Fermentation Science: Oregon State University

Thomas H. Shellhammer

Professor of Food Science

Nor’Wester Professor of Fermentation Science

Daniel C. Sharp

Willamette Valley, Oregon

Training students to be brewers

Photo’s courtesy of Lynn Ketchum

OSU Pilot Brewery 2 BBL brewhouse, 6 CCV

Photo’s courtesy of Steve Werblow

OSU has a long connection to hops • 1932

– Oregon largest hop producing region in the world with 34,594 acres (14,000 ha)

– Downy Mildew discovered in Oregon hop yards – U.S. Department of Agriculture establishes hop breeding

program • 1979

– Hop Research Council created • 1996

– Fermentation Science track created within Dept of Food Science

Shellhammer Lab Hops research, recent activity

• Isomerization kinetics • Bitterness research

– Native and reduced iso-alpha acids – Hop-derived polyphenols – Impact, time-intensity, quality

• Foam studies – Reduced iso’s

• Flavor stability – Hop-derived polyphenols

– Hop acids

Bitt

erne

ss In

tens

ity

Time

tmax

Imax Area

Duration

Shellhammer Lab Hops research, current projects

• Investigating the sources of citrus aroma/flavor from hops

• Hop harvest maturity influences on oil quality

• Basic studies on dry hopping • How hops affect beer flavor

stability • New methods for assessing

beer bitterness

Shellhammer Lab Hops research, current projects

• Investigating the sources of citrus aroma/flavor from hops

• Hop harvest maturity influences on oil quality

• Basic studies on dry hopping • How hops affect beer flavor

stability • New methods for assessing

beer bitterness

Hop Aroma

• What is it? • Where does it

come from? • How do I get it?

A line in the sand

Harvest

Quality “Quality is the indicator for the condition in which hop constituents are when being added to the beer/wort, i.e. the definition of quality indicates whether degradation took place from picking to dosage.” Forster, A. The quality chain from hops to hop products. In 48th IHGC Congress, Canterbury, Barth-Haas Research & Publications (http://www. barthhaas. com); 2001.

The degree of reduction in quality can be described by a quantitative measurement of aging components (or correlated components). ?????

Quality: A relative perspective

Assessing the aroma quality of hops

• Hop rubs and teas have limitations. • Come up with at least one descriptor for

each hop. • Rank them in order of most preferred to

least preffered.

Big Picture

• Quality Control Points – Cultivation – Harvest – Kilning – Conditioning – Packaging – Storage

Heat, time, moisture and oxygen =

What is it? Chemical Composition of Hops

SEM Image of Lupulin glands Forster, A. The quality chain from hops to hop products. In 48th IHGC Congress, Canterbury, Barth-Haas Research & Publications (http://www. barthhaas. com); 2001. NEED PERMISSION

Kishimoto, T.; Wanikawa, A.; Kono, K.; Shibata, K. Comparison of the Odor-Active Compounds in Unhopped Beer and Beers Hopped with Different Hop Varieties. Journal of Agricultural and Food Chemistry 2006, 54, 8855-8861. NEED PERMISSION

Principle Components Concentration (%w/w) Cellulose-lignins 40.0 - 50.0 Proteins 15.0 Alpha acids 2.0 - 17.0 Beta acids 2.0 - 10.0 Water 8.0 - 12.0 Minerals 8.0 Polyphenols and tannins 3.0 - 6.0 Lipids and fatty acids 1.0 - 5.0 Hop oil 0.5 - 3.0 Monosaccharides 2.0 Pectins 2.0 Amino acids 0.1

European Brewery Convention Hops and Hop Products, Manual of Good Practice; Getranke - Fachverlag Hans Carl: Nurnberg, Germany, 1997.

Harvest Timing: Total essential oil content during hop maturation

0

0.5

1

1.5

2

2.5

3

3.5

-30 -25 -20 -15 -10 -5 0 5 10 15 20

Conc

entr

atio

n (m

l/10

0g h

ops)

Harvest time point

Mt. HoodNuggetGalenaWillamette

Adapted from: Murphey, J.; Probasco, G. The Development of Brewing Quality Characteristics in Hops During Maturation. MBAA TQ 1996, 33, 149-159.

