By Harold McGee
A last side effect of freezing is freezer burn, that familiar brownish-white discoloration of the meat surface that develops after some weeks or months of storage. This is caused by water “sublimation”—the equivalent of evaporation at below-freezing temperatures—from ice crystals at the meat surface into the dry freezer air. The departure of the water leaves tiny cavities in the meat surface which scatter light and so appear white. The meat surface is now in effect a thin layer of freeze-dried meat where oxidation of fat and pigment is accelerated, so texture, flavor, and color all suffer.