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Sodium is an essential nutrient with important functions in regulating extracellular fluid volume and the active transport of molecules across cell membranes. However, recent estimates from NHANES III (Third National Health and Nutrition Examination Survey) data show that over 95% of men and over 75% of women exceed the recommended daily tolerable upper intake of sodium. Since these high levels of dietary sodium are associated with a high prevalence of hypertension, prehypertension and, possibly, other adverse effects on health, many national and international health organizations recommend that sodium intake be significantly decreased. Traditionally, salt (sodium chloride) has been used as a food preservative that kills or limits the growth of foodborne pathogens and spoilage organisms by decreasing water activity. Salt also performs other important functions in foods by adding flavor and masking bitter tastes, controlling growth of yeast and fermentative bacteria, and promoting binding of proteins and other components in foods to achieve desired textures. Many processed foods contain high levels of salt and several countries have developed national programs for significantly reducing the sodium chloride content in many processed foods and encouraging a decrease in discretionary salt use. This review considers published data on the apparent adverse health effects of excess salt intake as well as the important functions of salt in different foods and possible strategies for reducing sodium levels in processed foods while still producing safe foods that consumers find acceptable.

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The influence of pH adjusted with lactic acid or HCI or sodium chloride concentration on survival or growth of Escherichia coli 0157:H7 in Trypticase soy broth (TSB) was determined. Studies also determined the fate of E. coli 0157:H7 during the production and storage of fermented, dry sausage. The organism grew in TSB containing <6.5% NaCl or at a pH of 4.5 to 9.0, adjusted with HCI. When TSB was acidified with lactic acid, the organism grew at pH 4.6 but not at pH 4.5. A commercial sausage batter inoculated with 4.8 x 104 E. coli 0157:H7 per g was fermented to pH 4.8 and dried until the moisture/protein ratio was 1.9:1. The sausage chubs were then vacuum packaged and stored at 4°C for 2 months. The organism survived but did not grow during fermentation, drying, or subsequent storage at 4°C and decreased by about 2 log10 CFU/g by the end of storage. These studies reveal the importance of using beef containing low populations or no E. coli 0157:H7 in sausage batter, because when initially present at 104 CFU/g, this organism can survive fermentation, drying, and storage of fermented sausage regardless of whether an added starter culture was used.

The fate of Listeria monocytogenes during refrigerated storage was determined on several processed meat products, including ham, bologna, wieners, sliced chicken, sliced turkey, fermented semidried sausage, bratwurst, and cooked roast beef. The meats were surface inoculated with a five-strain mixture of <200 or ca. 105 L. monocytogenes cells per package, vacuum packaged, and stored at 4.4°C. Survival or growth of listeriae was determined for up to 12 weeks of storage or until the product was spoiled. The organism survived but did not grow on summer sausage, grew only slightly on cooked roast beef, grew well on some wiener products but not on others, grew well (103 to 104 CFU/g increase within 6 weeks) on ham, bologna, and bratwurst, and grew exceptionally well (103 to 105 CFU/g increase within 4 weeks) on sliced chicken and turkey. The rate of growth depended largely upon the type of product and the pH of the product. Growth was most prolific on processed poultry products. The organism generally grew well on meats near or above pH 6 and poorly or not at all on products near or below pH 5. These results indicate the importance of preventing postprocessing contamination of L. monocytogenes in a variety of ready-to-eat meat products.