Sodium helps preserve and flavor many processed foods, either in the form of table salt or as a component of added ingredients. The Nutrition Facts labels that appear on the packaging of processed foods are required to list the amount of sodium found in each serving of the food product.
Sodium in Food Preservation
Salt has been used as a preservative for centuries. The sodium and chloride ions reduce the water activity of foods, which refers to the amount of water that's available for supporting bacteria growth, or to allow other chemical reactions to take place. Salt might also draw water out of any bacteria present, which kills them or at least slows them down quite a bit. Salt also enhances fermentation, which is another technique for preserving foods.
Salt is an effective preservative on it's own, but sometimes additional preservatives are be necessary. Some of them work like salt to change the water activity, but others work by altering the chemical reactions that would normally result in spoiled foods and rancid fats. Sodium-containing preservatives include:
- disodium ethylenediaminetetraacetic acid
- sodium acetate
- sodium ascorbate
- sodium benzoate
- sodium deydroacetate
- sodium diacetate
- sodium erythorbate
- sodium lactate
- sodium nitrate
- sodium nitrite
- sodium phosphates
- sodium propionate
- sodium sulfite
You'll find these preservatives in a variety of foods including salad dressings, canned foods, baked goods, cured meats, canned meats, cheese, jams, jellies and fruit fillings. Look at the ingredients listed on the packages.
Sodium as a Flavor Enhancer
Salt is a flavor enhancer that you probably use in your cooking or at the table. But that accounts for just a small amount of the average daily intake of sodium -- less than 25 percent. You can use table salt and still stay under the recommended daily sodium intake of 1,500 to 2,400 milligrams as long as you avoid other sodium-containing ingredients.
Some flavorings that don't contain salt still contain large amounts of sodium. Monosodium glutamate strengthens your perception of the umami flavor found in savory foods like meat and fish. Sodium acetate is another flavor enhancer that is only slightly salty in flavor, but it appears to suppress bitter flavors in foods so it enhances the perception of sweet flavors. Soy sauce is also used as a flavor-enhancing ingredient, and it's extremely high in sodium.
Watching Your Sodium IntakeLook for sodium on the Nutrition Facts labels (even if the front of the package says "reduced sodium"), and remember the number listed is milligrams per serving. If you eat a whole can of chicken soup, you're really eating two or three servings, so make sure you account for all the sodium. Some common sources of dietary sodium are:
- baked goods (including breads and buns)
- lunch meats, bacon and sausage
- pasta meals like mac and cheese or spaghetti in a can
- snack foods
American Heart Association. "Processed Foods: Where Is All That Salt Coming From?" Accessed July 1, 2012. http://www.heart.org/HEARTORG/Conditions/HighBloodPressure/PreventionTreatmentofHighBloodPressure/Processed-Foods-Where-is-all-that-salt-coming-from_UCM_426950_Article.jsp.
Centers for Disease Control and Prevention. "World Salt Awareness Week Focuses on Link between Sodium and Stroke." Accessed July 1, 2012. http://www.cdc.gov/Features/Sodium/ .
Institute of Medicine Committee on Strategies to Reduce Sodium Intake. "Preservation and Physical Property Roles of Sodium in Foods." Accessed July 1, 2012. http://www.ncbi.nlm.nih.gov/books/NBK50952/.
Institute of Medicine Committee on Strategies to Reduce Sodium Intake. "Taste and Flavor Roles of Sodium in Foods: A Unique Challenge to Reducing Sodium Intake." Accessed July 1, 2012. http://www.ncbi.nlm.nih.gov/books/NBK50958/.
Institute of Medicine. "Dietary Reference Intakes: Electrolytes and Water." Accessed July 1, 2012. http://www.iom.edu/~/media/Files/Activity%20Files/Nutrition/DRIs/DRI_Electrolytes_Water.pdf.