What You Need to Know
During fermentation, wild yeasts convert sugars into CO₂ and ethanol, while lactobacilli produce lactic and acetic acids. The resulting acidification lowers pH, inhibiting spoilage microbes and giving the starter its characteristic sour flavor. The balance of yeast and bacteria is maintained by regular feedings and controlled temperature.
The Science
Primary Reaction
Fermentation of carbohydrates by yeast and lactic acid bacteria producing CO₂, ethanol, lactic acid, and acetic acid.