The combination of hot weather and lack of refrigeration can turn a holiday picnic into a miserable memory. Because bacteria (usually salmonella, E. coli, or staphylococcus aureus) multiply quickly when food is unrefrigerated, keep all cooked food or food you plan to cook in an insulated cooler with enough ice to hold it at 40 degrees F.
Be particularly careful of salads containing potatoes, eggs, pasta, meat or fish that are combined with mayonnaise. These foods are an ideal medium for the growth of bacteria that can make you very sick with nausea, vomiting, cramps, diarrhea, fever, and headache. The mayo itself usually isn't the problem - commercially produced mayonnaise is made with pasteurized eggs and contains vinegar and lemon juice that provide enough acidity to discourage bacterial growth. However, potatoes, pasta, meat and fish can reduce the acidity and encourage germs to grow in the mixture. And, of course, when mayo is homemade with fresh eggs, you can run into even more trouble. In any event, thoroughly chill all salad ingredients (including mayo) before you combine them, and keep the salads on ice or in the cooler at 40 degrees F. After serving, don't leave salads on the picnic table - return them to the cooler immediately.
Here are some other food safety tips:
- Carry your cooler in the air-conditioned car, not the trunk, and at the picnic site put it in the shade with the lid closed. Replace melted ice.
- Thaw meat before grilling so it cooks evenly.
- Cook meat to 160 degrees F (until the center is no longer pink), poultry to 180 degrees F, and ground poultry to 165 degrees F. Check temperature with a meat thermometer.
- Put leftovers in the cooler soon after grilling or serving.
- Don't eat any cooked food (including take-out) left unrefrigerated for more than an hour.
- Don't put cooked meat on a plate that has held raw meat.
- Wash your hands with hot, soapy water before and after handling food and after using the bathroom. Conscientious hand washing could prevent half of all foodborne illnesses.
You can have a healthier cookout if you avoid meat, and grill fish and lots of vegetables instead. But all the rules of safe food handling apply to whatever is on the menu.
Andrew Weil, M.D.