Posted: Tuesday, August 14 2019
By Lois Harris
Bacteriophage biocontrols have been approved for use and are commercially available in many countries, including the U.S., Canada, E.U. Israel, Switzerland, Australia and New Zealand. Most are water-based, free of chemicals and preservatives and are not genetically modified. But how do they stack up against standard antimicrobial processes like pasteurization, irradiation, chemical disinfectants and high pressure processing (HPP)?
Drs. Zachary D. Moye, Joelle Woolston and Alexander Sulakvelidze feel they represent a highly effective tool in a multi-level food safety system designed to prevent foodborne illness and recalls.
Phages occur naturally all around us in the environment, on fresh foods and in the intestinal tract of our bodies. They may be the oldest organisms on earth and they act like viruses, targetting and destroying—or significantly reducing the number of—specific pathogens like listeria, salmonella, E. coli and shigella.
Phages occur naturally all around us in the environment, on fresh foods and in the intestinal tract of our bodies.
Environmentally Friendly, Versatile and Cost-Effective
Unlike other antimicrobial processes, phage products don’t kill all bacteria indiscriminately. They target only specific bacteria, leaving the “good” bacteria to do their jobs. They are also easier on equipment than chemical disinfectants. And the fact that they are all-natural could be appealing to some customers who are more wary than ever about genetic modification, additives and preservatives.
What’s more, the product can be used at various points along the food processing system. Phages can be sprayed on fresh produce, applied to livestock just prior to slaughter, used as a cleaner on equipment surfaces and employed as a treatment for ready-to-eat meals. They are reportedly less costly than traditional methods – between one and four cents per pound of food treated, compared to 10 to 30 cents a pound for irradiation or HPP. However, these numbers don’t account for multiple applications of different phages that might be needed to address multiple kinds of bacteria.
In the past dozen or so years, the number of products available in the marketplace has risen dramatically, including several made by Intralytix, a Baltimore, Maryland company, Micreos Food Safety in the Netherlands, Passport Food Safety Solutions in Des Moines, Iowa, and Phgelux in Shanghai, China.
Drs. Moye, Woolston and, Sulakvelidze note that phage usage is not without drawbacks, however. One of the most attractive properties of phage biocontrols could also be their biggest limitation. Their specificity means that a preparation to combat one kind of bacteria (e.g. listeria) won’t kill all the different kinds of bacteria that may be present.
Phages also need to be refrigerated at between two and eight degrees Celsius, and can be rendered ineffective if combined with chemical sanitizers. In addition, initial contamination by bacteria treated with phages is reduced, but not necessarily completely eliminated.
This is due, in part, to the fact that the phages need to come into direct contact with the entire surface of the food, and work better on moist surfaces than dry foods.
Another challenge is the possibility that phage-resistant bacteria could emerge in future, although some experts recommend that using a cocktail of phages, rather than a single type, could reduce the risk of resistance. Treating food with phages only at the end of the production process – just before packing, for example – instead of spraying phages at the beginning, say, in a chicken barn – could also mitigate the chances of resistant bacteria developing.
Finally, it might take some time for this method to make it fully into mainstream use. While bacteriophages are completely natural, spraying a “virus” on food to protect it from contamination may not be accepted by either consumers or processors, unless it’s fully explained and understood.
About the Author
Lois Harris is principal writer and editor at Wordswork Communications, and she has been part of GFSR’s editorial community since 2017. She brings a strong background in writing for a number of food manufacturers, non-profit organizations, governments and universities to her work on GFSR’s behalf, and has a keen interest in the food safety issues that affect consumers and industry.