Studies find reusable produce containers often contaminated

Farmers MarketMultiple recent studies have revealed the reusable plastic containers used by farmers to ship fresh produce from farms to grocery stores could transfer pathogens such as E. coli, from contaminated produce onto clean produce when the containers are not sanitized thoroughly.

According to a recent article in Food Safety News, two Canadian studies found evidence of fecal bacteria left over in containers said to have already been sanitized. From these containers, University of Guelph food science professor, Keith Warriner, Ph.D., found contamination of innocuous strains of coliform E. coli, suggesting that the company’s sanitation process was inadequate.

“Judging the cleanliness of the containers using U.K. food safety standards of food surfaces, Warriner determined that 43% of containers failed sanitary standards when inspected this year,” the articles states.

This was not only the case in Canada, however as a study in California is finding similar results where produce containers exceeded reasonable expectations for cleanliness and failed to meet expected microbiological standards for surface sanitation even after their sanitation process was complete.

The article states that over a six-day period, University of California Davis extension research specialist Trevor Suslow, Ph.D., and his team inspected produce containers after they had been sanitized but before they had been given to growers to pack for shipments. This type of system is arranged so that growers rent the containers from the manufacturer and empty containers are sent back to the manufacturer to undergo a sanitation process before being packed with produce once again.

After swabbing container surfaces for bacterial indicators of uncleanliness, Suslow found 38% of samples to carry 100,000 bacterial cells, while 8% had more than one million. That, Suslow told Food Safety News, isn’t acceptable.

“Although we’re aware there’s a cleaning and sanitizing process, it appears to be inconsistent and we found a number of indicators of uncleanliness in our study.”

Although no cases of illness have been directly connected to produce containers, Suslow told Food Safety News it would be very difficult to trace an illness back to something as unsuspecting as a plastic container. “Taking a systems approach to produce safety, while there may be no recognized outbreaks linked to containers, we see a lot of sporadic illnesses where you never learn the cause,” he said.

One area of concern is that most containers have hinges and other pinch-points where food can get caught and stay trapped for a long time. The studies found numerous instances of mold and spoilage in these areas of the containers even after they had undergone the sanitization process.

With two independent studies raising such similar concerns about reusable containers, Suslow and Warriner say the best way to resolve this problem is for container manufacturers to recalculate their cleaning and sanitization processes. However, in the meantime, they suggest that growers and handlers should implement their own procedures for cleaning the containers and possibly test with rapid bacterial swabs themselves prior to using.

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