Myofibrils in muscle fiber

Skeletal muscles vary in shape and size. The central portion of a whole muscle is called the belly. The belly comprises smaller compartments called fascicule.

Each fasciculus consists in turn of approximately 100 to 150 individual muscle fibers that range from 1 to 40 micrometers in length and 10 micrometers in dimeter.

A muscle fiber comprises a number of long, thin, cylindrical rods known as myofibrils, the essential contractile units of muscle, which are separated from one another by a highlight specialized network of tubules the sarcoplasmic reticulum.

The sarcoplasmic reticulum, a specialized organelle that’s stores and releases calcium, is an interconnecting network of tubules running parallel with and wrapped around the myofibrils.

The major significant of the sarcoplasmic reticulum is its ability to store, release and take up calcium and thereby control muscle contraction.

Myofibrils are bathed in an aqueous fluid (sarcoplasm), which is about 75-80% water and contains mitochondria, enzymes, glycogen, adenosine triphosphate, creatine, phosphate and myoglobin.

Myofibrils range in diameter from 1 to 2 micrometers. They are grouped in clusters and run the length of the muscle fiber. In turn each myofibril comprises long, thin strands of serially linked sarcomeres. Sarcomeres are the functional unit of a muscle.
Myofibrils in muscle fiber

Meat protein

Proteins are the basic functional components of various high protein processed food products and thus determine textural, sensory and nutritional properties.

Protein is the dominant component in meat. Meat is rich in the essential amino acids – lysine, leucine, isoleucine and sulfur containing amino acids and in this sense meat is a high quality protein.

Meat is composed of three tissue: muscle tissue, connective tissue and adipose tissue. Inside the muscle tissue cell membrane, there are myofibrils containing alternating thin and thick protein filaments, namely the actin and myosin, which contract and relax in the living animal.

Myofibrils are the main component of meat structures which occupy about 70% of the volume of meat. 

Connective tissue is made up of protein and mucopolysaccharides. It is located throughout the muscle and determines the degree of meat tenderness.

Collagen is the most abundant protein found in mammals – in bone, cartilage, tendons, and ligament, enveloping muscle groups and separating muscle layers. The collagen content of meat and meat products is often of particular interest to food processors because it alters batter gelation properties.

The meat proteins, especially myosin, actin and to some extend tropomyosin, are the main water binding components in muscular tissue.

Interactions between meat proteins and water significantly affect the textural properties of meat. Approximately 97% of the water holding capacity of meat is related to the myofibrillar protein fraction. 

Protein meats contain small quantities of carbohydrates. When protein are heated to about 154 °C the amino acids in the proteins chains react with carbohydrate molecules and undergo a complex chemical reaction which resulted they turn brown and develop richer flavors. This reactions is called Maillard reaction.
Meat protein

Red Meat and Breast Cancer

Red Meat and Breast Cancer
Eating red meat may raise a woman’s risk of a common type of breast cancer, and vitamin supplements will do little if anything to protect her heart.

Women who ate more than 1½ servings of red meat per day were almost twice as likely to develop hormone-related breast cancer as those who ate fewer than three portions per week, one study found.

The other — one of the longest and largest tests of whether supplements of various vitamins can prevent heart problems and strokes in high-risk women — found that the popular pills do no good, although there were hints that women with the highest risk might get some benefit from vitamin C.

Antioxidants like vitamins C and E attach to substances that can damage cells. Scientists have been testing them for preventing such diseases as Alzheimer’s and cancer.

More than 8,000 women were randomly assigned to take vitamin C, E or beta carotene alone or in various combinations for nearly a decade. An additional 5,442 women took folic acid and B vitamin supplements for more than seven years.

Overall, there was minimal evidence of any cardiovascular benefit of any of these antioxidants and people should not start or continue taking them for that purpose. Among the 3,000 women in the study who had no prior heart disease but three or more risk factors for it, those who received vitamin C alone or in combination had a 42 percent lower risk of stroke. Smokers taking C also had a 48 percent lower risk.
Red Meat and Breast Cancer