The Science Behind the Hot Dog

Have you ever read the ingredients list on a package of hot dogs or lunch meat and found yourself wondering, “What’s this doing in here?”  Many processed meat products contain ingredients both familiar (e.g., pork, beef, sugar, salt) and unfamiliar to consumers.  Unfortunately, some consumers are turned away by ingredients that sound more like they belong in science labs than in kitchens.  However, these compounds are used to increase the quality and safety of products while keeping them affordable and accessible to the consumer (Why ship something that will spoil en route?).  So to answer your question of, “What’s this doing in here?”, here are the purposes of several components found in many processed meat products explained.

       

               

Sodium Phosphates

·         “Phosphates” can encompass a variety of compounds including mono-, di-, and triphosphates.

·         Whereas monophosphates act as buffering compounds, di- and triphosphates are used to increase the water-holding capacity in meat products (Aberle, Forrest, Gerrard, & Mills, 2001).

o   Increased water-holding capacity leads to products with greater tenderness and juiciness (Aberle et al., 2001).

o   These phosphate compounds act similarly to adenosine triphosphate (ATP), the major energy unit produced in most living things.

·         Phosphates may also deter the development of rancidity and improve product texture (Aberle et al., 2001).

Sodium Lactate

·         This weak acid is added to processed meats to control the growth of Listeria monocytogenes, a bacterium of concern in the world of processed, packaged foods (Zink, N.A.). 

·         Sodium lactate is able to disrupt the pH gradients that bacteria set up in their cellular membranes.  These gradients are vital for energy-producing machinery to work, so disruption of the gradient severely reduces a bacterium’s ability to thrive (Zink, N.A.).

Sodium lactate

Sodium Diacetate

·         Sodium diacetate is also added to meat to reduce the growth of L. monocytogenes (Zink, N.A.).

·         This compound dissociates into acetic acid (the active ingredient in vinegar) and sodium acetate.  Acetic acid can donate protons to the environment, thus lowering pH.  This action disrupts the proton gradient and weakens a bacterium’s ability to survive (Zink, N.A.).

Sodium diacetate

Sodium Ascorbate/Erythorbate

·         Sodium ascorbate and erythorbate are “isomers;” that is, their atomic makeup is the same but their conformations are different. 

·         Sodium ascorbate is naturally found in citrus fruits and vegetables, and its biologically active form, ascorbic acid, is commonly known as vitamin C (NCBI, N.A.).

·         Sodium erythorbate is more commonly used in processed meats since it is cheaper and its pH is much closer to that of meat (Mancini et al., 2007).

·         Both sodium ascorbate and sodium erythorbate act as cure accelerators: they reduce the amount of time needed for a product treated with nitrite to develop cured properties (Aberle, 2001).

So don’t fear those scientific-sounding ingredients on the back of a package.  Those ingredients are added with the consumer’s safety and satisfaction in mind.  Keep enjoying those hot dogs and brats at grill-outs this summer, and stock up on lunch meat for kids heading back to school.

References

Aberle, E.D., Forrest, J.C., Gerrard, D.E., & Mills, E.W. (Eds.).  (2001).  Principles of Meat Science (4^th ed.). Dubuque, IA: Kendall/Hunt Publishing Company.

Mancini, R.A., Hunt, M.C., Seyfert, M., Kropf, D.H., Hachmeister, K.A., Herald, T.J., Johnson, D.E.  (2007). Comparison of ascorbic acid and sodium erythorbate: Effects on the 24 h display colour of beef lumbar vertebrae and longissimus lumborum packaged in high-oxygen modified atmospheres.  Meat Science 75(1), 39-43.

NCBI (N.A.).  Ascorbic Acid—Compound Summary (CID 23667548).  Retrieved from http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=23667548&loc=ec_rcs#itabs-2d.

Zink, D.L.  (N.A.).  Post-processing interventions to control listeriosis  [PDF].  Retrieved from http://www.fsis.usda.gov/wps/wcm/connect/3ceeab5b-0bed-4bf6-8513-05f79df03e2b/Listeria_DZink_12.pdf?MOD=AJPERES&CACHEID=d548190c-c5e0-49ba-8771-52a14f42b830.

All compound images are courtesy of PubChem (http://pubchem.ncbi.nlm.nih.gov/).

