Constituents of Meat
Meat is obtained from the flesh of animals and used as food. It contains various constituents such as water, fat, and protein. It is composed of connective tissue, muscle fibers, adipose tissues, bones, and water. Connective tissue contains mucopolysaccharides and proteins. It provides support to muscles by creating adhesion between the cells in the muscles. The major proteins in connective tissues are reticulin, elastin, and collagen (Pearson, 2012). Adipose tissue, on the other hand, is a layer of fat. The major fats are marbling and cover fats. Cover fat is located in the cavity of the abdomen and gives insulation to the skin. Marble fat is found within the muscles and has perceived texture, juiciness, and flavor.
Meat is obtained from poultry and mammals. In mammals, there is pork from pigs, beef from cattle and veal from calves. Chicken, geese, turkey, duck, and quails. Meat is nutritious to our body since it gives phosphorus, iron, thiamin, vitamin b16, riboflavin, zinc, and niacin. It contains 18% protein, 75% water, 1.5% minerals, 3% fat and 1% glycogen. However, some of these constituents differ with body size, age, and genetics of the animal producing the meat. Water content for older animals is less. Beef has high levels of water as compared to goat, sheep, and pigs (Toldrá, 2007).
Proteins from the meat give toughness and shape to muscles. Pigments obtained from proteins gives the meat color. Blood and cell plasma are derived from proteins. Proteins from meat also help in the growth of hair, horn, and nails. Amino acids in meat are plenty in meat than in plants. The major amino acids composed in meat are valine, lysine, threonine, methionine, isoleucine, leucine and phenylalanine. The quality in meat decreases with an increase in the connective tissue (Toldrá, 2007).
Previously processing was done on meat to preserve it. It is also a means of adding variety from the change in flavor and texture created. Processing also increases the supply of meat since a carcass can be mixed with lean meat. Again, some foodstuffs can be added on meat like cereals and supplement the shortage. There are various procedures of processing meat including heat treatment, mincing, curing, salting, grinding and adding seasonings ("PRINCIPLES OF MEAT PROCESSING TECHNOLOGY," n.d.).
This is the process of adding curing agent to meat such as sodium nitrite present in common salt. This agent introduces an attractive red or pink color which increases consumers' desire. This is a major processing done for sausages, bacon, and ham which makes them heat stable. However, nitrite is only applied in small amounts in coloring and meat preservation. To prevent overdose, a mix proportion is prepared by manufacturers which limits the amount to 0.5%. With sodium chloride and nitrite in this proportion, the latter is called nitrite curing salt. This mixture is added at a level between 1.5-3% to achieve the required flavor ("List of the Best Meat Preservation Methods," 2018).
While applying this mix, contact is kept on myoglobin and the muscle tissue. This mixture also increases the pH of acidified meat fresh from slaughter. Nitrite interacts with myoglobin to form a heat-stable compound known as nitrosomyoglobin. At quantities of below 2%, nitrite is less toxic to consumers. Adding nitrite in the curing process is beneficial in a number of ways including:
- It makes fat stable retards rancidity in meat
- Enhances the flavor in meat after curing
- Inhibits the growth of microorganisms commonly in the canned meat where heat-resistant bacteria may have made way in the cans.
- Increases the demand to the consumer by introducing an appealing red or pink color.
Nutrients in Meat
These are the mechanical processes of reducing the sizes of animal tissues. Mincers and grinders are designed to cut or separate bones and hard tendons from soft meat tissues. Others are bowl cutters which chop and mix fat, lean meat or frozen meat. Ingredients such as extenders (binders/fillers), functioning additives (curing agents and salt) are added during the grinding and mincing processes. Emulsifying machines first allows mixing with seasonings and additives to before passing it in colloid mills to produce desirable sizes and emulsification in meat mixes.
Frozen meat is cut into slices using bowl cutters without thawing to prevent discoloration, bacterial growth, and drip losses. For small-scale processes, frozen meat cutting can be done using axes and cleavers. Fatty tissues are cut into cubes of 2-4cm to aid in chopping in emulsifiers and cutters. It can also be done for small-scale processing (Heinz, & Hautzinger, 2007).
