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Presentation at the Australian Craft Brewers Conference, Brisbane, 20 July 2016.
Hop Research: Understanding the contribution of hop
to beer flavour – our search for the Holy Grail
Presented by Dr Simon Whittock
This research was supported under
Australian Research Council's Linkage
Projects funding scheme
(LP140100160)."
Introduction
Why “Flavour”
Describing Flavour
Identification of compounds
Hop Derived compounds
Who & where?
Still to understand?
Our approach
Experimental infrastructure
Metabolomics
Conclusion
Presentation at the Australian Craft Brewers Conference, Brisbane, 20 July 2016.
Flavour: the moment when what
we put in our mouths and
what we smell converge
(Simran Sethi)
We describe our hops as
having distinctive FLAVOUR
because:
i) we wanted to make the
point that hop aroma
should be subordinate to
BEER FLAVOUR; and
ii) we deliberately broke
with the typical meaning
of “aroma hop”
Introduction
Why “Flavour”
Describing Flavour
Identification of compounds
Hop Derived compounds
Who & where?
Still to understand?
Our approach
Experimental infrastructure
Metabolomics
Conclusion
Presentation at the Australian Craft Brewers Conference, Brisbane, 20 July 2016.
Odour Descriptors:
Castro, J.B., Ramanathan, A., and Chennubhotla, C.S. (2013). Categorical
Dimensions of Human Odor Descriptor Space Revealed by Non-Negative
Matrix Factorization. PLoS ONE 8, e73289.
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0073289
Odour Maps:
Zarzo, M., and Stanton, D.T. (2009). Understanding the underlying dimensions
in perfumers’ odor perception space as a basis for developing meaningful odor
maps. Attention, Perception, & Psychophysics 71, 225-247.
http://link.springer.com/article/10.3758/APP.71.2.225
Flavour Networks:
Ahn, Y.-Y., Ahnert, S.E., Bagrow, J.P., and Barabási, A.-L. (2011). Flavor
network and the principles of food pairing. Scientific Reports 1, 196.
http://www.nature.com/articles/srep00196
Describing hop in beer:
Sensory training for hops and hop intensive beers – let’s speak one language
Alicia Munoz, Barth Haas, United Kingdom, 12th Trends in Brewing
Conference’, KU Leuven, Ghent, Belgium, 3-7 April 2016.
https://view.publitas.com/ku-leuven/tib-2016_brochure/page/10-NaN
The Language of Hops: How to assess Hop Flavour in Hops and Beer
Georg Drexler, Christina Schönberger, Elisabeth Wiesen, Mark Zunkel,
Sebastian Hinz, Alicia Muñoz Insa, World Brewing Congress, August 13-17,
2016, Denver, CO 80202, U.S.A.
http://www.worldbrewingcongress.org/Pages/default.aspx
1. citrus
2. solvents
3. spices
4. floral
5. fruit
6. herbal
7. milk/nuts/grain
8. sulphur
Description of FlavourIntroduction
Why “Flavour”
Describing Flavour
Identification of compounds
Hop Derived compounds
Who & where?
Still to understand?
Our approach
Experimental infrastructure
Metabolomics
Conclusion
Presentation at the Australian Craft Brewers Conference, Brisbane, 20 July 2016.
1. Isolation of the volatile compounds
• Distillation, Gas or solvent extraction, headspace analysis
2. Sensory relevance
• Aroma Extract Dilution Analysis (AEDA) - Headspace Gas Chromatography/Olfactometry
3. Concentration and identification
• Focus on aroma substances which have higher flavour dilution factors from AEDA GC/O
• Enrichment, determination of chemical structure, enantioselective analysis
4. Quantification and calculation of aroma values
• Isotopic dilution analysis (deuterium or carbon-13), standards for extraction, detection and
quantification.
• Concentration in food divided by the odor or taste threshold (water, oil, or other substrate)
5. Simulation of the aroma on the basis of the analytical results
• Recreate the flavour/aroma profile using mixtures of individual compounds.
6. Omission experiments
• Accounts for additive or antagonistic effects
Considerable effort required to understand which
compounds are responsible for perception of FLAVOUR
Key Literature
Food Chemistry Authors: H-D Belitz, Werner Grosch, & Peter
Schieberle. Published by Springer in 2009,
http://www.springer.com/us/book/9783540699330
Dunkel, A., Steinhaus, M., Kotthoff, M., Nowak, B., Krautwurst,
D., Schieberle, P., and Hofmann, T. (2014). Nature’s Chemical
Signatures in Human Olfaction: A Foodborne Perspective for
Future Biotechnology. Angewandte Chemie International Edition
53, 7124-7143.
http://onlinelibrary.wiley.com/doi/10.1002/anie.201309508/abstra
ct
many volatile compounds
few aroma active compounds
10000:350.
Introduction
Why “Flavour”
Describing Flavour
Identification of compounds
Hop Derived compounds
Who & where?
Still to understand?
Our approach
Experimental infrastructure
Metabolomics
Conclusion
Presentation at the Australian Craft Brewers Conference, Brisbane, 20 July 2016.
Hop derived compound classes with FLAVOUR properties in beer
α-acids polyphenols sesquiterpenes monoterpenoids monoterpenes thiols
~350 g/mol ~354 g/mol ~204 g/mol ~154 g/mol ~136 g/mol ~132 g/mol
bitterness
bitterness
perception?
mouthfeel
herbal and spicy
characterscitrus/floral floral/resin
specific fruits
garlic/sulphur
Iso-alpha acids
humulinonesisoxanthohumol
humulenol II;
humulene
epoxide III;
caryophylla-
4(12),8(13)- diene-5-
ol;
14-hydroxy-ß-
caryophyllene; 3Z-
caryophylla-3,8(13)-
diene-5α-ol; and 3Z-
caryophylla- 3,8(13)-
diene-5ß-ol
(R)-linalool;
geraniol, β-
citronellol
myrcene
4-mercapto-4-
methyl-
2-pentanone (4-
MMP)
Iso-α-acids.
