Vacuum packing or vacuum packaging is a method of packaging that removes air from the package prior to sealing. The intent is usually to remove oxygen from the container to extend the shelf life of foods and, with flexible package forms, to reduce the volume of the contents and package.
Vacuum packing reduces atmospheric oxygen, limiting the growth of aerobic bacteria or fungi, and preventing the evaporation of volatile components. It is also commonly used to store dry foods over a long period of time, such as cereals, nuts, cured meats, cheese, smoked fish, coffee, and potato chips (crisps). Vacuum packaging delicate food items can be done by using an inert gas, such as nitrogen. This helps prevent crushing fragile items and delicate foods such as potato chips.
On a more short term basis, vacuum packing can also be used to store fresh foods, such as vegetables, meats, and liquids, because they inhibit bacterial growth.
Depending on the product, the shelf life of vacuum packaged products can easily exceed 6-times normal bagged or wrapped packages. Non-food products can last indefinitely in the low oxygen environment of vacuum packaging. For example: vacuum packed beef can last up to six weeks refrigerated, and much longer when frozen.
When foods are frozen without preparation, freezer burn can occur. It happens when the surface of the food is dehydrated, and this leads to a dried and leathery appearance. Freezer burn also ruins the flavor and texture of foods. Vacuum packing reduces freezer burn by preventing the food from exposure to the cold, dry air.
In an oxygen-depleted environment, Anaerobic organisms can proliferate, potentially causing food safety problems. Vacuum packing is often used in combination with other packaging and food processing techniques.
Vacuum packaging also allows for a special cooking method, sous-vide. Sous-vide, French for under vacuum, involves poaching food that is vacuum sealed in a plastic bag.