According to the United States Department of Agriculture (USDA), "open dating" is the process of displaying a calendar date (as opposed to a code) on a food product in order to help stores determine the length of time to display a product for sale and allow the consumer to make purchase decisions based on freshness and quality. It is not a safety date. When a calendar date is used, both the month and day of the month must be stated. In the case of shelf–stable foods (foods that can be safely stored at room temperature; i.e., on the shelf) and frozen products, the year must also be expressed. Additionally, when a date is displayed on a product, there must be a phrase explaining the meaning of that date such as "sell–by" or "use before." immediately adjacent to the date. What do these different phrases mean? According to the USDA:
- A "sell–by" date informs a store of the length of time to display a product for sale. Consumers should purchase such products before this date.
- A "best if used by (or before)" date is a recommendation pertaining to the product’s optimal flavor or quality. It is not a purchase or safety recommendation.
- A "use–by" date is the suggested last date that the product will be at peak quality. The date has been determined by the manufacturer of the product.
- A "closed or coded date" is a packing number used by the manufacturer.
As with medications, proper storage is critical to the integrity and shelf life of food. The mishandling and/or improper storage of food can cause food–borne bacteria to grow and result in illness before or after the date displayed on a package. The USDA recommends that consumers follow these tips:
- When shopping, refrigerated or frozen items should be selected after non–perishable items. Meat or poultry in packaging that is torn or leaking should never be purchased. Products should be purchased prior to their expiration date. Perishable food items should be brought home immediately after purchase and refrigerated within 2 hours (1 hour when the temperature is above 90° F). The temperature of the refrigerator and freezer should be checked with an appliance thermometer. The refrigerator should be at or below forty degrees Fahrenheit and the freezer at or below zero degrees Fahrenheit. Handling recommendations that are listed on the product should be followed. Perishable food such as meat and poultry should be wrapped securely to maintain quality and to prevent meat juices from contaminating other foods. Fresh poultry, fish, ground meats and variety meats should be cooked or frozen within two days; other beef, veal, lamb or pork should be cooked or frozen within three to five days. Products should be frozen if they cannot be used within the appropriate time period. Once a perishable product is frozen, it does not matter if its date expires; foods that are kept continuously frozen are safe indefinitely. To maintain quality when freezing meat and poultry in its original package, the package should be wrapped again with foil or plastic wrap. Eggs can be stored in the refrigerator for three to five weeks after purchase. In general, canned goods remain in good condition if they are stored in a cool, clean and dry place. High–acid canned foods such as tomatoes, grapefruit and pineapple retain optimum quality for 12 to 18 months. Low–acid canned foods such as beef, poultry, fish and most vegetables retain optimum quality on the shelf for two to five years. Regardless of the date, cans that are bulging, dented or rusting should be thrown away because they may harbor harmful bacteria.