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The Importance of Aromas and Flavors on Beer

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.

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The Importance of Aromas and Flavors on Beer

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

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

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

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

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

  6. 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 15 - 60 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 • Roasted Malts • Burnt • Bitter • Coffee • Standard Malts • Cereal • Grain • Sweet • Nutty • Malty • Caramel/Color Malts • Caramel • Toffee • Nutty • Slightly burnt

  18. 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. Isovaleric Acid • Flavorcheesy, sweat socks • Production • Formed in old hops • Organic acid

  21. FERMENTATION RELATED FLAVORS Lyn Kruger Siebel Institute of Technology

  22. Esters • Flavorsfruity, 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. Diacetyl • Flavorbuttery, butterscotch • Production • During yeast growth in fermentation • When the yeast has to make a specific amino acid - valine

  24. Sulfur Compounds • Flavorsulfury, 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. Papery • 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

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

  29. Aldehydic • 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)

  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 • Flavorphenolic, cloves, spicy • Formation • Associated primarily with wild yeast • In some beer styles - deliberate

  33. Acidic • 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)

  34. Diacetyl • Flavorbuttery, butterscotch • Formation • Beer spoilage bacteria • Lactobacillus & Pediococcus • Wort spoiling bacteria • Enterobacteriacea

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

  36. Sulfury • Flavorsulfur, rotten eggs, mercaptan • Formation • Wort spoiling bacteria • Beer spoilage bacteria

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