(1) To identify the tender, intermediate and tough major muscles of the carcass.
(2) To demonstrate the reasons for differences in tenderness among muscles.
(3) To show the relative differences in chemical and histological measurements between tough and tender meat.
Reading material: Principles of Meat Science (4th ed.), Chapter 12, pages 233 to 246.
Relative rank in tenderness
|Psoas major||*Biceps femoris (sirloin)||Deep pectoral|
|Infraspinatus||Rectus femoris||Latissimus dorsi|
|Longissimus dorsi||Semitendinosus||Superficial pectoral|
|*Biceps femoris (round)|
PIGLT BRASS DLTS (sirloin)
PIGLT RASSB DLTS (round)
Top Ten “Tender” and “Tough” Cuts in Shear Force (pounds) from the National Beef Tenderness Survey
Top round steak
|Top blade steak||6.7||
Eye of round steak
|Top loin steak||7.2||
Bottom round steak
Eye of round roast
Chuck roll steak
|Chuck roll roast||7.6||
Chuck tender steak
Top round roast
|Round tip roast||7.9||
Bottom round roast
|Top sirloin steak||8.0||
Round tip steak
Source: Morgan et al. (1991).
Shear force = Pounds of force to shear one-half-inch cores, removed parallel to the muscle fibers, of cooked muscle from steaks and roasts.
Differences among muscles
1. Actomyosin effect
2. Background effect
3. Bulk density or lubrication effect
Differences among muscles because:
Muscle fiber diameter
Concentration of stromal proteins
Size of elastin fibrils
Solubility of collagen
Bulk density or lubrication effect
Amount of marbling
Distribution of marbling
Traits of “Tender” and “Tough” Meat
|Sarcomere length||3.6 µm||1.8 µm|
|Muscle fiber diameter||40 µm||80 µm|
|Amount of stromal protein||3 mg/g||8 mg/g|
|Size of elastin fibrils||.6 µm||4.0 µm|
|Amount of marbling||7%||2%|
|Distribution of marbling||extensive||collected|
Additional factors affecting meat tenderness
1. Breed type
Bos indicus (Brahman, Sahiwal, etc.) breeds tend to be tougher than Bos taurus breeds (Angus, Hereford, etc.). Bos indicus has greater amounts of calpastatin, a protein that interferes with postmortem degradation of muscle.
2. Locomotive versus support muscles
Less connective tissue in support muscles.
3. Quality grade effects
Prime has more marbling than Choice and Choice has more than Select.
4. Degree of doneness
As meat is cooked to more advanced degrees of doneness, the tougher it will get. Marbling helps to “insure” acceptable tenderness at higher levels of doneness.
Review of Material — What the student should know:
(1) The fundamental factors related to differences in meat tenderness.
(2) The role that actomyosin effects, background effects, and bulk density/lubrication effects plays singularly or in combination in meat tenderness.
(3) The relative differences in numerical values between “tender” and “tough” meat.