In the United States, all beef is inspected for safety by the USDA. The USDA also provides grading services that grade beef according to quality and/or yield. Both types of grading are optional and costs the producer (rancher) some money to pay for the USDA grader to provide a grade. We'll look at quality grades in this article since these are the most influential to the consumer. Two factors are used when the USDA grades beef for quality: physiological maturity and marbling.
In addition to looking at the bone structures, the lean tissue of the ribeye will help determine the physiological maturity of the animal. In a young animal, the muscle will be a light pink-red tone and the texture will be fine. While the animal matures, the lean tissue will become darker in color and more coarse.
Maturity is rated into five groups labeled from A to E (where A is the youngest). For most cattle, the age groups are approximately (some variation from sex to sex):
A - A < 30 months
B - 30 months < B < 42 months
C - 42 months < C < 72 months
D - 72 months < D < 96 months
E - 96 months < E
Marbling is the amount of fat that is distributed within a muscle (not surrounding the muscle). When determining marbling of a carcass, the quantity and distribution of fat in the ribeye at the 12th rib is examined. Beef with higher amounts of marbling usually produce more tender, flavorful, and juicy cuts. How maturity and marbling relate to determine quality grade is shown in the table below.
|Slightly abundant||Prime||Prime / Choice||Commercial|
|Moderate||Choice||Commercial||Commercial / Utility|
|Modest||Choice||Commercial||Commercial / Utility||Utility|
|Small||Choice||Standard||Commercial / Utility||Utility|
|Slight||Select||Standard||Utility||Utility / Cutter|
|Traces||Standard||Utility||Utility / Cutter||Cutter|
|Practically Devoid||Standard||Standard / Utility||Utility / Cutter||Cutter||Cutter / Canner|
For more information the Official U.S. Standards for Grades of Livestock and Carcasses can be found at http://www.ams.usda.gov/lsg/stand/st-pubs.htm.