Temperature and dough hydration affect how quickly and what kinds of acids develop during sourdough fermentation.

If the dough is kept warm and wetter, it tends to produce more lactic acid, which gives a mild, yogurt-like flavor. Cooler or stiffer dough encourages more acetic acid, which tastes more vinegary and sharp. Bakers adjust these factors to control the flavor of their bread. Also, warmer dough ferments faster but needs careful timing to avoid over-proofing, which can ruin texture.