濟州産 豚肉의 品種 및 屠體冷却方法에 따른 肉質 評價 硏究

Abstract

This study was to investigate the effects of pig breed and carcass chilling rate on meat quality traits in Jeju pork. This study involved 188 pigs from three different breeds as follows: commercial Jeju black pigs (JBP); native Jeju black pig×Duroc (JD); Jeju Landrace×Yorkshire×Duroc (JLYD). Pigs were slaughtered according to standard commercial procedures in a Korean abattoir. Within 45 min postmortem, muscle samples for histochemical analysis were taken from the longissimus muscle at the 8th thoracic vertebrae. Samples were cut into 0.5×0.5×1.0 cm pieces, promptly frozen in liquid nitrogen, and stored at -80℃ until subsequent analyses. Serial transverse muscle sections (10 μm) were obtained from each sample with a cryostat at -20℃ and mounted on glass slides. The myosin adenosine triphosphatase activities were detected after acid (pH 4.7) preincubation. About 300 fibers per sample were examined by an image analysis system and the muscle fibers were divided into type I, IIa, and IIb. Muscle pH was measured directly on carcass at the 7th/8th thoracic vertebrae using a spear type electrode at 45 min (pH45min) and 24h postmortem (pH24h). Following 24h of chilling, M. longissimus dorsi was taken to evaluate the meat quality traits. Drip loss was determined by suspending muscle samples standardized for surface area in an inflated plastic bag for 48h. The color of the meat was measured at the 8th/9th thoracic vertebrae at 24h postmortem with a chromameter after exposing the surface to the air for 30 min. The average of triplicate measurements was recorded and the results were expressed as C.I.E. L*, a*, and b*. The texture was measured after cooking, 2.0×2.0×2.0 cm3 pieces were cut for texture profile analysis (TPA). Three pieces for each sample were measured for TPA. JD contained a significantly lower mean area percentage of type IIb fibers than those of other breeds (P<0.05). The muscle pH45min and pH24h were significantly higher in JD (P<0.001). Drip loss and color parameters were significantly different between the breeds (P<0.001). The muscle pH45min and pH24h were significantly higher in JD Meat color and sensory evaluation value was closely related to postmortem metabolic rate and pH value. The muscle color and sensory evaluation value was positively related to pH value. However, the a* value of the JLYD group was the lowest at 24 h postmortem (P<0.001). NPPC color value and NPPC marbling value of the JD group were highest in the breed groups (P<0.001). The water-holding capacity and texture were significantly dependent on breed. For the water-holding capacity measurements, the JD group had significantly highest values of FFU, drip loss, and cooking loss (P<0.001). The JD group had the highest value of hardness (P<0.001), cohesiveness (P<0.01), and springiness (P<0.1). The L* value, a* value and b* value of the JD group was the highest at 24 h postmortem (P<0.001). In this study, JD group, which showed the highest muscle pH, the lowest drip loss, and L* values contained a significantly lower mean area percentage of type IIb fibers than those of other breeds. Comparing the fiber type composition and meat quality traits observed from the different breeds, the results imply that the longissimus dorsi muscle of native Jeju black pig×Duroc group is better meat quality trait than that of other breeds. JD group, which showed the highest muscle pH, the lowest drip loss, and L* values contained a significantly lower mean area percentage of type IIb fibers than those of other breeds.