In this article we will discuss about:- 1. Meat Inspection 2. Meat Grading 3. Qualities.
Animals are thoroughly inspected before and after slaughter. Although inspection procedures vary from country to country, they are centred around the same basic principles and may be performed by government officials, veterinarians, or plant personnel.
In general, these programmes include antemortem inspection, postmortem inspection, sanitation facilities and equipment, labels and standards, compliance, residue monitoring and evaluation. Different countries have set different guidelines for meat inspection procedures. Considering these, FAO has also prepared concise guidelines on the meat inspection, which has been adopted by many countries.
In general, the objectives of meat inspection programme are:
i. To ensure that only apparently healthy, physiologically normal animals are slaughtered for human consumption and that abnormal animals are separated and dealt with accordingly.
Antemortem inspection identifies animals not fit for human consumption. Here animals that are down, disabled, diseased, or dead (known as 4D animals) are removed from the food chain and labelled “condemned.” Other animals showing signs of being sick are labelled “suspect” and are segregated from healthy animals for more thorough inspection during processing procedures. Antemortem examination helps in diagnosing certain diseases that cannot be easily diagnosed during postmortem.
Diseases that can be detected at antemortem are ― tuberculosis, actinobacillosis, FMD, anthrax, rabies, tetanus, black quarter, mastitis, etc.
Major objectives of antemortem inspection are to:
i. Screen all animals destined to slaughter.
ii. Ensure that animals are properly rested and that proper clinical information, which will assist in the disease diagnosis and judgement, is obtained.
iii. Reduce contamination on the killing floor by separating the dirty animals and condemning the diseased animals if required by regulation.
iv. Ensure that injured animals or those with pain and suffering receive emergency slaughter and that animals are treated humanely.
v. Identify reportable animal diseases to prevent killing floor contamination.
vi. Identify sick animals and those treated with antibiotics, chemotherapeutic agents, insecticides and pesticides.
vii. Require and ensure the cleaning and disinfection of trucks used to transport livestock.
Postmortem inspection is extremely important phase of meat inspection. Routine postmortem examination of a carcass should be carried out as soon as possible after the completion of dressing in order to detect any abnormalities so that products only conditionally fit for human consumption are not passed as food.
All organs and carcass portions should be kept together and correlated for inspection before they are removed from the slaughter floor. Postmortem inspection of the head, viscera, and carcasses helps to identify whole carcasses, individual parts, or organs that are not wholesome or safe for human consumption.
In general, postmortem inspection involves:
i. Viewing, incision, palpation and olfaction techniques.
ii. Classifying the lesions into one of two major categories—acute or chronic.
iii. Establishing whether the condition is localized or generalized, and the extent of systemic changes in other organs or tissues.
iv. Determining the significance of primary and systemic pathological lesions and their relevance to major organs and systems, particularly the liver, kidneys, heart, spleen and lymphatic system.
v. Coordinating all the components of antemortem and postmortem findings to make a final diagnosis.
vi. Submitting the samples to the laboratory for diagnostic support, if abattoir has holding and refrigeration facilities for carcasses under detention.
vii. Trimming or condemnation of any portion of a carcass or whole carcass that is abnormal or diseased.
Major Changes in Muscle Postmortem:
After slaughter of animal, the life-sustaining processes slowly cease, causing significant changes in the postmortem (after death) muscle. These changes represent the conversion of muscle to meat.
1. pH Changes:
After exsanguination, oxygen is no longer available to the muscle cells, and anaerobic glycolysis becomes the only means of energy production available. As a result, glycogen stores are completely converted to lactic acid, resulting the pH to drop. Generally, the pH declines from approximately 7.0 to 7.2 in living muscle to a postmortem ultimate pH of approximately 5.4 to 5.5 in meat.
2. Protein Changes:
When the energy reserves are depleted, the myofibrillar proteins, actin and myosin lose their extensibility and the muscles become stiff. This condition is commonly referred to as rigor mortis. The time an animal requires to enter rigor mortis is dependent on the species, the chilling rate of the carcass and the amount of stress the animal experiences before slaughter.
In resolution of rigor mortis, the stiffness in the muscle tissues begins to decrease due to the enzymatic breakdown of structural proteins. This phenomenon can continue for weeks after slaughter in a process referred to as aging of meat. This aging effect produces meats that are more tender and palatable.
