But the bacteria-laden slime remained mostly under the produce industry’s radar until the October 2011 Jensen Farms listeria outbreak brought it to light, said Keith Schneider, a University of Florida associate professor in the Department of Food Science and Human Nutrition, Gainesville.
“It hasn’t been a problem in produce until sort of that perfect storm of events occurred in Colorado,” he said.
Conditions for that storm included a moist environment conducive to bacterial growth and equipment that wasn’t meant to handle cantaloupe and couldn’t be sanitized properly.
Schneider was one of six speakers at the 2012 Tomato Food Safety Workshop, Sept. 4, in Naples.
Vicky BoydWes Roan (left), quality control manager for Lipman, Immokalee, Fla., talks to Ian Bessell, business development director for ABC Research Laboratories, Gainesville, Fla., during a food safety training workshop. The half-day event preceded Florida's annual Joint Tomato Conference, which started Sept. 5The half-day training program, sponsored in part by the Florida Tomato Exchange, was designed to help industry representatives meet the state’s mandatory tomato good agricultural practices and tomato best management practices.
Schneider’s presentation on biofilm caught the attention of Rod Bernard, director of food safety for Southern Specialties Inc., Pompano Beach, Fla.
“People talk about sanitation, but they don’t go this far in depth,” Bernard said.
He said he’d made a lot of notes to take back to colleagues.
Biofilm is formed by bacteria as a survival method, Schneider said.
If bacteria — whether relatively benign or disease-causing — are left on a surface, they reproduce and begin to form a slime.
Pathogens may join benign counterparts in this slime, creating what Schneider called a bacterial condo.
Within 72 hours, the bacteria are fully protected from normal sanitation measures, including chlorine and soap, he said.
A good example of biofilm is the blackish slime that forms on the kitchen sink stopper or rubber garbage disposal gasket, Schneider said.
The blackish slime is exposed to daily soap and even bleach, yet continues to survive.
“Once a biofilm is formed, you basically need elbow grease,” he said. “What used to work won’t work any more because there’s this protective effect.”
Based on the reports he’s read, including the Food and Drug Administration’s investigation report, Schneider said that appeared to be what happened at Jensen Farms, Holly, Colo., which shipped cantaloupes in 2011 that were linked to 33 deaths.
Listeria monocytogene, which is present in the environment, made its way into the packingshed.
Moist conditions created by a dripping condensation line provided optimum conditions for bacterial reproduction.
In addition, the packing line was designed for potatoes, not cantaloupe, and couldn’t be properly sanitized, according to Schneider.
Had the equipment been designed for cantaloupe, a daily sanitation program would most likely have caught the pathogen before it had a chance to form the protective biofilm, he said.
“Routine sanitation is paramount,” Schneider said. “That’s where a problem like Colorado went from a non-issue to a huge problem.”