After the Beef Carcasses Are the Next Step Is Grading4
Carcass Grading
The purpose of carcass grading is to classify carcasses based on clearly defined quality attributes to ensure more consistent meat quality and consumer satisfaction.
From: New Aspects of Meat Quality , 2017
Automated grading of beef carcasses
P. Allen , in Improving the Sensory and Nutritional Quality of Fresh Meat, 2009
Abstract
Carcass grading forms the basis for quality-based payments to producers and is a common language to facilitate trade in carcasses. A good grading scheme can lead to improvements in efficiency, as producers have a financial incentive to modify their production methods to produce carcases that are the most desired by consumers. Different beef carcass grading schemes were introduced in the main beef-producing regions, but they all used trained classifiers to assess certain carcass characteristics. They were therefore seen as being subjective and prone to influence, thereby limiting their effectiveness. The development of instrumental objective methods to grade beef carcasses has mainly concentrated on using video image analysis technology (VIA) to mimic grader assessments. In Europe, the rules governing beef carcass grading were changed in 2003 to allow mechanical grading. This has led to many installations in several countries of three different systems. In the USA, handheld VIA systems have been authorised to augment the grader assessments. Future developments in Europe may include using saleable yield assessments from the VIA systems as the basis for quality-based payments; and in the USA there is a move towards fully automated assessment. Ideally, grading should be based on palatability, the consumer perception of quality, but reliable methods to measure this on-line are lacking.
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Primary processing of poultry
D. Barker , ... P. Stals , in Poultry Meat Processing and Quality, 2004
5.10.1 Vision systems
Grading carcasses and portions for quality has always been a key activity. Until relatively recently this was performed by eye. Some ten years ago the first in-line computer controlled vision systems began to come onto the market. Although initial progress was slow, vision systems have now become commonplace in today's high volume processing plants (Fig. 5.9). The first systems were installed to grade fresh birds in-line after air chilling. Advantages were labour savings and, perhaps even more importantly, more consistent grading. Accurate grading is essential if the best use is to be made of each individual carcass. The latest systems are now able to grade birds in-line immediately after plucking and either before or during automatic portioning to grade individual parts of the carcass such as wings, breast, thighs and drumsticks. Grading birds after plucking pinpoints the exact reasons for any downgrading and will reject unfit carcasses. Grading individual parts of the bird saves labour and allows the best use to be made of each individual portion. Work is also being carried out on using vision systems to detect disease on both the killing and evisceration lines.
Fig. 5.9. Grading birds with in-line vision system.
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SLAUGHTER-LINE OPERATION | Pigs
D.J. Bolton , in Encyclopedia of Meat Sciences, 2004
Carcass Grading, Weighing and Stamping
Pork carcass grading is generally based on a measurement of the fat and lean content of the carcass as determined by an electronic probe before chilling. Within the European Union, for example, the carcasses are divided into six classes and assigned a letter (S, E, U, R, O or P), which is indicative of lean meat content (S > 60%, E = 55–60%, U = 50–55%, R = 45–50%, O = 40–45% and P < 40%). In the United States, the weight of four cuts (ham, loin, picnic shoulder and Boston butt), measured after chilling, is also included in the carcass grading process. Each carcass is then weighed and all information regarding grade, weight, gambrel identification and farmers' slap number are registered electronically before being transferred to the main computer.
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SLAUGHTER-LINE OPERATION | Pigs
H. Channon , in Encyclopedia of Meat Sciences (Second Edition), 2014
Carcass Grading, Weighing, and Stamping
Pork carcass grading is generally based on carcass weight and a measurement of the fat and lean content of the carcass on the slaughter floor before chilling. In Australia, producer payments for pork carcasses are based on hot carcass weight and fat depth at the P2 site, located 65 mm from the midline of the carcass at the last rib. In Canada, the national grading system classifies pork carcasses into indexes based on measurement of fat and muscle depth 7 cm from the midline of the carcass between the third and fourth last thoracic ribs and carcass weight. Within the European Union, carcasses are divided into six classes and assigned a letter (S, E, U, R, O, or P), which indicates estimated lean meat content (S>60%, E=55–60%, U=50–55%, R=45–50%, O=40–45%, and P<40%). In the US, fat depth at the last rib may be measured and the expected yield of four cuts (ham, loin, picnic shoulder, and Boston butt) included in the carcass grading process. Information regarding grade, carcass weight, gambrel identification, and producer's tattoo number may be registered electronically and used in reporting back to producers. In Japan, fat thickness is measured at the narrowest point between the 9th and 13th thoracic vertebrae, carcass weight is obtained, and assessments of carcass appearance, meat, and fat color are then used by the grader to determine the grade of each carcass.
