Packaging makes food easy to handle and identify. It also helps protect them from spilling and from being bruised and broken. In addition, special packaging materials and methods protect foods from air, bacteria, insects, light, moisture, and odors – all of it which might spoil the food. Attractive packing also helps promote the sale of foods. The majority of foods, especially processed ones, are packaged. In most cases, machines pack the food into containers. Packaging is usually the last step in the processing of food.
Food companies use the kinds of packaging that best suit the needs and uses of their products. For example, eggs are packed in thick, sturdy cardboard or plastic cartons to protect them from breaking. Some foods, such as coffee, jelly, and peanut butter, are used a little at a time. They are packed in cans or glass jars that have a resalable lid. Plastic bags and wrap keep air away from meat, bread, potato chips, and many other foods. Such dairy products as milk and cottage cheese are packed in plastic containers that protect them from air and light.
In vacuum packing, a pump removes almost all the air from a package. Sometimes, a gas such as nitrogen or carbon dioxide is then pumped into the package to flush away any remaining air. Then the package is sealed.
Packaging may also make home preparation or use of food easier. For example, many frozen foods can be cooked in boil-in plastic bags, microwave-usable containers, or in aluminum trays. Aerosol cans dispense whipped cream, and plastic squeeze bottles dispense ketchup and mustard.