Modelling beef meat quality traits during ageing by early post-mortem pH decay descriptors
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Previous work has demonstrated that beef carcasses can be promptly and accurately classified into optimal quality and
cold-shortened in accordance to the concept of pH/temperature ‘ideal window’ by using carcass characteristics and
early post-mortem pH/temperature decay descriptors. The objective of this study was to assess the combined effects
of the aforementioned variables on the two main eating quality attributes of meat – namely, tenderness (measured as
shear force) and juiciness (measured as cooking loss) – during chill ageing. The pH and temperature in 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. The 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
and their similarity among the different endpoints post-mortem 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.
