Fat Oxidation and Rancidity

In addition to inflicting physical damage, freezing causes chemical changes that limit the storage life of frozen meats. When ice crystals form and remove liquid water from the muscle fluids, the increasing concentration of salts and trace metals promotes the oxidation of unsaturated fats, and rancid flavors accumulate. This inexorable process means that quality declines noticeably for fresh fish and poultry after only a few months in the freezer, for pork after about six months, for lamb and veal after about nine months, and for beef after about a year. The flavors of ground meats, cured meats, and cooked meats deteriorate even faster.