This is a recent story that I've seen run by several news outlets on food expiration dates:
The bottom line is that most dates stamped on packages are just a guess of when products will be at their highest quality. Most can be used far beyond the recommended date stamped on the package. There are three exceptions to this. Meat, dairy and formula have expiration dates that should be observed (they will say "exp." on the label). Otherwise, in some cases, the products will be good for years beyond the "best by" or "sell by" dates.
A quote: "Broad Leib (lead author of the study from Harvard Law School's Food Law and Policy Clinic) said food can be totally safe well past the date, from cereal to salad dressing, even eggs. She said "use by" or "sell by" dates on a product have "nothing to do with safety at all. It's just a manufacturer's best guess of when that food is going to be the freshest and at the best quality."
Another quote: "According to countless food safety experts, the National Food Lab, there's not been a single instance of food-borne illness or food poisoning linked with people eating food after that date," Broad Leib said."