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A colleague of mine–who shall remain nameless–and I got into a discussion about whether you need to buy freezer bags. His take? Pricier freezer-specific bags are generally a waste of money.
The question came up when we learned that all Ziploc bags adhere to the FDA's safety rules for freezing food. So if most resealable plastic bags can be used in the freezer, why buy the more expensive freezer bags at all?
It's an interesting question that spans everything from economics to material science.
Zip-top bags are made mostly of polyethylene–a highly resilient plastic. Polyethylene was first created in the late 1800's, and eventually found its way into everything from hip replacements to storm drains, plastic bags, and our oceans. One of the major reasons polyethylene has become so popular is because it's so stable. Up until 149°F, it doesn't really react to much, and is resistant to oils, alcohols, and acids.
As amazing as its properties are, this plastic did not find its footing in the kitchen until Silas Tupper began marketing air-tight storage containers in 1946. By 1954, the first zipper-locked storage bags—originally designed for pencils and pens—hit the market. By 1968, Dow Chemical Company saw the potential for food storage and created the Ziploc brand.
In short, freezer bags are thicker. How much thicker varies by brand, but Ziploc freezer bags are about twice as thick as non-freezer bags. This added thickness is supposed to help prevent tears and punctures, but it also increases the cost.
The main job of a storage bag is to prevent moisture and air from interacting with that's inside. That has less to do with how thick the bag is, and more on the quality of the freezer and the way the food is stored.
If you see a lot of ice crystals in your freezer, that's a sign of temperature fluctuation. When the freezer gets above 0°C, your food starts to release moisture. When it gets cold again, that moisture freezes into ice crystals. If your freezer can't consistently stay below that temperature, any bag is going to give you the same result.
FDA guidelines show that most foods last between three months and a year when frozen. However, I think using your frozen food before then helps prevent waste. How many times have you forgotten about something in the freezer because it's been in there so long?
Anything gotten in bulk, whether it's an entire deer or a whole purchase of steaks, should be placed in a dedicated chest freezer. They are designed to maintain low temperatures. You also don't access it as much, which cuts down on temperature fluctuation even more.
Either way, buying specific freezer-safe bags doesn't get you much. Though all plastic bags are relatively inexpensive, freezer-safe ones don't do a significantly better job at keeping frozen food safe—unless you're freezing something that can leak out easily or could puncture the bag.
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