This is a process of dressing meat products with smoke from raw wood. Smoke is created when cellulose and lignin are destroyed by thermal destruction from heat. Thermal action on wood dissociates about 1000 desirable and undesirable components in wood (Dierenfeld, 2015). These components are beneficial for processed meat in the following ways:
- Adds a smoking taste
- Fat oxidation retardation
- Aldehydes and phenols reduce the antioxidant impact
- Prevents microbial activities
- Aldehydes and carbonyls form an attractive smoke color
- Aldehydes cause hardening on the surface of casings or sausages
- Phenols, acids, and aldehydes preserve meat.
However, smoking is toxic in some levels from the benzopyrene residues which are carcinogenic. The carcinogenic level from smoking depends on the longevity of smoke application. Smoking is thus regulated at varying temperatures. Hot and cold smoking are the two types of smoking processes in meat. For both methods, smoke is allowed to diffuse into outer layers of meat to enhance preservation, color, and flavor.
Cold smoking is a common process that applied in the olden days to preserve meat. Today it is used to enhance color and flavor formation. An example is smoking blood sausages and liver sausages made out of precooked foodstuffs. Temperature is achieved at 15 to 26 degrees centigrade for cold smoking. Meat is hung away from the slow-burning sawdust smoke. Cold smoking consumes a lot of time and is repeated after a few days in a period of few hours each day.
Hot smoking, on the other hand, is conducted on a range of temperature of 60 and 80 degrees centigrade. Additional heat is applied in the heating chamber since smoke cannot attain this temperature. This high temperature ensures rapid flavor and color development. Similarly, heat is also regulated to prevent excess flavor and color formation. Sausages with a thin caliber are smoked for 10 minutes while those with a thick caliber (ham, bacon, and bologna) are smoked for up to one hour (Dierenfeld, 2015).
Meat products are extremely perishable and become hazardous for human consumption from disintegration by endogenous enzymes, chemical change, and microbial growth. These actions can be reduced by heating to kill enzymes and microorganisms, water removal by osmotic control and drying, temperature reduction to prevent bacterial growth and chemicals use to inhibit growth. Ancient methods of preservation include smoking, salting, sun and wind drying. Canning introduced in the nineteenth century has been adopted to preserve meat for years without destruction. Others include refrigeration, ionizing radiation, and smoking (Ercan & Soysal, 2013).
Proteins in Meat
Refrigeration was borrowed from the idea Romans used to preserve meat products. The temperature for freezing and chilling is between 0° to 4°C. Similarly, packaging technics applied include storing under a vacuum, nitrogen and carbon dioxide. This keeps the longevity of meat products up to 10 weeks. Chilling is mostly done closer to the meat's freezing point of - 15-degree centigrade to eradicate the effects of pathogens and development of harmful organisms. However, some pathogens are only inhibited at this temperature, for example, the harmless pseudomonas species found on the surface vacuum and chilled meat (ur Rahman, et al, 2018).
There are some dangers of freezing or chilling meat. For example, if the meat is put to temperatures below 10 degrees centigrade before the pH falls below 7, contacting of muscle fibers occurs causing the meat to be tough after cooking. Another problem which occurs is exudation of tissue fluids from contraction of muscle tissue during thawing (Savanovi? & Gruji?, 2017).
In the ancient times, meat was preserved by smoke from the wood fire. Nowadays there are effective methods like the use of a smoke generator. Products from wood smoke enhance appearances and flavor. For long storage, intensive smoking is encouraged which dries the meat from hot air and deposition of enhancers on the meat surface. However, intense smoking creates a detrimental effect on the color and flavor of the meat. The recent technology is to apply a solution of smoke constituents which reduces the level of unwanted substances as well as flavor ("Meat and meat products in human nutrition ...," n.d.).
This idea was introduced in 1960 to allow salt penetration in meat. Chopped meat is injected with salt or immersed in the solution and then tumbled. A salt solution at 2 to 8 % are used with sometimes polyphosphate used to extract myosin which is a water-soluble protein. The reaction between the protein and the salt improves the water holding capacity in meat (Offer, 1988). The strong gel produced from the setting proteins bind the meat together to allow slicing and shaping.
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