Saccharomyces is a genus of eukaryotic yeast, essential for the fermentation of beers:

• Main role: to consume the fermentable sugars and produce:

  • Ethanol → alcohol

  • CO₂ → natural carbonation

  • Aromatic compounds → esters, phenols, diacetyl

• Subspecies and strains:

  • Saccharomyces cerevisiae → ale, top fermentation, temperature 15–25 °C, fruity and spicy aromas

  • Saccharomyces pastorianus → lager, bottom fermentation, temperature 8–15 °C, more neutral profile

• Influences the fermentation speed, the attenuation and the aromatic profile depending on the strain, the wort gravity, the temperature and the available nutrients

In summary, Saccharomyces is the base yeast that defines the structure, the alcohol and the main aroma of almost all modern beers.