"I'm (Naturally) Cured!"

   Today on Meatingplace.com, one of the highlighted stories discussed the differences between naturally and conventionally cured meat products.  The original article can be seen here: http://www.meatingplace.com/Industry/TechnicalArticles/Details/42243.  Since my graduate research is focusing on the process of natural curing, I was definitely excited to see this sector of the meat industry in the spotlight.  Many consumers might wonder about the differences among conventional, natural, and organic meat products.  “Organic” is a well-defined, highly legalized term that can only be applied to foods that meet strict requirements.  “Natural” is more open for interpretation.  However, one of the qualifications for natural (and organic) meat products is the exclusion of synthetic nitrites and nitrates (Sebranek, Jackson-Davis, Myers, & Lavieri, 2012).  Nitrite (mostly in the form of sodium nitrite) is added to conventionally cured products such as bacon, ham, frankfurters, bologna, salami, and others.  Nitrite plays many roles in meat products: a color fixative, antioxidant, flavor imparter, and antimicrobial.  So how can “natural” products match up to their conventional counterparts without the addition of nitrite?  Let’s investigate.

   For thousands of years, salt was added to meat in the act of preservation, and the ancient packers eventually realized some salts preserved meat better than other salts.  The more effective salt, known as saltpeter, contained nitrate (Honikel, 2008).  Later, nitrite, which can be made from the nitrate added to meat, was discovered to be the major component in curing.  Next, scientists realized nitric oxide, made from nitrite, was the compound that bound to myoglobin (an oxygen-transporting molecule in muscle) during meat curing (Parthasarathy & Bryan, 2012).  Nitric oxide was also assumed to provide antimicrobial protection, especially against anaerobic bacteria like Clostridium botulinum, which can produce a deadly toxin that causes botulism (Cammack, Joannou, Cui, Martinez, Maraj & Hughes, 1999).  The interaction of nitric oxide and nitrite with metal-containing compounds can also deter lipid oxidation and, as a result, influence the flavor of cured meat products. (MacDonald, Gray, Kakuda & Lee, 1980).

   But if nitrite can do all these important, wonderful things, why would it need to be kept out of products?  In the 1960s and 1970s, concerns over the formation of nitrosamines in nitrite-containing meat products were raised (Sebranek & Bacus, 2007a).  Nitrosamines are carcinogenic, and can be formed between nitrite and secondary amines in a high temperature, low pH environment (Honikel, 2008).  The residual nitrite amount (that is, how much free nitrite is in the product after production) will determine the chances of nitrosamine formation: more residual nitrite increases the potential for these compounds to be made (Sebranek & Bacus, 2007a).  However, inclusion of cure accelerators, such as ascorbate and erythorbate salts, increases the rate of change of nitrite to nitric oxide, reduces the amount of leftover nitrite, and thus decreases the chances of nitrosamine formation (Parthasarathy & Bryan, 2012).  Applying this knowledge to meat product formulations has severely reduced the risk of dangerous nitrosamine levels in meat products, and today the amount of residual nitrite in meat products is about 1/5 of what it was forty years ago (Cassens, 1997).

   Still, some consumers prefer “natural” products for a variety of reasons, and meat scientists are continuing to develop methods to make such products.  The standard method involves the inclusion of nitrate or nitrite from a natural source such as vegetables (Sebranek & Bacus, 2007a).  Celery, spinach, beets, kale, and other vegetables are naturally rich in nitrate.  When powders made from these vegetables are treated with starter cultures (either before or after being mixed with other ingredients), the nitrate is reduced to nitrite that can work its magic inside meat products (Sebranek & Bacus, 2007a).  Certain problems arise from this, however: the exact amount of ingoing nitrite may only be guessed, and it is generally lower than the amount of ingoing nitrite in conventional products (Sebranek & Bacus, 2007a).  The lower level of original nitrite can, later on, jeopardize meat quality, depending on storage conditions (Sebranek and Bacus, 2007b).  Perhaps the most critical concern for natural meat products is food safety; while lower ingoing nitrite levels can mimic conventional flavor and color, sufficient antimicrobial activity may not be observed in natural products (Sebranek, 1979).

   While companies would never intentionally sell sub-par products, consumers should be aware that products made by different methods may have different qualities.  Natural meat products do not contain artificial ingredients, including pure sodium nitrite, and therefore the products’ flavor, color, or longevity may not match those of conventional meat products.  Also, if consumers are purchasing “natural” meat products merely due to concerns about nitrite intake, they should be aware that the miniscule amount of nitrite in meat products (7 grams of nitrite per 100 pounds meat, typically) contributes just a small fraction of nitrite to the human diet (Milkowski, Garg, Coughlin, & Bryan, 2010).  The safeguards that sodium nitrite provides against dangerous bacteria like C. botulinum, in my opinion, outweigh the minute risks of nitrosamine formation.

References

1.       Sebranek, J.G., Jackson-Davis, A.L., Myers, K.L., Lavieri, N.A.  (2012).  Beyond celery and starter culture: Advances in natural/organic curing processes in the United States.  Meat Science, 92, 267-273.

2.       Honikel, K.O.  (2008).  The use and control of nitrate and nitrite for the processing of meat products.  Meat Science,  78, 68-76.

3.       Parthasarathy, D.K., Bryan, N.S.  (2012).  Sodium nitrite: The “cure” for nitric oxide insufficiency.  Meat Science, 92, 274-279.

4.       Cammack, R., Joannou, C.L., Cui, X.Y., Martinez, C.L., Maraj, S.R., Hughes, M.N.  (1999)  Nitrite and nitrosyl compounds in food preservation.   Biochimica et Biophysica Acta, 1411, 475-488.

5.       MacDonald, B., Gray, J.I., Kakuda, Y., Lee, M.L.  (1980).  Role of nitrite in cured meat flavor: chemical analysis.  Journal of Food Science, 45(4), 889-892.

6.       Sebranek, J.G., Bacus, J.N.  (2007a).  Cured meat products without direct addition of nitrate or nitrite: what are the issues?  Meat Science, 77, 136-147.

7.       Sebranek, J., Bacus, J.  (2007b).  Natural and organic meat products: regulatory, manufacturing, marketing, quality and safety issues.  American Meat Science Association White Paper Series, 1, 1-15.

8.       Milkowski, A., Garg, H.K., Coughlin, J.G., Bryan, N.S.  (2010).  Nutritional epidemiology in the context of nitric oxide biology:  A risk-benefit evaluation for dietary nitrite and nitrate.  Nitric Oxide, 22, 110-119.