Prof. Dr. Mehmet Ali Kaşlıoğlu
(Expert in Food and Nutrition Science)
The quality of red meat is evaluated based on characteristics such as color, shine, firmness, taste, tenderness, and aftertaste. Yield grading is based on the maturity of the carcass and the degree of marbling. The pigment "myoglobin" gives meat its color. The first impression consumers get from meat products is the "color of the meat." Although color is not a direct indicator of meat quality, the psychological appeal of a bright red in beef is a key criterion for purchase. The color of meat can vary depending on the age of the animals and slaughter conditions. Meat from young animals is typically light red, while meat from older animals is dark red. However, this assessment is relative. The color of meat depends on how the iron it contains reacts with oxygen in the air and how myoglobin absorbs and reflects light of certain wavelengths. Beef is bright cherry red, lamb and mutton range from light red to dark brick red, and veal is pink-red.
In carcass grading, the weight of the carcass, the condition of the meat, its water-holding capacity, as well as errors and stress-inducing behaviors during transport, unloading, waiting in pens, and transfer to the slaughter area are considered. Texture, tenderness, marbling, and the condition of the longissimus dorsi muscle are other important characteristics. Physiological maturity refers to skeletal maturity and the maturity of lean meat, while marbling indicates the amount and distribution of intramuscular fat. High marbling means that monounsaturated fats are evenly distributed within the muscle. This gives beef a "melting" juiciness and tenderness. During cooking, the fat is absorbed into the muscle, adding extra softness and flavor to the meat.
Other important criteria are firmness and texture. High-quality carcass meat is firm and muscular. Texture refers to the smoothness, slight roughness, or grainy structure felt on the cross-sectional surface of the muscle. Meat with good texture is shiny, smooth, and even. Meat with poor texture has a dull and coarse surface. Freshly slaughtered meat has little aroma and flavor, a rubbery consistency, is difficult to chew and digest, and spoils quickly.
Meat from stressed animals is of poor quality. Under stress, the glycogen level in the animal decreases, and the meat becomes tough. This reduces the shelf life and storage stability of the meat and can cause digestive issues in consumers. The aging phase is the result of enzymatic reactions and represents the final stage of converting muscle into meat. The texture of fresh meat during rigor mortis is hard, dry, and low in aroma. Such meat is also not flavorful after cooking. Therefore, the meat is aged under hygienic conditions and in a cold environment for about 24 hours to make it ready for consumption.
The Meat Surface Should Not Be Dry
Healthy, high-quality, and fresh meat should be firm but soft with a non-dry surface. However, excessive moisture and a sticky texture are signs of unhealthy meat. These aspects should be considered when selecting meat. Additionally, the tenderness after cooking, the ease with which the meat can be cut into pieces, and the amount left in the mouth after chewing are indicators of meat quality. This is related to the moisture content of the meat.
Meat Should Be Sterile and Hygienic
To produce healthy meat, the meat and muscle tissue of the animal must be sterile. However, after slaughter, no microorganisms should be transferred to the meat through the knife, the hands of the slaughterer, or the environment. Therefore, hygienic conditions must be maintained during slaughter.
Rest Before Slaughter
In terms of meat quality, it is important that the animal is rested and not stressed before slaughter. If the animal is stressed or exhausted before slaughter, the meat obtained from it will be less durable. Under normal conditions, lactic acid forms in the muscle tissue after slaughter, and the pH level drops. A low pH contributes to the aging of the meat and makes it more durable. Therefore, it is essential to allow the animals to rest before slaughter. For meat from stressed animals, the opposite is true. Rest before slaughter is crucial for meat quality. To ensure meat quality, animals should be rested stress-free before slaughter. For example, animals transported over long distances must rest for 24 hours after transport.
Texture and Maturity of Meat
Texture refers to the softness or hardness that the meat leaves in the mouth after chewing. The texture of the meat depends on the size, number, and amount of muscle fibers and connective tissue. The glycogen level in the muscles at the time of slaughter is an important factor influencing meat quality. In this case, dark, tough, difficult-to-cook, flavorless, dry, and non-tender meat is produced. The main reason for this is the lengthy, crowded, and exhausting transport before slaughter and the associated stress. Such meat is referred to as "dark meat." The ideal pH for meat is between 5.3 and 5.7. Meat from stressed animals has a pH above 6, a dark color, a short shelf life, and becomes watery, tough, and flavorless after cooking.
Water-Holding Capacity of Meat
Water-holding capacity is the ability of meat to retain water after various processing steps such as cutting, grinding, and pressing. If the water-holding capacity is low, the loss is higher. Meat with low water-holding capacity has a very moist cut surface and therefore appears pale. Such meat is also called "weeping meat." Soft and juicy meat has a very low water-holding capacity.
When meat enters rigor mortis, the diameter of the muscle cells decreases, their length shortens, and contractions occur in the muscle cells. This reduces the cavities where water is stored, and water leaks out of the meat. As the protein filaments (myofibrils) shorten, water enters the cavities outside the myofibrils and flows out of the meat like in a channel. This reduces the water-holding capacity of the meat. Water loss is accelerated if the animal is slaughtered under stress.
Marbling (Fat)
The distribution of fat between muscle fibers gives the meat a mosaic or marble-like appearance, which is referred to as marbling. Marbling is an important criterion for determining the quality of the carcass and meat. Meat with very good marbling is more flavorful and mature.
In carcass grading, in addition to commercial characteristics, factors such as juiciness, color, texture, tenderness, taste, and aroma of the meat are considered. In particular, the maturity of the meat and the degree of marbling are decisive. The relationship between the quality grading of beef carcasses and the marbling level is important. High marbling means more tenderness and flavor. Even when crossed with other breeds, it retains these characteristics and produces excellent, high-quality beef. High marbling means that monounsaturated fats are evenly distributed within the muscle. This gives beef a "melting" juiciness and tenderness. During cooking, the fat is absorbed into the muscle, adding extra softness and flavor to the meat.
