easily contribute significant levels to the total diet. Pepperoni pizza is a good example of this because each of the major ingredients contains sodium. The pepperoni has sodium for preservation, meat binding, and flavoring. Sodium in the cheese contributes to texture and preservation as well as taste and flavor. Tomato sauce is seasoned with salt in addition to other herbs and spices. Finally, the crust contains sodium to control the leavening process and dough stickiness. The combination of these ingredients leads to an average sodium content of 668 mg/100 g, according to FDA’s Total Diet Study market basket data (FDA, 2007).
Soups are classic examples of complex, high-sodium foods. Some soups have high-sodium ingredients, such as cheese or sausage. However, even foods made from low-sodium ingredients, such as vegetables, are high in sodium due to the use of salt for flavoring. In soups, salt contributes not only to salt taste, but also to overall flavor, as discussed in Chapter 3 (Gillette, 1985; Rosett et al., 1997).
In chilled foods, sodium-containing compounds can play a role in preventing the growth of pathogens. Vacuum and modified-atmosphere packaging can create oxygen-free environments that favor the growth of Clostridium botulinum. Salt, in addition to other hurdles, can help prevent the growth of this organism. If oxygen is present, Listeria monocytogenes is often a concern because it can grow even at low temperatures. Salt addition can serve as one hurdle to the viability of this organism (Hutton, 2002).
Refrigerated or frozen meals often contain sauces or gravies. Besides contributing flavor, these sauces have a secondary role of preventing or masking warmed-over flavors. The fats in precooked meats have a tendency to experience lipid oxidation upon storage, resulting in rancid and “painty” odors and flavors (Hedrick et al., 1994). Using strongly flavored sauces can help to mask these flavors, and coating meats in sauces before storing can help to exclude the oxygen needed for these reactions to take place (Kuntz, 2000). Unfortunately, the sauces are often high in sodium.