Modelling meat eating quality traits during ageing as affected by early post-mortem pH decay

Previous work has demonstrated that beef carcasses can be accurately classified into optimal quality and cold-shortened in accordance to the concept of pH/temperature ’ideal window’ by early post-mortem pH/temperature decay descriptors. The objective of this study was to assess the combined effects of such variables on the two main eating quality attributes of meat-tenderness (measured as shear force) and juiciness (measured as cooking loss)-during chill ageing. The pH and temperature of longissimus thoracis muscle of 51 beef carcasses were recorded during 24 h post-mortem, and decay descriptors were then obtained by fitting exponential models. Measures of Warner-Bratzler shear force and cooking loss were obtained from cooked meat after 3, 8 and 13 days of cold ageing. A fitted mixed-effect models revealed that both meat tenderisation and cooking loss increased with ageing (p<0.01) although their rates slowed down in time (p<0.05). Beef carcasses with a higher pH (obtained at different endpoints: 1.5, 3.0, 4.5 or 6.0 h post-mortem) produced aged meat with increased tenderness (p=0.013) and increased water retention during cooking (p=0.016) than those of lower pH. Nonetheless, the slower the pH decay rate, as happens in a cold-shortened carcass, the lower the potential for tenderisation (p=0.038) and water retention (p=0.050) during ageing. Whereas sex affected shear force, with females producing meat of higher tenderness, aged meat of increased water retention was produced by heavier beef carcasses (p