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Poultry: Processing
S. Barbut , in Encyclopedia of Food and Health, 2016
Grading, Portioning, and Packaging
Poultry carcass grading is not mandatory in all countries, but is done in most large markets to facilitate sales. The grade is based on carcass conformation, relative muscling, the presence of tears/bruises/pinfeathers, and missing parts. Different countries usually have their own specifications, but generally speaking, a bird (chicken, turkey, or duck; see also meat compositional differences in Table 2 ) with adequate muscle deposition and no missing parts/esthetic defects will be classified as grade A. Minor defects will result in a grade B, and more serious defects will result in a grade C. The last two categories are usually not sold as whole birds, but rather as parts (no grade labeling required) or used for further processed products. Grading can be done by a qualified person or with the assistance of a computerized machine vision system, as indicated previously. The appearance of the carcass and final grade can also be affected by processing conditions used (e.g., high electrical stunning can result in some bone dislocation and blood spots), as well as feeding, growing, and transporting parameters (e.g., bruising during loading of birds) described in more details in other sections.
Table 2. Composition and nutritional value of different raw poultry meats
| Source of meat | Water (%) | Protein (%) | Fat (%) | Calcium (mg) | Calories (kcal) | ||
|---|---|---|---|---|---|---|---|
| Species | Meat | Skin | |||||
| Chicken | White | + | 68.6 | 20.3 | 11.1 | 0.86 | 186 |
| − | 74.9 | 23.2 | 1.6 | 0.98 | 114 | ||
| Dark | + | 65.4 | 16.7 | 18.3 | 0.76 | 237 | |
| − | 75.9 | 20.1 | 4.3 | 0.94 | 125 | ||
| Turkey | White | + | 69.8 | 21.6 | 7.4 | 0.90 | 159 |
| − | 73.8 | 23.5 | 1.6 | 1.00 | 115 | ||
| Dark | + | 71.1 | 18.9 | 8.8 | 0.86 | 160 | |
| − | 74.5 | 20.1 | 4.4 | 0.93 | 125 | ||
| All | + | 70.4 | 20.4 | 8.0 | 0.88 | 160 | |
| Duck | All | + | 48.5 | 11.5 | 39.3 | 0.68 | 400 |
| Goose | All | + | 50.0 | 15.9 | 33.5 | 0.87 | 370 |
| − | 68.3 | 22.7 | 7.1 | 1.10 | 160 | ||
| Quail | All | + | 69.7 | 19.6 | 12.1 | 0.9 | 192 |
| Pheasant | All | + | 67.7 | 22.7 | 9.3 | 1.3 | 180 |
| Pigeon | All | + | 48.1 | 15.7 | 20.2 | 1.0 | 250 |
Expressed on a 100 g portion of meat with/without skin.
Source: USDA (2011). National Nutrition Database for Standard Reference. Washington, DC: United States Department of Agriculture. www.nal.usda.gov.
Weighing of the ready-to-sell birds (whole bird or portions) is done manually or by automated weighing equipment connected to a computer network. A computerized system can also be employed to automatically print labels on individual/bulk packages. Automated portioning equipment is used in large plants where simple portioning is done (e.g., nine cuts commonly used for fast food chains), or more sophisticated cutting and deboning (e.g., breast meat fillets, drumstick meat) are performed by high-speed equipment guided by cameras/laser sensors that first produce accurate 3-D images of the portions to be cut. Selling portioned poultry to consumers interested in only buying certain parts (skinless breast fillets, drumstick meat) has allowed the industry to significantly increase sales and also move some items such as whole turkey (i.e., traditionally consumed during Thanksgiving and Christmas) to an all year-round product.
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Methods to measure body composition of domestic animals
Steven M. Lonergan , ... Dennis N. Marple , in The Science of Animal Growth and Meat Technology (Second Edition), 2019
USDA pork carcass grading
The USDA pork carcass grading system has never been used by the major packing companies in the United States. The pork slaughter companies developed their own grading system based on linear measurements for backfat thickness, degree of muscling, and carcass weight, and the packing company pays the pork producer the values of the carcass based on their own grading systems. The major pork processing companies currently use high tech, high speed, and excellent objective methods to determine the carcass value (usually the percentage muscle in the carcass) for payment to the pork producer.
