A recent outbreak of E. coli infections linked to potato salad in the Chicago area has many summer picnickers thinking about food safety. In truth, food safety should always be a concern, says a University of Georgia food scientist.

"It's not just E. coli," said Judy Harrison, an Extension Service food scientist with the UGA College of Family and Consumer Sciences. "There are always several organisms out there that can cause problems if they're allowed to multiply in food products."

Harrison said that's why good food-safety habits are important all the time. And they're doubly important when planning big meals or picnics.

Some of the more commonly found organisms that can cause food-borne illnesses are Staphylococcus aureus, Salmonella, Campylobacter and Listeria monocytogenes.

"The key is to keep foods at safe temperatures," Harrison said. For safety, keep foods either below 40 or above 140 degrees.

Often, as people prepare for summer picnics, they may make large containers of potato salad, macaroni salad and other chopped-up vegetable salads.

Harrison said the dangerous part of these foods isn't the mayonnaise. And it isn't the small pieces. It's the low-acid ingredients like the meats or vegetables mixed with the mayo.

The large quantity makes a safety difference, too. Large bowls or pieces of any food will cool slowly, even if immediately placed in the refrigerator. That lengthy cooling time can keep food in the danger zone long enough to allow harmful organisms to multiply if they're there.

So divide the food into small, shallow containers before refrigeration, Harrison said. That lets the food cool faster.

"The general rule is to avoid having foods in the danger zone --from 40 to 140 degrees -- for more than two hours, total," she said.

But at picnics, that can be hard to do. Small, shallow containers can help there, too, Harrison said. Take several small dishes of food instead of one large dish. And keep all the containers in an ice-filled cooler until you need them.

"Just replace the small dishes as they empty with fresh, still-cool ones," she said.

Keeping hot foods hot can present just as much a problem. First, make sure foods are cooked thoroughly.

Cook ground beef to at least 160 degrees. Beef muscle cuts, pork and veal must reach 160 degrees for medium and 170 degrees for well done. Cook poultry to 180 degrees. Insert an instant-read thermometer into the thickest part of the meat to check the temperature.

Serve the meat as soon as you cook it, Harrison said. Or keep it above 140 degrees until you serve it. After it's served, divide or cut leftovers into smaller portions, place it in shallow containers and cool it quickly.