ABSTRACT
Two intermediate filament proteins, desmin and vinculin, were immunofluorescently localised in porcine longissimus dorsi(∗∗) and iliocostalis muscles up to 7 days post mortem. Changes in tenderness of the m. longissimus and the water-holding capacity of both muscles were also monitored throughout this storage period. Longissimus muscle shows a rapid decline in the overall intensity of labelling for both desmin and vinculin. In contrast to the vinculin labelling, desmin labelling is preferentially lost from type IIB muscle fibres in the longissimus muscle. In the redder iliocostalis muscle, the loss of desmin and vinculin labelling was less rapid and did not show an obvious relation to muscle fibre type. In one sample with very high water loss, there were indications of greater extracellular space development and delayed loss of intermediate filament labelling. The time course of diminishing intermediate filament labelling is consistent with previous suggestions that degradation of these proteins is involved in post-mortem conditioning. The variations within and between muscles shown here may explain some of the variability in their mechanical properties. Additionally, it is suggested that intermediate filament integrity is necessary for the expulsion of water from the muscle cells during drip formation.
ABSTRACT
The susceptibility towards development of warmed-over flavour (WOF) was investigated in meat from turkey and chicken breast and thigh, and from pork longissiums dorsi muscle. Ground meat samples from these five sources were heated for 30 min in a water bath at 60, 70 or 80C, and the samples were stored at 5C for 0-4 days. During storage, WOF was quantified by measurement of thiobarbituric-acid reactive substances (TBARS) and by sensory evaluations. The increase in TBARS was modelled for each type of meat at the different heating temperatures by a first-order reaction, and it was shown that a common rate constant could be used for all types of meat. The estimated maximum levels of TBARS in meat samples decreased in the following order: turkey thigh > chicken thigh > turkey breast > chicken breast > port. For each type of meat, the estimated maximum level of TBARS rose when the heating temperature increased in the range 60-80C. This temperature effect was particularly obvious for the chicken samples. Thus thigh and breast meat from chicken heated to 60C was almost stable against oxidation during storage. Results obtained by measurement of TBARS were in good agreement with the sensory evaluations.
