By John H. Tibbetts
UGA’s Center for Food Safety is one of the leading institutions nationally and internationally that is conducting research to control, detect and eliminate food-borne bacterial pathogens. In 2016, Francisco Diez-Gonzalez, a food microbiologist, became the center’s director after 17 years with the University of Minnesota Department of Food Science and Nutrition.
Which bacterial foodborne pathogens pose the largest dangers in the United States?
We are concerned about three major pathogens. Salmonella causes a million gastrointestinal infections and an estimated 350 deaths in the United States each year. This organism can contaminate many foods, but it is most commonly found in eggs, raw milk, meat and poultry. Research is critical to help companies and regulators protect public health and reduce the pathogen’s high cost to industry. A study by the Grocery Manufacturers Association and the Food Marketing Institute estimated that the average cost of a food recall is $10 million. Recalls are triggered by the detection of salmonella in foods or by outbreaks caused by those foods.
The second organism is E. coli. The intestines of ruminants—animals such as sheep that ferment food, regurgitate and re-chew it before digestion—are the natural reservoir of this organism, particularly cattle. Consuming beef products such as hamburger traditionally has been the major reason why people get sick. More recently, though, some cases of E. coli infections have been related to fresh fruits, vegetables, and raw wheat flour and dough. E. coli doesn’t affect as many people as salmonella, but there have been a number of outbreaks in which young children have been hospitalized, and unfortunately some have died.
The third organism is listeria, which causes about 260 deaths a year in the United States out of about 1,500 infections. Before 2010, listeria caused a lot of problems in the meat industry, which implemented a number of regulatory controls in response. More recently, listeria has caused outbreaks in dairy foods as well as in some fruits and vegetables. We are finding more evidence that foods once traditionally considered safe carry bacterial pathogens.
How do you collaborate with the food industry?
The center has a long history of partnering with prominent food companies. Our industry partners support our research because they have brands to protect. In our quest to protect the food supply, we have developed improved tools to detect pathogens in products before they reach the market, as well as developing antimicrobial treatments to reduce the incidence of pathogens.
Why are bacterial pathogens being found in certain food commodities for the first time?
One reason is that the food supply has become very complex. We are using ingredients that we didn’t use before. For instance, companies are replacing wheat in some foods because of concerns about gluten, and they have to get creative in finding substitutes. Many of the new ingredients are coming from overseas, which increases the opportunities for contamination.
Do industry partners ask you to take on priority projects that affect public health?
Yes. The presence of E. coli in domestic wheat products became a top priority for several of our industry stakeholders. Since 2009, there have been four outbreaks in which people became sick after consuming raw wheat dough or flour. One of our projects is generating data that tells us how long this organism can survive in, say, a raw flour batch. Can it last one week? One year? Companies need this data to establish better ways to handle their raw materials and implement interventional strategies to prevent pathogens from reaching the market. We are also starting a research project to learn about listeria in some dry food products. In 2017, there were recalls of macadamia nuts and sunflower seeds for possible listeria contamination. It was long believed that listeria could not remain viable in dry foods or foods with very low water content. It turns out that although listeria doesn’t grow there, the organism can remain viable and infectious.
Is there one project that most excites you as center director?
I’d have to say hosting the Center for Food Safety annual meeting. This is an invitation-only event attended by a select group of our industry stakeholders, including food-safety authorities from major companies and representatives from the Centers for Disease Control and Prevention, the Food and Drug Administration, and the U.S. Department of Agriculture, as well as from state agencies responsible for food safety. The meeting allows key industry players to provide insights about current problems and concerns, showing the ways that companies are protecting the consumer. It also gives us an opportunity to gain a better understanding of the major players who act in a food-safety crisis. It is a role that the center has been proud to play for many years.