Sourdough is a natural leavening agent for bread. It is made from three ingredients:

• Flour(s)
• Water or other liquids such as juice, milk, yoghurt...
• Two types of microorganisms: lactic acid bacteria and yeast. These are either airborne and/or present in the raw materials.

Using sourdough (as a leavening agent) gives bread a very distinctive taste. Depending on which sourdough is used, the result can be very different. This is because the taste and flavour of sourdough depends, among other things, on the microorganisms that are present. These can vary around the world.