MEAT

By the word meat we mean the body tissues of animals that can be eaten as food, anything from frog legs to calves brains. However, we usually make a distinction between the meat animals -cattle, ships, pigs and poultry and fish and between meat and variety meats like- organs like livers, kidneys, and intestines and so on. Meat proper is muscle tissue whose function is to move some part of the animal. The next thing which comes into mind is why do need to eat meat at all. This is because the Bio- chemistry of most animals is pretty much the same as ours, their tissues supplying us the number and proportions of amino acids and proteins that we need. The history of meat consumption’s starts from the domestication of animals. Research in nutrition and medicine suggests that we are paying for our high consumption of meat and other animal products with our health. On an average we eat twice as much protein every day as we actually need and most of the proteins come from red meats, eggs and dairy products. The problem is not of the excess proteins in the diet but of the large amounts of saturated fats and cholesterol that accompany it. These substances lead to heart diseases.

TYPES OF MEAT

 The names for the various types apply to the specific animals from which they are obtained. The term beef, for instance, refers to meat from cattle over 9 months old. Meat from cattle that are 3 to 9 months of age is classified as calf. Veal comes from calves ranging in age from 1 to 3 months.

Pork is derived from hogs that are generally 5 months of age or older. Most of the meat from older and heavier hogs is utilized in various processed meats.

Lamb comes from sheep less than 14 months of age and usually weighing from 90 to 140 pounds (40 to 65 kilograms). Mutton refers to meat from sheep over 14 months of age.

Variety meats include liver, heart, tongue, brain, kidney, sweetbread (thymus gland), tripe (stomach of ruminant) and chitterlings (large intestine of pig). Each of these meats has a distinctive flavor and consistency when it is cooked.

In processed meats the properties of fresh meat have been modified through grinding, chopping, seasoning, the alteration of color, or heat treatment. Typical processed meat products include bacon, cured ham, corned beef, canned meats, precooked meats, and sausages.

Major components are:

• Lean muscle
• Connective tissue
• Fat
• Bones

Bones: Bones consists of cell, fibres and ground substancesIt has protective and supportive function in the skeleton. It provides for the internal support of the body and for the attachment of the muscle and tendons essential for locomotion. It protects the vital organs of the cranial and thoraces cavities and it encloses the blood-forming element of the bone marrow. In addition to this mechanical function, it plays an important metabolic role as modifiable store calcium that can be drawn upon as needed. The shape of the bone is an excellent guide for identification of the various cuts of meats.

Cartilage is a firm elastic substance often gets converted into bone.

 CONNECTIVE TISSUE:

Although the muscle tissue gives the meat its characteristic appearance and to some extent its flavour and texture, it is the connective tissue that determines the tenderness of the meat. Connective tissue in the meats forms walls of muscle fiber, binds them into bundles, surrounds the muscle as a membrane and makes up the tendons and ligament that attaches the muscle to the bones.

 We are concerned with three types of connective tissues: –

• Collagen: They are most abundant type. Wavy, non-branching threads that lie singly or in bundles characterize them. Massive accumulation of collagen as fiber is the tendon that  connects muscle to the bones. These fibers are white in color and are less elastic. They are composed of protein called collagen. Collagen when heated gets converted into gelatin (at the ordinary cooking level). This process is called hydrolysis.
• Elastin fibers: These fibers get the name from the ability to stretch much like a rubber band: that is to say they posse’s elasticity. They are yellow in color and are found in branches. They connect bones to bones.  They are composed of proteins called Elastin, which makes them much heavier than collagen. Elastic is the most undesirable because it does not break down upon heating. It may soften if temperature is sufficiently.
• Reticular fibers: These are fine branching threads composed of protein Reticulin. These threads form a dense network. They are in very small amount in muscle fiber. Reticular fibers also form the framework of the reticuloendothelias system(lymph nodes, spleen, tonsils etc. )

• Fat or adipose tissue: It is deposited in connective tissue in three location:

1. beneath the skin  subcutaneous fat
   1. between the muscle inter muscular fat
   1. it appears as fine flakes of fat on the surface of meat and is approved as marbling _ intra muscular fat

Muscle tissue:

There are three types of muscle tissue- Skeletal muscle, Cardiac muscle, Smooth muscle

Composition of meat:

Meat is made up of proteins, fat, minerals, (phosphorous, iron and calcium), some carbohydrates, nitrogenous and non –nitrogenous extractives, pigments, enzymes, vitamins and water.

