Perishable foods are those likely to spoil, decay or become unsafe to consume if not kept refrigerated at 40 °F or below, or frozen at 0 °F or below. Examples of foods that must be kept refrigerated for safety include meat, poultry, fish, dairy products, and all cooked leftovers. Refrigeration slows bacterial growth.

There are two completely different families of bacteria that can be on food: pathogenic bacteria, the kind that cause foodborne illness, and spoilage bacteria, the kind of bacteria that cause foods to deteriorate and develop unpleasant odors, tastes, and textures. The FoodKeeper App can help determine storage times for foods. Visit https://www.foodsafety.gov/keep-food-safe/foodkeeper-app