Modelling meat eating quality traits during ageing as affected by early post-mortem pH decay
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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<0.001). The
good fitting quality of the shear force (R2=0.847) and cooking loss (R2=0.882)
models indicated that both eating quality attributes can be approached by recording
the pH decline of a beef carcass during the first 3.0 hours after slaughter.