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Pork Meat Quality, Production and Processing on
D.F. Keenan , in Encyclopedia of Food and Health, 2016
Carcass Grading
The aim of carcass grading is to ensure fair payment to producers, obtain transparency, and compare/standardize across different markets. The set conditions are specific to market requirements for the commodity. In pork, lean content is the most highly sought attribute, and the basis for its assessment is uniformity in the following criteria: (a) the definition of grading standards, (b) systems of assessment, and (c) estimation formulas. Up until the mid-1980s, carcass grading was carried out subjectively by visual determination. However, a more objective approach has been carried out since then by the use of instrumental measurement. Despite this, the systems of pig carcass grading are far more developed than beef and lamb. A number of technologies are used to determine lean content of carcasses, and these vary greatly from country to country. Some examples include the Fat-o-Meater, the Hennessy probe, ultrasound system, x-ray absorptiometry, AutoFOM (automatic Fat-o-Meater), and a simple ruler to measure fat thickness. The adoption of the technologies will depend on initial cost, training required (operators), and the overall resultant benefits of its adoption. For example, some technologies such as x-ray absorptiometry would be impractical in a large-scale fast-moving production facility. Regardless of the technology adopted, fat thickness plays an important role in the determination of lean carcass percentage as it is the most variable tissue in the carcass, and as such, it is included in every calculation. In Europe, lean meat content is determined using the EUROP classification, which is based on muscle and fat thickness. In this system, lean meat occupies the following percentages: E = >55%, U = 50–55%, R = 45–50%, O = 40–45%, and P = < 40%.
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SLAUGHTER-LINE OPERATION | Sheep and Goats
C.E. Devine , K.V. Gilber , in Encyclopedia of Meat Sciences (Second Edition), 2014
Sheep and Lamb Carcass Grading
There is no international carcass grading system for sheep, lambs, and goats, but some generalizations can be made, and in particular, sex and age are important. Mutton is a female (ewe) or an adult noncastrated male (ram) or a castrated male (wether) with more than two permanent incisors in wear. A hogget is a young male sheep or a maiden ewe having no more than two permanent incisors in wear. Lambs are young sheep less than 12 months of age and without any permanent incisors in wear. New Zealand, Australia, and the EU account for almost 90% of lamb exports, but each country is serving specific markets and therefore the systems are not the same. The greatest sheep meat production is in China, followed by the EU, Australia, New Zealand, and the Middle Eastern countries (where goats are processed as well), all with different grading systems. Links to the various systems can be obtained from web links cited in further reading. VIASCAN systems (video analysis) based on carcass conformation are now being used.
In many systems, grading is based on the overall size and conformation and the fat cover. In New Zealand, the thickness of the fat based on measurement of total tissue depth over the 12th rib at a point 11 cm from the midline, called GR, is used (the fat cover on the longissimus muscle is not such a useful guide as in pigs). The export grades are based on three grades of leanness (A=devoid of external fat, Y=low fat, and P=medium fat). Excessive fat is trimmed and gives rise to another series of grades. There are then, superimposed on this, four weight grades (L=9–12.5 kg, M=13–16 kg, X=16.5–20 kg, and H=20.5 kg and more). Australia follows a similar, but not identical, system.
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Quality Evaluation of Meat Cuts
Liyun Zheng , ... Jinglu Tan , in Computer Vision Technology for Food Quality Evaluation, 2008
3.2 Predicting carcass grades
The overall objective of pork carcass grading is to identify the true commercial value of a carcass by segregating carcasses based on lean content. In Canada, the grading system has elements of both classification and grading schemes. The classification scheme objectively describes the carcass in terms of estimated yield and carcass weight, and the grading scheme assigns a yield and weight class ( Fortin, 1989). In value-based systems such as the Canadian system, the negative relationship between the subcutaneous fat thickness in the carcass and the amount of lean in the carcass is used to estimate the lean content of the carcass. The fat thickness is measured at a single site on the carcass mid-line at two locations (maximum loin and maximum shoulder). However, the accuracy of single-site technology is limited (Fisher, 1990).
