Meat marbling

Marbling is a term used to defined the fat content inside of beef muscle, known as intramuscular fat. Intramuscular fat is the flecks of white fat found within the actual lean muscle. Traditionally, this marbling is a top trait that determines the quality of meat. Marbling is most important in influencing the sensory attributes of flavour and juiciness and to a limited extent the tenderness of the product. Of these attributes, flavour may be the characteristic that is most dependent on marbling.

It impacts the tenderness, moistness, and overall flavour and has become one of the most well-known elements of steak evaluation. Wagyu beef is a superior beef, with the greatest amount of beef marbling and the max amount of oleic acids.

Marbling impacts steak's juicy flavours. Marbling keeps the meat moist during cooking, so natural juices don't evaporate in the pan.

Marbling that is fine-textured (small flecks) and uniformly distributed is preferred over marbling that appears as large, coarse flecks of intramuscular fat. High-quality marbled beef contains a high level of marbling, which translates to a high level of healthy monounsaturated fatty acids. The term “quality grade” is used by meat scientists to describe the level of marbling, along with other factors including fat thickness on the outside of the carcass, age of the cattle, and coloration of the beef.

There are eight total quality grades: Prime, Choice, Select, Standard, Commercial, Utility, Cutter and Canner. They have been used by the beef industry since 1927. Across almost every cut on beef carcasses, USDA Prime grade has the highest marbling content and costs the most on the market. Choice grade is accessible in a retail outlet like a grocery store.

The most lean and least marbled cuts tend to come from the legs, shoulder, and rump, where the muscles get a lot of exercise and result in much leaner cuts.
Meat marbling

Sources of meat

Of the many foods obtained from the land, humans tend to prefer animal foods, mainly beef, pork, poultry and mutton as well as their by-products e.g. cheeses, milk and eggs.

With the exception of pigs, meat may be obtained from animals specifically raised for meat production, or from animals surplus to other requirements. Thus beef may be obtained either from specially raise animals, male and other surplus calves or cows at the end of their milk-producing career.

The most important sources of meat in the United States is cattle. Horses have not been an important source of meat, except during wars when meat shortages have occurred.

However, in Africa, Middle Eastern and some Asian countries, especially in arid and semi-arid regions, camel meat is regarded as a main source of animal protein that equals and in some cases surpasses other meats in commercial importance.

The term red meat refers to flesh from beef, pork, lamb and goat. The term white meat refers to meat from poultry like chicken and turkey.

A market exists for domestically produced game-type meats. These include buffalo, bear, elk, kangaroo and rabbit. They are usually expensive and selected mainly as gourmet items. The meat is generally tough and very “gamey”. In general, this type of meat is prepared in moist heat. Meat usually contains 20-35% protein (weight basis).

Meat and meat products can be important sources of vitamin B6, vitamin B12, iron, zinc and selenium. The fat content varies from below 1% to above 40%. The fatty acid composition also varies between species.
Sources of meat

Collagen content in meat

The collagen content of meat and meat products is often of particular interest to food processors because it alters batter gelation properties and in Germany the levels of collagen in meat products are governed by food laws.

Textural differences can be related to connective tissue properties as well as aging potential. Buffalo breeds have high collagen content, low collagen solubility and a tough texture.

The collagen content was 10-13% of total protein. Connective tissue in the buffalo meat had a bigger contribution to toughness.

The total concentration of connective tissue components were not closely related to the scores for muscles fiber tenderness.

Tenderness is highest in meat from very young animals but subsequently declines with age and physical activity, along with an increase in the amount of collagen and its degree of complexity.

The collagen content increased significantly with advancing age of the male Murrah buffaloes. A hydroxyproline content of 0.12% was recorded in high protein diet fed young male buffaloes.

The muscles from young buffaloes of 1 to 2 years showed less collagen (0.91 to 1.71 g/100g) than from 12 old buffaloes (1.16 to 2.23 g/100g).

During the growth and development of meat animals, covalent cross-links increase in number and collagen fibers become progressively stronger. Therefore, meat from older animals, tends to be tougher than meat from the same region of younger animals.

The water solubility of collagen under the action of heat decreases gradually with increasing age, with the result that the meat progressively becomes less tender.
Collagen content in meat

Meat tenderizers

Meat tenderizers soften tough meat by breaking down collagen with enzymes. Most powdered tenderizers use the plant enzyme papain as the tenderizing agent.

