What should consumers know about food product dating?

-       Most dates on products are not expiration dates; that is, they don’t mean that the consumer has to throw the food out immediately after that date because it is unsafe to eat. Rather, the meaning is that, after the printed date, the food will begin to diminish in quality; the flavor, texture, and/or color might begin to deteriorate and/or the nutrients no longer remain exactly as promised on the container. Many nonperishable foods are safe to eat for weeks after the date on the packaging (even though the consumer might notice diminished quality). With perishable foods, this may not be the case.

-       Once a packaged product has been opened, the date usually doesn’t apply. A jar of mayonnaise or salad dressing on the store shelf may have a “best by” date 6 months in the future. Still, once opened, it should be refrigerated and kept for 2-4 months at most. The American Dietetic Association recommends that consumers throw out milk a week after opening and soft cheeses (such as brie and camembert) 3-4 days after opening even if that precedes the “sell by” or “use by” date. Food scientist Susan Brewer points out that milk is pasteurized to kill human pathogens. Therefore, the “best buy” dates apply to spoilage (not disease-causing) bacteria and flavor. Most products made from milk are either pasteurized or treated to eliminate pathogens in other ways (such as acidification rather than heat).

Source(s):

USDA Fact Sheets “Food Product Dating”

Susan Brewer, Ph.D., University of Illinois, Department of Food Science and Human Nutrition

Kraft Foods recorded phone message on mayonnaise