Microsession: Processing of Produce in Food Establishments: Implications of Microbial Safety


Karl Matthews

Karl Matthews

Karl Matthews, a leader of research on food microbiology at Rutgers University, implored attendees to not apply the same set of research results or standards based on field studies to those in food establishments when it comes to handling produce.

Matthews, Ph.D., Professor and Chair at Rutgers University, said that while a lot of documented data exists on handling of commodities on the production side, very little exists on food prep of produce at places such as restaurants, convenience stores and supermarkets.

“We found there is very little research that’s associated with what’s going on in food establishments with respect to how they’re handling leafy greens, what’s going into the water, if they are using an antimicrobial and really looking at cross-contamination,” said Matthews. “If you’re working in the food industry, you’re probably aware there is a lot of research, particularly in supermarkets, looking at the deli side of things and the cross-contamination of deli meats when you’re processing them. If you start delving in deep, I don’t think there’s one paper that we found that looks at what’s going on in the produce area of the supermarket with respect to microbial food safety.”

Matthews noted that on the retail side, an improperly cleaned sink, cooler or even floors could be a source of bacteria and potential contamination when washing and crisping produce.

“If you look at what they are doing commercially, and you try to one-size-fits-all and put it into retail, it doesn’t translate,” said Matthews. “I think that is kind of the misnomer — that people are led to believe, ‘Oh, we already understand cross-contamination.’ No, you understand it when you are taking baby greens and putting them into a water flume; you don’t understand when you are taking heads of lettuce and putting them into a sink, where you might have a 19-year-old kid or someone working with it.”

Matthews and his team at Rutgers put together a series of experiments on the effectiveness of using a sanitizer (electrolyzed water) versus tap water with heads of lettuce, full and cut cantaloupe and cilantro. Some commodities were inoculated; some weren’t. They looked at factors unique to retail, comparing low versus high volumes, the number of times the water was used in soaking, the refreshing of antimicrobials and water temperature. The result: electrolyzed water was the most effective microbial in mitigating cross-contamination and microbial load.