why test hops? to know the -acids, -acids and essential oils content for: determining peak...
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WHYTEST HOPS?
Rick ColeProprietor
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Why Test Hops?
• To know the a-Acids, b-Acids and Essential Oils Content for:• Determining Peak Harvesting Time• Blending for Product Consistency• Competitive Marketing
• To know the Moisture Content for:• Preparation for Storage
• To know the Hop Storage Index (HSI) for:• Monitoring Changes (Handling & Aging)
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A Little Chemistry - I
“Bitter Acid”:• First isolated from hop cones in late
1800’s• Its structure was unknown, but it had some
chemical characteristics similar to acids
• Improved chemistry in early 1900’s revealed there were actually two “Bitter Acids”• First called “Alpha Acid” (Greek for “Acid
A”)• Other called “Beta Acid” (Greek for “Acid
B”)
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A Little Chemistry – II
a-Acids:• Improved chemistry in mid-1900’s
revealed there were three variations!• Humulone
• Major component (Example: Citra Hops)• “Soft” bitter flavor, not “harsh”
• Cohumulone• “Harsher” bitter (some argument about it)• Variety high in cohumulone: Brewer’s Gold (US)
• Adhumulone• Smallest component• Contribution to bitterness not well understood
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A Little Chemistry – IIIa-Acids (cont.):
• Very Poorly soluble in water solutions• ~ 0.030% wt @ boiling temp. (270 mg/L)
• a-acids converted into isomerized-alpha acids (Iso-a-acids)• By heat and H2O during “The Boil”
• Slowly! (60 – 90 minutes)
• a-acids also converted into harshly bitter oxidized a-acids with time and temp.• Slow but relentless reaction with oxygen
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A Little Chemistry – IV Iso-a-Acids:
• “Isomer” (Greek)
• “Iso” = same, “mer” = parts, • “isomer” = same parts• Same a-acid parts, just rearranged
• Much more soluble in water solutions• About 100 times more soluble than a-acids• ~3.0% wt @ boiling temp. (270 mg/L)
• Iso-a-acids are actually the source of bitterness in beer
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A Little Chemistry - Vb-Acids:
• Also three variations• Lupulone • Colupulone• Adlupulone
• b-acids have little bittering capability• Even less soluble than the a-acids• Do not isomerize into more soluble forms
• b-acids do convert into oxidized b-acids• Much more soluble than original b-acids• Are harshly bitter
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Just for Fun!
Humulone Lupulone
a-Acid b-Acid
(One of These is Not Like the Other)
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Gray = Carbon Red = Oxygen Light Blue = Hydrogenhttp://pubchem.ncbi.nlm.nih.gov/compound/442911
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.)
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A Little Chemistry – VIEssential 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
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A Little Chemistry – VII
Sweaty/Onion/Garlic
Fruit Cocktail
Orange Tropical Fruit
Grapefruit
Melon
Green Apple
Tutti Frutti (Estery)
RoseFloral
Apricot/Peach
Green Hop
Pine
7.0
6.0
5.0
4.0
Taste Perceptions
Sweaty/Onion/Garlic
Apricot/Peach
Melon
Tutti Frutti (Estery)
“More Floral, Tutti Frutti and Melon
Notes”
Beer brewed with “Typical” Harvest
Cascade Hops
“More Sweaty/Onion/Garlic and
Apricot/Peach Notes”
Beer Brewed with “Late”
Harvest Cascade Hops
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Chem. SummaryBrewers Choose Hop Varieties for:
• Bitterness (Boiling Hops)• Iso-a-acids are primary beer bittering
agents• a-acids and b-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
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Determining Harvest Timing
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A Tale of Two Farms
Williamette Valley, Oregon (MapQuest)
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Williamette Sample Dates
Apples to Apples
Farm #2
201
0201
1
Farm #1
Williamette
Williamette
Williamette
Williamette
Farm #1
Farm #2
Pre-Harvest Sampling
Harvesting Samples
Post-Harvest Sampling
SeptemberAugust
2010, 2011 Data from Ref (2)
Seasonal Effect
2011 harvest is slightly earlier than the 2010
harvest for both farms.
Location Effect
#2 Farm’s Williamette
harvest is 5 days later in both
years.
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Cascade Sample DatesHarvest Variables & Harvest Indicators?
Cascade
Cascade
One of These is Not Like The Other
Farm #2
201
0201
1
Williamette
WilliametteFarm #2
Pre-Harvest Sampling
Harvesting Samples
Post-Harvest Sampling
SeptemberAugust
2010, 2011 Data from Ref (2)
6 days
Same day in 2010
Now, throw in…
Varietal Differences!
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215 220 225 230 235 240 245 250 255 2600
5
10
15
20
Hop Alpha-Acid Development(Content vs. Day of Year)
Wye Challenger '02
Wye Target '02
Golding '02
Admiral '02
Whitbread Golding '02
Cascade '10, '11
Williamette '10, '11
Day of Year (days)
Alp
ha
Ac
id C
on
ten
t (w
t %
)What Can We Learn from Harvest
Studies?
2002 Data from Ref (1)
2010, 2011 Data from Ref (2)
Harvest DatesIn Blue
AUG SEP
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215 220 225 230 235 240 245 250 255 2600
5
10
15
20
Hop Alpha-Acid Development(Content vs. Day of Year)
Golding '02
Cascade '10, '11
Williamette '10, '11
Day of Year (days)
Alp
ha
Ac
id C
on
ten
t (w
t %
)Predicting Harvest Maturity
2002 Data from Ref (1)
2010, 2011 Data from Ref (2)
Only if you are
harvesting for a-acids
Harvest DatesIn Blue
AUG SEP
✓
? ?
Can a-acid content predict harvest
maturity?
