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May 2001 Fruits, vegetables require care to prevent food illnessesWEST LAFAYETTE, Ind. - Ask Purdue University food microbiologist Richard Linton what foods he won't eat, and the answer might surprise you. He doesn't mention exotic seafood or fast-food fare. The food that frightens this associate professor of food science is raw vegetables. Just like a 4-year-old, he doesn't always eat his veggies. But unlike the preschooler, Linton has a good excuse. According to the congressional General Accounting Office, an estimated 85 percent of annual food illness outbreaks are caused by vegetables, fruits, seafood and cheeses – not the meat, dairy and egg products most people think of in connection with food poisoning. "There are two types of foods: those that are potentially hazardous and those that aren't hazardous themselves but can support pathogens," Linton says. "Fruits and vegetables themselves aren't often hazardous. But they can support pathogens that can make you ill." A recent New York Times article reported that despite technological advances, Americans may have a greater chance of getting sick from food than they did 50 years ago. Experts attribute this, in part, to Americans' increasing appetite for raw fruits and vegetables. "If we were to cook these products, it wouldn't be a safety concern," Linton says. "However, unlike beef or pork, we may not know how to prepare produce to kill the pathogens." By themselves, fruits and vegetables are poor surfaces for bacteria to thrive. They lack the protein, moisture and pH levels that meat, eggs and milk have. But vegetable farmers often use manure to help fertilize their fields, and that is where the trouble begins. "It might be grown in fields cultivated with manure, or adjacent to a farm field that contains livestock, and when it rains the manure spreads over the vegetable field," Linton says. "Then it's put into a truck with thousands of pounds of other produce, and it can spread." One of the biggest food illness outbreaks in the past decade came from coleslaw sold in an Indiana restaurant. Many people were surprised to find that it was the cabbage, and not the sauce, that apparently was contaminated. More recently, in 1999 a contaminated batch of orange juice caused one death and sickened 400 people. According to the Center for Disease Control, salads or salad bars accounted for 35 percent of the foodborne illnesses caused by produce, followed by fruit, 21 percent; lettuce, 17 percent; and sprouts, 10 percent. Another reason for the apparent increase in foodborne illnesses, Linton says, is that new, more deadly pathogens have emerged in the past few decades. "To get sick from Salmonella, you generally have to consume a million bacteria on that food," he says. "On the other hand, emerging pathogens such as the E. coli 0157:H7 strain or Listeria monocytogenes can cause a serious illness if there are as few as a dozen bacteria on that food. This has only become a known problem in the past few years." Linton says lettuce is a good example of a vegetable that can give food scientists the willies. "It grows close to the ground," he says. "It may become contaminated, and then new leaves grow up and cover the contaminated areas, allowing the pathogens to grow. It has a lot of surface area that can become contaminated, and it's wrinkled, so it has places that may not be cleaned thoroughly." Linton suggests salad lovers consider buying their greens prepackaged in bags. "Lettuce in bags has typically been given some type of cleaning and pathogen reduction step, such as a chlorinated water bath," he says. "That cleans every piece of lettuce better. On the other hand, if you buy a head of lettuce from the store, only the outside has been washed." There are a few ways consumers can protect themselves from dirty vegetables and fruits, Linton says. • Be extra careful with fruits and vegetables that are grown close to the soil. "That means potatoes, carrots, lettuce, strawberries – and those types of foods are going to be more risky," Linton says. • Wash fruits and vegetables carefully under cool, running water using a brush. Although there are sprays on the market that claim to clean fruits and vegetables, Linton urges consumers be careful about how they use the products. "You have to read the labels," he says. "Some products remove pesticide residues, but they don't claim to remove microorganisms. "There are anti-bacterial sprays, but if you read the labels on some of them, it says they need a contact time of 15 minutes, minimum. Not many people do that." • Be aware that foods with rough surfaces are harder to clean. "It's easier to clean an apple or a green pepper than it is to clean a strawberry," Linton says. "Bacteria like to attach in the little grooves and crevices." • Buy prepackaged forms of higher risk foods. Most prepackaged foods have been washed thoroughly and treated with an antimicrobial solution. Despite the precautions, there is still one food Linton won't touch. "Bean sprouts are a very risky food," he says. "The way they are grown and cultivated often don't meet the safety standards that they should. Salmonella has been associated with them for years." Unlike foodborne illnesses caused by meat and dairy products, which are most often caused by improper cooking, the best measures to prevent illness caused by produce take place on the farm, Linton says. He recommends vegetable farmers and fruit growers who would like to know more about production methods that can reduce the chances of illnesses read "Food Safety Begins on the Farm: A Grower's Guide to Good Agricultural Practices for Fresh Fruits and Vegetables." The 27-page pamphlet was produced by food safety experts at 22 land-grant universities and can be ordered from the Cornell Good Agricultural Practices Program at (697) 254-5383, or by e-mail at eab38@cornell.edu. Source: Richard Linton, (765) 494-6481; lintonr@foodsci.purdue.edu Writer: Steve Tally, (765) 494-9809; tally@aes.purdue.edu Purdue News Service: (765) 494-2096; purduenews@purdue.edu NOTE TO JOURNALISTS: A copy of the New Uses for Soybeans Contest video release is available from Brian Baxter at (317) 638-2338.
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