In order to improve accuracy, new concepts have been introduced. For example, Sather et al. (1996) studied the use of ultrasound imaging technology for predicting carcass quality in terms of lean meat yield. Meanwhile, a Danish company developed a digitized three-dimensional ultrasound system (AutoFom) which generates a full scan of the carcass (Busk et al., 1999). Using AutoFom, Busk et al. (1999) reported a residual mean square error of 1.84 for estimating lean meat percentage.
On the other hand, Soennichsen et al. (2001, 2002) conducted investigations regarding using a computer vision system (CVS) for assessment of the commercial quality of pig (swine) carcasses in small-scale slaughterhouses in Germany. Performance of the CVS apparatus alone was compared with that of CVS plus ultrasonic probe data and the AutoFom carcass grading instrument. Relative estimation error for weight of cuts was <5 percent for CVS in all cases except the loin (approx. 7 percent), which was slightly improved by the addition of ultrasonic probe data. However, AutoFom was slightly more accurate than the CVS techniques for most cuts. When the CVS was applied to evaluate the lean meat content of the belly cut from half carcasses, it was necessary to utilize ultrasonic probe data in order to achieve a low relative estimation error comparable with that of the AutoFom instrument.
In order to improve grading accuracy further, Fortin et al. (2003) focused on an approach integrating ultrasound with image analysis, which was significantly different from the approach of scanning the whole carcass. They developed a CVS prototype containing two components: video imaging to capture images of the carcass, and ultrasound imaging to scan a cross-section of the loin muscle. Figure 5.6 shows the set-up of such a system (Fortin et al., 2003). The system was used at a commercial abattoir to grade 241 carcasses (114 barrows and 127 gilts), which fell into three weight categories (<80.9, 80.9–89.0, and >89 kg) and three fat-thickness categories (<15, 15–21, and >21 mm). Saleable pork yields were determined from full cut-out values. Linear, two-dimensional, angular, and curvature measurements by the CVS provided an accurate and almost instantaneous assessment of conformation. Muscle area and fat depth 7 cm off the mid-line, measured by ultrasound at three-fourths of the last rib, alongside two- and three-dimensional measurements of the lateral side of the carcass, gave the best estimations of saleable pork yields. Results suggest that the CVS offer a novel approach to grading swine carcasses and appears to have commercial potential.
Figure 5.6. The two components of the Lacombe Computer Vision System for grading pig carcasses consist of a computer vision system to provide two- and three-dimensional measurements of a carcass, and an ultrasound system to provide fat thickness, depth and area of the loin (m. longissimus dorsi) (Fortin et al., 2003).
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CLASSIFICATION OF CARCASSES | Beef Carcass Classification
P. Allen , A. Oka , in Encyclopedia of Meat Sciences, 2004
Grading in the United States
A federal system of beef carcass grading was first introduced in 1927. The industry has changed considerably since then, and the scheme has evolved to reflect these changes. The purposes of the scheme are to aid quality-based marketing of cattle and to provide a common language for carcass trading. Grading is voluntary, and the service is provided by the USDA on a cost-recovery basis.
Beef carcasses are graded according to quality and yield grades. The yield grades estimate the amount of boneless, closely trimmed retail cuts from the high-value parts of the carcass – the round, loin, rib and chuck. The grades are numbered 1 to 5, YG1 having the highest expected yield and YG5 the lowest ( Table 4 ). The grades are calculated from a formula that includes the fat depth over the ribeye, the percentage kidney, pelvic and heart fat (KPH), carcass weight and ribeye area. The ribeye fat depth is measured at the 12th rib, three-quarters of the length of the ribeye from the chine bone, but skilled graders make an adjustment of this measurement to reflect unusual amounts of fat in other parts of the carcass. In other words, they assess how representative this fat depth is of total carcass fat. The amount of KPH fat is evaluated subjectively and expressed as a percentage of carcass weight, which is the hot carcass weight recorded by the scales. The area of the ribeye muscle is measured using a dot-grid.
Table 4. USDA yield grades
| Yield grade | % Closely trimmed retail cuts (BCTRC) a |
|---|---|
| 1 | ≥ 52.3 |
| 2 | 52.3–50.0 |
| 3 | 50.0–47.7 |
| 4 | 47.7–45.4 |
| 5 | ≤ 45.5 |
- a
- BCTRC = 51.34 − 5.78 (Fat opposite ribeye, inches) – 0.46 (Percentage KPH fat) – 0.0093 (carcass weight, pounds) + 0.74 (Ribeye area, in.2)
The yield grades have descriptions in terms of the external and internal fat deposits, and a stepwise procedure is adopted for determining the yield grade. First, the preliminary yield grade (PYG) is determined from the ribeye fat measurement. This is then adjusted for the carcass weight, using 600 pounds (ca. 270 kg) as the baseline, then for the percentage KPH and finally for the ribeye area.