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215 220 225 230 235 240 245 250 255 2600
5
10
15
20
Hop Alpha-Acid Development(Content vs. Day of Year)
Wye Target '02
Admiral '02
Day of Year (days)
Alp
ha
Ac
id C
on
ten
t (w
t %
)Varietal Differences
Notice the considerable
variation between varieties.
The early behavior of
one… 2002 Data from Ref (1)
2010, 2011 Data from Ref (2)
Date HarvestedIn Dark Blue
…does not predict the
later behavior of others.
AUG SEP
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Getting it Right?
215 220 225 230 235 240 245 250 255 2600
5
10
15
20
Hop Alpha-Acid Development(Content vs. Day of Year)
Wye Challenger '02
Day of Year (days)
Co
nte
nt
(wt
%)
Peak Harves
t?How do
you know?
2002 Data from Ref (1)
2010, 2011 Data from Ref (2)
Date HarvestedIn Dark Blue
AUG SEP
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Single Day Harvest?
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5
10
15
20
Hop Alpha-Acid Development(Content vs. Day of Year)
Golding '02
Admiral '02
Day of Year (days)
Co
nte
nt
(wt
%)
2002 Data from Ref (1)
2010, 2011 Data from Ref (2)
Larger, more mature cones hand-picked and tested
early.
What do you think those early maturing cones
look like at harvest, 15 days
later?
Date HarvestedIn Dark Blue
AUG SEP
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Cascade Study
215 220 225 230 235 240 245 250 255 2600
5
10
Cascade a-Acid, b-Acid and Hop Oil Development(Content vs. Day of Year)
a-Acid (g/100g)
b-Acid (g/100g)
Oil (g/4000g)
Day of Year (days)
Co
nte
nt
(wt
%)
Harvest DatesIn Blue
2002 Data from Ref (1)
2010, 2011 Data from Ref (2)
Properly chosen harvest
date?
Looks Good
AUG SEP
a-acid
b-acid
Oil (x40)
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Williamette Study
215 220 225 230 235 240 245 250 255 2600
5
10
Williamette a-Acid, b-Acid and Hop Oil Development(Content vs. Day of Year)
a-Acid (g/100g)
b-Acid (g/100g)
Oil (g/4000g)
Day of Year (days)
Co
nte
nt
(wt
%)
Harvest DatesIn Blue
2002 Data from Ref (1)
2010, 2011 Data from Ref (2)AUG SEP
Properly chosen harvest
date?
Hmm…a-acid
b-acid
Oil (x40)
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Can You Judge Maturity on Appearance?
2)
Data from Ref (3)
?Test Characteristics vs. Days to Harvest
Later harvest is better for Oils
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Pre-Harvest TestingMaturation Summary:
• Know what the brewer wants:• a-Acids for bittering• Essential Oils for aroma & flavor (finishing)
• Determine approach to harvest date• Peak harvest varies
• Field to field• Season to season• Variety to variety
• Appearance can be deceptive • Later is better for finishing hops
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Drying Hops
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Moisture ContentFresh Hops:
• Fresh hop cones contain 70-80% moisture by weight
• Quickly turns to mush: think of “bagged Lilly blossoms”
• Drying heat oxidizes a-acids and vaporizes oils • Good: Less than 140 °F• Better: Less than 120 °F• Best: Less than 100 °F
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Moisture ContentDried Hops:
• Too Dry- Less than 6% moisture: • Cones become brittle, • Crumble with handling, • Lose resins as “shake-out” and • Don’t pelletize as well
• Goal Moisture Content: 8-10%
• Too Moist - More than 12% moisture: • Prone to spoilage by mold and mildew• Potential risk of fire
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Yes! 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.
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Why Test Hops?For the Grower:
• Know the a-Acids, b-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)
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265 275 285 295 305 315 325 335 345 355 3650
20
40
60
The Hop Storage Index (HSI)(Absorption vs Wavelength)
Wavelength (nm)
Sp
ec
ific
Ab
so
rpti
on
Co
ee
fic
ien
t (l
/g c
m)
Hop Storage Index & Aging
HSI = A275
275
nm
A325
325
nm
0% Oxidized HSI = 0.20
50% Oxidized HSI = 0.78
80% Oxidized HSI = 1.5
100% Oxidized HSI = 2.4
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HSI & Freshness
0 20 40 60 80 1000.2
2
The Hop Storage Index (HSI)(HSI vs Degradation)
Hop Acids (a-Acids and b-Acids) Lost (%)
HS
I
A27
5/A
325
(lo
g s
cale
)
Completely Oxidized
Fresh Hops
2
3
1
0.8
0.6
0.4
0.2
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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.
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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)
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Monitor and Maintain the Quality of Your Product!
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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…
COMPETITION…YOU HAVE...
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Large Idaho Hop Farm
Elk Mountain FarmsAt 1700 acres, this is one of the largest hop farms in the world and grows hops exclusively for Anheuser-Busch.
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Texas Large-Hop Farm
“What we lack in acreage, we make up for in size.”
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Rick Cole, Proprietor
Midwest Hop and Beer Analysis, LLC319 Water Street
Evansville, WI 35356-1200
608 882 HOPS (4677)
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References1) Jelle de Keukeleire, Geert Ooms, Arne Heyerick, Isabel Roldan-Ruiz, Erik van Bockstaele and Denis de
Keukeleire, Formation and Accumulation of a-Acids, b-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.
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Additional Resources• 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
• http://allaboutbeer.com/hop-harvest/ (Elk Mountain Farm)• http://goodbeerhunting.com/blog/2014/9/1/reaping-what-you-sow-anh
euser-busch-and-goose-island-bring-a-hop-farm-back-to-life (Elk Mountain Farm)