Proteins: 15 to 20 % in any type of cut in meat. It is directly related to amount of lean tissue in it. Amount of protein decreases as the fat and bones content increases.

 Fats and carbohydrates: fat is essential to all metabolism. The fat cell begins to store droplets of fats only after the available nutrients exceed the amount necessary for organ production.

 Two types of carbohydrates are found in meats:

1. Glycogen- stored mainly in livers.
2. Glucose-, which is found in blood.

Pigments

Myoglobin and hemoglobin are two pigments, which contribute to red color of the meat.

Hemoglobin transports the O2 in the blood stream and myoglobin holds O2 in the muscle for contraction. Organ meats have more hemoglobin than skeletal muscle because of their greater blood supply.

Enzymes:Protein splitting enzymes may be responsible for increasing tenderness during ageing or ripening.

Minerals: phosphorous and iron are the chief minerals in meat. Potassium is found in muscle fiber and sodium is found in fluids.

Extractives

Lactic acid is always present in the muscle tissue of the animal. There is always increase in the amount of lactic acid after the rigor mortis sets in. the nitrogenous extractives found in muscle are the end product of protein metabolism. Some authorities regard the nitrogenous extractives as the source of meat flavour.

Following is the percentage constituent of beef muscle: –

Water              – 67%

Protein           – 19%

Fat                  – 13%

Carbohydrate – 1%

Slaughtering procedures:

• In order to get the best quality of meats it is very important to slaughter the animal in the prescribed manner. Animals may be slaughtered in jhatka or halal method depending on consumer sentiments.
• The animals should be fed well  24-48 hours before  slaughtering. 
• Once animals are brought to the slaughterhouse, they should be given rest of minimum 24 hours to maintain adequate strength of lactic acid, after slaughter.
• Animals are given 90 volts electric shock for less than 10 seconds. The stunning process gives rise to blood pressure and makes the heart to pump the maximum amount of blood. This process ensures perfect bleeding and improves the keeping quality of the meat.
• The animal should be bled immediately after stunning within 5 sec.

Rigor Mortis:

It means the process by which the body becomes stiff after death.

Meats from animals that have just been dressed are soft and pliable. The fat becomes cool and hardens. At the same time several changes occur in the muscle protein.

• Decrease in glycogen by its conversion to lactic acid.
• A simultaneous drop in Ph
• A development of rigor or stiffening and with greater changes the muscle become soft and plaint.
• Changes in muscle to electrical resistance.
• Changes in the elasticity of the muscle
• Changes in the elasticity of the muscle fiber.

The onset of rigor, occur in two stages:

In the first stage the Ph drops to about 6.2. This stage is little affected by temperature but is affected by the physiological state of muscle. The drop in the ph is proportional to the amount of the glycogen changed to lactic acid.

In the second stage, which is affected by temperature, the ph continues to drop and stiffening takes place, each small drop in the ph being accompanied by a comparatively large increase in stiffening.

The Rigor Mortis is characterized by:

1. Dullness of muscle through lack of transparency
2. Contraction and hardening of muscle
3. Stiffness and hardening of muscle

It is associated with the breakdown of adenosine tri phosphate and its non-replacement because of the lack of oxygen.

Rigor Mortis normally appears about 10 hours after the death of the animal and disappears after 24 hours. Various factors affect its onset, degree and its disappearance. The Ph of the freshly killed animal is 7.0 and it drops to 5.6 due to the conversion of glycogen to lactic acid. The low ph is a desirable factor for keeping quality of meat The hardening of fat after death of the animal is due to fall in temperature not due to rigor mortis.

