Comparison of Meat Quality and Muscle Fiber Characteristics between Porcine Skeletal Muscles with Different Architectures

Abstract

This study aimed to compare the similarities, physicochemical properties, and muscle fiber characteristics of porcine skeletal muscles. Fourteen types of muscles were collected from nine pig carcasses at 24 h post-mortem and classified by muscle architecture into two main groups, namely parallel and pennate. The muscles were further differentiated into three subtypes per group. These included fan-shaped, fusiform, and strap for the parallel group, and unipennate, bipennate, and multipennate for the pennate group. Parallel-fibered muscles, which were composed of larger I, IIA, IIX, and IIXB fibers and a lower density of IIA fibers, showed higher redness and yellowness values than pennate-fibered muscles (p<0.05). However, the relative fiber area was not significantly different between the parallel and pennate groups (p>0.05). In the subtypes of parallel architecture, the strap group showed lower moisture content and higher redness values than the other subtypes and had considerably higher amounts of oxidative fibers (I and IIA; 72.3%) than the fan-shaped and fusiform groups (p<0.05). In the pennate group, unipennate showed comparatively lower moisture content and higher lightness than other pennate subtypes and was composed of smaller I, IIA, and IIX fibers than the bipennate and multipennate groups (p<0.05). Finally, a different trend of muscle clustering by hierarchical cluster analysis was found between physicochemical properties and muscle fiber characteristics. These results suggest that the physicochemical properties and muscle fiber characteristics of porcine skeletal muscles are not significantly dependent on morphological properties but are rather related to the intrinsic properties of the individual muscles.

Keywords: meat quality; muscle architecture; muscle fiber characteristics; parallel; pennate.

Fig. 1.. Representative porcine skeletal muscles classified according to muscle structure.

Fig. 2.. Transverse sections of porcine skeletal muscles stained using immunohistochemistry.

Muscle fibers were classified into six types according to the distribution of myosin heavy chain (MHC) isoforms: I, MHC I/slow; IIA, MHC 2a; IIAX, MHCs 2a and 2x; IIX, MHC 2x; IIXB, MHCs 2x and 2b; IIB, MHC 2b. Magnification was set to ×100.

Fig. 3.. Dendrogram of porcine skeletal muscles from the hierarchical cluster analysis (HCA).

(A) The Euclidean distance of HCA by meat quality properties ranged from 0.20 (high similarity) to 1.36 (low similarity). (B) The Euclidean distance of HCA by muscle fiber characteristics ranged from 0.08 (high similarity) to 1.40 (low similarity). MA1–ME3 and FA1–FE1 indicate the same groups within the same Euclidean distance.