52 Meat refrigeration 3.2.2 Prediction of tenderness There is great interest in the development of any measurement method that can be applied soon after slaughter, which will predict the tenderness of meat. Many laboratory techniques(Dransfield, 1986; Dransfield, 1996) have been used to detect changes in the muscle down to the molecular level. However there is no routine test which can indicate how much of the ten derising has occurred or, more usefully, how much longer a piece of meat must be stored In 1988 Marsh et al. proposed that the pH in the longissimus dorsi at 3 h post-mortem may have a use as a predictor of tenderness. However, sub equent studies involving large numbers of animals(Marshall and Tatum 1991; Shackelford et al., 1994) found that it was not highly correlated with tenderness. Thus it is not a reliable method of identifying potentially tough or tender meat Cross and belk reviewed. in 1994. all the non-invasive technologies capable of objectively determining yield or the eating quality of the lean meat in live animals or carcasses in commercial situations. Technologies included X-ray, nuclear magnetic resonance, electrical conductivity analy sis, near-infrared reflectance, video image analysis, optical fat/lean probes, optical connective tissue probes, bioelectrical impedance analysis, velocity of sound and elastography Elastography, which measures the internal dis- placement of small tissue elements in response to externally applied stress using ultrasonic pulses, was thought to have the best potential in the future. It may be capable of depicting muscle structure at the muscle bundle level, and of detecting differences in elasticity of muscle bundles, connective tissue amounts and the quality of intramuscular fat 3.2.3 Consumer appreciation of ageing Consumer assessments of unaged beef are variable, ranging from 'moder- ately tough'to'moderately tender' whilst beef conditioned for 9 days at 1C receives largely favourable reactions, being scored"'moderatelyto very' tender(Dransfield, 1985). Consumer panels, however, have rarely been used to assess the factors affecting conditioning. They have usually been measured by laboratory taste panels and mechanical tests. A type of shear'test is frequently used on cooked meat and the measurements are usually well related to sensory assessments(Dransfield, 1986) The results of Dransfield (1986) illustrate the effect of conditioning on a taste panel's assessment of texture of 3 beef joints. Tenderness increased in all 3 joints (Table 3. 1) and these changes were reflected in increases in the overall acceptability In further work roasted sirloin joints from a six-year-old cow were com- ared with an 18-month-old heifer at storage times of 2-15 days at 2C. By 3.2).By 15 days both joints showed significant vement in tenderness(Table3.2.2 Prediction of tenderness There is great interest in the development of any measurement method that can be applied soon after slaughter, which will predict the tenderness of meat. Many laboratory techniques (Dransfield, 1986; Dransfield, 1996) have been used to detect changes in the muscle down to the molecular level. However, there is no routine test which can indicate how much of the ten￾derising has occurred or, more usefully, how much longer a piece of meat must be stored. In 1988 Marsh et al. proposed that the pH in the longissimus dorsi at 3 h post-mortem may have a use as a predictor of tenderness. However, sub￾sequent studies involving large numbers of animals (Marshall and Tatum, 1991; Shackelford et al., 1994) found that it was not highly correlated with tenderness. Thus it is not a reliable method of identifying potentially tough or tender meat. Cross and Belk reviewed, in 1994, all the non-invasive technologies capable of objectively determining yield or the eating quality of the lean meat in live animals or carcasses in commercial situations. Technologies included X-ray, nuclear magnetic resonance, electrical conductivity analy￾sis, near-infrared reflectance, video image analysis, optical fat/lean probes, optical connective tissue probes, bioelectrical impedance analysis, velocity of sound and elastography. Elastography, which measures the internal dis￾placement of small tissue elements in response to externally applied stress using ultrasonic pulses, was thought to have the best potential in the future. It may be capable of depicting muscle structure at the muscle bundle level, and of detecting differences in elasticity of muscle bundles, connective tissue amounts and the quality of intramuscular fat. 3.2.3 Consumer appreciation of ageing Consumer assessments of unaged beef are variable, ranging from ‘moder￾ately tough’ to ‘moderately tender’ whilst beef conditioned for 9 days at 1 °C receives largely favourable reactions, being scored ‘moderately’ to ‘very’ tender (Dransfield, 1985). Consumer panels, however, have rarely been used to assess the factors affecting conditioning. They have usually been measured by laboratory taste panels and mechanical tests. A type of ‘shear’ test is frequently used on cooked meat and the measurements are usually well related to sensory assessments (Dransfield, 1986). The results of Dransfield (1986) illustrate the effect of conditioning on a taste panel’s assessment of texture of 3 beef joints. Tenderness increased in all 3 joints (Table 3.1) and these changes were reflected in increases in the overall acceptability. In further work roasted sirloin joints from a six-year-old cow were com￾pared with an 18-month-old heifer at storage times of 2–15 days at 2°C. By 8 days, the heifer joint showed significant improvement in tenderness (Table 3.2). By 15 days both joints showed significant improvements. 52 Meat refrigeration