Sensory and instrumental analysis of longitudinal and transverse textural variation in pork longissimus dorsi

In the present study sensory and instrumental analysis of the textural properties of pork longissimus dorsi were performed and analysed using multivariate data analytical methodologies. The aims were to determine how textural properties of musculus longissimus dorsi varied transversely, longitudinally, between left and right muscles, and as a function of ageing. By training the panel in the descriptive texture profile method the panellists were able to clearly detect, discriminate and describe the textural variation in the samples, except for the transverse variation. Sensory evaluation revealed a non-significant trend (P > 0.05) of decreasing tenderness from dorsal (nearest the spinal column) to medial sampling position. When analysed instrumentally, using a modified Warner-Bratzler shear force apparatus, the transverse muscle variation was found to increase in force (N) required for deformation from dorsal to lateral sampling position. Overall, these two methods agreed in that the dorsal position was the more tender of the three positions investigated. Lengthwise muscle variation was highly defined when assessed using sensory analysis, whereas instrumental analysis was unable to detect this variation. The sensory analysis revealed that tenderness decreased and hardness increased as the sample position approached the caudal end of the muscle. Additionally, sensory analysis revealed a major turnover point in textural properties at the end of the ribcage area in that tenderness showed a marked decrease in this area and hardness and juiciness increased correspondingly in the same area. Both sensory and instrumental analysis showed that muscles from left and right side of the carcass differed significantly (P < 0.05) in their textural properties. The right side muscle was clearly defined into stages more so than the left side muscle. In addition, the right loin was found to be harder per se than the left loin, which was postulated to be caused by a greater amount of work performed by right muscles compared to left muscles. Significant differences (P < 0.05) in sensory textural attributes were observed overall with increased ageing. The variation within muscles, which contributed to the overall change in texture with ageing, was found to be due to changes in the longitudinal variation, in that the individual chop variation observed at the cranial end became less pronounced when the meat was aged. Differences observed between the cranial and caudal end remained, regardless of ageing for 4 or 7 days. No changes could be seen in the transverse texture during ageing. In general, sensory and instrumental analyses were found largely to be predictive indexes of each other. However, these two methods could not be said to be causally predictive in that they did not measure the same physical properties of the meat. For instance sensory determined tenderness is a result of the type and rate of deformation and the heterogeneity of the sample assessed, whereas instrumental measurement is a result of resistance to shearing. The present study showed significant variation between longitudinal locations and this variation is critical when designing sensory texture profiling experiments of meat from loins. Moreover, the textural differences between left and right loin muscles must be considered when texture prediction is the objective if an applicable conclusion is to be drawn. (C) 2004 Elsevier Ltd. All rights reserved.