Relationship of Carcass Weight to Muscle Fiber Characteristics and Pork Quality of Crossbred (Korean Native Black Pig x Landrace) F2 Pigs

A total of 168 carcasses of crossbred (Korean native black pig x Landrace) F-2 pigs were divided into four carcass weight groups (A, 70-79 kg; B, 80-89 kg; C, 90-99 kg; D, 100-109 kg). The influence of carcass weight on muscle fiber characteristics and meat quality traits of pork, from the longissimus dorsi, were investigated. Carcass traits such as loin-eye area and back-fat thickness were found to increase with increasing carcass weight. Fat content, sarcomere length, drip loss, and meat color values (L*, a*, and b*) also increased with increasing carcass weight. However, moisture content and Warner-Bratzler shear force decreased with increasing carcass weight. A decrease in the compositions of type I and IIA fibers and an increase in the composition of type IIB fibers were observed with increasing carcass weight. The heavier carcasses showed type I and IIB fibers of bigger size and a smaller size of type IIA fibers. Fiber number percentage and the diameter of type IIB showed a significant positive correlation with carcass weight, fat content, and lightness (p < 0.05). Fiber diameter of type IIB was positively correlated with loin-eye area, but was negatively correlated with moisture content. However, muscle fiber characteristics had no correlation with back-fat thickness, ultimate pH, Warner-Bratzler shear force, and b* value. In conclusion, crossbred pig which has of high composition and size of type IIB has high lightness (L* value) and water-holding capacity (drip loss). Therefore, excessively high weight of carcass has influence on pale and exudative properties in pig because of muscle fiber characteristics, especially type IIB fiber.