Meat and Poultry Composition & Muscle Structure

Meat and Poultry Composition

• Water content is typically 70-75%
• Protein content is 15-20%
• Fat content varies from 5-30% based on animal type, breed, feed, age and cut
• Carbohydrates present include glycogen, glucose, and glucose-6-phosphate
• Minerals include phosphorus, iron, zinc, and copper
• B vitamins (niacin, riboflavin, thiamin) and vitamin A (from liver) are present

Muscle Structure

• Muscles are cross-sections of myofibrils
• Myofibrillar proteins include myosin (60%), actin (2nd most abundant), and tropomyosin (least abundant)
• Actin and myosin are responsible for muscle contractions, relaxation, and movement
• Myofibrils consist of sarcomeres: Z-line = Z-disk
• Myofilaments are arranged into sarcomeres, which are arranged into myofibrils.
• Myofibrils form bundles called fibers.
• Fibers are enclosed by sarcoplasm and sarcolemma

Post-Mortem Changes & Definition of Meat

• Rigor mortis involves lower pH, ATP depletion, contracted muscle, and occurs over 24-48 hours for softening
• Meat includes the muscle of animals, red meat, poultry, and fish, as well as organs and glands

Meat Classification

• Steer (male, castrated before maturation)
• Heifer (young female that hasn't calved)
• Cow (female with calf)
• Bull (mature male that hasn't been castrated)
• Calves are animals aged 3-8 months
• Immature bovines are males or females, 3 weeks - 3 months old that are fed milk, veal
• Lamb (up to 1 year), hogget (up to 2 years), and mutton (over 2 years) are classifications of sheep, with older meat having a stronger flavour
• Pork primarily comes from young swine
• Mature swine produce boar taint (androsterone) upon sexual maturity with testicular steroid androsterone being the primary cause of boar taint in pubertal boars (7 months)

Grades of Meat

• Grades include Prime, AAA, AA, A, rated for marbling content and age (less than 24 months)
• A grade contains 1.5% marbling
• AA grade contains 25% marbling
• AAA grade contains 67.5% marbling
• Prime grade contains 4.7% marbling
• Higher grades must have youthful animal characteristics, quality meat colour, muscle firmness, and well-developed muscles

Meat Colour

• Beef muscle is burgundy/purplish in anaerobic environments
• Myoglobin reacts to oxygen, creating bright red meat
• Beef that has turned brown during extended storage may be spoiled; check for odour and texture

USDA Beef Grades

• Prime beef has the most marbling; less than 3% of graded beef meets these criteria
• Choice beef has less marbling than prime and is the most popular
• Select beef is lower priced with less marbling, variable tenderness and juiciness
• Kobe Beef (Wagyu): Buddhist dietary ban against meat for 1000 years prior to 1868 that results in low meat and beef consumption, Wagyu cattle, bred and raised outside of Japan then shipped back for final feeding with sake/beer and massage

Cuts of Meat

• No mandatory system exists for naming retail meat cuts
• The most expensive cut is rib eye roast, short lion and sirloin cuts
• 44% of all beef sold is ground
• Leanest cuts are round and loin including sirloin, tenderloin, top loin, top round, and eye round

Poultry

• Poultry includes fowl like turkey, chicken, and duck that are all domesticated for meat
• Chicken is the most consumed meat and eggs whose popularity increases because of diet

Chickens

• Broilers/fryers are either sex, under 10 weeks old, and weigh 3–5 lbs
• Roasters are either sex, 9-11 weeks old, and weigh 6–8 lbs
• Capons are neutered male chickens, less than 4 months old, and weigh 12–14 lbs
• Cornish game hens, cross of Cornish hen with another breed, 5–6 weeks old, and weigh less than 2 lbs and are very tender
• Mature chickens are over 10 months old and are former tough breeders

Turkeys

• Turkeys are broad-breasted white
• Fryer/roaster turkeys are under 12 weeks old and weigh 7 pounds
• Young hens are under 6 months old and weigh 14 pounds
• Young toms are under 6 months old and weigh 26 pounds
• Other poultry types include ducks (7-8 weeks, 3-7 pounds) and geese (11 weeks, 6-12 pounds)

Meat Processing

• Stunning is done with electric gas
• Slaughter involves severing the carotid artery and jugular vein, bleed for 1.5-2 minutes
• Scalding is carried out in a vat of water at 52 degrees for 15-150 seconds, temperature not to exceed 53.5 degrees to prevent discoloration
• De-feathering is by hand, drum plucker, or bowl plucker
• Finishing and waxing are used for ducks, quails, and turkeys
• Evisceration involves removing organs, head, and neck
• Washing is done with chlorinated water, feet are removed, air or slush ice cooling air chill or wet chill birds, and a spray wash cabinet with a brush and chlorinated water is used
• High-tech portioning uses water jet cutters controlled by a computer to trim fat, portion, and de-bone chicken
• Grading (Canadian standards) applies only to whole birds, no grades apply to cut-up poultry, and grading is based on cosmetic differences

Explores meat and poultry composition, including water, protein, and fat content, as well as carbohydrates and minerals. Covers muscle structure, myofibrillar proteins, and post-mortem changes like rigor mortis. Crucial for understanding meat quality.