Factors Used to Establish Meat Quality Grades

Kind and Class In meat grading, each species is referred to as a kind. Each kind is then divided into classes based on gender and maturity.

Maturity, the physiological age of an animal, has a large impact on meat quality of poultry, beef, pork, and lamb. Maturity is the grade factor which has the largest effect on meat tenderness. In general, meat from younger animals is more tender than the meat from older animals although this is not always the case when comparing very young animals to those in a rapid period of growth.

Bone and cartilage characteristics are used to determine the maturity of a carcass. Young animal bodies contain much more cartilage than the bodies of older animals as the cartilage is converted to bone as the animal ages. Shapes and color of ribs also change as an animal matures. The color of meat becomes darker red as an animal ages. The texture of meat from more mature animals is much coarser than the texture of meat from younger animals.

Marbling (visible intramuscular fat) is considered to be an important meat quality. The USDA maintains photographs which define ten levels of marbling. In lamb carcasses, marbling is indicated by the amount of flank streaking (streaks of fat beneath the sheath of connective tissue which surrounds the flank muscle). Marbling in pork is indicated by the streaks of fat visible in the muscles between the ribs known as feathering.

Firmness, when used in quality grading, refers to firmness of the flank area or a lean cut surface. Because fat is much more firm than muscle when chilled, carcasses with more fat will be firmer. Although firmness makes no direct contribution to meat palatability, firm retail cuts are more attractive than soft retail cuts because they hold their shape better. Firmness is also an important quality in cuts which will undergo extensive processing.

Conformation and Fleshing Conformation refers to the proportionate development of carcass parts or wholesale cuts, and to the ratio of muscle to bone. Fleshing refers to the amount of muscling present. These two factors do not affect palatability, but they do affect the shape and attractiveness of retail cuts. For example, thinly fleshed thighs and drumsticks are less attractive to customers than those that have more muscle and appear to be "meatier".

Finishing refers to the amount, character, and distribution of external, internal, and intramuscular fat. A small amount of fat is desirable for optimum meat quality. In poultry, for example, a small amount of fat beneath the skin during dry cooking prevents the meat from drying out. Other meats benefit in a similar way. On the other hand, too much fat on a carcass decreases the retail cut yield.

Carcass Defects in poultry are of special importance. Exposed flesh from cuts, tears, missing skin, and broken bones detract from the appearance of the bird. The number and severity of the defects which are permitted varies by location. Defects on the breast have a larger impact on quality grade than will defects on other carcass areas.

To Learn More

Meat Grading and Certification - Information from the Agricultural Marketing Service of the USDA.

Factors Affecting Poultry Quality - Information about poultry grades from the Cooperative Extension Service of the University of Georgia College of Agricultural & Environmental Sciences.

Beef Quality and Yield Grades - Information about Beef grading from Department of Animal Science Texas Agricultural Extension Service.

Yield Grades and Quality Grades for Lamb Carcasses - Information about Lamb grading from Cooperative Extension, Institute of Agriculture and Natural Resources, University of Nebraska, Lincoln.