Sourdough is likewise a starter dough that contains not only grain-flour products and water but also starter cultures (lactobacilli) in their active state.
Suitable micro-organisms constantly produces acids, flavor precursors, and flavors in sourdough, which then transfers the microbial activity into the main dough. The acids present in the sourdough originate exclusively from the on-going sourdough fermentation. The pH-value of fully mature sourdough will vary according to whether rye or wheat flour has been used and the grade to which it has been milled but will always be in the range between 3.2 and 4.5 and its acidity between 10 and 30.
A souring process is almost indispensable for rye bread as it modifies certain ingredients in the rye flour in a certain way; without it, the flour would not be capable of baking at all.
All according to the type of bread and the exact flavour required, the proportion of sourdough will lie anywhere between 15 and 50 percent. Sourdough can be used as a motherdough for other types of sourdough. Sourdough can be kept without difficulty in the chilled state (< 5°C), when it falls into inactivity. Before sourdough is further processed it can be made capable of baking again by adding flour, water, and heat.
starter dough