Beef quality grades are designed to sort carcasses according to their expected palatability, that is their tenderness, juiciness and flavour. The quality grading is based primarily on marbling, that is the amount of intramuscular fat, but also on maturity. Graders evaluate the amount of marbling fat in the ribeye muscle after the carcass has been ribbed between the 12th and 13th ribs. Quality grades are called Prime (most marbling), Choice, Select and Standard (least marbling) ( Table 5 ). Each quality grade is divided into three marbling score subclasses; for example, Prime is divided into Abundant, Moderately Abundant and Slightly Abundant. Each degree of marbling is divided into 100 subunits, but in practice marbling scores are generally referred to in tenths within each marbling grade, e.g. Slightly Abundant90, Moderately Abundant50, and so on.
Table 5. USDA marbling grades
| Quality grade | Marbling score |
|---|---|
| Prime+ | Abundant00–100 |
| Prime0 | Moderately Abundant00–100 |
| Prime− | Slightly Abundant00–100 |
| Choice+ | Moderate00–100 |
| Choice0 | Modest00–100 |
| Choice− | Small00–100 |
| Select+ | Slight50–100 |
| Select− | Slight00–49 |
| Standard+ | Traces34–100 |
| Standard0 | Practically Devoid67–100 to Traces00–33 |
| Standard− | Practically Devoid00–66 |
Maturity is the second criterion of beef quality grading. Maturity refers to the physiological age of an animal rather than the chronological age and is used mainly because the latter is generally not available. The indicators of maturity are the bone characteristics, the degree of ossification of the cartilage of the sacral and lumbar vertebrae and the spinous processes of the thoracic vertebrae (increases with age), and the colour (which darkens with age) and texture (which becomes more coarse with age) of the ribeye muscle. Carcass maturity grades are labelled A to E, A being 9–30 months and E being over 96 months ( Table 6 ). Carcasses are separately assessed for maturity based on ossification ( Table 7 ) and on lean colour and texture ( Table 8 ); when the two do not agree, a balancing is carried out with slightly more weighting on the bone score.
Table 6. USDA maturity grades
| Carcass maturity | Approximate live age |
|---|---|
| A | 9–30 months |
| B | 30–42 months |
| C | 42–72 months |
| D | 72–96 months |
| E | > 96 months |
Table 7. USDA skeletal ossification grades
| Maturity group | |||||
|---|---|---|---|---|---|
| Vertebrae | A | B | C | D | E |
| Sacral | Distinct separation | Completely fused | Completely fused | Completely fused | Completely fused |
| Lumbar | No ossification | Nearly completely ossified | Completely ossified | Completely ossified | Completely ossified |
| Thoracic | No ossification | Some ossification | Partly ossified | Considerable ossification (outlines of buttons are still visible) | Extensive ossification (outlines of buttons are barely visible) |
| Thoracic buttons | 0–10% | 10–35% | 35–70% | 70–90% | > 90% |
Table 8. USDA lean maturity descriptions
| Maturity | Lean colour | Lean texture |
|---|---|---|
| A | Light cherry red | Very fine |
| B | Light cherry red to slightly dark red | Fine |
| C | Moderately light red to moderately dark red | Moderately fine |
| D | Moderately dark red to dark red | Slightly coarse |
| E | Dark red to very dark red | Coarse |
The final quality grade is determined by combining the marbling and maturity grades according to a detailed plan ( Figure 2 ). A stepwise procedure is used to determine the final quality grades of Prime, Choice, Select, Standard, Commercial, Utility and Cutter.
Figure 2. Relationship between marbling, maturity and carcass quality grade assuming that the firmness of lean is comparably developed with the degree of marbling and that the carcass is not a 'dark cutter'. * Maturity increases left to right (A to E). ** The A maturity portion of the figure is the only portion applicable to bullock carcasses. (Source: USDA (1996) Standards for Grades of Slaughter Cattle and Standards for Grades of Carcass Beef. Washington, DC: USDA.)
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