A mild loaf is not a broken loaf — many bakers actually chase that gentle, sweet-wheat flavour. But if you want real tang, sourness is something you build, not something that just happens. It comes from acids produced by the bacteria in your culture, and you have several levers to turn them up.
Open the free bake log →This is the most reliable lever. After shaping, retard the dough in the fridge overnight — and a longer cold proof (24–48 hours) lets acetic acid, the sharper, more vinegary acid, accumulate slowly. A loaf proofed 36 hours cold will taste noticeably tangier than the same dough baked the same evening.
Whole wheat and rye carry more minerals, enzymes and wild microbes, which feed faster, more acidic fermentation. Swapping even 15–25% of your flour for rye or whole wheat usually deepens both flavour and sourness. Rye in particular is famous for tangy, complex bread.
Building with a starter that is past its peak, or keeping it a touch hungrier between feeds, raises acidity. A stiffer starter (lower hydration, around 50–60%) tends to favour acetic, sharp notes, while a wet, frequently fed starter stays milder and lactic. If your bread is flat in flavour, try a less pampered culture.
Slower, cooler fermentation generally tastes more sour than fast, warm fermentation, which leans sweet and mild. Lengthening bulk slightly (without over-proofing) and proofing cool both push toward tang. Slightly higher hydration can also help acids develop.
There is a ceiling: push fermentation too far and you cross from pleasant tang into acetone-sharp, gummy, over-proofed bread that bakes flat. Sourness and structure are linked, so change one lever at a time and taste the result.
Because so many factors feed into flavour, the only way to dial in your ideal sourness is to change a single variable per bake and write down what you tasted. A bake log makes "the 30-hour cold proof with 20% rye" repeatable instead of accidental.
Log proof times, flour & flavour — free →