why test hops? to know the -acids, -acids and essential oils content for: determining peak...

WHYTEST HOPS?

Rick ColeProprietor

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)

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”)

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

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

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

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

Just for Fun!

Humulone Lupulone

a-Acid b-Acid

(One of These is Not Like the Other)

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.)

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

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

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

Determining Harvest Timing

A Tale of Two Farms

Williamette Valley, Oregon (MapQuest)

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.

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!

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

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?

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

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

Single Day Harvest?

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

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

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)

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)

Can You Judge Maturity on Appearance?

2)

Data from Ref (3)

?Test Characteristics vs. Days to Harvest

Later harvest is better for Oils

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

Drying Hops

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

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

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.

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)

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

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

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…

COMPETITION…YOU HAVE...

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.

Texas Large-Hop Farm

“What we lack in acreage, we make up for in size.”

Rick Cole, Proprietor

Midwest Hop and Beer Analysis, LLC319 Water Street

Evansville, WI 35356-1200

Rick.Cole@MidwestHopAnalysis.comwww.MidwestHopAnalysis.com

608 882 HOPS (4677)

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.

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)