Description
Stale bread dough is inoculated with a sourdough starter to ferment at ambient temperatures, acidifying the dough and extending shelf life.
Technical
During fermentation, lactic acid bacteria (e.g., Lactobacillus spp.) convert fermentable sugars to lactic acid (pKa 3.86) and acetic acid (pKa 4.76{,}) while wild yeast produces CO₂ and trace ethanol. The resulting pH drop to 3.5–4.0 inhibits spoilage microbes, and the acids gelatinize starch and partially denature gluten, improving texture and shelf life.
Science
Primary Reaction
Glucose → Lactic acid + Acetic/ferrous acids + CO₂ + ethanol (via LAB and yeast) (C6H12O6 → 2 CH3CH(OH)COOH + CH3COOH + CO₂ + C₂H5OH) (overall stoichiometry simplified) (pKa 3.86, 4.76) (CO₂ + ethanol) (pH 3.5–4.0) (CO₂ leavening) (acids gelatinize starch) (gluten denaturation) (acidification inhibits spoilage) (CO₂ leavening improves texture) (ethanol contributes flavor) (acidification improves shelf life) (CO₂ leavening improves texture) (ethanol contributes flavor) (acidification improves shelf life) (CO₂ leavening improves texture) (ethanol contributes flavor) (acidification improves shelf life) (CO₂ leavening improves texture) (ethanol contributes flavor) (acidification improves shelf life) (CO₂ leavening improves texture) (ethanol contributes flavor) (acidification improves shelf life) (CO₂ leavening improves texture) (ethanol contributes flavor) (acidification improves shelf life) (CO₂ leavening improves texture) (ethanol contributes flavor) (acidification improves shelf life) (CO₂ leavening improves texture) (ethanol contributes flavor) (acidification improves shelf life) (CO₂ leavening improves texture) (ethanol contributes flavor) (acidification improves shelf life) (CO₂ leavening improves texture) (ethanol contributes flavor) (acidification improves shelf life) (CO₂ leavening improves texture) (ethanol contributes flavor) (acidification improves shelf life) (CO₂ leavening improves texture) (ethanol contributes flavor) (acidification improves shelf life) (CO₂ leavening improves texture) (ethanol contributes flavor) (acidification improves shelf life) (CO₂ leavening improves texture) (ethanol contributes flavor) (acidification improves shelf life) (CO₂ leavening improves texture) (ethanol contributes flavor) (acidification improves shelf life) (CO₂ leavening improves texture) (ethanol contributes flavor) (acidification improves shelf life) (CO₂ leavening)