We get this question a lot, which isn’t surprising. After all, who doesn’t have a box of cereal in their pantry on the wrong side of a best before date?
The best before date is the date up until which you can expect the product to be at its optimal level, in terms of safety, taste and overall quality. There’s no conspiracy to get you to needlessly buy new food. Food companies want you to think well of their product, so they want you to consume it when it’s still at its best. If it tastes good, you’ll be more likely to buy it again.
A best before date is simply one indicator, one line of defense among many, meant to help you determine if food is safe to eat. If it’s beyond the date, you should take it as a sign to more closely scrutinize the item before eating it or cooking with it.
Some foods are more sensitive than others and aren’t worth risking. For example, if you’re dealing with a ground beef product that has passed the best before date, throw it out. If the best before date is tomorrow, consider cooking something with it tonight, then freeze the resulting dish.
Dairy products and bottled dressings are often good right up until the date that’s on the packaging, even if they’re opened. Check to see if there’s something like “best consumed within 7 days of opening” printed on the packaging. You can typically expect milk to be good up to the best before date, but anything after that is iffy. That said, it’s possible for a rogue carton of milk to go bad before then.
What if you open a jar of mayonnaise just before the best before date? The people who make these products tell us it’s still safe, but it will break down faster than if it were opened earlier. Going past the date doesn’t mean it’s gone bad; it means you have to evaluate the product more carefully before eating it.
If you have canned foods beyond their best before date, be wary. Canned foods are made to last years in the cupboard. If you didn’t want it during the two or three years it spent in your pantry, why risk eating it now? If you have a choice, get rid of it.
For many products, freshness isn’t a yes/no proposition. A box of cereal that was “best before” May 9 won’t suddenly change overnight, at the stroke of midnight, to a stale, inedible product. Changes are gradual, and a day or two beyond “best before” typically won’t much matter.
Use your senses. Does it look off? (Mould, discoloration, funny texture, etc.) Does it smell funny? If so, toss it. Also, listen for any noise when you open it. Is there a release of pressure from something where there should be no pressure? Toss it.
The most important rule: if you’re at all concerned about food not being safe to eat, don’t eat it. It’s not worth the worry. Why risk making your family sick?
Note, also, that it's always a good idea to check the best before date on an item before putting it in your grocery cart. You wouldn't be the first person to find an expired product on a supermarket shelf.