Can salt expire?

In this brief directory, we will look into the question “can salt expire” and provide tips on how to best store salt.

Can salt expire?

Salt itself does not expire, but some salt products can show a more limited shelf life.

Salt is considered a microbiologically stable product due to its low moisture and low content of nutrients other than minerals. Remember that, like us, microbes claim to have water and food to survive.

Actually, salt is a powerful preservative that in foods creates an inhospitable environment for spoilage and pathogens (harmful microorganisms) growth by trapping water and making it unavailable for microbial growth [1].

Salt products contain iodine, additives, or other ingredients like spices and herbs. These non-salt ingredients degrade or lose efficiency over time, leading to a reduced shelf life of salt. 

How does salt expire?

Actually, salt does not expire but has a best-before date. This means that past that date, salt will be safe to eat but may not be at its best. 

For example, it may have lost added iodine. Iodine is a micronutrient required for thyroid hormone production and has been added to salt worldwide as part of a public health program to fight against iodine-related deficiency disorders [2].

However, iodine dissipates over time. According to a study by Diosady and others [2], iodine may undergo 25%  losses after a year of storage, even if stored under adequate conditions. 

Iodine is often added to table salt and marine salt in the market.

Anti-caking are additives added to salts to prevent cluster formation, but they lose effectiveness over time and clumping may occur. 

Kosher salt, plain table salt, coarse sea salt, fine sea salt, sea salt, and table salt are examples of salts that may contain this ingredient.

Often, salt is found mixed with other ingredients, such as herbs and spices. These lose aroma and color compounds during storage, reducing the quality of composed salts. 

Finally, salt is highly hygroscopic, which means that it easily absorbs moisture from the environment, particularly those with relative humidity above 75% [1]. 

If incorrectly stored, salt will soak up water from the ambient and form clumps, losing quality. Moisture gain can also accelerate iodine degradation [2].

How long does salt last?

Salt brands label the shelf life of iodized salt to be around 5 years [3]. Table salt and marine salt are often found added with iodine in the market. 

Importantly, as iodine degrades over time, salt should be correctly stored to minimize losses. 

Salts added of anticaking elements are recommended to be consumed within 5 years for best quality, after which anti-caking loses its activity and clumping may occur.  

Kosher salt, plain table salt, coarse sea salt, fine sea salt, sea salt, and table salt are examples of salts that may contain this ingredient. Iodine and anticaking ingredients can be both added to salt, also lasting 5 years [3]. 

If no anticaking is used, as is the case with Himalayan or Pink salt, recommended dates drop to around 3 years [3], because these salts can become caked over time by absorbing water from the environment.

However, if properly stored, these salts last indefinitely.

Can I consume old salt? How to tell if it is spoiled?

Yes, you can consume old salt, even if it has passed its best-before date, it still offers no harm to your health. 

But if the salt shows signs like a strange smell or appearance, or large clumps, it suggests spoilage, and the salt should be discarded.  

How to store salt properly to ensure quality?

Store salt in an air-tight container, in a dry place. Salt is hygroscopic, and can absorb steam, and any unwanted odors easily. 

Moreover, studies revealed that the stability of iodine in iodized salts depends on the moisture content of the surroundings and the pack type.

In high relative humidity environments and water-permeable packs, salt can lose up to 37% of iodine within 3 months [3].

Conclusion

In this brief guide, we answered the question “can salt expire?” and provided tips on how to best store salt.

Citations

1. Man CMD. Technological functions of salt in food products. In: Kilcast D, Angus F, editors. Reducing Salt in Foods: Woodhead Publishing; 2007. p. 157-73.
2. Diosady LL, Alberti JO, Mannar MGV, FitzGerald S. Stability of Iodine in Iodized Salt Used for Correction of Iodine-Deficiency Disorders. II. Food and Nutrition Bulletin. 1998;19(3):240-50.
3. Morton salt expiration guide. Available on: https://www.mortonsalt.com/article/morton-salt-expiration-guide/