Conversion of Muscle to Meat

Aug 15, 2018

JanealYanceyBy Contributing Author : Janeal Yancey, Ph.D., University of Arkansas  

Muscle is not meat… not yet.

Most people understand that when we eat meat, we are eating an animal’s muscle. But actually, that muscle has to go through a conversion process to become the meat we consume.

When an animal dies, several things happen.

First, the heart stops beating and circulating blood around the body. In meat processing plants, the blood is removed as part of the harvest process. Blood is responsible for bringing oxygen to the muscles and for bringing waste products away from the muscle.

Even though the animal has died, the muscle is still living and breaking down nutrients for energy. Because the oxygen is gone, the way the muscle breaks down energy changes, and it begins to produce a waste product called lactic acid (this is the same acid that is produced when you work out too hard and your muscles cramp.) In a living animal, the lactic acid would be sent in the blood to the liver. In the conversion of muscle to meat, there is no blood, so the lactic acid builds up in the muscle. The acid in the muscle causes the pH to decline. Live muscle has a neutral pH around 7, but will begin to drop soon after the blood is gone.

The acid build up also releases calcium into the muscle and causes it to contract. Muscles actually don’t use energy to contract, but rather to relax after contraction. As the calcium causes the muscle to contract, the energy in the muscle is used to relax further. Then more calcium causes more contraction, so more energy is needed to relax. This cycle continues until all the muscle’s energy is used and the muscle contracts without being able to relax. When that happens, the muscle stiffens and is in rigor mortis, which is Latin for the ‘stiffness of death.’

Depending on the species of animal, the completion of rigor may take a couple of hours to as long as a day. The final pH of meat, prior to cooking, is around 5.5, which is more acidic than live muscle. That acidic pH is essential for the flavors associated with meat.

Dr. Yancey is a mom of two fabulous little girls and an advocate of the meat industry. She has a passion for providing education and information to anyone who has questions, follow her blogs to stay informed!


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