Bassam Annous, a microbiologist at the Agriculture Department’s food safety technologies research unit in Wyndmoor, Pennyslvania, has been experimenting on how pasteurization may reduce levels of salmonella infections on fruits and vegetables.
He said the process wouldn’t work with leafy vegetables or apples because it causes lettuce to wilt and apples to turn brown, but he said there’s no reason it couldn’t be used for citrus fruits, avocados and perhaps tomatoes.
"If the rind is thick, the flesh is not affected," he said. Annous said there’s another benefit — the process kills other pathogens that cause produce to decay, and so the treated produce lasts longer on the shelf.
The process involves immersing the fruits in water heated to 169 degrees Fahrenheit for three minutes then sealing each fruit in a plastic bag to prevent re-contamination before rapidly cooling the produce in ice water.
Annous said colonies of salmonella often aren’t affected by chlorine rinses and other sanitation measures processors use because the bacteria cling to the rind and form a protective biofilm around them. Pathogens left on the rind of fruits and vegetables are transferred to the flesh of the produce during cutting or processing.