Impact of Artificially Induced Respiratory Deficient Yeast on Beer Flavor and Fermentation

Maria Josey, Dawn Louise Maskell, R. Alex Speers

Research output: Contribution to journalArticle

Abstract

Respiratory deficient cells or “petites” are the most common type of mutation found in brewing yeast. High levels of petites are known to contribute to unwanted flavors in beer along with yeast flocculation problems during fermentation. However, a minimal amount is known regarding the impact of petites when present at naturally occurring frequencies. Accordingly, this study investigated if petites, which are present at low frequencies, affect beer flavor and fermentation profiles. Laboratory [20 mL] fermentations were undertaken with yeast that contained a range of petite populations 3.7, 5.1, 8.7, and 10.8%. During fermentation, the yeast in suspension, wort density, and alcohol were monitored. At the end of the fermentation, the beer was analyzed for volatile flavor compounds. Correlations between petite levels and levels of vicinal diketones, acetate esters, and medium chain fatty acid (MCFA) ethyl esters existed. Higher alcohol levels were unchanged (propan-1-ol, 3-methyl butanol, 2-methyl butanol, and isobutanol) with increasing levels of petite concentrations. Similarly, the yeast in suspension behavior and the change in wort density attenuation between the control and petite enriched fermentations were not significantly different (P > 0.05). This study suggests that low concentrations of petites in the pitched yeast would not be detectable in the final product characteristics.
Original languageEnglish
Pages (from-to)21-29
Number of pages9
JournalJournal of the American Society of Brewing Chemists
Volume77
Issue number1
Early online date6 Feb 2019
DOIs
Publication statusPublished - 2019

Fingerprint

beers
Fermentation
flavor
Yeasts
fermentation
yeasts
wort (brewing)
butanol
Suspensions
Esters
alcohols
esters
Alcohols
Flocculation
medium chain fatty acids
flocculation
flavor compounds
brewing
Acetates
Fatty Acids

Keywords

  • Beer flavor
  • Saccharomyces cerevisiae
  • brewer’s yeast
  • fermentation
  • petite mutation
  • respiratory deficient

ASJC Scopus subject areas

  • Biotechnology
  • Food Science
  • Applied Microbiology and Biotechnology

Cite this

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title = "Impact of Artificially Induced Respiratory Deficient Yeast on Beer Flavor and Fermentation",
abstract = "Respiratory deficient cells or “petites” are the most common type of mutation found in brewing yeast. High levels of petites are known to contribute to unwanted flavors in beer along with yeast flocculation problems during fermentation. However, a minimal amount is known regarding the impact of petites when present at naturally occurring frequencies. Accordingly, this study investigated if petites, which are present at low frequencies, affect beer flavor and fermentation profiles. Laboratory [20 mL] fermentations were undertaken with yeast that contained a range of petite populations 3.7, 5.1, 8.7, and 10.8{\%}. During fermentation, the yeast in suspension, wort density, and alcohol were monitored. At the end of the fermentation, the beer was analyzed for volatile flavor compounds. Correlations between petite levels and levels of vicinal diketones, acetate esters, and medium chain fatty acid (MCFA) ethyl esters existed. Higher alcohol levels were unchanged (propan-1-ol, 3-methyl butanol, 2-methyl butanol, and isobutanol) with increasing levels of petite concentrations. Similarly, the yeast in suspension behavior and the change in wort density attenuation between the control and petite enriched fermentations were not significantly different (P > 0.05). This study suggests that low concentrations of petites in the pitched yeast would not be detectable in the final product characteristics.",
keywords = "Beer flavor, Saccharomyces cerevisiae, brewer’s yeast, fermentation, petite mutation, respiratory deficient",
author = "Maria Josey and Maskell, {Dawn Louise} and Speers, {R. Alex}",
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Impact of Artificially Induced Respiratory Deficient Yeast on Beer Flavor and Fermentation. / Josey, Maria; Maskell, Dawn Louise; Speers, R. Alex.

In: Journal of the American Society of Brewing Chemists, Vol. 77, No. 1, 2019, p. 21-29.

Research output: Contribution to journalArticle

TY - JOUR

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AU - Speers, R. Alex

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N2 - Respiratory deficient cells or “petites” are the most common type of mutation found in brewing yeast. High levels of petites are known to contribute to unwanted flavors in beer along with yeast flocculation problems during fermentation. However, a minimal amount is known regarding the impact of petites when present at naturally occurring frequencies. Accordingly, this study investigated if petites, which are present at low frequencies, affect beer flavor and fermentation profiles. Laboratory [20 mL] fermentations were undertaken with yeast that contained a range of petite populations 3.7, 5.1, 8.7, and 10.8%. During fermentation, the yeast in suspension, wort density, and alcohol were monitored. At the end of the fermentation, the beer was analyzed for volatile flavor compounds. Correlations between petite levels and levels of vicinal diketones, acetate esters, and medium chain fatty acid (MCFA) ethyl esters existed. Higher alcohol levels were unchanged (propan-1-ol, 3-methyl butanol, 2-methyl butanol, and isobutanol) with increasing levels of petite concentrations. Similarly, the yeast in suspension behavior and the change in wort density attenuation between the control and petite enriched fermentations were not significantly different (P > 0.05). This study suggests that low concentrations of petites in the pitched yeast would not be detectable in the final product characteristics.

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