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Fermentation Science: Oregon State University
Thomas H. Shellhammer
Professor of Food Science
Nor’Wester Professor of Fermentation Science
Daniel C. Sharp
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
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). ?????
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
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.
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?