Take Safety on Your Picnic

Picnicking is a special part of many summertime activities. If picnic foods are not handled safely, they can cause foodborne illness. To prevent illness, take safety on your picnic.

Three reasons why picnic foods can be hazardous

  • Food receives a lot of handling. Picnic foods — such as potato or macaroni salads, sandwich fillings, hamburger patties and cut watermelon — often receive a lot of handling during preparation. Handling increases the risk of contamination with harmful bacteria.
  • Food is not cooled rapidly after cooking. Some common picnic foods require precooking and are prepared in large quantities. Cooked foods must be rapidly cooled by putting in shallow pans and refrigerating immediately after cooking so harmful bacteria does not grow. Warm temperatures promote bacterial growth.
  • Equipment to keep hot food hot and cold food cold is usually not used and food sits out for long periods of time. Warm temperatures support the growth of harmful bacteria. The longer food is at warm temperatures, the more likely foodborne illness will result.

Preparing food safely

Wash hands before handling food and use clean utensils and containers. Dirty hands, utensils, containers and any work surfaces can contaminate food with harmful bacteria and viruses.

Do not prepare foods more than one day before your picnic unless it is to be frozen. Cooking foods in advance allows for more opportunities for bacteria to grow. Cooked foods need to be rapidly cooled in shallow pans. Spread the food out in as many pans as is needed so that food is no more than two inches deep. Over 67% of reported cases of foodborne illness are due to improper cooling. Frozen foods can be used if thawed in the refrigerator.

Mayonnaise-based foods need to be kept cold. Mayonnaise alone is too acidic for bacteria to grow in it. However, when mayonnaise is mixed with other foods, (particularly those that have been handled a lot and/or are protein foods), bacteria can grow if this mixture is kept too warm.

Cut melons need to be kept cold. Many people do not realize that melons, such as watermelons and cantaloupe, can cause foodborne illness. Bacteria, such as Salmonella and Shigella (common causes of foodborne illness), are often present on the rind. Therefore, wash melons thoroughly before cutting then promptly refrigerate cut pieces. Melons, unlike most other fruits, are not acidic and so can support the growth of harmful bacteria.

Packing for safety

Keep cold food cold. Keep cold food at 40oF or colder to prevent bacterial growth. To do so, pack cold foods in a sturdy, insulated cooler with plenty of ice or frozen gel packs. Freeze your own blocks of ice in milk cartons or plastic containers for use in the cooler. Put cold foods in water-proof containers or wrap in plastic wrap or aluminum foil and completely immerse in the ice inside the cooler. If using frozen gel packs or containers of homemade ice, place them between packages of food. Never just set containers of food on top of ice.

The trunk of your car can reach temperatures of 150oF so it is best to transport coolers in the passenger area of the car. When you arrive at the picnic site, put a blanket over the cooler and place it in the shade to maintain cold temperatures. Keep the cooler closed until ready to use the contents.

Keep hot food hot. Keep hot foods at 140oF or hotter to prevent the growth of harmful bacteria. Take-out foods or foods cooked just before being transported to the picnic can be carried hot. Wrap hot food in towels, then newspaper, and place inside a box or heavy paper bag. Keep these foods warm on a lit grill or use within one hour.

If you cannot keep cold food cold and hot food hot, take foods that do not need refrigeration:

  • peanut butter sandwiches
  • dried fruit, nuts, unpeeled fresh fruit — apples, oranges, bananas
  • jelly sandwiches
  • unopened cans of food, meat, fish or fruit
  • cookies and cakes
  • crackers

Wash your hands. Pack moist towelettes if you think your picnic site might not have handwashing facilities available. Hands carry harmful bacteria and viruses that contaminate food and cause illness.

Pack plenty of utensils and dishware. Never use the utensils and dishware that have touched raw foods, such as meat, fish and poultry, to store fresh or cooked foods unless they have been washed between use. Juices from some raw foods contain harmful bacteria that can contaminate other foods and cause foodborne illness. Because proper washing might be difficult at a picnic, pack extra plates and utensils to prevent cross-contamination. Better yet, consider using disposable plates.

Cooking food at the picnic

Wash hands before handling food and use clean utensils and containers. Dirty hands, utensils, containers and any work surfaces can contaminate food with harmful bacteria and viruses.

Thoroughly cook food all at one time. Never partially cook food, let it sit, then finish cooking it later. This provides conditions that allow harmful bacteria to grow and possibly form toxins. (Toxins are poisons formed by some bacteria.) Some toxins are not destroyed by cooking, so reheating the food later will not make it safe.

Cooking at the picnic. Whether cooking indoors or outside on a grill, meat and poultry must be cooked thoroughly to ensure that harmful bacteria are destroyed. Grill raw poultry until the juices run clear and there is no pink close to the bone. Hamburgers should not be pink in the center.


Keep cold foods cold during serving the meal. Do not let cold foods sit out for more than one hour. Any leftovers should be put back in the cooler right after they are served. The longer foods are held at unsafe temperatures the more likely that bacteria can grow and cause foodborne illness.

Keep hot foods hot during serving the meal. Cooked foods are just as perishable as raw foods, so once grilled foods are cooked do not let them sit out for more than one hour. Plan preparation so food is eaten shortly after it is cooked.

Prevent contamination. Keep foods covered to prevent contamination by insects. Many insects can carry harmful bacteria and viruses on their bodies.

Handling leftovers

Because most picnic leftovers have been sitting out for more than one hour and have had many people handling them, throw them out. The more time that food has been sitting at unsafe temperature, the more likely harmful bacteria has grown.

Cold foods kept in a cooler that still has ice may be safe. If the ice is melted, throw out the food. Cold water cannot keep foods cold enough to be safe.


Written by Angela M. Fraser, Ph.D. – Food Safety Specialist
This article can be found at http://www.ces.ncsu.edu/depts/foodsci/ext/pubs/picnic.html

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