Meat Texture Lecture Notes

Introduction to Meat

  • Discussion of meat structure and factors influencing tenderness and toughness.

  • Focus on cooking methods for beef, pork, and lamb, while poultry and fish are not covered in this course.

  • Two meat lectures planned: 1) Structure, tenderness, toughness, and cooking methods; 2) Color and flavor of meat.

Structure of Meat

  • Meat consists of three main components: muscle fibers, connective tissue, and fat.

Muscle Fiber Proteins

  • Also known as myofibular proteins or actomyosin.

  • Key proteins:

    1. Actin – small spherical proteins arranged like strings of beads, forming thin filaments.

    2. Myosin – shaped like a golf club with filament and head parts, forming thick filaments.

  • Actin and myosin combine in a structure known as a sarcomere, which is the fundamental unit of muscle fibers.

  • A sarcomere spans from Z line to Z line, with contraction facilitated by myosin heads interacting with actin molecules, resulting in shorter, thicker sarcomeres.

Arrangement of Muscle Fibers

  • Sarcomeres are arranged end-to-end to form fibrils.

  • A bundle of fibrils forms a muscle cell or muscle fiber, which is covered by a membrane called the sarcolemma.

  • Muscle fibers are grouped into bundles surrounded by connective tissue, forming larger muscles which connect to bones via tendons.

Connective Tissue

  • Consists of a ground substance embedded with collagen and elastin fibers.

    • Collagen:

      • Appears white and is structured as three twisted ropes; does not stretch; converts to gelatin when heated.

    • Elastin:

      • Less common, yellowish, and stretches; remains intact during cooking, contributing to toughness in certain muscles.

  • Amount and quality of connective tissue vary among muscles and species:

    • More connective tissue in frequently used muscles (e.g., legs, neck); less in less used (e.g., loin).

    • Cross-linking of collagen increases with the age of the animal, making it tougher and requiring longer heating for gelatin conversion.

Fat in Meat

  • Fat is found both within muscle tissue (marbling) and between muscle bundles, influencing meat quality and flavor.

  • Common fatty acids in meat include:

    • Oleic acid (18 carbons, 1 double bond)

    • Palmitic acid (16 carbons, saturated)

    • Stearic acid (18 carbons, saturated)

  • Meat quality grades are based partly on fat content, with Prime cuts having desirable marbling.

Factors Affecting Tenderness

  • Tenderness is crucial for meat edibility; various factors influence it:

    1. Connective Tissue: More lead to increased toughness, but its amount alone does not indicate tenderness, as younger animals may have tough connective tissue.

    2. Collagen and Solubility: Higher collagen levels and cross-linking lead to tougher meat.

    3. Elastin: Does not break down during heating, contributing to toughness.

    4. Presence of Fat: Dilutes connective tissue, promoting tenderness.

    5. Cooking Method: Generally tenderizes connective tissue, improving tenderness (collagen solubilization).

Impact of Muscle Fiber Proteins on Tenderness

  • After slaughter, muscles transition to rigor mortis, increasing toughness due to stable actin-myosin links.

  • Aging meat weakens muscle proteins, allowing for greater tenderness due to enzyme activity.

  • Mechanical processing (grinding, pounding) reduces toughness by damaging muscle fibers and connective tissue.

  • Heating affects muscle proteins:

    • Denaturation increases toughness with higher temperature.

Cooking Methods

  • Two primary cooking strategies: Dry heat (for tender cuts) and moist heat (for tougher cuts).

Dry Heat Methods

  • Suitable for tender cuts:

    • Roasting: Cook meat on a rack at 325–350°F; lower temperatures enhance juiciness.

    • Broiling: Place meat under heating element, promotes browning and flavor.

    • Frying: Cook meat in a bit of fat for heat transfer and non-stick characteristic.

Moist Heat Methods

  • Used for tougher cuts to prevent drying out:

    • Braising: Brown meat, add small liquid amount, cover, and slow-cook to breakdown connective tissue.

    • Boiling: Less common, generally inferior in flavor compared to braising.

Tenderizing Additions

  • Salt: Enhances myofibular protein water solubility, reducing cooking loss from syneresis. Brining improves water retention during cooking.

    • Example of cooking loss data shows decreased weight loss with increased salt in meat at various cooking temperatures.

  • Enzymes: Used as meat tenderizers (e.g., papain, ficin, bromelain); should be applied to raw meat before cooking to allow for action before denaturation occurs during heat.