meats

Nutrient Content

• Protein: An excellent source (7 grams per ounce)
• Fat: Varies across types and cuts
• Carbohydrates: none

Types of Meat

Composition of Meat

• Structure of meat is composed of:
• Water
• Muscle
• Connective tissue
• Adipose (Fatty) Tissue
• Bone
• The proportion of each of the components listed above varies according to animal and anatomy

Muscle

• Made up of individual muscle cells (muscle fibers)
• Each fiber is surrounded by an outer membrane (sarcolemma)
• Each fiber is filled with cell fluid and a bundle of muscle fibriles
• Smaller fibrils = finer bundles, creating a delicate and velvety texture
• Serve as the contractile components of the muscle fiber
• Fibrils
• Play an important role in contraction and relaxation
• Each muscle fibril is segmented (Sarcomeres)
• Sarcomeres contain 2 proteins: actin (thin) and myosin (thick)
• Contraction occurs when sarcomeres shorten when thin and thick slide past eachother
• Shortening creates a protein called actinomyosin
• Energy for muscle contraction is adenosine triphosphate (ATP)

Muscle Types

• In order to make large amounts of ATP for energy, you need Oxygen (O2)
• There are 2 types of muscles:

Pigments

• Color of meats come primarily from pigment containing proteins
• Hemoglobin transports O2 throughout the body; found mostly in bloodstream
• Myoglobin receives O2 from bloodstream and stores it in muscle
• Higher myoglobin concentrations = more red color
• Factors influencing myoglobin concentration:
• More myoglobin in heavily exercised muscles due to higher oxygen needs
• More myoglobin in older animals as they have had more oxygen flow through muscles
• Species and genetics
• Fast twitch fibers correlate to lighter meat and lower myoglobin count
• Slow twitch fibers correlate to redder meat and higher myoglobin count
• Exposure to oxygen changes color:
• Myoglobin (purplish red) + O2 => Oxymyoglobin (bright red) + O2 => Metmyoglobin (brownish red)
• Storing meat for too long turns meat a faded color
• Effects of heat on color
• Denatures pigment-containing proteins:
• Well-done meat is grayish brown

Connective Tissue

• A part of ligaments and tendons. Acts as glue that holds muscles together
• Collagen
• Most abundant connective tissue:
• Pearly white, tough, and fibrous
• Converts to a gel when exposed to moist heat
• The molecular structure of collagen are 3 polypeptide strands twisted together and held by hydrogen and covalent bonds
• Proline
• Hydroxyproline
• Glycine
• Elastin & Reticulin
• Other connective tissue proteins
• AKA silver skin
• Factors determining amount of connective tissue
• Muscles used for movement have more collagen, like the neck, shoulders, and legs
• Age, as collagen concentration increases with age
• Amount of connective tissue determines toughness and cooking method
• Cook meat with high amounts of collagen in slow moist heat at low temperatures
• Tough tissues turn into softer gelatin

Adipose Tissue

• Fat serves as insulation under the skin & padding for sensitive organs
• Cover Fat is fat that is on the outside of the meat
• Helps meat retain moisture
• Marbling is fat within muscles or intramuscular fat
• Desirable attribute
• Ranchers might feed cattle a richer grain before slaughtering
• The fat of marble meats melts and contributes to the perception of flavor and juiciness

Bone

• Bones are used to identify cuts of meat
• Bone marrow is the soft, fatty, material in the center of bones

Additives

• Organic Meats are raised without antibiotics or hormones
• Antibiotics
• Given to animals to shield from disease and promote growth
• The problem with antibiotics is that large scale use of antibiotics in livestock productions is believed to have contributed to the emergence of antibiotic resistance bacteria known as superbugs
• In 2015, the FDA issued the Veterinary Feed Directive mandating that antibiotics be administered only with veterinarian approval and there must be a withdrawal period prior to the slaughter in order to reduce residue of the antibiotics
• Hormones
• USDA allows hormone use in cattle and sheep but not in pork
• Hormones are used to promote rapid weight gain and decrease production costs
• The problem with hormones are that it causes environmental issues and it is controversial to use

Meat Inspection

• Federal Meat Inspection Act (1906)
• Inspection of meat crossing state lines or entering the US mandatory
• Inspections done by the USDA Food Safety & Inspection Service
• A guarantee that the meat is whole
• Does not ensure quality or tenderness

Meat Grading

Purchasing Cuts of Meat

• Two major types of meat cuts are wholesale and retail
• Wholesale (primal): Large cuts
• Prior to supermarket, carcass is divided into 9 wholesale cuts
• Retail cuts
• Smaller cuts sold to consumer

Meat Tenderness

• People enjoy tender meat
• Natural tenderizing is determined by various factors:
• Cut of meat
• Age of animal at slaughter
• Animal's genetics and heredity
• Diet. If the animal is grain fed, it leads to more flavor and tenderness.
• Marbling. The more marbling leads to more tenderness

Natural Tenderizing

• Rigor Mortis
• Latin for “stiffness of death”
• The stiff state after death when muscles contract
• Reverses in 1-2 days
• pH changes during rigor mortis
• Cells use glycogen in the absence of oxygen
• Glycogen causes lactic acid which reduces pH from 7 to 5.8 (more acidic)
• Increases the water holding capacity of the meat
• Increases tenderness
• Aging
• Improves tenderness and flavor
• Protease enzymes in muscle fibers break apart myofibrils
• Occurs rapidly between 3-7 days post mortem
• Dry aging (air dried) vs Wet aging (vacuum sealed bags)
• Dry aging also improves flavor by dehydrating meat

Artificial Tenderizing

• Enzymes: Proteolytic enzymes break down proteins in muscle fibrils
• Acids: Marinades w/ acids or alcohol break down outside surface of meat
• Mechanical tenderization: grinding, cubing, needling, pounding physically break down tissue