3. Postmortem Quality Problems
Meat quality may be affected by both the pre-slaughter handling of the live animals and the post slaughter handling of the carcasses.
Some of the common problems associated with improper handling of meat animals or meat are:
a. DFD Meat:
Dark, firm and dry (DFD) meat is the result of an ultimate pH that is higher than normal. DFD meat is often the result of animals experiencing extreme stress or exercise of the muscles before slaughter. Stress and exercise use up the animal’s glycogen reserves, and, therefore, postmortem lactic acid production through anaerobic glycolysis is diminished.
The resulting postmortem pH of DFD meat is 6.2 to 6.5, compared with an ultimate pH value of 5.4 or 5.5 for normal meat. The dry appearance of this meat is thought to be a result of an unusually high water-holding capacity, causing the muscle fibres to swell with tightly held water. Because of its water content, this meat is actually juicier when cooked and eaten. However, its dark colour and dry appearance result in a lack of consumer appeal.
b. PSE Meat:
Pale, soft and exudative (PSE) meat is the result of a rapid postmortem pH decline while the muscle temperature is too high. This combination of low pH and high temperature adversely affects muscle proteins, reducing their ability to hold water and causing them to reflect light from the surface of the meat so the meat appears pale. PSE meat is especially problematic in the pork industry. It is known to be stress-related and inheritable.
c. Cold Shortening:
Cold shortening is the result of the rapid chilling of carcasses immediately after slaughter, before the glycogen in the muscle has been converted to lactic acid. With glycogen still present as an energy source, the cold temperature induces an irreversible contraction of the muscle (i.e., the actin and myosin filaments shorten). Cold shortening causes meat to be as much as five times tougher than normal. This condition generally occurs in lean beef and lamb carcasses that have higher proportions of red muscle fibres and very little exterior fat covering.
Electrical stimulation (the application of high-voltage electrical current to carcasses immediately postmortem) reduces or eliminates this condition by forcing muscle contractions and using up muscle glycogen. Thaw rigor is a similar condition that results when meat is frozen before it enters rigor mortis. When this meat is thawed, the leftover glycogen allows for muscle contraction and the meat becomes extremely tough.
Meat grading segregates meat into different classes based on expected eating quality (e.g., appearance, tenderness, juiciness, and flavour) and expected yield of saleable meat from a carcass. Grading of carcass is based on standards, and standards are based on measurable attributes that describe the value and utility of the product. In contrast to meat-inspection procedures, meat-grading systems vary significantly throughout the world.
Different countries have different meat quality standards. For example, in the United States, cattle are raised primarily for the production of steaks and are fattened with high-quality grain feed in order to achieve a high amount of marbling throughout the muscles of the animal.
Therefore, greater marbling levels improve the USDA quality grade. However, in Australia cattle are raised primarily for the production of ground beef products, and the highest quality grades are given to the leanest cuts of meat.
Some of the characteristics of meat used to assess quality and assign grades include: conformation of the carcass; thickness of external fat; colour, texture, and firmness of the lean meat; colour and shape of the bones; level of marbling; flank streaking; and degree of leanness. These factors are good indicators of different characteristics important to consumers.
Importance of Grading in Meat Trade:
Grading is considered essential and beneficial to producer, processor and purchaser of meat.
Grading is important to the producer at the farm because:
i. He gets a higher income for his produce by way of sorting and fixing a differential rating for the various groups.
ii. It enables him to adopt modern animal production programmes consistent with the market demands.
iii. It ensures a healthy competition amongst producer to produce better quality of livestock.
Grading is important to the processor at the packing plant because:
i. He gets a higher income by way of sorting and differential pricing of the carcasses and cuts.
ii. It enables him to satisfy a wide variety of consumers and thereby his business turnover is increased.
iii. He could conserve his valuable time by placing orders through telephones, etc. since he is assured of the quality being ordered by him.
Grading is important to the purchaser at the retail counter because:
i. He is assured of the quality of the product being purchased.
ii. He is free to choose, depending upon his purse and taste.
iii. He is fully satisfied with the expenditure.
iv. The grade of the product forms a good guide to his cooking procedures.