Quality check for meats

The following guidelines are to be borne in mind to ensure that the product is of correct specification and quality.

• Age of the animal
• Setting of the meat
• Color of the meat
• Odours of the meat
• PH (hydrogen ion concentration)
• Evidence if proper bleeding
• Evidence of any infection

Age of the animal:

Recommended age group of animals for slaughter:

Setting of the meats:

The meat should be well set. The meat surface should not be slimy. The fat should be firm and white with no bad odours. The meat should be firm and not spongy.

Odours:

The normal mutton should not have any odours. Sometimes the odours is might have been acquired by foodstuffs, drug administration, or by absorption.

Boiling test for abnormal odours and taste:

Abnormal odours are common in meat commodities after slaughter but not when they cooled. It may reappear when meat is cooked. To detect this meat is subjected to boiling test:

Boil the meat in a closed container. During boiling the lid is lifted and the vapour is smelt. Abnormal odours and taste should be noted and the meat should be received accordingly.

The ph (hydrogen ion concentration)

Estimation of ph gives indication as to the keeping quality, as it is related to the extent of bacterial contamination and post slaughter biochemical activities in the muscle. If animals are exhausted at the time do slaughter then the glycogen of the muscle goes down and the ph level goes up? The meats with higher ph level are considered to be of poor quality.

Acids in meat tend to arrest bacterial growth. No spoilage occurs at ph 3.5. Normally at ph 5 and below the condition are not favourable for bacterial growth and chances of spoilage are remote.

Color:

Evidence of appropriate colour is the evidence of quality meat. Colour is caused by meat pigment, which is called myoglobin. The extent of such influence, in this connection depends on feeding, pre and post slaughter, and packaging, air, curing

Evidence for proper bleeding or for infection

Multiple shades of colour like gray, bluish or other unusual colours render the meats unfit. The bluish colour indicates improper bleeding, which could be from fever, fatigue or cold slaughtering. The flesh looks darker, flabby and watery. The organs appear congested.

Tenderness in meat

Connective tissue: it is generally agreed that amount of connective tissue directly related to the tenderness of meat. Cut of meat with much connective tissue are tougher than those containing little connective tissue.

Fat: Good marbling of meat throughout the meat tissues increases the tenderness. Fat separates and dilutes the connective tissue fibers and makes them more available to heat treatment.

Age: meats from younger animals are tender than older one. It could be due to lack of muscular development in younger animal. Tenderness of muscle decreases as the diameter of the muscle increases with the age of animal. Older animal with greater muscle development have increases connective tissue.

Location: The location of the cut is an indicative of its tenderness. The least used muscles are tenderer than those that are fully developed, those found in neck, chunk and round cuts.

Temperature: the temperature at which meat is cooked is cooked will alter the tenderness of the meat and affect the contraction of the fibers. High temperature and over cooking causes toughening of meats. Whether or not the meat tenderizes, depends on the relationship between of collagen and coagulation of the muscle protein. If hydrolysis of collagen predominates, the meats may become tender. If hardening of muscle protein dominates the cooking process the meat increases in toughness.

Grinding and pounding: Grinding breaks and cuts the muscle fiber and connective tissue and making it possible for all the ground meat to be prepared in a fashion similar to those tender cuts. Pounding is used to tenderize the meat; this process breaks and tears only the surface meat fibers connective tissue fibers.

Ageing: it is an important method of tenderizing meat. When Rigor Mortis occurs in an animal’s carcass, the muscle is hard and the muscle protein acting and myosin joins to form act myosin. As a result of this, some muscle fibers contracts and alternating fibers are stretched. As ageing continues, after onset of rigor mortis, the much softer and muscle fiber appear to straighten out with noticeable break. Fiber breaks are caused by enzymatic action on the protein.

Because of discoloration of meat and moisture loss, only cuts of meats such as ribs and loins with thick covering of fat that can be cut off are suitable for ageing. Lamb is occasionally aged; pork is never aged because of its high fat content, veal does not have the proper fat covering for the ageing process.

