Karen Blakeslee and Fadi Aramouni at Kansas State University say the shelf life of some candy, like hard candy, may be indefinite, but there have been cases of salmonella poisoning from the consumption of expired chocolate.
"The shelf life depends on the type of candy, packaging and storage conditions," Blakeslee says in a statement.
If a candy appears extremely sticky or has a grainy texture, then it has most likely expired and the crystallization of sugar can result in an off flavor, have a change in color or turn moldy if it contains fruits or nuts.
As a general rule, the softer the candy, the shorter the shelf life, but heat can cause some candies to melt and chocolate can get a powdery look to it -- called bloom -- due to temperature changes, but it is still fine to eat, Blakeslee says.
The National Confectioners Association suggests:
-- Dark chocolate can be kept for one to two years if wrapped in foil and stored in a cool, dark place.
-- Milk and white chocolate last no more than eight to 10 months.
-- Jellied candies, caramels and gum, once opened, can last six to nine months.