The Importance of Aromas and Flavors on Beer

Sensory Analysis

Lyn KrugerSiebel Institute of Technology

The Importance of Aromas and Flavors on Beer

Sensory Analysis: The Importance of Aromas and Flavors on BeerLyn Kruger, Siebel Institute of Technology

The sensory analyst is considered an “instrument”

Senses are used to: perceive and react to characteristics of food and beverages

Sensory Analysis


The sensory analyst is considered an “instrument”:

Measure Analyze Interpret

Sensory Analysis


Humans as instruments cognitive and cultural bias individual acuity differences

Sensory Analysis


Sensory analysts may vary from one test to the next:

Fatigue Adaptation

Sensory Analysis


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

Sensory Analysis


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 Evaluation: What we know


Olfactory System


Trigeminal Sensation


Establish memory for aromas and flavors recognize and identify aromas and flavors choose correct descriptors

Sensory Evaluation: Training objectives


Flavor Wheel


Aroma impressions first, “drive by” then 2-3 short sniffs Small sips Allow sample to sit on tongue for a moment, then swallow

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

Basic Tastes: Sensory procedure


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

Basic Tastes: What happens

Sensory Analysis


BREWHOUSE ASSOCIATED FLAVORS


Positive Flavors Malty Hoppy Bitter

Off flavors Dimethyl sulfide (DMS) Isovaleric acid

Flavors Associated with Brewhouse


Standard Malts Cereal Grain Sweet Nutty Malty

Caramel/Color Malts Caramel Toffee Nutty Slightly burnt

Roasted Malts Burnt Bitter Coffee

Malty: Typical Flavors


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

Hoppy & Bitter


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

Dimethyl Sulfide (DMS)


Flavorcheesy, sweat socks

Production Formed in old hops Organic acid

Isovaleric Acid

Sensory Analysis


FERMENTATION RELATED FLAVORS


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)

Esters


Flavorbuttery, butterscotch

Production During yeast growth in fermentation When the yeast has to make a specific amino acid - valine

Diacetyl


Flavorsulfury, rotten eggs, burnt rubber, striking a match

Production Intermediates in amino acid metabolism When yeast needs to make sulfur

containing amino acids

Sulfur Compounds

Sensory Analysis


STORAGE ASSOCIATED FLAVORS


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

Flavors associated with Product Storage


Flavorpapery, wet cardboard, stale.

Formation Oxidation of linoleic acid Forms trans-2-nonenal (an aldehyde) Very low flavor threshold (1 ppb) Oxygen /light promotes reaction

Papery


Flavorcooked breakfast cereal, oxidized, cooked

Formation Overpasteurization( particularly in the presence of air) Oxidation reactions

Bready / Cooked


FlavorNutty, toffee, honey, green apples, aldehydic

Formation Degradation of amino acids Oxidation of higher alcohols Oxidation of isohumulones Oxidation of lipids Oxidation of ethanol (acetaldehyde)

Aldehydic

Sensory Analysis


CONTAMINATION RELATED FLAVORS


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

Flavors associated with Contamination


Flavorphenolic, cloves, spicy

Formation Associated primarily with wild yeast In some beer styles - deliberate

Microbial: Cloves / Spicy


Flavorsour, vinegar, sour milk, acetic, lactic acid, acidic

Formation Beer spoilage bacteria Lactic acid bacteria - Lactobacillus & Pediococcus Produce lactic acid and acetic acid (only Lactobacillus)

Acidic


Flavorbuttery, butterscotch

Formation Beer spoilage bacteria Lactobacillus & Pediococcus Wort spoiling bacteria Enterobacteriacea

Diacetyl


Flavorcooked vegetable, corn, olives, oysters

Formation Wort spoiling bacteria Often grow in plate heat exchangers

DMS


Flavorsulfur, rotten eggs, mercaptan

Formation Wort spoiling bacteria Beer spoilage bacteria

Sulfury

The Importance of Aromas and Flavors on Beer

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