Why do “best by” and “use by” dates sometimes seem conservative?

Can with expiration dateMany people say that they’ve eaten a lot of foods that looked and tasted just fine after the “use by” dates. Perhaps because manufacturers don’t know the conditions in the consumer’s home (especially the temperature and humidity) and how carefully (or carelessly) the product might be handled before it gets there, they choose to err on the side of caution. Another reason for conservative estimates may be that companies want to make every effort to avoid complaints, bad publicity, and lawsuits. But the main reason is this: once a product loses some of its original color, texture and/or nutritional value, it is no longer at its best. The “best by” date is supposed to be an indication of that turning point. However, the product may still taste fine and other changes be too minimal to notice. Customers would like to know when noticeable changes that interfere with enjoyment occur. But that’s an individual call. Some people have more sensitive taste buds and higher standards than others.

 There is yet another reason why product dating may be inaccurate. When new products are developed, manufacturers want to get them on the market as soon as possible. They don’t want to wait a year for the product information needed on the packaging. Therefore, they may get data on nutrition and shelf life by what’s called accelerated testing. The product might be subjected to greater than usual temperatures and/or humidity to simulate a year’s time in a few months. According to food scientist Susan Brewer, “accelerated shelf –life testing was designed and is accurate for assessing microbial growth; it is less accurate for quality attributes.”


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


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