Meat Tenderness and Tenderization

• Meat Quality

  • fresh meat must first look good, then meet visual expectation by tasting good

  • Color and texture affect visual preference

  • Palatability: Tenderness, flavor, and juiciness affect taste preference

It has been recognized for a long time that muscles within and between carcasses vary in tenderness.

Tenderness is a palatability trait that has the greatest influence on consumer satisfaction and is therefore an economically important trait; thus it is important to know what factors affect meat tenderness and how to manage those factors.

• Differences in tenderness among muscles can be attributed to one or more of these effects:

  • Actomyosin (muscle fiber) effect

    • sarcomere length: shorter sarcomere = tougher

    • Muscle fiber diameter: larger fibers = tougher

    • White fibers

    • Number of Sarcomeres and Fragmentation: more fragmentation = more tender

  • Background (connective tissue) effect

    • stromal protein concentration

      • EX: collagen, elastin, reticulin

    • Solubility of collagen (insoluble): decreases tenderness

    • Size of elastin fibrils

  • Bulk density and Lubrication (marbling) effect

• Connective Tissue Review

  • connective tissues in meat are affected by the age (maturity) of the animal hormones and muscle function

    • Maturity and Hormones cause:

      • Cross-linking between collagen fibers, which decreases meat tenderness

      • A decrease in the heat solubility of collagen, which also decrease meat tenderness

    • Muscle Function and Connective Tissues (CT):

      • Muscles used for locomotion have more CT than muscles used for skeletal support; therefore, muscle associated with the limbs (leg, shoulder, chuck, round) have more CT and are generally more tough than muscles found in other parts of the carcass.

• The bulk density/lubrication effect, also known as the marbling effect, is estimated by:

  • amount of marbling

  • distribution of marbling

• Marbling

  • Density: fat is less dense, and therefore more tender than muscle and connective tissue

  • Lubrication: Fat melts during cooking and the oil lubricated the bite during chewing, allowing muscle bundles to slide down during chewing, which is perceived as tender

  • Juiciness: improves perception of tenderness; water and lipid contribute to cooked meat juiciness, thus, more fat = oil/lipid after cooking

• Meat Tenderization

  • Methods to improve meat tenderness must:

    • cause post-rigor mortis sarcomeres to be longer (prevent shortening during rigor mortis development)

      • Cold Shortening: is a cold induced shortening of the sarcomere during carcass chilling

        • Can be prevented by accelerated glycolysis or slower chill rates early postmortem

      • Ways to make sarcomeres longer:

        • Holding carcasses at high temperatures immediately after slaughter (accelerates glycolysis)

        • Electrical stimulation of hot carcasses at slaughter to deplete ATP (accelerates glycolysis)

        • Feeding live animals to deposit excess subcutaneous fat (slows chill rate)

        • Stretching or the maintenance of tension on sarcomeres during rigor mortis onset will prevent or decrease sarcomere shortening

          • Hung by the H bone so the weight of the leg helps release tension

            • drawback is less space

    • Disrupt the integrity of the myofibrils

      • Endongenous Enzymes: naturally present in meat and cause the proteolysis of meat during aging, which improves meat tenderness.

    

    • • Higher cowpastatin level differences: bos indicus vs. taurus

      • Endogenous enzyme activity can be enhanced by:

        • Cooler aging

          • 1 to 6 weeks at 0 to 3 ∞C

        • Holding/storing meat at high temperatures (postrigor)

          • 20 ∞C for 24 h

        • Holding/storing carcasses at high temperatures (prerigor)

          • 16 ∞C for 16 h

        • High voltage electrical stimulation of carcasses

          • disrupts lysosome causing the release of cathepsin

        • Calcium chloride solution infusion into meat pre- or post-rigor

          • consumers are apprehensive towards “injecting meat”

        • Heat activated – activated during cooking

        • Examples: Swifts Pro-Ten and Adolf’s Meat Tenderizer

        • Usually added during marination as an ingredient

        • Most common enzymes used are derived from tropical plants:

          • Papain – from papaya

          • Bromalin – from pineapple

          • Ficin – from figs

          • Rhozymes – fungal enzymes with proteolytic activity can be added to meat to improve meat tenderness

          • Consumers are less apprehensive towards “natural injections”

        • High Voltage Electrical Stimulation will tear or sever myofibrils, causing an increase in tenderness.

        • Mechanical severance can come from equipment designed to sever

          • Blade tenderization

          • Cubing (more severe)

    • Disrupt the integrity of the connective tissues