Hoppy Aroma and Flavor - Home - 2014 ACS Northwest …norm2014.sites.acs.org/Hop Chemistry.pdf · Hoppy aroma and flavor in beer is a product of the ... • Measured by BUs (spectrophotometric

Hoppy Aroma and Flavor Daniel C. Sharp, M.S. Food Science and Technology Michael Qian, Thomas H. Shellhammer Oregon State University Department of Food Science and Technology

How is beer made?

Barley

Hops Yeast

Water

Hops in Beer: An Overview

Hops in Beer: An Overview

What is Hop Aroma/Flavor? Hoppy aroma and flavor in beer is a product of the coordination of physical, biochemical, and chemical phenomena that occur during brewing and psychophysical phenomena during consumption.

Humulus lupulus fam. Cannabaceae

• Dioecious perennial • Climbing plant (c. 6 meters) • 100+ cultivars

Photo: Indie Hops

Lupulin glands

SEM Image of Lupulin glands Forster, 2001

Hops composition Principle Components Concentration (%w/w) Cellulose + lignin 40.0 - 50.0 Protein 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 Pectin 2.0

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

Hops composition Principle Components Concentration (%w/w) Cellulose + lignin 40.0 - 50.0 Protein 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 Pectin 2.0

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

Hop Acids and their solubility

Peacock, 1998

The most important reaction in hop chemistry?

Beer Sample – Iso-alpha acids by HPLC

2.5 5 7.5 10 12

mAU

0

100

200

300

400

DAD1 A, Sig=270,4 Ref=360,100 (VAA 6-18-13\VAA 6-18-13 2013-06-19 12-22-20\002-0301.D)

isocohumulone

isohumulone

isoadhumulone

Measuring Bitterness in Beer Bitterness Units (IBUs) and [iso-α acids] (IAAs) What does the IBU measure? • Whatever gets extracted by iso-octane • Whatever absorbs at 275 nm. • Combined α, β, iso’s, oxidized materials, polyphenols

1 BU ≠ 1 ppm iso-alpha acid

y = 1.2x + 2.0 R² = 0.905

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0

IBU

Iso alpha acids concentration [ppm]

Correlation between total IAA & IBU

Beer Bitterness Key Points

• Most bitterness attributed to isomerization of α-acids during boiling. Different analogs contribute differently.

• Measured by BUs (spectrophotometric ally)

…but 1 BU ≠ 1 ppm iso-alpha acid • Bitterness also comes from other hop material, eg.

Polyphenols, tannins, oil components, oxidations products.

Questions so far?

Design by Victor Algazzali Graphics from http://www.bojensen.net/index.html

Hop Aroma

Table adapted from: Eyres, G.; Dufour, J.

Hops composition Principle Components Concentration (%w/w) Cellulose + lignin 40.0 - 50.0 Protein 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 Pectin 2.0

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

Essential Oil

Hop Oil Composition

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

Hop Oil Composition

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

Physical Effects Objective: Identify the effect of hopping regime on the contribution of hop volatiles to hop aroma in beer.

CC

V

Kettle Whirlpool

• Factors • Hopping Regime • Hop Cultivar (Simcoe, Hallertau Mittlefrueh)

• Response • (Chemical) Volatiles • (Sensory) Descriptive Analysis

60 minute boil ~100 C, 20 min 18 C, 48 hours

Stir Bar Sorptive Extraction GC-MS Analysis Target Analytes α-pinene β-pinene 3-carene β-myrcene Limonene p-cymene β-citronellal Linalool β-caryophyllene β-farnesene α-humulene E-citral α-terpineol Z-citral geranyl acetate β-citronellol Nerol E-β-damascenone Geraniol β-ionone Eugenol α-eudesmol β-eudesmol Terpinen-4-ol

Significant Analytes

3-carene

β-myrcene

Linalool

β-farnesene

α-humulene

geranyl acetate

β-citronellol

Geraniol

Eugenol

Terpinen-4-ol

Biochemical Effects

O

HO

OH

OH

OOH

Yeast OH

OHO

HO

HO

OH

OHH2O

Non-Odor Active Odor Active

• Factors – Yeast strain → glycosidase activity

• Response – Change in volatile composition

Homework

HS-SPME GC-MS of Big Sky IPA and Budlight

HS-SPME GC-MS of Big Sky IPA and Budlight

HS-SPME GC-MS of Big Sky IPA and Budlight

β-M

yrce

ne Lina

lool

β-C

itron

ello

l

Ger

anio

l

Big Sky IPA hop aroma – Principle compounds (by conc.)

Compound ~Conc. (ppm) Sensory Threshold Description

Myrcene 0.160 ppm 0.01 ppm Metallic, Green, Slight Pine

Linalool 0.174 ppm 0.008 ppm Fruity and Floral. Fruit Loops

α-terpineol 0.071 ppm 0.33 ppm Pine β-citronellol 0.016 ppm 0.04 ppm Citrus Floral Geraniol 0.026 ppm 0.004 ppm Floral Citrus

References • Forster, A. The quality chain from hops to hop products. In 48th IHGC Congress, Canterbury, Barth-

Haas Research & Publications (http://www. barthhaas. com); 2001.

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

• Peacock, V. Fundamentals of Hop Chemistry. Tech. Q.-Master Brew. Assoc. Am. 1998, 35, 4–8.

• 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.

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

• ASBC Methods of Analysis – Beer Flavor Database http://www.asbcnet.org/MOA/Flavors_Database.aspx (accessed June 15, 2014)

• Kishimoto, T.; Kobayashi, M.; Yako, N.; Iida, A.; Wanikawa, A. Comparison of 4-Mercapto-4-Methylpentan-2-One Contents in Hop Cultivars from Different Growing Regions. J. Agric. Food Chem. 2008, 56, 1051–1057.