Freezer burn does not make food unsafe, merely dry in spots. Meat or fish might look discoloured (greyish-brown) or dry in spots. Freezer burn is moisture loss. Cut freezer-burned portions away either before or after cooking the food. Heavily freezer-burned foods may have to be discarded for quality reasons. Freezer burn is dehydration on the surface of frozen food due to air exposure. The telltale signs are whitish splotches—ice crystals—on the food itself. It isn't a pathogen and has nothing to do with food safety, just food quality.

Protective glaze is one of way to prevent freezer burn. Protective glaze is a coating of ice, which has been applied to the surface of a frozen food product. Freezing is a natural means of preserving food and extending shelf-life, but the freezing process does not entirely prevent quality deterioration, particularly if the item is exposed to air. Through a process known as sublimation, frozen water in the ice crystals on the surface of a product can evaporate when they are exposed to air, this loss of water from the product causes dehydration of the exposed surface, leaving a distinctive matt finish and cardboard-like texture. This drying out of a product is typically referred to as ‘freezer burn’, and whilst it is not a food safety hazard, it is detrimental to both the appearance and the eating quality of the product, and in the worst cases, it can make it unmarketable.

Glaze for oily fish species such as herring, mackerel and salmon, exposure to air during cold storage can also cause rancidity and discolouration due to the oxidation of the oils naturally present in fish muscle. Freezer burn is of particular concern for individually quickly frozen products (IQF) such as fish fillets or prawns. Because it is difficult to exclude all of the atmospheric air from trade or consumer packages of IQF product, there will inevitably be headspaces and air cavities between individual pieces within the container. By adding a coating of ice to the surface of the product, each individual item can be protected from the sublimation process, and any evaporation will only affect the ice crystals of the glaze rather than those within the product itself.