Burning Question: Does Rinsing Fruit Make a Difference?
The Big Concern Is Harmful Bacteria Deep in Cut Leafy Greens
By HEIDI MITCHELL
Jan. 27, 2014 7:39 p.m. ET
People are eating more raw and organically grown fruits and vegetables these days. And that has many consumers concerned whether they are properly cleaning their produce. Michael Doyle, a professor of food microbiology at the University of Georgia and director of its Center for Food Safety, offers his opinion on how to wash fresh food—and whether it's OK to rub an apple on your shirt.
Harboring Enemies
When it comes to anything plucked from the produce aisle, Dr. Doyle says there are two main concerns—pesticides, which he doesn't worry much about, and microorganisms, which he does. "There have been lots of studies done by the government showing that pesticide contaminant tends to be at levels that are below health concerns," he says.
The more serious threat is microorganisms, especially salmonella, listeria and certain strains of E. coli. These sicken more consumers as a result of eating fruits and vegetables than eating meat or poultry, he says. The bacteria are sometimes spread through contaminated irrigation water and can settle on the surface of fresh produce, particularly those with layered leaves.
"Washing produce with tap water should help reduce residual pesticides and any dirt on the surface, where listeria and other bacteria often harbor," he says. But if harmful bacteria are present deep in the leafy greens that have been cut, "the extra washing you do at home isn't going to help," he says.
In the Bag
Even when bagged lettuce says it's been double washed, microorganisms that make their way into the water at the processing facility can spread onto whatever is being washed, Dr. Doyle says. Also, once the lettuce or spinach has been cut, surface microbes can become entrapped within the leaf itself. "When that happens, there is no washing it out, no matter what you do," says Dr. Doyle. "This may be one reason why bag salads and cut greens have been some of the biggest culprits in spreading foodborne illnesses recently."
He recommends consumers buy heads of lettuce instead of cut, bagged lettuce. "Remove the outer leaves, wash your hands, then rinse the remaining leaves," he says. Fresh herbs, like basil, rosemary, cilantro and parsley, also should be washed. And keep fresh produce away from other bacteria carriers, like raw chicken.
Extra Precautions
Homemade cleansing solutions with bleach, vinegar or lemon juice are fine for bathing fruits and vegetables, though Dr. Doyle says they aren't likely to kill all harmful bacteria or microorganisms present. Store-bought produce washes have been shown to eliminate even more bacteria and microbes, but a good 20-second wash under the tap should be sufficient for most uncut produce. "Any longer won't make much of a difference," says Dr. Doyle. Neither will higher temperature, since getting the water hot enough to destroy bacteria will wilt the lettuce.
A trusty method to ensure clean produce: peeling. "Removing the outer peel has been one of the strategies for avoiding illnesses when visiting foreign countries for a long time," says Dr. Doyle. "And it can apply at home."
Risky Business
Small amounts of bacteria in food won't affect most people, whose bodies usually fight off minor infections. But older or very young people, and pregnant women, are at greater risk and should always wash produce carefully before eating. Dr. Doyle recommends everyone avoid eating alfalfa and bean sprouts unless they are cooked. "Because of the way they are grown and washed, you cannot be sure that they are not harmful," he says. "I like bean sprouts, and I eat them, but only after they've been put into a boiling bowl of Vietnamese pho" soup.
The dietary benefits of eating fresh fruit and vegetables are high, but assuring that the produce is free of microbes is also essential. "I always rinse my produce under the tap," says Dr. Doyle. As for that old-school method of rubbing an apple on one's shirt? "There have been studies that show that the friction from rubbing a paper towel on an apple does remove bacteria," he says. "So if you rub it vigorously on your shirt, that probably would do the trick."