What You Need to Know
During fermentation, endogenous amylases in the bread hydrolyze starches into glucose, which is then metabolized by Saccharomyces cerevisiae to produce ethanol and CO₂. Lactic acid bacteria such as Lactobacillus spp. convert residual sugars into lactic acid, lowering the pH to 3.5–4.5 and imparting a characteristic sourness. The combined activity yields 0.5–2 % ABV and a mildly acidic, yeasty flavor profile.
The Science
Primary Reaction
Starch → glucose → ethanol + lactic acid