Hot Cold Clean

FAYETTEVILLE, Ark. — Burgers, potato salad and sweet, juicy watermelon. It’s a menu that conjures fond memories of cook-outs on hot summer afternoons, unless your family and friends were joined by some unpleasant guests — food borne bacteria.

Researchers at the University of Arkansas offer a three-pronged approach to avoid inviting those microscopic hordes that can ruin your day in the park. To prevent food borne illness, Pam Brady from the department of food science advises, “Remember the three prongs of picnic safety: Hot, Cold and Clean.”

In other words, keep hot foods hot, keep cold foods cold and keep everything clean. From what she has seen at picnics, Marjorie Fitch-Hilgenberg, associate professor in dietetics, believes many people have gotten the basic message but may be foggy on the details. They may bring salads in an ice chest and grill the meat well, but ice melts and burgers cool quickly.

“Food is sitting on a picnic table in 90-degree heat. People are worrying about the flies, but I’m worrying about bacteria,” Fitch-Hilgenberg says.

Food science professor Michael Johnson also worries that a hot summer day is the perfect temperature for bacteria to thrive. “For safe food handling, temperature is key. Cold food should be stored under 35 or 40 degrees Fahrenheit and hot food above 140 degrees. The range in between is where bacteria grow.”

The first step is to get the foods hot enough to begin with. Fitch-Hilgenberg and Johnson both emphasize grilling burgers to the well-done stage, which they are quick to point out means no pink in the center, but not tough and tasteless meat. Johnson suggests carrying a thermometer reserved for use with meats. Check the temperature at the center of burgers or steaks or the thickest part of chicken. Burgers should be cooked to an internal temperature of at least 160 degrees and poultry to 165 degrees.

Hot or cold, nothing should sit out on the picnic table for more than two hours. After grilling, don’t leave burgers sitting on the picnic table where they can cool to the perfect growth range for bacteria. Instead, cook more as needed, Johnson advises, and serve them immediately.

It’s hot outdoors, and the challenge is to keep those many delicious picnic foods cold. Fitch-Hilgenberg suggests taking an extra cooler — or two or three — and freezing ice in chunks, which last much longer than the small cubes in bagged ice.

“I like to use a rectangular sheet cake pan to make ice,” Fitch-Hilgenberg says. “I put that chunk of ice in the bottom of the cooler, add ice cubes with the food and top it all off with another chunk of ice. It lasts through the hottest weather.”

She also suggests leaving a chunk of ice in the cake pan and pulling it out of the cooler at the picnic to use as a serving tray for potato salad or deviled eggs. It keeps the food cool when out on the table and makes it easy to return the potato salad to the cooler when everyone runs off to play softball.

Fitch-Hilgenberg suggests using several coolers. One cooler can carry extra bagged ice. Another can be dedicated to beverages and to snacks that can tolerate the constant opening and closing of the cooler. She suggests stocking the snack cooler with nutritious choices such as fresh fruit and vegetables and string cheese, all of which hold up well.

Another cooler can hold raw meat. She suggests preparing hamburger patties at home and freezing them in advance so they stay below 40 degrees until they hit the grill. If it is necessary to carry meat in the same cooler with other foods, it should be well sealed and placed on the bottom of the cooler below the other foods.

Anything that goes into an ice chest, whether canned beverages or prepared foods, should be cooled before being packed to help retain cool temperatures. Even milk can be a good picnic food, but Fitch-Hilgenberg suggests partially freezing it before putting it into the ice chest.

Fitch-Hilgenberg notes that mayonnaise has gotten a bad name, and unjustly so. It’s not the mayonnaise in potato salad that causes problems, but rather bacteria introduced during preparation or bacteria that develops while the salad is sitting out in the heat of the day.

“Actually, mayonnaise is highly acidic since it’s made with vinegar or lemon juice,” Fitch-Hilgenberg says, referring to the level of acidity and alkalinity in a food, known as the pH balance. “You need to look at the pH of a food, not just the temperature. Most bacteria are pH-sensitive. That’s why a dill pickle lasts a lot longer than a fresh cucumber.”

Just like in the kitchen at home, anyone grilling meats or serving other foods needs to wash hands frequently. When out in the woods with no running water, Brady recommends, picnickers should pack lots of disposable Handi-wipes. Washing is key to preventing cross-contamination from raw meat to cooked meat or vegetables.

Johnson, a microbiologist who has conducted research with food borne pathogens over the years, has developed his own three-pan plan for safe grilling. His method prevents cross-contamination from raw to cooked meat. Johnson uses large cake pans, and his raw burgers are all separated with waxed paper spacers so that it is easy to pick them up without touching the meat directly. The first pan is used for raw meat only. Cooking utensils go into the middle pan. Johnson uses two sets of turners for his burgers. One is used with the raw meat and the other with the cooked burger. Cooked items go into the third pan, and no raw meat or raw meat utensil touches them.

Johnson also emphasizes washing hands while cooking. He points out that cross-contamination can occur when the cook picks up a bun to toast it on the grill using hands that have handled raw meat.

Fitch-Hilgenberg adds that the sweet, juicy watermelon can also carry bacteria on its rind. She advises thoroughly washing the outside of the melon at home, then popping it into a bag and carrying it to the picnic whole. If the melon is cut at home, it has to be packed in the cooler until time to eat.

“Cut and serve it right there at the table,” she says. “It’s ready to go, and it’s one of the simplest desserts.”

The UA faculty members recommend some useful Web sites: www.fightbac.org, which includes detailed information about safe cooking temperatures, and the Food and Drug Administration’s Center for Food Safety and Applied Nutrition, which offers “Outdoor Eating Food Safety Tips” at www.cfsan.fda.gov/~dms/fsdup107.html.