Harvest Date: Oil Content by Location 2010 Harvest

0

0.5

1

1.5

2

2.5

3

0 0.5 1 1.5 2 2.5 3

Con

cent

ratio

n (m

l/100

g ho

ps)

Harvest Time Point

Cascade Oil volume at 8 % moisture

Farm 1

Farm 2

Farm 3

Early Typical Late 0

0.5

1

1.5

2

2.5

3

0 0.5 1 1.5 2 2.5 3C

once

ntra

tion

(ml/1

00g

hops

)

Harvest Time Point

Willamette Oil volume at 8 % moisture

Farm 1

Farm 2

Farm 3

Early Typical Late

Difference exists between hops harvested at different locations.

Adapted from: Eyres, G.; Dufour, J. Hop Essential Oil: Analysis, Chemical Composition and Odor Characteristics. In Beer in Health and Disease Prevention; Preedy, V. R., Ed.; Academic Press: San Diego, 2009; pp. 239-254.

Composition

Schönberger, C.; Kostelecky, T. 125th Anniversary Review: The Role of Hops in Brewing. J. Inst. Brew 2011, 117, 259–267.

Principle Odor Compounds in Hops

Spicy/Herbal Piney/Woody Floral Citrus Fruity/Tropical

Epoxides Myrcene Nerol Limonene Linalool

Eudesmol Beta-Pinene Geraniol Citral Esters

Farnesol Alpha Pinene Geranyl Acetate Citronellol

Caryophyllene Oxide Farnesene Linalool

Caryophyllene Citronellol Sulphur

Compounds

Alpha Terpineol

Humulene

Odor Active Compounds: Fresh Hops

Harvest Timing: Oil Profile

Howard, G.A., Slater, C.A. Effect of Ripeness and Drying of Hops on the Essential Oil. J. Inst. Brew. 1958, 64, 234-237.

0

200

400

600

800

1000

1200

1400

1600

0 0.5 1 1.5 2 2.5 3

Conc

entr

atio

n (m

g/10

0 g

hops

) Harvest Time Point

Cascade Myrcene

Early Typical Late

Aroma compound concentrations: Hallertau MF

Adapted from: Bailey, B.; Schonberger, C.; Drexler, G.; Gahr, A.; Newman, R. The Influence of Hop Harvest Date on Hop Aroma in Dry-Hopped Beers. TQ 2009.

0123456789

-6 -3 0 3 6 9 12 15 18 21 24

Con

cent

ratio

n (µ

l/100

g ho

ps)

Harvest time point

LinaloolGeraniolHumulene Epoxide II

• Hop oil contents increased an average of 30% from day -3 to day 21..

Indicators of Degradation 2010 Harvest

0

2

4

6

8

10

12

14

16

18

20

22

24

0 0.5 1 1.5 2 2.5 3

Conc

entr

atio

n (m

g/10

0 g

hops

)

Harvest Time Point

Cascade isovaleric acid

Early Typical Late 0

2

4

6

8

10

12

14

16

18

20

22

24

0 0.5 1 1.5 2 2.5 3

Conc

entr

atio

n (m

g/10

0 g

hops

)

Harvest Time Point

Willamette isovaleric acid

Early Typical Late

Preliminary brewing: Cascade

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

Fruit Cocktail

Tropical fruit

Melon

Grapefruit

Estery (tutti fruitti)

Green Apple

RoseFloral

Green Hop

Pine

Apricot/Peach

Sweaty/Onion/Garlic

Orange

Typical Late

• Typical harvest hops = apple, apricot/peach, and sweaty/onion/garlic notes.

• Late harvest hops = higher melon and floral notes.

Big Picture

• Quality Control Points – Cultivation – Harvest – Kilning – < 60 C – Conditioning – Humidity control – Packaging – Storage

Baling

80 kg bales

Farmers bales

SEM Image of Lupulin glands Forster, A. The quality chain from hops to hop products. In 48th IHGC Congress, Canterbury, Barth-Haas Research & Publications (http://www. barthhaas. com); 2001.

Baling

Forster, A. The quality chain from hops to hop products. In 48th IHGC Congress, Canterbury, Barth-Haas Research & Publications (http://www. barthhaas. com); 2001.

Storage Temp

So what?

• Harvest timing matters. – Changes in the amount and profile of hop oil.

• Baling – Keep under 60 kg

• Storage – Low temp (0 C) for < 1 year.

• Communicate with your customer. • Sensory Result?

Acknowledgments

• Shaun Townsend, OSU • OSU-USDA ARS Hops Group • Indie Hops • Goschie Farms • Coleman Farms