Different Meat Grades:
Two major purposes underlying grading are:
i. To find out the expected palatability characteristics of meat and this consideration is termed as “quality grade.”
ii. To find out the expected yield to trimmed, boneless, retail cuts from a carcass and this consideration is termed as “yield grade”.
Because of the large biological variation in the characteristics of meat animals and their carcasses, the task of grading is complex and difficult.
a. In the case of beef, lamb and mutton, separate standards have been developed for quality grades and yield grades. These carcasses can be graded for quality only, yield only or both.
b. The standards for grades of veal and calf are primarily quality grades.
c. The standards for grades of pork are essentially yield grades but limited consideration is also given to differences in quality.
Meat grading in USA is considered as the best in the world for obvious reasons of higher per capita income and better standards of living. Grades for different type of meat adopted by USDA are summarized in Table 29.1.
Retail Meat Cutting:
Whole carcasses are usually fabricated into more manageable primal (major) or sub-primal (minor) cuts. In developed countries, different primal and sub-primal cuts are usually packaged separately and sold to retailers that further fabricate them into variety of products.
Pork carcasses are usually divided into two sides, and each side is divided into four lean cuts plus other wholesale cuts. The four lean cuts are the ham, loin, Boston butt (Boston shoulder), and picnic shoulder.
Beef carcasses are split into two sides, each side is divided into quarters, the forequarter and hindquarter, between the 12th and 13th ribs. The major wholesale cuts fabricated from the forequarter are the chuck, brisket, foreshank, rib, and shortplate. The hindquarter produces the short loin, sirloin, rump, round, and flank.
Lamb carcasses are divided into two halves, the foresaddle and hindsaddle. The foresaddle produces the major wholesale cuts of the neck, shoulder, rib, breast, and foreshank. The hindsaddle produces the major wholesale cuts of the loin, sirloin, leg, and hindshank.
Qualities of Meat:
Meat quality is defined by the yield, compositional, technological, wholesomeness and palatability characteristics such as appearance, juiciness, tenderness and flavour. The relative importance of these quality characteristics differs for different type of consumers.
Yield and Gross Composition:
This comprises of the quantity of salable meat obtained from meat animal, ratio of fat to lean, and muscle size and shape. Minimum level of fat is desirable as majority of consumers prefer higher ratio of muscle to fat. In another words, the amounts of lean that can be recovered from carcass indicate the quality of meat. This is also important from economic point of view.
Appearance and Technological Characteristics:
The visual identification of quality meat is based on color, marbling and water holding capacity. The meat should have a normal colour that is uniform throughout the entire cut. In general, colour of meat should be bright red or pink. Brown, purple or grey colour of meat is not desirable. Muscle tissue should also have marbling, i.e., small streaks of fat within the muscle. The marbling will increase the juiciness, tenderness and flavour the product.
pH and water holding capacity are two important technological characteristics of meat. These ultimately influence the cooking yield, juiciness and tenderness of meat. Water holding capacity can be witnessed by carefully observing the meat surface or bottom of the retail package. There should not be any excess water oozing out of meat surface. Higher water holding indicate more yield and higher juiciness of cooked product. Type and level of fat and chemical composition of lean also greatly influence the technological characteristics of meat.
Besides, good technological properties, meat should be safe to eat, free from parasites, microbial pathogens and hazardous chemicals. There is growing concern among the consumers that meat should come from animal that are reared and slaughtered as per approved norms and laws.
It encompasses juiciness, tenderness and flavour. Juiciness depends on the amount of fat and water retained in a cooked meat product. Juiciness increases flavour and tenderness of meat. Time and method of cooking also greatly affect juiciness.
Tenderness can be attributed to a person’s perception of meat, such as: softness to tongue, resistance to tooth pressure, ease of fragmentation, mealiness, adhesion and residue after chewing. Tenderness is influenced by several factors, such as the animal’s age, sex or the muscle location.
Meat flavour is believed to be due to the breakdown products of ATP or energy, sulfur and nitrogen compounds and water soluble components of the muscle. Each species have a slightly different flavor due to difference in composition of fat within the muscle. Animals with different uses and different diets will deposit fat that contains different products. The fat melts during cooking and gives each species its own distinctive flavour.