Dry ageing: Meat is held at 34-38deg F for three to six weeks. The humidity may be low (70-75%) to keep the cut surface dry or relatively high (85-()%) to purposely grow mould. If the latter method is used, evaporative loss is decreased. Meat procured for hotels is aged by this method.

Fast ageing: in this method meat is held for two days at a temperature of 21deg. C. at high humidity. Microbial is retarded by the use of ultraviolet light. Most of the meats marketed in retail market are aged in this manner. Additional ageing occurs in 6-10 days, that it takes for meat to be transported, marketed, stored and cooked.  

Vacuum packaging: The weight loss and surface spoilage that occurs in ageing can be lessened if the meat is packaged in a moisture and vapor proof film. Meat vacuum packed in this manner should not loose in tenderness, juiciness and flavor for 1or 2 weeks but has a significant reduction in weight loss.

Freezing: The effect of freezing on meats has been studied very avidly and it is found that it makes little or no difference.

EnzymesMeats can be made tender by the use of the proteolytic enzymes such as papain, an enzyme found in papaya leaf. When meat tenderizers are used, uniformity of tendencies is difficult to obtain. In large cuts, only the application affects the surface of the meats.

Bromelin and Facin are also being used instead of Papain. The enzymes are mixed in salt solution and used as dry mixture or as a liquid drip.

The enzymes tenderizes the meats by breaking down the outer fiber of the muscle fiber , collagen , and the elastin material found in the muscle tissue. Enzymes activity is slow at room temperature; it is most active in the range of 60-70deg C. hence action of tenderizer takes place only during cooking of the meat. Cooking meat until it is well cooked deactivates the enzymes – cooking it short of well-done stage may permit the continued the activity of enzymes in the muscle fiber by hydrolyzing the actomyosin.

Ante mortem:

The tenderizing solution (PAPAIN) is introduced in the jugular area of the animal for even distribution of throughout the body tissue this tenderizing process has been approved as successfully increasing the tenderness of beef. 

At present beef subjected to ante mortem enzyme process is being produced commercially and marketed as “proten”. Tough cuts of meats that have been treated by this method can be cooked by dry heat method.

Acid material:

Adding acid material to the meat does not increases its tenderness. Neither soaking meat in vinegar for 48 hours nor praising it has increased its tenderness.

Marbling

Marbling is intra muscular fat tissue that contributes to meat quality. Marbling causes the meat to be firm and to reflect a desirable colour of the lean meat. Marbling fat provides moist heat while cooking by covering the individual muscle cells with lipids. This condition assists in breaking down connective tissue when heat is applied to the meat. Fat also provides liquid and creates a desirable mouth sensation during chewing (mastication). Fat thus contributes more to flavour than to tenderness. 8-9% fat in steaks or roasts is adequate for good flavour.Quality is greater than this add very little to the meat palatability.

LAMB AND MUTTON

In India where sheep and goat farming is not advanced and scientific, often the older animals which have tougher meat are slaughtered.Generally the female goats and sheep are slaughtered at a later stage because first they are used for breeding only.The male animals are however slaughtered earlier and therefore much tender in texture.To get the best quality of meat the lamb is received double with reproductive organs intact to identify if it is male or female animal.Best quality mutton is bright red in colour, close grained and firm.It has a great deal of fat that is evenly spread over the muscular tissue and within the muscles also.

Quality determination of Lamb and Mutton.

1. The flesh of lamb is lighter in colour than that of Beef.Mutton flesh is darker.
2. The lean meat of Lamb and Mutton has a fine, velvet like texture.
3. The fat is very firm, brittle and white.
4. The cut surface of bone is porous and of reddish colour.
5. Compact and evenly fleshed.

The illustration given here shows a carcass of Lamb and Mutton with its basic cuts.

Cuts of Lamb / Mutton

Except the above mentioned cuts there are some more edible parts obtained from a carcass which are termed as Offal (Abats) i.e. heart, liver, kidney etc. of butcher’s meats and giblets of poultry etc.

LAMB/ MUTTON OFFALS — ABATS d’agneau /mouton