Salt has been used as a seasoning and preservative for thousands of years. It was so sought-after that, in ancient Rome, soldiers often drew part of their pay in salt. Among its many uses, salt plays a large role in canning and preserving. The particular product used for this purpose is fine-grained and free of iodine and anti-caking ingredients that could discolor foods.
Canning salt is a particular variety of salt that is used, as the name suggests, in canning foods. The lack of additives, like iodine and anti-caking ingredients, means that it will not turn vegetables — particularly pickles — a dark color, nor will it make their liquid cloudy. Pickles made with table salt would be perfectly safe to eat, but they wouldn’t look very pretty.
This type of salt is also used in preserving meats, like salt-cured ham or sausage. It is vital tat the cook use the specified amount of salt called for in the recipe so the meat (or pickles) will be safely preserved. If not enough salt is used, bacteria can grow in the preserved food.
Salt made for canning can be used as table salt, but without the anti-caking agents, it could clump on humid days. One solution for this is to place a few grains of uncooked white rice in the salt shaker. Salt that has already caked can be separated — the cook just has to spread the salt on a baking sheet and warm it in a moderate oven for a few minutes. The heat will evaporate the moisture.
Canning salt is available in most supermarkets, where other canning supplies are sold. Shoppers can look for canning jars, lids, and bands, and fruit pectin, and chances are, this salt will be in the same area. It is also available from stores in rural areas where canning and preserving food is common.