My whole life I have been very fortunate to have home-raised beef in my freezer. It is not often that I have had to buy meat in the store, however, I do enjoy perusing the meat counter whenever I go grocery shopping to see what is available and how much it costs. Recently, I was shopping with a fellow meat science grad student when something in the meat counter caught our eye.
This picture shows two very different appearing steaks. The package on the right appears normal, being the typical bright cherry red color that we would expect to see. The package on the left, however, is a much darker color.
The condition of this product is known in the industry as being a “dark cutter.” As the name implies, it produces a very dark, unappealing product. It is caused by long term stress of the animal that can be influenced by genetics, environment, or management.
The simple explanation: Stress causes muscles to tense. When this happens all the energy in the muscles is used. When the animal is harvested, there is no energy left in the system to produce lactic acid and cause the meat to have a drop in pH. This leads to product that is darker in color, firm in texture due to holding water, and dry on the surface since all the moisture is held within the cut. For a more scientific explanation, read on. If this is enough, skip to the final paragraph.
To get scientific: muscle tissue stores energy in the form of glycogen. When we use our muscles, that glycogen is converted to lactic acid. (Think about when you try a new workout and are often sore the next day. This is due to a buildup of lactic acid in your muscles since you used the muscle’s energy.) When an animal is stressed for a long period of time, it uses up the glycogen within the system and depletes the lactic acid. (Think about when you’re stressed. Do you tense up? Do you clench your fists and your jaw? Your muscles are working. The same thing happens to livestock.)
When an animal is harvested, a lot of things happen as muscle is converted to meat. One of these things is a drop in pH. Living muscle tissue is very neutral, with a pH of approximately 7.0; whereas beef has a pH of approximated 5.6 (making it more acidic than living muscle). The drop in pH is caused by all of the glycogen that is left in the system at harvest being converted to lactic acid. If an animal has been stressed for a long period of time, there is no glycogen available in the system, and there won’t be any lactic acid to drop the pH. This causes the meat to have a very dark color and bind water tightly, creating a dry, tacky surface. This produces a product that is dark, firm and dry.
It is important to note, that this product is still safe to consume, but due to its high level of moisture, is often used in further processed products. Dark cutting beef is only found in approximately 1-2% of harvested cattle, often following severe changes in harsh weather. Producers do all they can to limit this occurrence by controlling the animal’s environment and stress level. Housing animals indoors, providing shade in the summer if housed outdoors, consistent feeding times, treating sickness, these are just a few practices that producers use to help mitigate stress of the animal. Animal care is a priority to producers and ensuring a safe, high quality product for consumers is their mission.