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Sensory Analysis
The Importance of Aromas
and Flavors on Beer
Lyn Kruger
Siebel Institute of Technology
Sensory Analysis
The sensory analyst is considered an “instrument”
 Senses are used to:
 perceive and react
 to characteristics of
 food and beverages
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
Sensory Analysis
The sensory analyst is considered an “instrument”:
 Measure
 Analyze
 Interpret
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
Sensory Analysis
 Humans as instruments
 cognitive and cultural bias
 individual acuity differences
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
Sensory Analysis
Sensory analysts may vary from one test to the next:
 Fatigue
 Adaptation
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
Sensory Analysis
 Ability to discriminate between harmful and benign stimuli
 Health and age play a role
 Ability to improve with practice
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
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
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
Olfactory System
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
Trigeminal Sensation
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
Sensory Evaluation: Training objectives
 Establish memory for aromas and flavors
 recognize and identify aromas and flavors
 choose correct descriptors
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
Flavor Wheel
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
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
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
Basic Tastes: Sensory procedure
 Avoid oversaturation and sensory fatigue
 Allow 15 - 60 seconds between samples to readapt receptors
 Less flavored samples before highly flavored samples
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
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
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
Sensory Analysis
BREWHOUSE ASSOCIATED
FLAVORS
Lyn Kruger
Siebel Institute of Technology
Flavors Associated with Brewhouse
Positive Flavors
 Malty
 Hoppy
 Bitter
Off flavors
 Dimethyl sulfide (DMS)
 Isovaleric acid
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
Malty: Typical Flavors
 Standard Malts
 Cereal
 Grain
 Sweet
 Nutty
 Malty
 Roasted Malts
 Burnt
 Bitter
 Coffee
 Caramel/Color Malts
 Caramel
 Toffee
 Nutty
 Slightly burnt
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
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
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
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
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
Isovaleric Acid
 Flavor
cheesy, sweat socks
 Production
 Formed in old hops
 Organic acid
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
Sensory Analysis
FERMENTATION RELATED
FLAVORS
Lyn Kruger
Siebel Institute of Technology
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
 Ethyl Acetate
(Fruity)
(Solvent)
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
Diacetyl
 Flavor
buttery, butterscotch
 Production
 During yeast growth in fermentation
 When the yeast has to make a specific amino acid - valine
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
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
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
Sensory Analysis
STORAGE ASSOCIATED
FLAVORS
Lyn Kruger
Siebel Institute of Technology
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
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
Papery
 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
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
Bready / Cooked
 Flavor
cooked breakfast cereal, oxidized, cooked
 Formation
 Overpasteurization( particularly in the presence of air)
 Oxidation reactions
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
Aldehydic
 Flavor
Nutty, toffee, honey, green apples, aldehydic
 Formation
 Degradation
 Oxidation of
 Oxidation of
 Oxidation of
 Oxidation of
of amino acids
higher alcohols
isohumulones
lipids
ethanol (acetaldehyde)
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
Sensory Analysis
CONTAMINATION RELATED
FLAVORS
Lyn Kruger
Siebel Institute of Technology
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
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
Microbial: Cloves / Spicy
 Flavor
phenolic, cloves, spicy
 Formation
 Associated primarily with wild yeast
 In some beer styles - deliberate
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
Acidic
 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)
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
Diacetyl
 Flavor
buttery, butterscotch
 Formation
 Beer spoilage bacteria
 Lactobacillus & Pediococcus
 Wort spoiling bacteria
 Enterobacteriacea
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
DMS
 Flavor
cooked vegetable, corn, olives, oysters
 Formation
 Wort spoiling bacteria
 Often grow in plate heat exchangers
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology
Sulfury
 Flavor
sulfur, rotten eggs, mercaptan
 Formation
 Wort spoiling bacteria
 Beer spoilage bacteria
Sensory Analysis: The Importance of Aromas and Flavors on Beer
Lyn Kruger, Siebel Institute of Technology