Science, Tech, Math › Science How Does Salt Preserve Food? Share Flipboard Email Print Christopher Hope-Fitch / Getty Images Science Chemistry Chemistry In Everyday Life Basics Chemical Laws Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated September 08, 2019 Salt draws water out of cells via the process of osmosis. Essentially, water moves across a cell membrane to try to equalize the salinity or concentration of salt on both sides of the membrane. If you add enough salt, too much water will be removed from a cell for it to stay alive or reproduce. A high concentration of salt kills organisms that decay food and cause disease. A concentration of 20% salt will kill bacteria. Lower concentrations inhibit microbial growth until you get down to the salinity of the cells, which may have the opposite and undesirable effect of providing ideal growing conditions. Other Chemical Preservatives Table salt or sodium chloride is a common preservative because it is non-toxic, inexpensive, and tastes good. However, other types of salt also work to preserve food, including other chlorides, nitrates, and phosphates. Another common preservative that works by affecting osmotic pressure is sugar. Salt and Fermentation Some products are preserved using fermentation. Salt may be used to regulate and aid this process. Here, salt dehydrates the growing medium and acts to maintain fluids in the yeast or mold growing environment. Uniodized salt, free from anti-caking agents, is used for this type of preservation.