Humulinones develop
during oxidation of hops
and can be absorbed
during dry hopping
Isomerised during
wort boiling
Epoxides and
diepoxides of
humulene and
caryophyllene form
during oxidation,
derivatives formed
during wort boiling
Glycosides
Yeast
biotransform
ation. (S)-
linalool from
myrcene
Direct
absorption
in beer
when late
or dry
hopping
Thought to be
derived from
conjugated amino
acid precursors in
presence of yeast
Taniguchi et al. (2013). J
Agric Food Chem 61, 3121-
3130.
Oladokun et al. (2016).
Food Chemistry 205,
212-220.
Van Opstaele et al.
(2013). J Agric Food
Chem 61, 10555-
10564.
Takoi et al.
(2011). J Inst
Brew 116,
251-260.
Castro et al.
(2015) J Inst
Brew 121,
197-203.
Ochiai et al. (2015) J
Agric Food Chem 63,
6698-6706.
Introduction
Why “Flavour”
Describing Flavour
Identification of compounds
Hop Derived compounds
Who & where?
Still to understand?
Our approach
Experimental infrastructure
Metabolomics
Conclusion
Presentation at the Australian Craft Brewers Conference, Brisbane, 20 July 2016.
Who is publishing in the field of Hop FLAVOUR
Odourant Polyfunctional Thiols from hop
(specific fruit notes)
Sonia Collin, Jacques Gros (KU Leuven, Belgium)
Toru Kishimoto (Asahi, Japan)
Oxygenation products of sesquiterpenes
(spicy characters)
Filip Van Opstaele, Tatiana Praet (KU Leuven, Belgium)
Monoterpenes and monoterpenoids
Martin Steinhaus (German Research Centre for Food
Chemistry | Leibniz Institut, Freising, Germany)
Kiyoshi Takoi (Sapporo Breweries Ltd, Japan)
Hop utilisation and quality
Tom Shellhammer (Oregon State University, USA)
Conferences:
Trends in Brewing
Young Scientist’s Symposium
World Brewing Congress (incorporates
ASBC and MBAA meetings in 2016)
ISHS-Humulus
EBC Congress
IV International Humulus Symposium, Yakima, Washington 2015
Introduction
Why “Flavour”
Describing Flavour
Identification of compounds
Hop Derived compounds
Who & where?
Still to understand?
Our approach
Experimental infrastructure
Metabolomics
Conclusion
Presentation at the Australian Craft Brewers Conference, Brisbane, 20 July 2016.
Still a lot to understand..
Brewery factors:
• Timing of hop addition
• Temperature and duration of exposure
• Interactions with yeast
• Interactions with filtration or pasteurisation
• Interactions with CO2 or alcohol
Hop factors:• Mode of transfer to beer (biotransformation, glycosides,
oxidative or enzymatic changes)
• Optimisation of growing, harvesting and processing
• Variation between or among cultivars
• Biosynthesis and genetic control
Introduction
Why “Flavour”
Describing Flavour
Identification of compounds
Hop Derived compounds
Who & where?
Still to understand?
Our approach
Experimental infrastructure
Metabolomics
Conclusion
Presentation at the Australian Craft Brewers Conference, Brisbane, 20 July 2016.
HPA’s approach to Research
Vertically integrated company conducting hop breeding, propagation and deployment, cultivation, processing,
sales and marketing
Currently ~95% of our acreage is planted to our own proprietary varieties developed in a dedicated plant breeding
program.
Critical for HPA to be able to continue to offer:
i) hop products with physical, chemical and quality characteristics desired by brewers; and
ii) novel varieties with truly distinctive character
Introduction
Why “Flavour”
Describing Flavour
Identification of compounds
Hop Derived compounds
Who & where?
Still to understand?
Our approach
Experimental infrastructure
Metabolomics
Conclusion
Presentation at the Australian Craft Brewers Conference, Brisbane, 20 July 2016.
Variation, biosynthesis and genetic controlIntroduction
Why “Flavour”
Describing Flavour
Identification of compounds
Hop Derived compounds
Who & where?
Still to understand?
Our approach
Experimental infrastructure
Metabolomics
Conclusion
Presentation at the Australian Craft Brewers Conference, Brisbane, 20 July 2016.
Metabolomics….Headspace GC-MS, female and male plants, two sites
Genotyping, linkage map construction,
quantitative trait loci identification
Sample, dry, store
hops and male
flowers
High throughput,
small scale
fermentation Headspace GC-MS of volatiles from experimental fermentation
Introduction
Why “Flavour”
Describing Flavour
Identification of compounds
Hop Derived compounds
Who & where?
Still to understand?
Our approach
Experimental infrastructure
Metabolomics
Conclusion
myrcenelinalool caryophyllene
humulene
Presentation at the Australian Craft Brewers Conference, Brisbane, 20 July 2016.
Putting it all together..
• More precise selection of parents for
breeding
• Efficient selection of superior varieties
• Improve cultivation
• Understand biosynthesis and
accumulation of key/marker
compounds
• Optimise timing of harvest, kilning,
handling, processing and packaging
Maximise opportunity for brewers
to make great beer!
Introduction
Why “Flavour”
Describing Flavour
Identification of compounds
Hop Derived compounds
Who & where?
Still to understand?
Our approach
Experimental infrastructure
Metabolomics
Conclusion
