Newswise — Freezer burn is a common problem that significantly affects the color, texture and flavor of frozen foods. An article in the Journal of Food Science Education explains what freezer burn is, how to prevent it and how self-defrosting freezers and individually quick frozen products contribute to the problem.
In the narrowest use of the term, freezer burn describes only the loss of moisture from the surface of frozen foods over time. Freezer burn yields an opaque dehydrated surface to food and causes deterioration in color, texture and flavor on the surface of frozen foods during storage. Freezer burn turns beef from red to brown, skinless chicken breasts from pink to tan, and shrivels frozen green beans.
"Freezer-burned food is safe to consume from a microbial perspective, but is of poor eating quality," said lead researcher Shelly Schmidt, PhD from the University of Illinois at Urbana-Champaign. "If the freezer-burned area is not too extensive you can simply cut the affected portion(s) off before or after cooking."
"The best thing a consumer can do to keep the freezer from burning their food is to seal (or reseal) frozen food products properly and consume the food within the recommended amount of storage time," according to Schmidt.
Freezer burn occurs when moisture is lost from the frozen food surface via sublimation -- the transition of ice directly to the vapor phase -- without going through the liquid phase. Sublimation occurs because the vapor pressure of ice at the surface of the food is greater than the vapor pressure of water in the air.
Two modern conveniences have inadvertently contributed to an increase in the dehydration aspects of freezer burn: self-defrosting (or frost free) freezers and individually quick frozen products. Self-defrosting freezers contain a heating coil that regularly melts the ice layer of the refrigeration coils, preventing frost accumulation in the freezer compartment. While this removes unwanted frost, it keeps the vapor pressure of the air inside the freezer compartment low, promoting sublimation from the food's surface. Individually quick frozen products or those products that have multi-servings promote sublimation because of their large exposed surface area and because they lack the surplus ice associated with traditionally frozen " block" products.
The time it takes frozen food to develop freezer burn varies according to the type, quality and integrity of the packing materials, storage temperature and air circulation inside the freezer.
To read the article "How Does the Freezer Burn our Food?" visit http://www3.interscience.wiley.com/cgi-bin/fulltext/122278975/PDFSTART
Founded in 1939, the Institute of Food Technologists is a nonprofit scientific society with more than 20,000 individual members working in food science, food technology, and related professions in industry, academia, and government. IFT serves as a conduit for multidisciplinary science thought leadership, championing the use of sound science through knowledge sharing, education, and advocacy. For more information: www.IFT.org
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