Evaluation of Muscle Fiber Characteristics Based on Muscle Fiber Volume in Porcine Longissimus Muscle in Relation to Pork Quality

Abstract

In livestock science and meat science, muscle fiber characteristics have been evaluated based on a cross-sectional area (CSA) of muscle fiber. However, muscle fiber is not planar but cylindrical. Thus, muscle fiber volume and volume-based characteristics were evaluated in this study. In addition, their relationships to pork loin quality was assessed and compared with that of CSA-based muscle fiber characteristics. Muscle fiber type IIB was underestimated by CSA-based evaluations with 1.6 times in fiber size and 2.6 times in relative composition. The pennation angle, which ranged from 48.00° to 83.33°, determined the real CSA and total number of fibers (TNF) on the surface of a loin chop. Significant (P < 0.05) correlation coefficients were found: fiber volume (r = –0.37) and volume % (r = –0.37) of type IIX with loin length; volume % of type IIX with CIE L* (r = 0.40); volume % of types IIX (r = 0.39) and IIB (r = –0.39) with Warner-Bratzler shear force. Although those correlations to loin quality differed from those of CSA-based characteristics, the Z-scores did not show any significance between the 2 correlation coefficients, except for TNF. Therefore, the conventional methodology for muscle fiber characteristics can be used for evaluating the relationship to pork quality; however, the new methodology is more useful in estimating the characteristics of muscle fiber, which is elongated and cylindrical and to correct the underestimated fiber size and composition of type IIB.

Muscle Fiber Characteristics on Chop Surface of Pork Loin (M. longissimus thoracis et lumborum) Associated with Muscle Fiber Pennation Angle and Their Relationships with Pork Loin Quality

“…2A); however, muscle fiber composition (relative area) did not differ between the F-Vertical and M-Vertical. The size and composition relationships in glycolytic fibers (IIX and IIB) with pH and tenderness observed in the present study are in accordance with the findings in previous studies that demonstrated their positive or negative correlations with pH or tenderness, respectively, regardless of the animal species, breed, gender, age, and muscle type (Choi and Kim, 2009;Joo et al, 2013;Karlsson et al, 1993;Kim et al, 2013a;Kim et al, 2018;Larzul et al, 1997;Ryu et al, 2008). The CIE L* and CIE a* in meat color are highly affected by the fiber size and composition (Hwang et al, 2010;Kim et al, 2010;Kim et al, 2013a;Ozawa et al, 2000), that is, oxidative fibers are positively correlated with CIE a*, whereas glycolytic fibers are negatively correlated with CIE a* but positively correlated with CIE L* due to their diverse reliance on oxygen and consequent demands of myoglobin for energy metabolism of different muscle fiber types (Cassens and Cooper, 1971;Kim et al, 2010;Ozawa et al, 2000;Whipple et al, 1992).…”

“…Muscle fibers were leaned at 51.33° to 69.00° in the porcine LTL muscle, which is within the range of previous observations in porcine LTL (48.00° to 83.33°) or bovine longissimus lumborum (31.36° to 53.90°) muscles (Kim et al, 2018;Derington et al, 2011).…”

Cellular development in muscle differs between Angus steers from low and high muscle score selection lines1

“…The muscle histological sample collection site on the carcass, tissue orientation during mounting and freezing, and avoidance of measurements of myofibers that were sectioned at oblique angles (see Myofiber characteristics subsection of Materials and Methods) were undertaken to minimize error in determinations of myofiber types, size, and numbers. However, it is recognized that the number of myofibers apparent in a muscle cross section will differ from the number of myofibers in the entire anatomical muscle due to intrafascicular termination of myofibers, and that the size of myofibers, in particular of fast glycolytic (type 2X or 2B) myofibers, may be underestimated using histological techniques compared with newer volumetric methods (Kim et al, 2018). However, the methods used in the present study provide meaningful comparisons between the muscling lines, as in our previously published studies using these techniques (Greenwood et al, 2006a(Greenwood et al, , 2006b(Greenwood et al, , 2009.…”

Meat: Valuable Animal-Derived Nutritional Food. A Review

“…Therefore, Muscle fiber (long, narrow, multinucleated cells) characteristics such as fiber size, fiber type dissemination, and relative composition have a linkage to meat quality attributes including color, tenderness, water holding capacity (WHC) and sensory qualities [28]. Connective tissue principally made of fibers of collagen which are straight, inextensible and non-branching and of elastin which is elastic, branching and yellow becomes much more resilient to breakdown by under a three-dimensional network formation and a high tensile strength development during animal's tissue maturation influences the quality attributes of meat to consumers as meat tenderness or texture is regarded in high esteem [26,29].…”