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Published on: September 30, 2018
Parameters affecting ethyl ester production by Saccharomyces cerevisiae during fermentation
S M G Saerens1, F Delvaux, K J Verstrepen
1Centre for Food and Microbial Technology, Department of Microbial and Molecular Systems, Katholieke Universiteit Leuven, Kasteelpark Arenberg 22, B-3001 Heverlee, Belgium. Sofie.Saerens@biw.kuleuven.be
Applied and Environmental Microbiology
|November 13, 2007
Summary
Ethyl ester production in fermented beverages is influenced by fatty acid precursors and temperature. Precursor availability, not enzyme activity, is the main factor limiting ethyl ester formation, guiding flavor modification strategies.
Area of Science:
- Enology and Fermentation Science
- Biochemistry of Aroma Compounds
- Yeast Metabolism
Background:
- Volatile esters are key aroma compounds responsible for fruity notes in fermented beverages like beer and wine.
- Understanding factors influencing ester production is crucial for controlling beverage flavor profiles.
Purpose of the Study:
- To investigate the impact of fermentation parameters on ethyl ester production.
- To identify the primary limiting factor for ethyl ester biosynthesis in yeast.
Main Methods:
- Fermentation experiments varying unsaturated fatty acid levels, temperature, carbon, and nitrogen content.
- Analysis of ethyl ester biosynthesis gene expression (EEB1, EHT1).
- Correlation of precursor availability with ethyl ester formation.
Main Results:
- Higher unsaturated fatty acids decreased ethyl ester production; higher temperatures increased specific ethyl esters (octanoate, decanoate).
- Gene expression levels were not limiting for ethyl ester production, unlike acetate esters.
- Increased medium-chain fatty acid precursors significantly enhanced corresponding ethyl ester formation.
Conclusions:
- Fatty acid precursor availability is the major limiting factor for ethyl ester production under tested conditions, not enzyme activity.
- Targeting fatty acid biosynthesis pathways and process parameters offers potential for flavor modification in fermented beverages.
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