The shelf life of salt is 1 year for iron-added table salt, 8 years for added selenium salt, calcium salt, and zinc salt, and 18 months for iodized table salt. Pure edible salt has no shelf life.

Table salt comes from different sea salts, well salts, mineral salts, lake salts, soil salts, etc. Their main component is sodium chloride, and the state stipulates that the sodium chloride content of well salt and mineral salt shall not be less than 95%.

Table salt contains barium salts, chloride, magnesium, lead, arsenic, zinc, sulfate and other impurities. Relevant regulations stipulate that the barium content shall not exceed 20mg/kg. Too much magnesium and calcium in table salt can make the salt taste bitter.

Edible salt is the main source of salty taste in dishes, and has the function of enhancing the freshness and original taste; salt is a colorless and transparent cubic crystal with a melting point of 801°C and a boiling point of 1413°C. The relative density is 2.165. It has a salty taste, easily deliquesces when containing impurities, and is soluble in water or glycerin.

Salt preservation method:

1. Sealed storage. Iodized salt is easily oxidized and decomposed by heat, light, wind and other factors, so iodized salt should be stored in a covered, colored sealed container. Container, and put it in a dry, cool place to avoid sunlight exposure.

2. Avoid high-temperature stir-frying. Iodized salt will decompose at high temperatures, so you don’t need to stir-fry with salt when cooking. Add iodized salt when the vegetables are medium-cooked, which can reduce the loss of iodine.

3. Edible salt should be white, salty, no peculiar smell, no obvious foreign matter unrelated to salt, uniform and moderate particles, and good drying fluidity. Iodized salt will decompose into elemental iodine and evaporate when exposed to high temperatures. Therefore, do not use salt to "bake the pot" when cooking. You should wait until the vegetables are ripe before adding salt. This can reduce the loss of iodine.

Ordinary edible salt on the market has no shelf life, but the shelf life of edible salt with added trace elements such as iodine, zinc, selenium, calcium, and riboflavin is one year.