Insight Into Freezer Burn
We all know that long-term freezing is costly, it compromises quality, and the food perishes at a faster rate than other food storage methods. Although canned meat is very tender and flavorful, most people simply do not do that enough because of the convenience factor of the freezer. So let’s take a look at what causes freezer burn, what preventative steps we can take to avoid it, and how to clean the freezer out.
Feeling the Burn
The food is not “burnt” at all; it has suffered a loss of moisture. It’s a combination of dehydration with the decomposition (or degradation) of the food quality. The color, texture, and flavor are compromised, the latter due to lipid oxidization (Schmidt & Lee, 2009). The science says that the food itself is safe to eat, although who would want to? You can simply cut off the freezer burnt section either before or after cooking with no ill effects—unless you count the waste of food.
In 1st grade science we learned the three stages of water as being solid, liquid, and vapor (gas). Freezer burn is from sublimation, when the solid ice goes straight to vapor and skips the intermediary liquid step (Schmidt & Lee, 2009).
If the food is very tightly wrapped, the water vapor has nowhere to go and the food will not go to waste. If you say “But I’ve had freezer burn happen to that sealed plastic bag of garden zucchini,” all that I can say is I can relate! But in that case, it is because that plastic bag was not perfectly airtight. If the container is not perfectly airtight, those vapor leave to equalize with the “cabin pressure” of the entire freezer, never to return to that food product.
How could the food be dehydrated and full of ice crystals at the same time?
Glad you asked. It’s all about equilibrium, and no I’m not waxing philosophical here. The whole reason that the moisture is sucked up and out of the food is because the vapor pressure in the container is different and it’s all attempting to equalize. The other half of that cycle (remember 1st grade science class) is that the vapor in the air is condensing into ice. That ice is immediately drawn to the coldest surface to be found—the coils (or condenser) in the floor and sides of the freezer. The equilibrium never really happens, so it is a vicious cycle. The result is this—the more ice buildup you have in your freezer, the more freezer burn you will get, creating more ice in your freezer.
Freezer Burn Prevention
Two things increase the likelihood that you will have an ongoing battle: a self-defrosting freezer and quick frozen food products (“Freezer Burn. . .”, 2009). It’s seems contradictory that a “frost-free” or self-defrosting freezer would give you more of the problem instead of less. Back to the equilibrium—it uses a heater coil to melt ice, but that throws off the pressure in the compartment. You’ve also probably noticed that the quick frozen chicken “burns” faster than the solid hunk of chicken packaged by the meat counter. There is more surface area to the food when the food items are loose in the bag.
So apart from telling you what not to buy the next time you are in the market for a fridge (or for those quick frozen fish), these are my best suggestions:
1) Don’t stand there and gawk. Open the door as infrequently as possible and for short duration. Every time that door opens, you reset the cycle of equalizing the cabin pressure. Think of the movie “Airplane” when the door to the plane opened in flight.
2) Get your food cozy. Package it together into one frozen solid mass.
3) Wrap your food very tightly in something freezer-proof. If you use plastic bags, get the super-thick freezer kind. We like to use a vacuum sealer or butcher paper (often both). Plastic containers are tough—you have to leave some headspace for the food to expand during freezing, but if you leave too much, you’ll have freezer burn every time.
4) Vacuum Seal! Here’s my tip for soups and liquids, to avoid the plastic containers—I put liquid in a bowl in the freezer until it becomes a soup-sicle. Then I run the bowl under warm water until the soup-sicle pops right out. It’s now ready to vacuum seal. Vacuum sealing bags do not allow any room for the ice-to-vapor process to occur. This increases the lifespan of frozen foods dramatically, and that vacuum sealer pays for itself with what does not get thrown away.
How to Defrost
Plan to defrost your freezers at least once a year. When was the last time you did this? It might be time, at the beginning of a new year, to pull the plug on your units. You should not allow the ice to build up beyond ¼ inch, so if you are fighting an older or less efficient model, you may have to go through this process more than once a year. Follow your user’s manual or go by these basic instructions:
1) Unplug the unit
2) Remove all food items and place them in an alternate freezer, refrigerator, or cooler
3) Place several old towels in the freezer, and at the edge of the unit
4) Allow the freezer’s ice to melt naturally (have a bucket handy for wet towels)
5) You can help the melting process along by using a dull, plastic scraper. Some manuals say this acceptable, some say not to do this. Use your discretion.
6) Once most of the ice is melted and/or scraped, use hot water and vinegar to clean the interior
7) Dry the freezer thoroughly
8) Turn on the freezer and restock. If any food items thawed, do not re-freeze them.
Freezer burn in frozen foods . (2009, April 15). IFT Newsroom. Retrieved from http://www.ift.org/newsroom/news-releases/2009/april/15/freezer-burn-in-frozen-foods.aspx
Maintaining the home: Freezer care and cleaning. (2005). Retrieved from http://nmhomeofmyown.org/maintaining/maintaining_pdf/FreezerCare.pdf
Schmidt, S. J., & Lee, J. W. (2009). How does the freezer burn our food?. Retrieved from http://onlinelibrary.wiley.com/doi/10.1111/j.1541-4329.2009.00072.x/pdf
rubber chicken: Whiskey Media
water cycle: www.infobarrel.com
ice in freezer: www.instructables.com
airplane cabin: www.rgbstock.com