This is partially incorrect as it isn’t the only reason the sourdough can become sour. The sourness comes from the relative mix of bacteria. I believe the acron

This is partially incorrect as it isn’t the only reason the sourdough can become sour. The sourness comes from the relative mix of bacteria. I believe the acronyms are BAC vs LAC but may be wrong on that. One is more milky and the other is more acidic, and which thrives proportionately better depends on the relative hydration and type of flour (whole vs white vs rye etc etc etc).