ROCHESTER, N.Y. — Recent research results on tomato harvesting and handling give buyers the backup they need when growers and shippers try to negotiate out of food safety requirements, according to a panel at the Center for Produce Safety Research Symposium.
The fourth annual symposium was at the Wegmans Conference Center and attracted more than 300 attendees in late June. It included presentations from 16 scientists whose fresh produce research projects received CPS funding.
Two of the projects involved pathogen transfer risks and survival rates in different aspects of harvesting and handling field-grown tomatoes.
Michelle Danyluk, an assistant professor specializing in microbial food safety and quality at the University of Florida, looked at “established standards” to remove dirt and debris from tomatoes during field packing — using cloths to wipe and shine — and the reuse of cartons in repack operations.
The two-year project showed cloths easily transfer pathogens from one tomato to at least 25 more tomatoes.
Danyluk also documented that dirt on cartons harbors pathogens and transfers them to tomatoes. Danyluk said the results were expected, but the rate of pathogen transfer was higher than anticipated.
“Now that there is data, we will go back and talk to our suppliers to make sure (they meet our requirements),” said Michael Burness, vice president of global quality and food safety at Chiquita Brands International Inc.
Burness was one of four panelists who discussed practical applications of research following scientists’ presentations on pathogen transference.
Also on the panel was Jorge Hernandez, senior vice president for food safety and quality assurance at US Foods.
“We have been working with our suppliers to stop this (use of cloths) and this gives us data to back up our requirements,” Hernandez said.
In a separate research project, Lynne McLandsborough, an assistant professor in the department of food science at the University of Massachusetts-Amherst, studied the survival, transfer and inactivation of salmonella on plastic materials used during the harvest of field tomatoes.
She specifically documented salmonella levels on plastic bins and gloves workers use to gather tomatoes from the fields.
Data from the 25-month research project led her to conclude that the pathogen does survive easily on the surfaces of the bins, especially if dirt is allowed to accumulate because it provides a “safe place” for the salmonella to live.
McLandsborough also measured salmonella levels on different types of gloves being used in the industry: vinyl, latex, nitrile and low-density polyethylene.
Under an electron microscope the varying roughness of the gloves’ surfaces revealed the nitrile gloves to be much smoother, thus providing fewer locations for pathogens to survive and multiply. Nitrile gloves also showed less pathogen accumulation and could be more effectively cleaned between uses.
“Our conclusion? Glove material matters,” Landsborough said.
Panelist Filindo Colace, vice president of operations for Club Chef Chef LLC (a Castellini Co.), said he was pleased the research supported his company’s decision to use nitrile gloves. He said Danyluk’s research on pathogen transference via tomato cleaning cloths proved Club Chef was also correct to ban them.
Chiquita’s Burness said the researchers’ work reinforces the need to focus on clean.
“It’s all so simple with this data,” Burness said about tomato harvesting. “No cloths, new bins, nitrile gloves.”
Reggie Brown, another panel member and executive vice president of the Florida Tomato Growers Exchange, expressed caution as far as the need for growers to buy new equipment.
“This shows we can find some contamination but not specific differences between new and old (harvest bins and buckets),” Brown said.
“Our regulations require daily washing and inspection of bins, but these businesses have to be economically successful. We can’t chase down every boogie man. … And we don’t want to move a raw agricultural product to become a finished product.”