Food Safety Basics: Storage, Leftovers and Cross-Contamination

Safety first

Foodborne illness usually shows up as vomiting, diarrhea and abdominal pain, sometimes with flu-like symptoms. [1] FDA says it usually begins within 1 to 3 days, but can start within 20 minutes or up to 6 weeks later. [1] FDA says children, older adults, pregnant women and people with weakened immune systems can be especially vulnerable. [1] If you think you or a family member has a foodborne illness, FDA says to contact your healthcare provider. [1] For breathing trouble or swelling of the face or throat after eating, call 911 (this may be an allergic reaction; see food allergy basics).

The four steps

FDA sums up home food safety as four steps: clean, separate, cook and chill. [2]

Storage

FDA advises keeping the refrigerator at or below 40°F (4°C). [3] Foods that need refrigeration should not sit at room temperature for more than two hours (one hour if the air temperature is above 90°F), and that includes leftovers, "doggie bags" and take-out. [3] FDA also says food can make you very sick even when it does not look, smell or taste spoiled. [3] Perishable fresh produce such as strawberries, lettuce, herbs and mushrooms belongs in a clean refrigerator at 40°F or below. [1]

Freezing stops bacteria from growing but does not kill most of them, and freezer burn is a quality issue, not a safety issue. [3] FDA names three safe ways to defrost food: in the refrigerator, in cold water and in the microwave; it says never to thaw at room temperature. [2]

Leftovers

FDA says to divide large amounts of leftovers into shallow containers for quicker cooling in the refrigerator. [2] It lists a safe reheating temperature of 165°F for leftovers and casseroles and says to bring sauces, soups and gravy to a boil when reheating. [2] MedlinePlus advises using ready-to-eat foods as soon as you can and heating leftovers until they are steaming hot, because Listeria can grow even at refrigerator temperatures. [4] FDA advises checking leftovers daily for spoilage. [3]

How many days leftovers keep: not described in the sources we read, so we give no number. Ask a food-safety authority such as your local health department or a university extension service.

Keeping raw and cooked foods apart

FDA says never to place cooked food on a plate that previously held raw meat, poultry, seafood or eggs unless the plate has been washed in hot, soapy water. [2] Raw produce should be kept separate from raw meat, poultry and seafood. [1] Washing fruits and vegetables with soap, detergent or commercial produce wash is not recommended, and washing reduces bacteria but does not eliminate it. [1] Firm produce such as melons and cucumbers can be scrubbed with a clean produce brush. [1]

Dates and spoilage

FDA says a "use by" date is a quality date, not a food safety date, with infant formula the exception: it must be used by the date on the package. [3] Mold is a sign of spoilage and can grow even under refrigeration. [3] Dented, swollen or leaking cans are covered on our page about fresh, frozen and canned produce.

Who should be extra careful

FDA names pregnant women, children under 5, older adults and people with cancer, diabetes, HIV/AIDS, transplants and autoimmune diseases as higher-risk groups, and advises them to avoid foods such as raw sprouts, unpasteurized milk and unwashed fresh vegetables. [5] More: pasteurized versus unpasteurized foods and the preparation overview.

Limits

This page is a plain summary of two FDA pages and one MedlinePlus page. We could not read USDA FSIS or CDC pages (access errors), so we do not give temperature charts for meat, specific refrigerator days for leftovers or guidance on home canning.