Description
Yeast metabolizes sugars into ethanol, CO2, and flavor compounds under anaerobic conditions.
Technical
Saccharomyces cerevisiae converts glucose → 2 pyruvate (glycolysis) → 2 acetaldehyde + 2 CO2 → 2 ethanol (alcohol dehydrogenase). Concurrent production of esters (isoamyl acetate), fusel alcohols (phenylethanol), and organic acids.
Culinary Significance
Creates foundational alcoholic beverages while developing complex aromatics. Governs texture through CO2 production in bread and effervescence in sparkling wines.
Science
Primary Reaction
C6H12O6 → 2C2H5OH + 2CO2 (ΔG = -235 kJ/mol)
Parameters
Temperature
18°C optimal
12°C to 35°C range
Lager yeasts (12-15°C), ale yeasts (18-24°C)
Time
10-14 days
3 days – 6 weeks
Beer: 1-2 weeks, Wine: 2-4 weeks
Equipment
Fermentation vesselairlock