Sourdough is a type of bread that is baked using naturally occurring yeast and given a long, slow rising period. In comparison with commercial yeast-based breads, it produces a characteristic sour flavour and a chewy crumb. This is mainly because of the production of lactic acid.
In more general terms it is any bread that is made from a sourdough starter. The starter (also known as a poolish or levain) is essentially a pre-fermenting process that helps to develop its characteristic flavour. Commercial starters are available but they may not have the sour flavour of a true sourdough bread.
Mass-produced versions of sourdough bread are baked with traditional baker’s yeast and have acids and flavourings added to simulate the sour flavour. However, these barely qualify as a true sourdough bread even under the loosest of definitions.
Sourdough is a real artisan bread. Do not be fooled by the cheap imitation in the supermarkets. Find a proper baker and try real sourdough, or even better, try making it yourself. I am telling you now, the result will be a revelation…