According to the Food and Drug Administration (FDA), food can be safe forever from a foodborne-illness standpoint - but if shelf-stable food has been on the shelf for an extended period of time, you might not want to eat it because the quality may not be good. In this case, the "best if used by" date on the label of the product is an indication whether or not the quality of the food is good. Food quality deals with the taste, texture, and nutritional value of food. For example, freezer burn, rancidity, and food spoilage are all quality-related issues. The FDA does not require an expiration date for shelf-stable foods, since the storage time for these foods is a quality issue, not a food safety concern.
Source: Excerpted from FDA/CFSAN Food Safety A to Z Reference Guide, September 2001