Nitrate salts were identified as a unique meat preservative agent in the 19th century. Related nitrite compounds remain valued today for their effect on meat color and flavor, while preventing the growth of potentially deadly microbes. Food regulations limit the amount of nitrate or nitrite that may be added to meats, though most human exposure to these compounds occurs through eating vegetables.
Salt and Meat Preservation in History
Cultures worldwide have known for thousands of years that the addition of salt can preserve meat, fish and other foods -- extending their safe storage life. By interfering with microbes' biological processes and reducing available water, salts retard the growth of bacteria that can lead to spoilage and food poisoning.
While it was known that certain salts could cause meat to have a lasting red color, the reasons were unknown. In the late 19th century, researchers found that the particular salts responsible for these effects were nitrates.
Effects and Mechanisms of Nitrates
Sodium nitrate and potassium nitrate impart a lasting red or pink color, distinctive salty flavor and subtly altered texture to treated meats. By combining with the naturally present myoglobin in meat, nitrates preserve and increase the meat's red color during cooking, an effect many chefs and diners find appealing.
Nitrates were also found to exert very strong antibacterial effects, even in relatively low concentrations. Nitrate salts' antimicrobial potency is a powerful tool against clostridium botulinum and other pathogens that tend to grow in stored meat and can lead to severe food poisoning and death.
Nitrites Take Over From Nitrates
Further research on nitrate salts discovered that their primary effects were actually caused by a closely-related successor compound, nitrites, that formed as the nitrates naturally broke down in the meat. This finding led to the general replacement of nitrates in commercial meat preservation with nitrites, although both manufacturers and home-producers retain the option of using nitrates if they choose.
Nitrite Safety Concerns
The first upper limits on nitrite concentrations in meat were imposed in the U.S. in the 1920s. Research in the second half of the 20th century suggested that certain nitrite byproducts could present a safety risk under certain conditions. In the acidic environment of the stomach and during high-temperature cooking, nitrites can be converted into follow-on nitrosamines, a family of compounds that may have carcinogenic effects in high concentrations. Scientists, manufacturers and diners began to consider the safety benefits of nitrites' antibacterial power against the potential safety drawbacks arising from nitrosamines.
Nitrites in Foods
The U.S. food regulations today limit the concentration of nitrite and nitrates in cured meat to 200 parts per million, a level that preserves the antimicrobial power of those compounds while preventing the generation of high nitrosamine concentrations. The U.S. Department of Agriculture also mandates that commercial producers add ascorbic acid, also known as vitamin C, or its precursor erythorbic acid to nitrite-treated meats, as these two chemicals equally inhibit nitrosamine formation.
Research by the European Food Safety Authority has found that most nitrites in the human diet occur naturally in leafy vegetables such as celery and cabbage, which usually contain higher nitrite concentrations than processed meat.
References
- Iowa State University: Nitrite and Meat Curing
- "European Food Safety Authority Journal"; Nitrate in Vegetables -- Scientific Opinion of the Panel on Contaminants in the Food Chain; June 2008
- University of Minnesota Extension; Nitrite in Meat; Richard J. Epley, et al.
- Montana State University; Meat Color; Jane Ann Boles, Ronald Pegg
- The Linus Pauling Institute; Nitrosamines and Cancer; Richard A. Scanlan, Ph.D.; November 2000
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