Higher quality food vacuum sealers have heavier-duty pumps made of sturdier parts. They can withstand frequent use and don't need to cool down between uses.
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Why Is Vacuum So Great at Preserving Food?
Contact with oxygen is what deteriorates food, causing spoilage. In the freezer, it causes ice to form, creating freezer burn. Vacuum packing removes almost all of the oxygen from the food container. When there is little oxygen to react with, food stays fresher longer in the pantry and the refrigerator, and won't get freezer burn in the freezer. That’s really all there is to it.
It is not possible to remove 100% of the oxygen by vacuum sealing. So vacuum-sealed food doesn’t last forever. But it can remove enough oxygen to greatly extend shelf life. Some estimates are that vacuum sealing extends the life of frozen food by up to 5 years!
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The Two Types of Food Vacuum Sealers: External and Internal
There are two main types of food vacuum sealers: edge sealers and chamber vacuum sealers (typically called “chamber vacs”). Both types have advantages and disadvantages.
Edge sealers, also called external sealers or suction sealers, are the simplest and most common type of automatic vacuum sealer. You simply fill a bag with food, place the bag in the sealer, and begin the sealing process. The vacuum is created inside the bag only, which makes it nearly impossible to seal anything but solid foods (because the pump will suck out liquid as it sucks out air).
Many edge sealers have options for moist foods and soft foods, allowing you to control the amount of vacuum they pull so as not to draw moisture up into the pump or crush soft food (bread, for example) with too much vacuum. Decreasing the vacuum leaves air in the bag, however, so you may get similar results by just using a Ziploc or other food storage bag for soft/moist foods. One clever workaround is to freeze liquids before vacuum sealing.
They use special resealable bags that have a small hole through which vacuum is pulled. Handheld sealers are tiny and generally don't pull a super strong vacuum, but because the bags are reusable, usually for up to 10 times, they're great for leftovers and sous vide (as opposed to long term freezer or pantry storage).
In general, edge sealers are the most economical choice, but are sometimes not as well made as chamber vacuums. Most consumer brands--like FoodSaver and Seal-a-Meal--are not designed for heavy use. The pumps overheat easily, so you need to let the machine cool down in between uses. This can be frustrating and time consuming if you're freezing, say, half a cow or a few bushels of veggies from your garden.
But for a few steaks or a tray of chicken breasts, they're great.
How do you know if your edge sealer has good internal components? Simple: spend more than $300 for it (like this Weston Pro 2300 edge sealer that gets good reviews). But if you're going to spend that much, you might want to start thinking about a chamber vacuum sealer instead.
