Quality refers to the overall appearance and palatability of the edible portion of the carcass. In 1996, quality grades were changed so that “B” maturity carcasses with Slight or Small marbling would grade Standard. Therefore, USDA Quality Grades for young beef (“A” and “B” maturity) — Prime, Choice, Select, and Standard — are recommended as the basis for quality evaluation. Marbling and carcass maturity are factors evaluated for grading beef for quality. Generally, marbling found at the 12-13th rib juncture is the main factor determining quality grade of young cattle. Maturity includes a subjective evaluation of the extent of ossification (conversion of cartilage to bone) of the vertebral column, texture and color of the lean color, firmness, and texture of lean. In December 2018, USDA included dentition as a part of the quality grading rules. Cattle with two (2) or fewer permanent incisors could be approved for age verification under 30 months of age and qualify for “A” maturity and grade Prime, Choice, Select and Standard.
Maturity is an estimation of the physiological age of the carcass and is determined by evaluating the size, shape, and ossification of the bones and cartilage and the color and texture of the lean. Physiological age may not be the same as the actual age of the animal in months and years; however, in most cases, they are roughly the same. There are five degrees of maturity — A, B, C, D, and E. Approximate chronological age groupings for “A” and “B” maturity carcasses and recommended numerical scores are shown in the following table:
|Numerical Scores and Maturity/Age Groupings|
|A||1.0 – 1.9||9 – 30 months|
|B||2.0 – 2.9||30 – 42 months|
A numerical score of 1.5 would suggest that the carcass was in the middle of “A” maturity, while a score of 1.9 would be appropriate for a carcass at the upper end of “A” maturity but not quite into “B” maturity. Initial maturity score is determined by the skeletal characteristics with adjustments made according to characteristics of the lean tissue. However, lean characteristics cannot be used to adjust final maturity of the carcass more than one full maturity group.
Marbling is the amount of flecks of fat in the lean (intramuscular) and is the primary factor determining quality grade after maturity has been determined. Marbling is evaluated visually in the ribeye muscle, which is exposed between the 12th and 13th ribs. Marbling contributes to meat tenderness and is also associated with the palatability traits of juiciness and flavor. There are nine degrees of marbling, ranging from Practically Devoid to Abundant. It is recommended that marbling be given a decimalized numerical score corresponding to the relative development within that degree. For example, a Small-20 equates to a numerical score of 5.2 or 520 (5.2 × 100), shown in the table below.
Quality grades vary in the number of degrees of marbling within a grade. Although marbling is the primary determinant of quality grade, and numerical scores for grade can be determined from the following marbling table, final quality grade can be lowered for carcasses of “B” maturity, ‘dark cutters’, callous or those with soft, coarse textured lean.
Recommended descriptive and numerical marbling scores for quality grades of “A” maturity carcasses are given below.
|Prime||Abundant||10.0 – 10.9|
|Prime||Moderately Abundant||9.0 – 9.9|
|Prime||Slightly Abundant||8.0 – 8.9|
|Choice||Moderate||7.0 – 7.9|
|Choice||Modest||6.0 – 6.9|
|Choice||Small||5.0 – 5.9|
|Select||Slight||4.0 – 4.9|
|Standard||Traces||3.0 – 3.9|
|Standard||Practically devoid||2.0 – 2.9|
Relationships between marbling scores and intramuscular fat percentages are shown below:
|Marbling and Intramuscular Fat|
|Marbling Score||Intramuscular Fat, %|
It is recommended that a representative of the USDA Agriculture Marketing Service or a highly trained person be used to assess quality grade factors when collecting carcass data.
Color of the ribeye is used as an indicator of maturity or physiological age. The eye appeal of beef at the retail counter is highly dependent on desirable color. Dark cutters are carcasses that produce lean tissue that is dark red to almost black and often result from cattle that have been stressed prior to slaughter. Meat from dark cutting carcasses is safe to eat and its palatability is not seriously affected. However, the color reduces consumer acceptability and lowers carcass value dramatically.
Firmness of lean refers to the relative firmness or softness of the ribeye.
Texture of lean refers to the apparent fineness or coarseness of muscle bundles within the ribeye.
Recommended numerical scores and descriptions for color, firmness, and texture of lean are as follows:
|Numerical Scores and Maturity/Age Groupings|
|7||Light cherry red||Very firm||Very fine|
|5||Slightly dark red||Moderately firm||Moderately fine|
|4||Moderately dark red||Slightly soft||Slightly fine|
|3||Dark red||Soft||Slightly coarse|
|2||Very dark red||Very soft||Coarse|
|1||Black||Extremely soft||Very coarse|
More direct measures of palatability than quality grade include Warner-Bratzler shear tests for tenderness assessment and trained sensory panel evaluation for tenderness, flavor, and juiciness. However, cost and availability will restrict usage of these methods.