Salt is generally added to canned foods to enhance their flavor. With the exception of fermented pickles and sauerkraut, salt is an optional ingredient. Salt can be omitted for canning tomatoes, vegetables, meats, poultry, and seafood since the amount added does not contribute to the safety of the food. However, in fermented sauerkraut and brined pickles, salt not only provides characteristic flavor but also is vital to safety since it favors the growth of desirable bacteria while inhibiting the growth of others.
Types of Salt and Salt Substitutes in Canning
Therefore, do not attempt to make sauerkraut or fermented pickles by cutting back on the salt required.
Canning salt or pickling salt is pure salt. It contains no additives. This is the best choice for canning, pickling, and sauerkraut.
Table salt is safe to use for canning. However, it usually contains anti-caking additives that may make the brine cloudy or produce sediment at the bottom of the jar. Even plain table salt has these anti-caking ingredients. Table salt labeled as iodized salt is not recommended for fermenting pickles and sauerkraut, or for canning because the iodine may cause them to darken, discolor, or be spotty. It will also cause unusual colors to form in some vegetables. For example--cauliflower will sometimes turn pink or purple.
Kosher salt is a coarse, flaked, pure salt that can also be used in canning. Its crystalline form measures differently from regular salt. Since flaked salt may vary in density, is not recommended for making pickled and fermented foods where salt concentration is a critical factor for microbial growth.
Sea salt is evaporated sea water and contains various minerals. It is safe to eat but minerals in the salt may cause canned foods to discolor.
Rock salt, ice cream salt, and solar salt are used to melt ice, freeze homemade ice cream, and to soften water. Since they are not considered suitable for human consumption, do not use them for home food preservation.
Salt substitutes contain chemicals that provide a salty flavor but contain little or no sodium. Most salt substitutes contain potassium chloride. Some people think the potassium chloride has a metallic taste. One brand adds L-lysine to mask the metallic flavor. Do not substitute potassium chloride for sodium chloride in fermentation recipes. One way to lower the sodium content of sauerkraut or pickles is to rinse the product with water just before heating and serving. But never do this before canning. Lowering the salt content this way will lower the acid content (raise the pH) and possibly render the product unsafe to eat or quick to spoil. If you choose to use a salt substitute, it would be best to can without the salt substitute and add it when serving the food. Serving foods with spices and herbs is another way to add flavor without the addition of salt or salt substitutes
http://extension.psu.edu/food/preservation/news/2012/types-of-salt-and-salt-substitutes-in-canning.
