When an expert like James Marsden, Distinguished Regents Professor of Food Science at Kansas State University, starts talking about processing aids, it’s as if a menu of choices pops up in his head.  The professor is best known for his work on reducing Shiga Toxin-producing Escherichia coli in beef, so he’s very familiar with the intervention methods that achieve this. But in going down the list of processing aids that might be used to eliminate E. coli before it can reach consumers, it’s clear there are some choices that would be wiser for producers than others. “While the very definition of a processing aid is a substance used in food production that are not present in any concerning amount in the end product, they are not always without controversy. Two that come to mind are the industrial-like ammonia process used by Beef Products Inc. to make its lean finely textured beef that the public came to know as ‘pink slime’ and the transglutaminase powder known as ‘meat glue.'” The USDA has a zero-tolerance policy for seven strains of E. coli. “It’s very hard to achieve that,” says Marsden. But one thing that helps producers in this effort is processing aids. Both the U.S. Food and Drug Administration and the U.S. Department of Agriculture approve processing aids for foods ranging from meat and poultry to other food products. They are not supposed to change the appearance or taste of the product in any way and, more importantly, they cannot negatively impact food safety or public health. Anything added to food, including processing agents, is regulated as a food additive. That means the processing agent must be “generally recognized as safe,” or GRAS, in order to be approved for use in foods. Food additives and processing agents are either on the GRAS list because of their history of safety, or because companies who use them have gone through scientific processes to prove their safety. Processing aids are not considered ingredients, however, and therefore are not required to be listed on ingredient lists on nutrition labels.

The Food Safety News series on processing aids is sponsored by Micreos.
Both agencies recognize three types of processing aids: those that are used and removed, those that are converted into components that naturally occur at insignificant levels without changing the finished product, and some that remain in food at low levels without any technical or functional effect. Not all processing aids are as complicated as BPI’s ammonia process or transglutaminase. Take hot water and steam, for example. Thermal processing of beef carcasses using hot water and/or steam is a processing aid that’s been highly effective in reducing E. coli O157:H7 and other pathogens, according to Janet Riley at the American Meat Institute. Hot water and steam leave no residues and have no lasting effect on the product. Marsden says the use of high-pressure washes in ready-to-eat lunchmeats and hot dogs have virtually eliminated Listeria monocytogenes, the bacterium that causes the infection listeriosis, in these products. As recently as the late 1980s, Listeria contamination seemed to some to be an insolvable problem for the ready-to-eat products. Killing antimicrobials is just one of the functions processing aids play during the food production process. Others include removing impurities, preventing crystallization, controlling pH levels, controlling bacteria in chill water, scalding agents that remove feathers, and others. Not every solution can be applied to every product, however. For example, restrictions on Kosher and Halal meats dictate that thermal processes cannot be used. And processing aids that are effective on one pathogen strain might not work on another. That’s something Marsden is dealing with now, as there are six strains of E. coli that have recently been banned from beef, in addition to E. coli O157:H7, which has been banned since 1993. Only insignificant amounts at safe levels should remain in the food once a processing agent is used, but Marsden says food companies must be aware of how the consumers view chemicals. Some the public accept without a second thought, such as using lemon juice, vinegar or citric acid, which have not raised consumer concern. Fruit and vegetable washes, which are often comprised of organic acids or chlorine, have also raised little concern. The addition of ammonia to lean finely textured beef , on the other hand, became so controversial that almost all beef companies stopped using product processed this way when it gained national attention in the spring of 2012. Transglutaminase powder, or ‘meat glue,’ as mentioned above, has also raised consumer concern over the past couple years.

  • Oleg

    What is the meaning of labeling products that are loaded with substances unhealthy? It would be good if farmers have just begun using high-quality fertilizers, so that the effects and quality of their products (vegetables and fruits) will be on a high standard and it will ensure consumers the highest quality on the market.. I’ve just read an interesting article on http://goo.gl/7isoG about agriculture and food safety.

  • Mike

    with regard to pathogens in ‘textured beef’- why not concentrate effort on getting people to cook it properly-rather than trying to find inventive ways to let them undercook it safely!

  • Mike_Mychajlonka_PhD

    Dan, I find it curious that your article contains a graphic link to a “final report” written by Professor Marsden regarding the efficacy of using a bacteriophage preparation (Listex P100) in ready to eat meat products even though your article seems to make no mention of bacteriophages as processing aids for meat. You report (but do not quote) Professor Marsden as saying that high pressure washes in lunch meats and hot dogs have virtually eliminated Listeria monocytogenes in these products. Firstly, the previous paragraph speaks of thermal processing (i.e., high temperature) washing rather than high pressure. Secondly, Professor Marsden’s final report cites a paper (Gunther et al. 2009) as saying that a combination of Listex P100 treatment, FOLLOWING a thermal (not pressure) treatment of hot dogs showed a five log reduction of L. monocytogenes. As a result, I find myself quite confused as to the exactly what you are trying to say. Lastly, I think is should be mentioned (to aid the non-technical folks who read these articles) that the apparent efficacy of processing aids varies according to whether the target pathogens are naturally present or have been artificially introduced into the matrix being studied. Apparent efficacy as measured against inoculated pathogens may be higher (by two logs or more) as opposed to efficacy against pathogens naturally present. Of course, only the latter is the real-world situation.

  • Mike_Mychajlonka_PhD

    Both the meat industry and its regulators seem to agree that an organism as clearly non-invasive as Shiga-toxin-carrying E. coli (STEC) is nevertheless a pathogen. This unfortunate situation inexorably leads one to the conclusion that the way to make meat safe is to eliminate this pathogen. We know that STEC is dangerous because it carries within it a lysogenic bacteriophage that also carries the genes for making Shiga toxin. We also know that lysogenic bacteriophage generally contain a lytic trigger such that when its host (i.e., STEC) is in trouble, the lysogenic bacteriophage immediately ceases its dormant phase (i.e., terminates lysogeny) and enters its lytic cycle (during which Shiga toxin is manufactured). We already know that Escherichia coli is very susceptible to heat. We also know that a low-intensity heat-shock such as a “high” temperature wash may trigger is enough to terminate lysogeny and trigger the lytic phase. If all we measure are CFU of STEC, we will see numbers decrease dramatically and congratulate ourselves on a job well-done when the reality may well be that the kill we witnessed had two causes: (1), the effects of the heat itself and (2), the cell death caused by the induction of the lytic phase of the Shiga toxin lysogen. Are we within zero-tolerance regulations for STEC in meat? Certainly. Are we safe? Well, we already know that Shiga toxin can cause HUS all by its lonesome and without recourse to any live STEC. The lesson here: If Shiga toxin is the cause of the problem, Shiga toxin is what needs to be measured.

  • scott

    great article.