1.2 to 2.4
•  HSI does vary slightly with variety and
growing conditions – Best to get an initial
reading on your harvest each year.
Protect Your Product From:
•  Heat
• 
Every 10 °C (18 °F) decrease in temperature
roughly doubles the storage life
•  Moisture
• 
• 
• 
<6% - Dry, brittle, fragile
8% – 10% - Ideal range
>12% - Moisture is catalyst for chemical (and
biologically induced) change
•  Oxygen – Reduce Exposure
• 
• 
• 
Reduce surface area (compress or pelletize)
Protective barrier (impermeable packaging)
Remove oxygen (vacuum or inert gas packing)
Monitor and Maintain the
Quality of Your Product!
Why Test?
•  Protect Your Investment
• 
• 
Large infrastructure investment
Large labor investment
•  Market Your Product
• 
• 
• 
Known/Certified level of quality
Improved negotiating position
Grower/Brewer trust
•  REMEMBER…
YOU HAVE...
COMPETITION…
Large Washington Hop Farm
Elk Mountain Farms
At 1800 acres, this is the largest hop farm in the
world; grows hops exclusively for Anheuser-Busch.
Texas Large-Hop Farm
“What we lack in acreage, we make up for in size.”
Rick Cole, Proprietor
Midwest Hop and Beer Analysis, LLC
319 Water Street
Evansville, WI 35356-1200
Rick.Cole@MidwestHopAnalysis.com
www.MidwestHopAnalysis.com
608 882 HOPS (4677)
References
1)  Jelle de Keukeleire, Geert Ooms, Arne Heyerick, Isabel Roldan-Ruiz, Erik van Bockstaele and Denis de
Keukeleire, Formation and Accumulation of α-Acids, β-Acids, Desmethylxanthohumol, and Xanthohumol
during Flowering of Hops (Humulus lupulus L.) 4436 J. Agric. Food Chem. 2003, 51, 4436−4441
2)  Daniel C. Sharp, Harvest Maturity of Cascade and Willamette Hops, Master of Science Thesis, Oregon
State University, Presented January, 2013.
3)  Murphey, J. M.; Probasco, G. The Development of Brewing Quality Characteristics in Hops During
Maturation. MBAA TQ 1996, 33, 149– 159.
Additional Resources
• 
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http://msue.anr.msu.edu/news/
determining_when_hops_are_ready_to_harvest
https://www.alphaanalyticstesting.com/why-test/
http://www.gorstvalleyhops.com/2011%20September%20newsletter.pdf
http://byo.com/grains/item/848-hop-chemistry-homebrew-science
https://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/37394/
DanielSharpC2013.pdf?sequence=1
http://pubs.acs.org/doi/abs/10.1021/jf034263z
http://msue.anr.msu.edu/news/
harvest_time_approaching_for_hop_growers_1
http://bioweb.uwlax.edu/bio203/s2009/sewalish_andr/Humulus
%20Lupulus%20
%20Common%20Hops/Hop%20Anatomy%20and%20Chemistry
%20101.html