Copyright 1997 Alan T. Hagan. All rights reserved.
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Storage life for salt is indefinite. So long as you keep it dry and do not let it get contaminated with dirt or whatever, it will never go bad. Over time, iodized salt may turn yellow, but this is harmless and may still be used. Salt it rather hygroscopic and will adsorb moisture from the air if not sealed in an air-tight container. If it does adsorb moisture and cakes up, it can be dried in the oven and then broken up with no harm done.
All salt, however, is not the same. Salt comes in a number of different varieties, each with its own purpose. Very little of the salt produced in the US is intended for use in food. The rest of it, about 98%, has other uses. Therefore, it is important to be certain the salt you have is intended for human consumption. Once you are satisfied it is, you should then determine its appropriateness for the tasks to which you might want to set it to. Below is a partial list of some of the available salts. I hope to make it more complete as I find better information.
- Table Salt
- This is by far the most widely known type of salt. It comes in two varieties; iodized and non-iodized. There is an ingredient added to it to absorb moisture so it will stay free flowing in damp weather. This non-caking agent does not dissolve in water and can cause cloudiness in whatever solution it is used if sufficiently large quantities are used. In canning it won't cause a problem since there is very little per jar. For pickling, though, it would be noticeable. If you are storing salt for this purpose, you should be sure to choose plain pickling salt, or other food grade pure salt. In the iodized varieties, the iodine can cause discoloration or darkening of pickled foods so be certain not to use it for that purpose.
- Canning Salt
- This is pure salt and nothing but salt. It can usually be found in the canning supplies section of most stores. This is the salt to be preferred for most food preservation or storage uses.
- Kosher Salt
- I'm not precisely sure what makes kosher salt different from canning salt. I'm presuming that it must have been processed in a particular manner in accordance with the kosher dietary laws of the Jewish faith because it is used in preparation of kosher foods. It is generally larger in grain size than table or canning salt and may have even been rolled to produce "flaked" kosher salt. Grain size can vary from manufacturer to manufacturer.
- Sea Salt
- This type of salt comes in about as many different varieties as coffee and from about as many different places around the world. The "gourmet" versions can be rather expensive. In general, the types sold in grocery stores, natural food markets and gourmet shops have been purified enough to use in food. It's not very suitable for food preservation, though, because the mineral content it contains (other than the sodium chloride) may cause discoloration of the food.
- Rock or Ice Cream Salt
- This type of salt comes in large chunky crystals and is intended primarily for use in home ice cream churns to lower the temperature of the ice filled water in which the churn sits. It's also sometimes used in icing down beer kegs. It is used in food preservation by some, but none of the brands I have been able to find label it as food grade so I would not use it for this purpose.
- Solar Salt
- This is also sometimes confusingly called "sea salt". It is not, however, the same thing as the sea salt found in food stores. Most importantly, it is not food grade. It's main purpose is for use in water softeners. The reason it is called "solar" and sometimes "sea salt" is that it is produced by evaporation of sea water in large ponds in various arid areas of the world. This salt type is not purified and still contains the desiccated remains of whatever aquatic life might have been trapped in it. Those organic remains might react with the proteins in the foods you are attempting to preserve and cause it to spoil.
- For those of us fortunate enough to live far enough south to not need it, halite is the salt that is used on roads to melt snow and ice. It, too, is not food grade and should not be used in food preservation.
- Salt Substitutes
- These are various other kinds of metal salts such as potassium chloride used to substitute for the ordinary sodium chloride salt we are familiar with. They have their uses, but should not be used in foods undergoing a heated preservation processing, they can cause the product to taste bad. Even the heat from normal cooking is sometimes sufficient to cause this.
DISCLAIMER: Safe and effective food storage requires attention to detail and proper equipment and ingredients. The author makes no warranties and assumes no responsibility for errors or omissions in the text, or damages resulting from the use or misuse of information contained herein. Placement of or access to this work on this or any other site does not mean the author espouses or adopts any political, philosophical or meta-physical concepts that may also be expressed wherever this work appears.