Comparative review of muscle fiber characteristics between porcine skeletal muscles

Abstract

Meat derived from skeletal muscles of animals is a highly nutritious type of food, and different meat types differ in nutritional, sensory, and quality properties. This study was conducted to compare the results of previous studies on the muscle fiber characteristics of major porcine skeletal muscles to the end of providing basic data for understanding differences in physicochemical and nutritional properties between different porcine muscle types (or meat cuts). Specifically, the muscle fiber characteristics between 19 major porcine skeletal muscles were compared. The muscle fibers that constitute porcine skeletal muscle can be classified into several types based on their contractile and metabolic characteristics. In addition, the muscle fiber characteristics, including size, composition, and density, of each muscle type were investigated and a technology based on these muscle fiber characteristics for improving meat quality or preventing quality deterioration was briefly discussed. This comparative review revealed that differences in muscle fiber characteristics are primarily responsible for the differences in quality between pork cuts (muscle types) and also suggested that data on muscle fiber characteristics can be used to develop optimal meat storage and packaging technologies for each meat cut (or muscle type).

Keywords: Muscle fiber characteristics; Muscle fiber type; Pig; Skeletal muscle.

Fig. 1.. Muscle fiber staining via histochemistry and muscle fiber type classification.

(A) Muscle fiber typing based on differences in myosin ATPase lability in acidic and alkaline solutions. (B) Muscle fiber classification based on differences in succinic dehydrogenase (SDH) and myosin ATPase activity, and the distribution of myosin heavy chain (MHC) isoforms using anti-MHC I/slow and 2a. I, slow-twitch and oxidative (slow-oxidative) fiber; IIA, fast-twitch and oxidative (fast-oxidative) fiber; IIB, fast-twitch and glycolytic (fast-glycolytic) fiber. Data were obtained with permission from the Meat Science Laboratory, Seoul National University, Korea and presented after modification.

Fig. 2.. Comparison of the muscle fiber characteristics of 19 porcine skeletal muscles reported in previous studies (summarized in Table 1).

(A) Muscle fiber size (cross-sectional area). (B) Relative muscle fiber area. (C) Muscle fiber density. SO, slow-twitch and oxidative; BB, M. biceps brachii; BF, M. biceps femoris; DI, M. diaphragm; GS, M. gluteus superficialis; GR, M. gracilis; IS, M. infra spinam; IN, M. infrahyoid; MA, M. masseter; PM, M. psoas major; RA, M. rectus abdominis; RF, M. rectus femoris; SM, M. semimembranosus; ST, M. semitendinosus; SU, M. subcapularis; SDF, M. superficialis digital flexor; VA, M. vastus; LL, M. longissimus lumborum; LT, M. longissimus thoracis; LTL, M. longissimus thoracis et lumborum; ND, no data; FO, fast-twitch and oxidative; FG, fast-twitch and glycolytic.

Fig. 3.. Comparison of porcine skeletal muscles according to the proportions of different muscle fiber type (contractile, slow and fast; metabolic, oxidative and glycolytic) (A and B) and cross-sections of representative muscles with high ratios of slow-twitch and oxidative fibers (M. diaphragm and M. rectus abdominis) and fast-twitch and glycolytic fibers (M. longissimus lumborum) (C).

Bar = 100 µm. The results shown in Table 1 and Fig. 2 were reconstructed to indicate A and B. Images were obtained with permission from the Meat Science Laboratory, Seoul National University, Korea and presented after modification. BB, M. biceps brachii; BF, M. biceps femoris; DI, M. diaphragm; GS, M. gluteus superficialis; GR, M. gracilis; IS, M. infra spinam; IN, M. infrahyoid; MA, M. masseter; PM, M. psoas major; RA, M. rectus abdominis; RF, M. rectus femoris; SM, M. semimembranosus; ST, M. semitendinosus; SU, M. subcapularis; SDF, M. superficialis digital flexor; VA, M. vastus; LL, M. longissimus lumborum; LT, M. longissimus thoracis; LTL, M. longissimus thoracis et lumborum. SO, slow-twitch and oxidative; FO, fast-twitch and oxidative; FG, fast-twitch and glycolytic.