Edible salt has a shelf life.

Edible salt with added special nutrients has a different shelf life: 1 year for salt with iron nutrients, 2 years for regular iodized salt, 5 years for refined iodized salt, 3 years for low-sodium salt, and 8 years for selenium-added salt, calcium-added salt, and zinc-added salt. The state regulations of the salt can be exempted from the shelf life, but does not mean that there is no shelf life, the shelf life is longer. It is best to consume the salt labeled with a shelf life within 1 year to ensure the taste. Pure salt itself has no shelf life, but table salt with added special nutrients has a shelf life.

Iodized salt is susceptible to oxidation and decomposition by heat, light and wind, etc. Edible salt, whose main ingredient is sodium chloride, is quite stable and will not decompose or evaporate over time. It is also the main source of salty flavor.

Introduction of physical properties of salt:

The color of salt can be pure and transparent (e.g., sodium chloride), opaque or with a metallic luster (e.g., pyrite). In most cases the transparency or opacity of a salt's surface relates only to the single crystals that make up the salt. When light hits the salt, it is reflected back by grain boundaries (the boundaries between crystals) and larger crystals appear transparent, while multiple crystals clustered together look more like white powder.

Salts come in many colors, such as: yellow (e.g., sodium chromate), orange (e.g., potassium dichromate), red (e.g., potassium ferricyanide), lilac (e.g., cobalt chloride), blue (e.g., copper sulfate, ferricyanide), green (e.g., nickel chloride hexahydrate), colorless (e.g., sodium chloride, magnesium sulfate), and in powder form white. Most minerals, inorganic pigments, and synthetic organic dyes are salt. salts, and the ability of some salts to take on other colors is caused by the presence of unpaired electrons in the d orbitals of transition elements. Salts with different flavors can excite different taste sensations.