Freeze
How to Prevent Freezer Burn Once and For All
So you never have to throw out a pint of ice cream again.
Freezers are magical appliances: They allow us to save homemade soups and sauces for months on end, keep ice cream frozen for our daily after-dinner sundaes, and store ice for cocktail parties (a must). As essential as it is to freeze leftovers and frozen pizzas for zippy suppers, freezers aren’t always our friends. In fact, they can sometimes be the foe—namely, when so-called “freezer burn” infiltrates our supply of frozen foods.
Let’s get one thing clear: Freezer-burned food is completely safe to eat. According to the Food and Drug Administration (FDA), “freezer burn is a food-quality issue, not a food safety issue.” The FDA notes that freezer burn often presents itself as “as grayish-brown leathery spots” on the food in question. So even though freezer burn doesn’t always look or taste quite right, it doesn’t mean your food is spoiled or otherwise harmful if consumed.
That being said, freezer burn can render the items in your freezer wholly unappetizing, covering them in swaths of ice crystals and leaving them with a bland, off taste. So how does freezer burn form? It’s actually quite simple: As Shelly Schmidt, professor of food chemistry at the University of Illinois at Urbana-Champaign, explained, freezer burn is simply a byproduct of moisture loss, or dehydration.
When food is exposed to the cold, dry environment of a freezer, its water content—in the form of ice—undergoes sublimation, a process by which solids are transformed directly into a gaseous state. After this ice is drawn out from frozen food as vapor, it’s then redeposited on the surface as ice crystals. This is why freezer burn so often results in food that’s simultaneously discolored, shriveled, or leathery and covered in ice crystals.
Okay, but how do I avoid freezer burn in the first place?
Now that we’ve cleared up what freezer burn actually is, we’re in a better place to protect our food from its not-so-tasty effects. Because freezer burn results from contact with the freezer’s cold, dry air, the simplest way to avoid the problem is by minimizing that exposure in the first place.
“Different types of [materials] will vary in how much air they let through them, as well as odors and what we call moisture vapor, or airborne moisture,” says Elizabeth Andress, food safety specialist and professor of foods and nutrition at the University of Georgia. Plastic or silicone zip-top bags are one great option for limiting air exposure, and for larger items, double-wrapping first with plastic wrap and then with heavy-duty aluminum foil will do the trick.
Though these solutions are pretty solid, if you’re looking for the maximum level of protection against freezer burn, you may want to bite the bullet and purchase a vacuum sealer—especially if you plan on freezing food often and for long periods of time. “In addition to pulling the air out of the package, they are much more preventative at letting anything [in the air] transmit through the plastic itself,” says Andress.
Whether you’re using a high-tech vacuum sealer or good ol’ cling wrap, the same principle applies: Keep your frozen food wrapped as securely and tightly as possible. Your make-ahead meals, ice cream, and dino nuggets will thank you.
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Written by: Anabelle Doliner
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13 Comments
That is, a well sealed FoodSaver or chamber vac bag, can go straight from the freezer into a pot of boiling water to reheat, to cook, or to finish cooking.
As for ice cream, I find that if you press a piece of plastic wrap tightly against the ice cream (so that there are no air pockets), it keeps quite well and doesn't develop ice crystals. This is similar to what Jaques Pepin suggests, but you don't have to pre-scoop and wrap.
And like you we have always washed and reused bags until they were too small.
But the real breakthrough came, when our last FoodSaver died and I vowed enough! I purchased an Avid Armour Chamber vacuum. It is so much better than a FoodSaver. The bags are 10X cheaper, and the unit is so much more versatile in that one can vacuum seal liquids without having to freeze first.
We still have a FoodSaver generic type for some larger bags such as chips and for using an external vacuum line for sealing jars, etc., that will not lay down within the chamber vac.
But for 90% of things it is a dream. No special patterned nylon bags, though composite bags do hold out permeable gases such as O2 better. One can even cut off the top of a Ziploc type PE bag and use that in a chamber vac.
I buy meat and veggies when I find then on quick sale. Then I bring them home and repackage into vac bags, now using the chamber vac. We save a lot of money that way and even are able to help out a granddaughter in college with her food by supplying vac packed meats, veggies, prepared foods, and treats that she can't afford ordinarily.
The operative word is "sublimation." You write as if you don't have much of a science background and have questionable credentials to write an authoritative piece on freezer burn in that you are relying on the authority of others whom you cite.
Sublimation is the phase transfer of a solid (water) to a gas (water vapor) without going through the liquid phase. Thus the ice crystals that collect inside a partially filled container which has been in a freezer for a while is the water that came from the food, whose vapor condensed on another surface.
In other words, freezer burn = dehydration for the most part and the resultant changes to the food is usually pretty much irreversible. You are correct however in that the food value is more or less unaffected.
In the simplest terms, if there is no headspace above the food, then there is no room place for water vapor from sublimation to go. Wrapping tightly slows but does not entirely stop freezer burn. Vacuum sealing stops it completely along with other issues such as slow oxidation and other chemical reactions that can occur even at low temperatures.
FoodSaver type machines are great, but a chamber vacuum machine is the ultimate.
Really, Food52 should get a science editor...
I'm a Ph.D. Organic Chemist, retired
Having a partially used container of ice cream in the freezer. Store in a zip
Lock and no more ice crystals Saves space too!
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