Vacuum packing is a method of packaging that removes air from the package before sealing. This method involves placing items in a plastic film package, removing air from inside, and closing the box. The intent of vacuum packing is usually to remove oxygen from the container to extend the shelf life of foods and, with flexible package forms, reduce the contents and package volume.
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 time, such as cereals, nuts, cured meats, cheese, smoked fish, coffee, and potato chips (crisps). On a more short-term basis, vacuum packing can also store fresh foods, such as vegetables, meats, and liquids, because it inhibits bacterial growth.
A few food items should not be vacuum-sealed or require a few simple steps before they are safe to vacuum seal. These food items are often ones containing anaerobic bacteria, which can grow without air.
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Raw Mushrooms: Due to their natural ripening process, fresh mushrooms may decay faster if vacuum sealed. Cooked mushrooms will vacuum-seal perfectly, though!
Fresh Bananas: Vacuum sealing fresh bananas can quicken their ripening time. But it is perfectly safe and easy to vacuum-seal bananas once they are peeled and frozen.
Raw Garlic & Onion: These food products produce a natural gas that may result in a loss in the vacuum, leaving them vulnerable to becoming spoiled.
Soft Cheeses: It is perfectly safe to vacuum-seal hard cheeses, but soft cheeses such as blue cheese, brie, camembert, ricotta, and other soft and unpasteurized cheeses can produce mold faster in a vacuum than in regular air.
Freshly Cooked Vegetables: Hot steam from cooking or steaming vegetables may cause a loss in a vacuum. So it is crucial first to let your hot vegetables come to room temperature before vacuum-sealing.
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Some food items need to be blanched before they can be safely vacuum sealed. Many common vegetables emit a natural gas when stored, and so if these vegetables are kept in a vacuum-sealed bag, the gas causes the vegetables to spoil. Therefore, to vacuum seal vegetables safely, it is best practice first to blanch them. Blanching is a cooking process in which a food product, usually a vegetable or fruit, is dipped in boiling water, removed after a brief interval, and then plunged into iced water or placed under cold running water to stop the cooking process. The blanched food items then need to be adequately dried. From then, they can safely be vacuum sealed and frozen for later use. The vegetables that require this process generally belong in the Cruciferae or Brassicaceae family and include vegetables such as Arugula, Broccoli, Brussel Sprouts, Cabbage, Cauliflower, Kale, Radishes & Turnips.