Salt is an important ingredient in many ways. A normal percentage is about 2% of the total flour weight
It is open to add salt at different stages, during autolysis, adding with the starter, or even after having added the starter. But there exists a continuous discussion on what is best.
Other say the key to using salt successfully is to dissolve it into the water and use it after the autolyse stage. This is for two reasons. If you sprinkle salt directly onto your dough it will draw water out of the dough and you may well end up with holes in your dough as the water splits the two layers of dough. The second reason is that salt also inhibits fermentation due to the osmotic pressure effect, as mentioned below. As the salt draws the water out of the wild yeast it retards the fermentation so to give your bread the best chance possible then it is best to wait until the sourdough cultures have had a chance to get a hold
Even some say salt affects the absorption rate of the flour and in turn this affects the properties of the gluten. Important term to learn is 'tenacity' and that is the dough's tendency to fight against being stretched. The earlier you add the salt, or an increase in the amount of salt, the more tenacious your dough will be. This decreases the elasticity and also the 'extensibility' - a dough's property of expanding like a balloon, but it also has a positive effect on 'plasticity' - a loaf's ability to hold its shape.
Some explanations to why salt is important
Salt acts as a natural antioxidant in the dough and not only adds taste but especially helps bring out the flavors and aromas present in the flour and other ingredients.
Next to its role in boosting the flavor of your bread, salt plays a role in tightening the gluten structure and adding strength to your dough. It helps the loaf to hold on to the carbon dioxide gas that is formed during fermentation, supporting good volume.
Salt slows down fermentation and enzyme activity in dough. The salt crystals draw water away form their environment (salt is ‘hygroscopic’). When salt and yeast compete for water, salt wins and the yeast is slowed down.
Because of its moisture maintaining properties, salt can prevent bread from getting stale but it can also (this is especially true in humid environments) absorb moisture from the air and leave you with soft crusts and soggy bread.