Commercial meat tenderizers containing enzymes are available for consumers to use, but they are effective only on fairly thin cuts of meat because they penetrate to a depth of only ½ to 2 millimeters. In general tenderizers work on the surface of the meat.

Meat tenderizers contain enzymes that break down proteins of muscle, fibers and connective tissue. They are sprinkled on meat which as then pierced with a fork to drive the enzymes below the surface, where they hydrolyses cell proteins tissue where activated by the heat of preparation.

Meat tenderizers enzymes extracted from a number of plants, including papaya, pineapple fig, kiwi and ginger.

The enzymes act slowly at refrigerator or room temperature, and some five times faster between 60 and 70° C, so nearly all the tenderizing action takes place during cooking.

Some of the best tenderizers for meats have an alcohol base as beer and hard coder. The fermentation chemical process gives these products the tenderizing quality.
Meat tenderizers

Listeria contamination in meat and meat products

Listeriosis caused by Listeria monocytogenes is a significant public health concern and as a result of its clinical severity and high mortality rates, worldwide food borne outbreaks in which meats products were implicated have occurred.

Although Listeria monocytogenes was recognized as a cause of human disease for more than 7 years, it was not until the 1980s that food borne association as realized and accepted. The number of Listeria outbreaks is large.

The number of voluntary recalls by food processors due to know or suspected Listeria – contaminated food products, is even larger.

Listeria has exceptional growth conditions. The organism grows well on minimal nutrients, and at temperature raging from 1 to 45 °C, and can grow in biofilms that coat surfaces and prevent Listeria from being removed by cleaning or killed by disinfectants. It can grow at pH range 4.4 to 9.6.

Listeria can produce biolfim on a variety of surfaces commonly used in food processing plants, including stainless steel, nylon, teflon and polyester floor sealer.

Although Listeria monocytogenes is frequently present in raw meat the pathogen is of higher concern for the safety of products that may be consumed without further cooking.

Occurrence of the pathogen in cooked ready to eat products is predominantly due to recontamination during handling procedures such a slicing and packaging.
Listeria contamination in meat and meat products

Beef fat content

Fat is an essential component of meat for sensory perception of juiciness, flavor and texture, Fat in meat also supplies fatty acids that cannot be synthesized by humans.

However, regular consumption of red meat is associated, epidemiologically with increased risk of coronary heart disease, due to its fat composition.

Fat content can vary widely, according to the grade of meat and its cut. Several cuts of beef are lower in fat than an equal amount of some poultry choices.

Ground beef is a product with a high fat content; even extra lean ground beef gets more than 53 percent of its calories from fat and 21 percent from saturated fatty acid.

Fat especially in the form of marbling, melts during heating, thereby increasing the flavor and perceived tenderness of the meat.

According to research at the University of Missouri in 1985, beef lose mass when cooked, but the lean beef loses water and the regular beef loses fat and cholesterol.
Beef fat content

Tenderizing meat by enzymes

Tenderizing meats may be desirable prior to cooking. The less tender cuts of meat may be artificially tenderized to break down the proteins of muscle or connective tissue.

The amount and distribution of connective tissues and the size of both muscle fibers and bundles of fibers determine the tenderness of meat.

Meat can be tenderized by the use of natural and artificial tenderizers. The tenderizing action results from the hydrolysis of the amide linkages of the protein in the meat. Most powdered tenderizers use the plant enzyme papain as the tenderizing agent. The art of using enzymes for tenderizing meat is an old one. Wrapping of meat in papaya leaf before cooking results in tenderization.

Commercial papain sprinkled on the surface of meat penetrates to a depth of 1 mm per hour. In general tenderizers work on the surface of the meat.

Some enzymes treat the muscle tissue and others treat the connective tissue. For example, the enzymes chymopapain, or papain and ficin exert a greater effect on tenderising muscle fibers than connective tissue, while bromelain degrades connective tissue more than the myofibrils.

Meat tenderizers enzymes extracted from a number of plants, including papaya, pineapple fig, kiwi and ginger.

The enzymes act slowly at refrigerator or room temperature, and some five times faster between 60 and 70°C, so nearly all the tenderizing action takes place during cooking. Exceeding 85 °C denatures the enzyme, thus inhibiting its activity.

Some of the best tenderizers for meats have an alcohol base as beer and hard coder. The fermentation chemical process gives these products the tenderizing quality.
Tenderizing meat by enzymes