To keep unwanted guests like Salmonella and E. coli from your picnic, follow this basic advice:
Keep hot foods hot and cold foods cold. Anything perishable should be kept at room temperature for no more than two hours.
Bring along antibacterial wipes or hand-washing liquid to clean your hands before laying out (and eating) the food.
Bring two coolers: one for food and one for drinks. Since you’ll probably open the drinks cooler more often than the food cooler, this prevents warm air from reaching your perishables.
Avoid bringing anything made with fresh eggs, which can become a breeding ground for bacteria.
Avoid bringing meats, fish, potatoes, and pasta mixed with mayo. These foods can reduce the acidity of the mayonnaise (which keeps bacteria at bay) encouraging the growth of bacteria. Instead, bring your salad ingredients in separate containers and mix when you’re ready to serve.
Keep your cooler in the air-conditioned car.
Thaw meat before grilling so it cooks evenly. Cook to an internal temperature of 160°F. Poultry should cook to 180°F.
Keep raw meats, fish, and poultry (and the containers on which they sat) separate from cooked foods.
Wash the outer surface of fruits, including melons, well before cutting.