Everyone has seen the dates posted on various food products – “Use-By …”, “Best-By …”, “Sell-By …”. What do these different categories of food dating mean and are there exceptions to these designations?
With the exception of infant formula, food dating is not required by the Federal government. Several states, however, impose dating requirements on some foods to assure that they remain safe and are consumed at optimal times. 
“Open Dating” refers to the calendar dates that are seen on food products. The three most common of these dates are:
- “Sell-By” date
- “Use-By” date
- “Best if Used By (or Before)”
“Sell-By” date is perhaps the most important of the dating designations. It tells the store how long to keep the product up for sale. Food should not be purchased if this date has expired. Once at home, food past the “Sell-By” date may be able to be consumed safely for varying lengths of time, depending on the type of food (poultry, eggs, canned meats, etc.) and the way that the food was processed (sealed at plant, fresh, or uncooked).
“Use-By” date is established by the manufacturer of the product and refers to when the food is best eaten. The quality of the product is thought to decline after the “Use-By” date, but it does not always mean that the product is unsafe or should be discarded. If the food has been handled property and refrigerated at 40 degrees F or below, most foods remain safe for a period of time, even past the “Use-By” date. An exception to this is baby formula which should not be purchased or used after this date.
“Best if used by” date is similar to the “Use-By” date. It is recommended by the manufacturer for best flavor or quality. It is not a purchase or safety date.
In addition to calendar dating, “Closed” or “coded” dating may be used, particularly in foods in cans or boxes that can be stored for longer periods of time. This enables manufacturers to rotate their stock as well as to locate their products in the event of a recall. According to the U.S. Department of Agriculture (USDA), “In general, high-acid canned foods such as tomatoes, grapefruit and pineapple will retain best quality on the shelf for 12 to 18 months; low-acid canned foods such as meat, poultry, fish and most vegetables will retain best quality on the shelf for 2 to 5 years — if the can remains in good condition and has been stored in a cool, clean, dry place.”
Obviously, food product dating alone is not always the best guide for determining when a food if safe to consume. Use of the dating criteria, along with the following guidelines, however, will help insure food safety:
- Purchase foods prior to the “Sell-By” or “Use-By” date.
- If the food is perishable, refrigerate or freeze promptly.
- Most foods with a “Use-By” date should be consumed prior to the expiration of that date.
- Eggs purchased prior to their “Sell-By” or “EXP” date, and kept refrigerated will maintain their quality for 3 to 5 weeks.
- Infant formula should not be purchased or used past the “Use-By” date.
- Foods that have a “Sell-By” date or no date should be cooked or frozen following guidelines from the USDA.
- Once a perishable product has been handled and frozen properly, the expiration date can be disregarded.
In spite of the dating designation, food that smells bad, tastes bad, or looks bad probably is bad and should not be eaten. Typically, these changes are related to spoilage bacteria that can cause foodborne illness. Remember that, when in doubt . . . throw it out!