Meat Tenderness and Tenderization

Palatability

Taste preference

• Tenderness, flavor, and juiciness affect this

What is the most economically important trait of meat?

Tenderness

• Has the greatest influence on consumer satisfaction

What 3 effects determine the tenderness of muscles?

1. Actomyosin (muscle fiber) effect

2. Background (connective tissue) effect

3. Bulk density and Lubrication (marbling) effect

What measures the actomyosin (muscle fiber) effect?

• Sarcomere length

  • Shorter = contracted = tougher

• Muscle fiber diameter

  • Type 1 fiber = smaller diameter = more tender

  • Larger = tougher

• # of sarcomeres / fragment

  • In resolution phase, less degredation = tougher

What measures the background (connective tissue) effect?

• Stromal protein concentration

• Solubility of collagen

  • Collagen is insoluble; becomes gel-like when cooking

• Size of elastin fibrils

  • Similar concept to muscle fiber size; larger = tougher

Stromal proteins

Connective tissue proteins

• Collagen, elastin, reticulin (veins and arteries)

Denuding

Removing all external fat and connective tissue from the surface of a meat cut

What are connective tissues in the meat affected by?

Age (maturity), hormones, and muscle function

How does age affect connective tissues?

Older animals have more collagen, decreasing tenderness

• Also decreases heat solubility of collagen

Muscles associated with the limbs (ex: leg, shoulder, chuck, round) should have (less/more) connective tissue, making them (tougher/more tender) than muscles found elsewhere.

More, tougher

Middle meats

Come from supportive muscles

• More tender due to lower # of connective tissue

Locomotive meats

Come from locomotive muscles (ex: leg, shoulder, chuck, round)

• Tougher due to increased # of connective tissue

What measures the bulk density (lubrication) effect?

• Amount of marbling

• Distribution of marbling

  • Same as beef quality grades!

Bulk Density / Lubrication / Muscle Fiber Dilution Theory

Theory developed to explain the perceptions of tenderness as it relates to marbling

Density

Fat is less dense and, thus, more tender than muscle or connective tissue

• Part of the Bulk Density / Lubrication / Muscle Fiber Dilution Theory

Lubrication

Fat melts during cooking and the oil lubricates the bite during chewing, allowing muscle bundles to slide during chewing, which is perceived as tender

• Part of the Bulk Density / Lubrication / Muscle Fiber Dilution Theory

Juiciness

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

• Part of the Bulk Density / Lubrication / Muscle Fiber Dilution Theory

Halo effect

Perceived increase in tenderness due to the amount of fat in the product

What must methods to improve meat tenderness do?

1. Cause post-rigor mortis sarcomeres to be longer

   1. Prevent shortening during rigor mortis development

2. Disrupt the integrity of the myofibrils and/or

   1. Can be as simple as cutting across the grain

3. Disrupt the integrity of the connective tissues

   1. Still insoluble

How can we cause sarcomeres to increase in length?

• Holding carcasses at high temps immediately following 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; prevents cold shortening)

How can we prevent cold shortening?

Accelerating glycolysis or using slower chill rates early postmortem

Stretching and sarcomere length

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

TAMU Tenderstretch and why isn’t it used more often?

Uses the weight of the leg to maintain tension on the longissimus muscle sarcomeres during chilling/rigor mortis development—stretching.

• Carcass is hung by the obturator foramen of the H bone.

• Takes up more space than is readily available at most meat plants

How can you disrupt the integrity of myofibrils?

Via endogenous or exogenous enzymes

Endogenous enzymes

Enzymes found within the body

• Calpain

• Cathepsin

• Calpastatin

Calpains

Endogenous enzyme that depends on calcium

• Capable of postmortem proteolytic degradation of the Z-lines during the resolution phase

• Improves tenderness

Cathepsins

Endogenous lysosomal enzyme

• Capable of postmortem proteolytic degradation of actin/myosin during the delay phase ONLY

  • Never released during the resolution phase, even during electrical stimulation and extended aging

Calpain system

Consists of two calcium-dependent enzymes and the specific inhibitor calpastatin

What actives the caplain system postmortem?

Calcium released from the mitochondria and the SR

Calpastatin

Inhibits calpain activity

• Increases meat toughness

What cattle have higher concentrations of calpastatin?

Bulls and Bos indicus

How can endogenous enzyme activity be enhanced?

• Cooler aging

• Holding/storing meat at high temperatures (postrigor)

• Holding/storing carcasses at high temperatures (prerigor)

• High-voltage electrical stimulation of carcasses

  • Disrupts lysosome causing the release of cathepsin

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

  • Sets off calpains

Exogenous Enzymes

Enzymes that are added to the body—not naturally present—and exhibit proteolytic activity

• Heat activated—during cooking

• Usually added during marination as an ingredient

Where are most exogenous enzymes derived from?

Tropical plants

Where does the exogenous enzyme Papain come from?

Papaya

Where does the exogenous enzyme Bromalin come from?

Pineapple

Where does the exogenous enzyme Ficin come from?

Figs

How can myofibrils be severed?

• High voltage electrical stimulation

• Mechanical severence

  • Blade tenderization

  • Cubing (more severe)

• Hydrodyne

  • Detonated explosives in water-filled chambers with packaged meat

How can you disrupt the integrity of connective tissues?

• Marination with salt and acids

• Rhozymes

• Tropical plant enzymes

  • All increase tenderness

Rhozymes

Fungal enzymes with proteolytic activity that can be added to improve meat tenderness

• Ex: Aspergillus oryzae

Cooler aging meat for more than 56 days does what?

Could make connective tissue proteins susceptible to proteolysis by endogenous enzymes

What does moist heat cookery do?

Converts collagen to gelatin, improving tenderness

• Braise, stew, port roast, crock pot

What does dry heat cookery do?

Denatures connective tissue proteins with heat, improving tenderness

• BBQ brisket, pulled pork, etc

  • Long cooking at low temp (~250 Fahrenheit)

Which palatability factor is the most researched?

Tenderness

(T/F) Meat tenderness is simple to duplicate with scientific instrumentation

False. It is difficult

What factors are part of the perception of tenderness?

• Softness to tongue and cheek

• Resistance to tooth pressure

• Ease of fragmentation

• Adhesion

• Residue after chewing

Slice Sheer Force

• For hot samples

• Slices are utilized

• Straight blade

• Results have a higher numerical value

Warner-Bratzler Shear Force

• For cold or chilled samples

• Cores are utilized

• Triangular blade

• Results have a lower numerical value

Warner-Bratzler vs Slice Shear Force

• Shear force is detected with both types

• Cannot compare SSF values to WBSF values

What can shear force be compared to?

Bite force