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Cold Shorting FYI

OldDog/NewTricks

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Effective measures to prevent cold shortening
By Roxana Lien on 8/1/2007

In this article:
Time, temperature and pH control
Fat content
Electrical stimulation

As meat chills after slaughter, temperature and pH must be monitored to prevent rigor mortis from compromising tenderness. (photo courtesy USDA)
Cold shortening — or muscle shortening — is a process that occurs as meat chills, immediately after slaughter. Fact is, all species undergo rigor mortis, albeit at different rates. In the case of meat, product shrinks up to a third or more of its original size, resulting in a loss of water, soluble proteins and vitamins and minerals.

Cold shortening is triggered by ATP (adenosine triphosphate) as well as a release of calcium ions, a phenomenon that occurs as a result of cold stimulation. Once calcium is released, muscle contraction is inevitable.

So without proper temperature control, rigor mortis can wind up compromising tenderness. Hence, both temperature and pH — an indicator of the rate of rigor mortis — require monitoring.

In fact, all of the following should be considered in order to ensure quality product:

Time, temperature and pH control
As a general rule, maintaining muscle temperature between 59 degrees F and 61 degrees F during rigor mortis minimizes problems associated with cold shortening. Keep in mind that the refrigerated area is continually being filled with hot meat, resulting in temperature fluctuations. So, be sure to assess heat transfer occurring in these areas to make certain refrigerating equipment is suitable for the task. With rigor mortis, colder is not better.

With beef and lamb, it's also important to keep pH under 6.0. With pork, the time before the onset of rigor mortis fluctuates between 45 minutes and three hours.

Fat content
Fat modifies speed of chilling because it acts as an insulator — and not just the layer of fat on the animal's back. The animal's full fat content plays a role.

So, it's best to sort animals by body composition in order achieve uniform chilling.

Electrical stimulation
Electrical stimulators are used to accelerate rigor mortis. The contraction and relaxation induced by electric current exhaust all ATP reserves, making contraction impossible.

Electrical stimulators hasten the drop in pH after death. They also function as tenderizers since they break down muscle fibers during extreme contraction. The technology is used for beef, lamb, veal and turkey.
 

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