The interaction between pH and temperature decline early postmortem on thecalpain system and objective tenderness in electrically stimulated beef Longissimus dorsi muscle

The study investigated the effects of pH and temperature decline early post mortem (pm) on calpains and calpastatin activities and objective tenderness in M. longissimus thoracis et lumborum. A total of 40 sides were used to g enerate a range of pH and temperature declines, by different stimulation tr eatments (i.e. low voltage stimulation applied for either 10 or 40 s 3 min pm), and chilling treatments (fast or slow). Both rapid glycolysis, or a sl ow chilling regime significantly reduced mu -calpain level at 4 h pm (P < 0 .001 and P < 0.05, respectively). There were significant interactions betwe en pH and temperature at 1.5 h pm on Cl-calpain and calpastatin activities at 24 h pm (P < 0.05). Rapid glycolysis resulted in lower shear force and c ompression measurements at day 1, although because of low ageing rates, an intermediate pH decline (i.e. pH 5.9-6.2 at 1.5 h pm) resulted in the most tender meat after 14 days ageing. Higher shear forces in the slow glycolysi ng sides appeared to be associated with the later activation of tenderising process, as well as physical shortening. The optimum pH decline early pm v aried with days ageing, with an intermediate pH decline resulting in the lo wer shear forces for meat aged for 14 days. <(c)> 2001 Published by Elsevie r Science Ltd.