A food recall occurs when there is reason to beleive that a food may cause consumers to become ill. A food manufacturer or distributer intiates the recall to take foods off the market. In some situations, food recalls are requested by government agencies (USDA or FDA).
Some reasons for recalling food include:
Discovery of an organism in a product which may make consumers sick
Discovery of potential allergen in a product
Mislabeling or misbranding of food. For example, a food may contain an allergen, such as nuts or eggs, but those ingredients do not appear on the label.
Recalls and Alerts (foodsafety.gov)