Acetic Acid

The sharp, vinegar-like acid in sourdough, made by some of the bacteria in a starter. It gives a stronger, tangier bite than lactic acid. Cooler, stiffer fermentation tends to favor acetic acid, so a stiff starter or a long cold retard usually makes a more noticeably sour loaf.

By Henry Hunter · Updated October 1, 2026

Henry's notes from the bench

• Want a more sour loaf? Try a stiffer levain and a longer rest in the fridge. Small changes in temperature and hydration move the flavor more than you'd expect.