Types of Salt used for Preserving

Purity is important. For example, extra pure pickling salt is sold, so that impurities will not cause discoloration in the pickles.

From the Middle Ages until well into the 19th century, the only fully satisfactory salt for curing meat and fish was considered to be bay salt, made by solar evaporation from sea water on the coasts of France and the Iberian peninsula, and valued for its good flavour as well as for its purity. The preference for bay salt, which would now be called sea salt, had another reason. Because the process of solar evaporation is slow, large crystals tend to be formed. These dissolve relatively slowly in any curing process, avoiding the risk of what is called ‘salt burn’, an unwelcome phenomenon which occurs when fine salt is used; this dissolves quickly and produces a sudden high concentration, which at once dehydrates the outer layers of the food, making them relatively impervious and denying the benefit of salting to the inner layers.