cold shortening

Cold shortening is a postmortem quality issue in meat processing that results from the rapid chilling of carcasses before the muscle's glycogen has converted to lactic acid. When glycogen is still present as an energy source, cold temperatures trigger an irreversible muscle contraction, making the meat up to five times tougher than normal. This typically affects lean beef and lamb carcasses with less fat covering, as their muscles cool too quickly before rigor mortis sets in. A similar condition, thaw rigor, occurs when meat is frozen before rigor mortis and becomes tough upon thawing due to leftover glycogen. Electrical stimulation of carcasses postmortem can help prevent cold shortening by using up muscle glycogen.1