The JMGA (Japanese Meat Grading Association) Beef Carcass Grading Standard was developed to measure carcasses yielding higher marbling scores than effectively captured by other methods. In 2008 Japan raised the bar with their grading standard, whereby the BMS (Beef Marbling Score) grade range is now 3-12 (eliminating 1 and 2) and now a BMS of 3 requires the beef to exhibit a minimum of 21% intramuscular fat.
Under this Japanese system, carcasses are first cut or “ribbed” between the sixth and seventh rib for quality inspection.
First the carcass is assigned a letter designation based on “yield grade”. There are three yield grades: A, B and C, which are initially estimated via an equation that determines yield percentages.
Next the beef is assigned a quality grade between one and five based on marbling, meat color, texture, fat coloration and fat quality.
Yield score is determined by an estimated cutability percentage that is calculated from four carcass measurements, obtained at the sixth and seventh rib sections. This yield grading system has proven accurate and objective, resulting in the following grades as determined by percentage.
Grade A: 72% and above
Grade B: 69% and above
Grade C: Under 69%
After being assigned a letter grade, the meat quality scores are determined based on marbling, meat coloration and firmness, as well as the texture, luster and overall quality of the fat. Below is a breakdown of the relationship between the beef marbling evaluation results and the resulting assignment of a numerical grade.
Below Average: 2
Meat color is evaluated by a “Beef Color Standard” which consists of seven sequential numerical values or “standards” which are based on the coloration and brightness of the beef. Average color ranges number from 1-6 and carcasses in this color range are graded as average to excellent on the quality grade scale.
Firmness and texture of meat are evaluated by visual appraisal and then classified into one of five grades. Firmness is measured in a range from very good to inferior, and texture is evaluated and placed on a scale ranging from very fine to coarse.
The color, luster and quality of fat is evaluated objectively against the Beef Fat Standards prepared as seven continuous standards. The remaining two factors, luster and quality, are evaluated simultaneously by visual appraisal.
In recent years there has been a focus within the industry to develop an automated and objective carcass measurement utilizing the latest digital camera technology and image analysis software to calculate important traits such as:
- Rib Eye Area
- Rib Eye Shape
- Intermuscular Fat Percentage
- Meat Color Quality
- Fat Color Quality
- Meat Fineness/ Coarseness Index
- Marbling Pattern and Quality
This technology is currently in use in several countries, serving as a research tool to collate accurate carcass data for possible use in parameter estimation for genetic analysis(BLUP). The hope is to create value for producers and consumers by implementing a fast, economical, accurate and objective system of measuring beef quality and characteristics via a standardized, internationally recognized methodology.