Objectives:
(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.
Tenderness measurements in meat science research
- Trained (9 = extremely tender; 1 = extremely tough) and/or consumer sensory panels (9 = like extremely; 1 = dislike extremely)
- Warner-Bratzler shear (WBS) force (1/2-inch core removed from cooked steak, parallel to the muscle fibers, and mechanically sheared: lower values more tender than higher values)
Relative rank in tenderness
| Tender | Intermediate | Tough |
|---|---|---|
| Psoas major | Biceps femoris (sirloin) | Deep pectoral |
| Infraspinatus | Rectus femoris | Latissimus dorsi |
| Gluteus medius | Adductor | Trapezius |
| Longissimus dorsi | Semitendinosus | Superficial pectoral |
| Triceps brachii | Semimembranosus | |
| Biceps femoris (round) | ||
| Source: Ramsbottom et al. (1945). Comparative tenderness of representative beef muscles. J. Food Sci. 10:497-508. doi:10.1111/j.1365-2621.1945.tb16198.x | ||
PIGLT BRASS DLTS (sirloin) or PIGLT RASSB DLTS (round)
| Very Tender WBS < 3.2 kg | Tender 3.2 < WBS < 3.9 kg | Intermediate 3.9 < WBS < 4.6 kg | Tough WBS > 4.6 kg |
|---|---|---|---|
| M. psoas major | M. longissimus thoracis et lumborum | M. supraspinatus | M. pectoralis profundus |
| M. infraspinatus | M. gluteus medius | M. gluteobiceps | M. trapezius |
| M. spinalis thoracis | M. tensor fasciae latae | M. semitendinosus | M. brachialis |
| M. serratus ventralis thoracis | M. pectorales superficiales | M. adductor | M. extensor carpi radialis |
| M. biceps brachii | M. teres major | M. vastus lateralis | M. flexor digitorum superficialis |
| M. vastus medius | M. rectus femoris | M. latissimus dorsi | |
| M. rhomboideus | M. semimembranosus | ||
| M. triceps brachii | |||
| M. subscapularis | |||
| Source: Belew et al. (2003). Warner-Bratzler shear evaluations of 40 bovine muscles. Meat Sci. 64:507-512. doi:10.1016/S0309-1740(02)00242-5 | |||
Top ten "Tender" and "Tough" cuts in shear force (pounds) from the National Beef Tenderness Survey
| "Tender" cuts | Shear force (pounds) | "Tough" cuts | Shear force (pounds) |
|---|---|---|---|
| Tenderloin steak | 5.7 | Top round steak | 11.7 |
| Top blade steak | 6.7 | Eye of round steak | 10.3 |
| Top loin steak | 7.2 | Bottom round steak | 9.7 |
| Rib roast | 7.3 | Rump roast | 9.5 |
| Rib steak | 7.4 | Eye of round roast | 9.2 |
| Ribeye steak | 7.5 | Chuck roll steak | 9.2 |
| Chuck roll roast | 7.6 | Chuck tender steak | 9.0 |
| Clod roast | 7.9 | Top round roast | 9.0 |
| Round tip roast | 7.9 | Bottom round roast | 8.9 |
| Top sirloin steak | 8.0 | Round tip steak | 8.9 |
| Source: Morgan et al. (1991). National Beef Tenderness Survey. J. Anim. Sci. 69:3274-32-83. doi:10.2527/1991.6983274x | |||
Key findings:
- Tenderloin steak and top blade steaks ranked first and second.
- Top round steak ranked last.
- Roasts were more tender than steak counterparts.
Differences among muscles
- Actomyosin effect
- Background effect
- Bulk density or lubrication effect
Differences among muscles because:
Actomyosin effect
Sarcomere length
Muscle fiber diameter
Sarcomere/fragment
Background effect
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
| Trait | "Tender" | "Tough" |
|---|---|---|
| Sarcomere length | 3.6 µm | 1.8 µm |
| Muscle fiber diameter | 40 µm | 80 µm |
| Sarcomere/fragment | 6 | 15 |
| Amount of stromal protein | 3 mg/g | 8 mg/g |
| Size of elastin fibrils | .6 µm | 4.0 µm |
| Collagen solubility | 28% | 6% |
| 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.