where 0 (initial pH) was 7.1 and 0 ÿ 1 (ultimate pH)
was 5.7. The exponential rate constant (2) for the lamb
LD was 0.92 hÿ1
.
3.1.2. Calpains and calpastatin
In the ®rst 9 h post-mortem there was only a slight
decrease in the average m-calpain level compared to the
initial level of 1.3 units/g [Fig. 3(a)]. However, between
9 and 18 h there was a rapid decline to 0.17 units/g and
by 96 h there was no detectable m-calpain activity. In
contrast, m-calpain levels over the ®rst 18 h post-mortem
showed little variation from the initial levels of 1.8
units/g. Even at 168 h the mean level was 1.02 units/g.
In contrast, calpastatin levels declined steadily from 3.7
units/g at 45 min to 0.64 units/g by 24 h and were
undetectable by 96 h.
3.1.3. Toughness
The mean shear strength of the LD declined from
11.3 kgF at 6 h to 7.1 kgF at 24 h and 3.8 kgF by 96 h
post-mortem [Fig. 3(a)]. During the ageing period the
variability in shear force between the LD from the six
animals decreased 5-fold.