American Society of Brewing ChemistsEventsMeeting Archives 

Origins and Troubleshooting Flavor Defects in Beer

Origins and Troubleshooting Flavor Defects in Beer

October 16 - 17, 2008

ASBC Headquarters, St. Paul, MN, U.S.A.

 

This course is sold out.

 

Course Description

This course emphasizes finding the answers to why yeast does what it does. Attendees will explore the causes of more than 15 different beer flavor defects and learn troubleshooting skills to help prevent their occurrence. Included with the course materials are numerous fishbone diagrams—visual tools that will aid in understanding the factors that affect different flavor defects in beer.

 

Beer flavor defects covered include esters, higher alcohols, hoppy, oxidized (stale, papery), sulfitic, sulfidic (H2S, rotten eggs), lightstruck (skunky), DMS (cooked vegetable), soapy (fatty acid, caprylic), bacterial (infected, sour), diacetyl (VDK, buttery), acetaldehyde (green apples), spicy (clove-like), metallic, and musty flavors and yeast viability and vitality.

 

Course Topics

Beer flavor compounds and yeast metabolism

  • Typical fermentation profiles

  • Yeast nutrition 101

  • Fermentation: Yeast vs. the brewer

 

Flavor wheel

  • Class and first-tier terms

  • Key flavor attributes and troubleshooting—Fishbone diagrams

 

Esters

  • Ethyl hexanoate

  • Isoamyl acetate

  • Geraniol

  • Why yeast does what it does: Esters… lipids…membranes!

  • Formation of acetate esters by yeast

  • Pattern of yeast growth vs. ester production

  • Happy vs. unhappy yeast: Impact on ester production

  • Cause-and-effect fishbone diagrams

 

Higher alcohols

  • Why yeast does what it does: Higher alcohols….amino acids…proteins!

  • Pattern of yeast growth vs. higher alcohol production

  • Happy vs. unhappy yeast: Impact on production of higher alcohols

  • Cause-and-effect fishbone diagrams

 

Hoppy flavors

  • Kettle hop

  • Hop oil

 

Oxidized (stale, papery) flavors

  • Pathways for the formation of oxidized flavors

  • Enzymatic vs. non-enzymatic lipid oxidation and influence of SO2

  • “The good, the bad, the ugly”: Participants in beer flavor stability

  • Fishbone diagrams of yeast, brewhouse, and fermentation factors affecting beer oxidation

  • Fishbone diagrams of conditioning, finishing, and packaging factors affecting beer oxidation

  • Fishbone diagrams of malt parameters affecting beer oxidation

  • Review paper of oxidized flavors in beer

 

Sulfitic flavors

  • Why yeast does what it does: Sulfur…amino acids…proteins!

  • Pattern of yeast growth vs. SO2 production

  • Happy vs. unhappy yeast: Influence of yeast vitality and viability on SO2 production

  • Fishbone diagrams of factors affecting SO2 production

 

Sulfidic (H2S, rotten eggs) flavors

  • H2S

  • Mercaptan

  • Pattern of yeast growth vs. production of sulfidic flavors

  • Happy vs. unhappy yeast: Influence of yeast vitality and viability on production of sulfidic flavors

  • Fishbone diagram of factors affecting H2S production

  • Fishbone diagrams of factors affecting the production of sulfidic flavors

 

Lightstruck (skunky) flavors

  • Formation of lightstruck flavors

  • Fishbone diagram of factors affecting light resistance in beer

  • Hop products used in brewing

  • Reduced isomerized hop extracts

 

DMS (cooked vegetable) flavors

  • Formation and volatilization of DMS

  • Fishbone diagrams of factors affecting DMS levels in beer

 

Soapy (fatty acid, caprylic) flavors

  • Isovalerate

  • Fishbone diagram of factors affecting soapy off-flavors

 

Bacterial (infected, sour) flavors

 

Diacetyl (VDK, buttery) flavors

  • Why yeast does what it does: Diacetyl…..amino acids….proteins!

  • Pattern of yeast growth vs. VDK production

  • Happy vs. unhappy yeast: Influence of yeast vitality and viability on production and reduction of diacetyl

  • Fishbone diagrams of factors affecting VDK production

 

Acetaldehyde (green apples) flavors

  • Why yeast does what it does: Acetaldehyde…..energy and building blocks!

  • Fishbone diagrams of factors affecting acetaldehyde production

  • Happy vs. unhappy yeast: Influence of yeast vitality and viability on production of acetaldehyde

 

Spicy (clove-like) flavors

  • Phenolic

  • Origins of 4-VG and 4-VP

  • Fishbone diagrams of factors affecting medicinal off-flavors

 

Metallic flavors

 

Musty flavors

 

Yeast viability and vitality

  • Fishbone diagrams of factors affecting yeast viability and vitality

 

Tentative Schedule

Thursday, October 16: 9:00 a.m. - 4:00 p.m.

Friday, October 17: 8:00 a.m. - 12:00 p.m.

 

Course Faculty

Greg Casey

Director, Brewing Process Development

MillerCoors Brewing Company

Golden, Colorado, U.S.A.

 

Sue Thompson

Sensory Manager

MillerCoors Brewing Company

Milwaukee, Wisconsin, U.S.A.