Photo of picnic meal When grilling meet, leave the raw meat packaged in the cooler until it is time to cook, and then grill the meat until juices run clear or the pinkness disappears.

Summer picnics and cookouts are a common source of food poisoning. Classic symptoms include stomach cramps, vomiting, diarrhea, fever and flu-like symptoms. While food-borne illness is a mere inconvenience for a day or two for most people, it can be particularly dangerous for older adults, infants, children and pregnant women.

To help prevent microorganisms from proliferating in the picnic basket, Jill West, a registered dietitian and certified diabetes educator at UC Davis, offers the following tips to keep foods safe:

Choose foods carefully

Meat, seafood, mayonnaise, eggs, milk and many dairy products have the greatest danger of spoiling. So instead of packing deli-roasted chicken and potato salad, consider packing the basket (or preferably, the cooler) with safer choices. Bread, crackers, cheese and peanut butter have a longer shelf live, as do condiments like jam, mustard, ketchup and pickles or relish. Pretzels, vegetables or chips with salsa are good alternatives for snacking, and when it comes to dessert, it's best to avoid cream or custard-filled concoctions, and choose cookies, cakes, fruit-filled pies, strawberries, watermelon and other summer fruits instead.

Be prepared

Prepare foods ahead of time and limit the time food is kept out of the refrigerator during a picnic as any germs already on the food or introduced during preparation are more likely to multiply and cause illness. A single bacterium can replicate itself to more than two million in seven hours under warm, outdoor temperatures.

Avoid cross-contamination

During preparation, wash hands frequently and keep work surfaces and utensils clean. Use a separate cutting board (preferably plastic) and utensils for meats to avoid spreading microorganisms.

The right temperature

Remember to keep cold foods cold and hot foods hot. Cold foods should be kept in the refrigerator until it is time to leave. For hot foods, time the cooking with departure and transfer it directly from the oven to the car. Eat cold and hot foods within one hour.

Packing foods that need cooling, like casseroles or pasta salads, in small containers helps them chill faster, but also enables them to be set out and eaten as they are needed.

Getting around

Transport foods to be kept cold in an insulated cooler with ice or ice packs. Figure that about one quarter of the space should be taken up by the ice. A block of ice will last longer than ice chips or cubes. Put the cooler in the air-conditioned car rather than in the hot trunk.

Store it right

At the picnic, keep the cooler in the shade. Use a separate cooler for cold drinks to avoid frequent opening and closing of the one containing perishable items. At the beach, partially bury the coolers in the sand, cover them with towels or blankets and put an umbrella over them for shade.

When grilling meet, leave the raw meat packaged in the cooler until it is time to cook, and then grill the meat until juices run clear or the pinkness disappears. Never partially cook the meat at home, then finish grilling it at the picnic. Half-cooked meat is a recipe for bacterial growth. If meat is marinated, pack along some clean marinade for basting while grilling, and then transfer cooked meat to clean plates that have not contained raw meat.

The party's over

Perishable food that has been left outside for longer than one hour in hot weather should be thrown away. Food that has been put away promptly should be safe if there is still ice in the cooler upon arrival at home and the food feels cool.