Introduction to Meat Science and Composition

Vocabulary flashcards covering meat classifications, muscle histology, connective tissues, protein fractions, lipid types, and chemical composition.

Meat

The edible portion of mammals—the flesh of animals used for food—generally defined as skeletal muscles, but in a broader sense including organs and glands.

Red Meat

Meat derived from mammals, including beef, veal, lamb, and mutton, containing high concentrations of myoglobin.

White Meat

An inclusive culinary classification referring to meat from poultry species such as chicken, turkey, and duck.

Steer

A young male cattle (also called a bullock) raised primarily for beef production.

Heifer

A young female cattle that has not yet calved.

Veal

Meat originating from young calves of beef cattle, either male or female, between the ages of $3\,\text{weeks}$ and $3\,\text{months}$.

Lamb

Meat originating from domestic sheep that are less than $14\,\text{months}$ of age.

Mutton

Meat originating from domestic sheep that are over $14\,\text{months}$ of age (often $1\text{--}3\,\text{years}$ old).

Chevon

Culinary term referring to the meat harvested from adult domestic goats.

Capretto

Culinary term for meat derived from young goats (also referred to as kid).

Chemical Composition of Lean Meat

Muscle tissue containing approximately $72\text{--}75\%$ water, $15\text{--}20\%$ protein, $5\text{--}40\%$ fat, and minimal carbohydrate ($0.5\text{--}1.5\%$ stored as glycogen in muscle).

Myofibrillar Proteins

Proteins making up approximately $13\%$ of muscle protein that are responsible for muscle contraction and relaxation and are soluble in concentrated salt solutions; includes actin and myosin.

Sarcoplasmic Proteins

Soluble metabolic proteins constituting about $7\%$ of muscle proteins, found in the sarcoplasm, and soluble in water or dilute salt solutions; includes cellular enzymes and pigments.

Stromal Proteins

Connective tissue proteins making up approximately $2\%$ of muscle protein that provide structural support and are insoluble in water or neutral salt solutions; includes collagen, elastin, and reticulin.

Actomyosin

The overlapping protein complex formed between actin and myosin during muscle contraction.

Myoglobin

A sarcoplasmic heme pigment located in muscle fibers that binds and stores oxygen for cellular metabolism and governs meat color.

Depot Fat

Adipose tissue deposits stored subcutaneously, between muscles (intermuscular), or within body cavities around organs; composed of $>90\%$ triglycerides.

Entrapped Water (Immobilized Water)

The major portion of water in meat (up to $85\%$) retained by capillarity forces within the protein-dense myofibrillar network between thick and thin filaments.

Free Water

Water located in the sarcoplasm, nuclei, organelles, and between muscle fibers that is held weakly and easily lost.

Ruminant Fatty Acids

Lipids from ruminants (beef and lamb) characterized by a higher proportion of saturated fatty acids (SFAs) and lower polyunsaturated fatty acids (PUFAs) due to microbial biohydrogenation in the rumen.

Skeletal Muscle

Striated, voluntary muscle tissue that constitutes the primary component of an animal carcass, providing body locomotion and weight support.

Cardiac Muscle

Striated, involuntary muscle tissue restricted exclusively to the heart, providing continuous rhythmic contractions to circulate blood.

Smooth Muscle

Non-striated, involuntary visceral muscle found within internal organs including the digestive tract, reproductive tract, and blood vessel walls.

Epimysium

A relatively thick outer connective tissue sheath that encloses the entire muscle.

Perimysium

The sheath of connective tissue that groups and surrounds bundles of muscle fibers (fascicles).

Endomysium

The delicate layer of connective tissue that directly envelopes each individual muscle cell (fiber).

Myofibril

A cylindrical contractile component inside a muscle fiber, $1\text{--}2\,\text{mm}$ thick, characterized by alternating cross-striated A-bands and I-bands.

Sarcomere

The fundamental repeating structural and contractile unit of striated muscle, defined as the segment extending from one Z disc to the next Z disc.

A-Band

The dark, anisotropic cross-striation band of a myofibril consisting of thick filaments (myosin) and overlapping thin filaments.

I-Band

The light, isotropic cross-striation band of a myofibril composed primarily of thin filaments (actin).

Collagen

The most abundant connective tissue protein in animals, which contracts when heated dry but hydrolyzes and converts into gelatin in moist-heat cooking.

Gelatin

A water-soluble protein product derived from collagen that has been cooked long enough to break down its triple-helix structure into smaller peptides.

Elastin

A yellow-colored, elastic connective tissue protein found in blood vessel walls and ligaments that does not soften or tenderize during cooking.

Reticulin

A minor connective tissue protein found mainly in younger animals, functioning as a structural precursor to collagen or elastin.

Subcutaneous Fat

Adipose tissue deposited directly underneath the skin (also known as cover fat), visible after skinning.

Intermuscular Fat

Adipose tissue deposited between adjacent muscle bundles, commonly known in butchery as seam fat.

Intramuscular Fat (Marbling)

Flecks and streaks of adipose tissue dispersed within the lean muscle mass, enhancing meat juiciness, tenderness, and flavor.

Suet

The hard, protective adipose tissue situated around the kidneys and other glandular organs of cattle and sheep.

Glycogen

The principal reserve carbohydrate stored in animal muscle and liver tissue, providing fuel for contraction through glycolysis.