"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.

Not in MY McNuggets!

Red flags unfurled and waved wildly in my mind when I saw this article from Food Safety Magazine: “High Arsenic Levels Found in U.S. Chicken.”  The original article can be viewed here: http://www.foodsafetymagazine.com/news/high-arsenic-levels-found-in-us-chicken/.  Now, arsenic can be a deadly thing; after all, it’s often the poison of choice in melodramas.  Just a small amount can be lethal: an oral dose of 60 mg is fatal to the average human (Minnesota Department of Health, 2012).  However, would companies really sell chicken meat that contains a known poisonous substance?  And just how reliable is the research that this article quotes?  Let’s take a closer look at the facts:

The Food Safety Magazine article alludes to “Arsenic species in poultry feather meal” published in a 2012 volume of Science of the Total Environment.  Rather than testing arsenic levels in chicken meat that would be directly eaten, the researchers looked at arsenic levels in feathers, which are not directly eaten by consumers.  The researchers reasoned that since feather meal is often used a protein source for fertilizers and animal feeds, the use of arsenic-tainted feather meal for these purposes could have harmful effects on humans.  This is a well-intentioned but perhaps unnecessary concern.  After all, the researchers found the concentration of inorganic arsenic in their samples was approximately 2 parts per billion (National Chicken Council, 2013).  The maximum contaminant level for arsenic in drinking water is 10 parts per billion (Environmental Protection Agency, 2012).  The average level of arsenic in soil is 3-4 parts per million (Agency for Toxic Substances and Disease Registry, 2011).  Therefore, the chicken feathers contained less arsenic than may be found in both water and soil.

*             *             *

Another issue with the Science of the Total Environment article is the reference to the product roxarsone, allegedly added to the diets of broilers (chickens raised for meat production).  However, the researchers admitted that no connection between roxarsone and the presence of inorganic arsenic in feathers could be found:   

“In this study we had no information on the precise contribution of roxarsone to inorganic arsenic exposure in feather meal.” (Nachman, Raber, Frcesconi, Navas-Acien & Love, 2012).

Still, the researchers expressed their continued concern about the use of this product:

 “However, given the common use of roxarsone in poultry production, the increase in inorganic arsenic exposure in livers of chickens fed roxarsone, and the likely accumulation of inorganic arsenic in feathers, inorganic arsenic measured in feather meal in this study may have originated from the practice of administering roxarsone to broiler chickens in the context of industrial poultry production.” (Nachman, et al., 2012).

However, this concern is virtually unfounded today: since June 2011, roxarsone has no longer been used to supplement the diets of broilers (National Chicken Council, 2013). 

*             *             *

The last detail to raise doubt in this study is the relatively small sample size from which arsenic levels were determined.  Samples of feathers came from twelve locations: one each from Tennessee, Pennsylvania, California, and Idaho; two from Arkansas, four from Oregon, and two from China (Nachman, et al., 2012).  However, the specific locations and suppliers from whence the feathers came were not mentioned.  Basing analyses on such a small sample and not disclosing the origins of the sample materials is ill-practice in the world of peer-reviewed journals (Hofacre, 2012).  These samples might have all come from farms raising “free-range” broilers experiencing greater contact with soil and unregulated water sources, or from farms raising conventional broilers living in a controlled, indoor environment.  Such different rearing methods could arguably result in different levels of exposure to arsenic.

In conclusion, since arsenic is present in the air, water, and soil, it’s not surprising a small amount would end up on chicken feathers.  But remember, the arsenic levels found on the feathers were extremely low, and if contaminated feathers might pose a problem when added to fertilizers or animal feeds, they would not be added.  Given the thorough processing feathers endure before they are included in fertilizers or feeds, there is adequate time to check for feather quality and the presence of any contaminants (Moritz & Latshoaw, 2001). But again, the arsenic is appearing on feathers, not meat.  In fact, the U.S. Department of Agriculture monitors chicken meat for arsenic levels, and in the past 20 years has found zero samples that violate the level set by the U.S. Food and Drug Administration (National Chicken Council, 2012).  With strict guidelines in place for levels of components in meat, milk, and all manner of animal products, the U.S. food supply is kept as safe as possible. 

