1. The Importance of Aromas and Flavors on Beer
Lyn Kruger
Siebel Institute of Technology

2. The sensory analyst is considered an “instrument” Senses are used to:
Sensory Analysis
The sensory analyst is considered an “instrument”
Senses are used to:
perceive and react
to characteristics of
food and beverages

3. The sensory analyst is considered an “instrument”: Measure Analyze
Sensory Analysis
The sensory analyst is considered an “instrument”:
Measure
Analyze
Interpret

4. cognitive and cultural bias individual acuity differences
Sensory Analysis
Humans as instruments
cognitive and cultural bias
individual acuity differences

5. Sensory analysts may vary from one test to the next: Fatigue
Sensory Analysis
Sensory analysts may vary from one test to the next:
Fatigue
Adaptation

6. Ability to discriminate between harmful and benign stimuli
Sensory Analysis
Ability to discriminate between harmful and benign stimuli
Health and age play a role
Ability to improve with practice

7. Sensory Evaluation: What we know
Can taste many flavor compounds
Basic tastes
sweet, salty, sour, bitter, umami
Acute sense of smell
Trigeminal sensations:
burning, cooling, tingling
> 1,000 odors and flavors in beer

8. Olfactory System

9. Trigeminal Sensation

10. Sensory Evaluation: Training objectives
Establish memory for aromas and flavors
recognize and identify aromas and flavors
choose correct descriptors

11. Flavor Wheel

12. Basic Tastes: Sensory procedure
Aroma impressions first, “drive by” then 2-3 short sniffs
Small sips
Allow sample to sit on tongue for a moment, then swallow

13. Basic Tastes: Sensory procedure
Avoid oversaturation and sensory fatigue
Allow seconds between samples to readapt receptors
Less flavored samples before highly flavored samples

14. Basic Tastes: What happens
Beer sample quickly moderates towards 37°C in the mouth
Immediate (in some individuals copious) secretion of saliva in response to oral stimulation
This is promoted in beer by its acidity, alcohol content and high level of carbonation.
Saliva is a well-buffered, high pH (7.0) diluent, and influences the sensory perception of beer

15. BREWHOUSE ASSOCIATED FLAVORS
Lyn Kruger
Siebel Institute of Technology

16. Flavors Associated with Brewhouse
Positive Flavors
Malty
Hoppy
Bitter
Off flavors
Dimethyl sulfide (DMS)
Isovaleric acid

17. Malty: Typical Flavors
Standard Malts
Cereal
Grain
Sweet
Nutty
Malty
Caramel/Color Malts
Caramel
Toffee
Slightly burnt
Roasted Malts
Burnt
Bitter
Coffee

18. Use Aroma hop varieties Aroma Associated with Hop Oils :
Hoppy & Bitter
Hoppy
Use Aroma hop varieties
Aroma Associated with Hop Oils :
Floral Compounds
Citrus Compounds
“Noble aroma” -herbal, spicy - oxidation products
Bitter
Use Bittering hop varieties
Bitter flavor associated with resins

19. Dimethyl Sulfide (DMS)
Flavor creamed corn, vegetable, oysters, tomato juice
Formation
Precursor (S-methyl methionine [SMM]) formed in the barley
Some SMM remains in the malt
During wort boiling SMM is converted to DMS and lost by volatilization

20. Flavor cheesy, sweat socks
Isovaleric Acid
Flavor cheesy, sweat socks
Production
Formed in old hops
Organic acid

21. FERMENTATION RELATED FLAVORS
Lyn Kruger
Siebel Institute of Technology

22. Flavors fruity, banana, apples, perfumy, solvent, nail varnish remover
Esters
Flavors fruity, banana, apples, perfumy, solvent, nail varnish remover
Production
Reaction of alcohol group and acid group in the yeast cell
Iso amyl acetate (Fruity)
Ethyl Acetate (Solvent)

23. Flavor buttery, butterscotch
Diacetyl
Flavor buttery, butterscotch
Production
During yeast growth in fermentation
When the yeast has to make a specific amino acid - valine

24. Flavor sulfury, rotten eggs, burnt rubber, striking a match
Sulfur Compounds
Flavor sulfury, rotten eggs, burnt rubber, striking a match
Production
Intermediates in amino acid metabolism
When yeast needs to make sulfur containing amino acids

25. STORAGE ASSOCIATED FLAVORS
Lyn Kruger
Siebel Institute of Technology

26. Flavors associated with Product Storage
Any flavor changes after maturation - generally negative (off-flavors)
Few exceptions (e.g. barley wines)
Flavors normally associated with staling of the beer
Papery
Bready/Cooked
Skunky
Aldehydic

27. Flavor papery, wet cardboard, stale.
Formation
Oxidation of linoleic acid
Forms trans-2-nonenal (an aldehyde)
Very low flavor threshold (1 ppb)
Oxygen /light promotes reaction

28. Flavor cooked breakfast cereal, oxidized, cooked
Bready / Cooked
Flavor cooked breakfast cereal, oxidized, cooked
Formation
Overpasteurization( particularly in the presence of air)
Oxidation reactions

29. Flavor Nutty, toffee, honey, green apples, aldehydic
Formation
Degradation of amino acids
Oxidation of higher alcohols
Oxidation of isohumulones
Oxidation of lipids
Oxidation of ethanol (acetaldehyde)

30. CONTAMINATION RELATED FLAVORS
Lyn Kruger
Siebel Institute of Technology

31. Flavors associated with Contamination
These flavors are generally off-flavors
Can be microbial or non-microbial
Microbial
Variety - depending on microorganism
Cloves (eugenol, 4-vinylguaicol)
Acidic (lactic, acetic acid)
Diacetyl
DMS
Sulfur

32. Microbial: Cloves / Spicy
Flavor phenolic, cloves, spicy
Formation
Associated primarily with wild yeast
In some beer styles - deliberate

33. Flavor sour, vinegar, sour milk, acetic, lactic acid, acidic
Formation
Beer spoilage bacteria
Lactic acid bacteria - Lactobacillus & Pediococcus
Produce lactic acid and acetic acid (only Lactobacillus)

34. Flavor buttery, butterscotch
Diacetyl
Flavor buttery, butterscotch
Formation
Beer spoilage bacteria
Lactobacillus & Pediococcus
Wort spoiling bacteria
Enterobacteriacea

35. Flavor cooked vegetable, corn, olives, oysters
DMS
Flavor cooked vegetable, corn, olives, oysters
Formation
Wort spoiling bacteria
Often grow in plate heat exchangers

36. Flavor sulfur, rotten eggs, mercaptan
Sulfury
Flavor sulfur, rotten eggs, mercaptan
Formation
Wort spoiling bacteria
Beer spoilage bacteria