References

Agency for Toxic Substances and Disease Registry.  (March 3, 2011).  Toxic substances portal – arsenic.  Retrieved from http://www.atsdr.cdc.gov/phs/phs.asp?id=18&tid=3#bookmark03

Environmental Protection Agency.  (May 21, 2012).  Basic Information about arsenic in drinking water.  Retrieved from http://water.epa.gov/drink/contaminants/basicinformation/arsenic.cfm

Hofacre, C.L., (2012, April 24). Bloomberg chicken study is flawed.  The Baltimore Sun.  Retrieved from http://articles.baltimoresun.com/2012-04-24/news/bs-ed-chicken-study-letter-20120424_1_peer-review-chicken-samples

Minnesota Department of Health.  (November 21, 2012).  Arsenic.  Retrieved from http://www.health.state.mn.us/divs/eh/hazardous/topics/arsenic.html#health

Moritz, J.S. & Latshaw, J.D.  (2001).  Indicators of nutritional value of hydrolyzed feather meal.  Poultry Science, 80, 79-86.

Nachman, K.E., Raber, G., Francesconi, K.A., Navas-Acien, A., & Love, D.C.  (2012).  Arsenic species in poultry feather meal.  Science of the Total Environment, 417-418, 183-188.

National Chicken Council.  (September 18, 2012).  Arsenic & chicken? No need to worry.  Retrieved from http://www.nationalchickencouncil.org/arsenic-chicken-no-need-to-worry/

National Chicken Council.  (May 11, 2013).  NCC responds to misleading Johns Hopkins study; says arsenicals no longer fed to broilers.  Retrieved from http://www.nationalchickencouncil.org/ncc-responds-to-misleading-johns-hopkins-study-says-arsenicals-no-longer-fed-to-broilers/

Minnesota Department of Health.  (November 21, 2012).  Arsenic.  Retrieved from http://www.health.state.mn.us/divs/eh/hazardous/topics/arsenic.html#health

It's NOT a "Jungle" in There

   This last week I had the privilege to tour several meat processing facilities, and I was utterly amazed at what I saw.  If I had any notions of dirty, dank, blood-flecked rooms, they quickly vanished on the first tour.  Such unsanitary conditions would not be in harmony with the respect every decent meat product business holds for the needs of consumers.  After all, who wants to make food that makes a person sick?  This attitude of respect has caused a great revolution in the meat industry since the days of the infamous Chicago stockyards.  Now, companies strive to attain the greatest levels of cleanliness to ensure high-quality products are made on their grounds.  At each stage of meat processing, from procuring ingredients to shipping products, the highest standards of care are followed to optimize product wholesomeness.

  Prior to each tour through the facilities, my group’s tour guides provided us with attire meant not only to keep us safe but also to avoid contaminating the facility and meat products.  We removed our jewelry and watches and donned hairnets, hard hats, ear plugs (safely attached to the hard hats by a cord), safety glasses, frocks, and rubber overshoes.  We took every tour backwards: first we saw the shipping department, then packaging, then cooking, and lastly formulation.  If any little buggies happened to hop on us at the shipping department and hopped off in the formulation area, they would be killed as they ventured on raw product through the cooking process.  At strategic points we washed our hands and shuffled through white sanitation foam or across boot-scrubbing machines.  We DID NOT touch the machinery or products as we followed our guides through the plant.  As products moved from one phase to the next, they were scrutinized by trained workers looking for defects.  At certain stages, ingredients or products were removed for quality tests.  Quality assurance teams were on site to check for both product quality and safety.  Products were frozen or stored in modified atmosphere packaging (MAP) to ensure their safety as they traveled to consumers.  If a product looked suspicious at any stage in this process, it was removed from the line and dealt with accordingly.

   In addition to striving for product safety and quality, we saw that companies are making great efforts to reduce waste, be environmentally friendly, and treat workers fairly.  No company wants to make a person sick, and at each facility we saw innovations to improve the wholesomeness of meat products.  These clean, well-lit, inspected places were far cries from the filthy and foul factories portrayed in Upton Sinclair’s The Jungle.  Modern facilities are filled with personnel and equipment to ensure that every product made will nourish and satisfy the customer.  Also, consumer handling instructions are applied to every package to inform the consumer on how best to prepare the product.  When companies respect the consumers’ needs for safe products and consumers follow the companies’ advice, everybody wins.