New Zealand Journal of Agricultural Research abstracts

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Differences in the post-mortem kinetics of the calpain system in meat from bulls and steers

B. C. THOMSON*
P. M. DOBBIE
N. R. COX

AgResearch
Ruakura Research Station
Private Bag 3123
Hamilton, New Zealand

N. J. SIMMONS

MIRINZ
P.O. Box 617
Hamilton New Zealand.

*Present address: School of Life Science and Technology, Victoria University of Technology, Werribee Campus, P.O. Box 14428, Melbourne City MC, Vic 8001, Australia.

Abstract  Strip loins (longissimus thoracis et lumborum) from bulls with normal ultimate pH (NOR, pHu < 5.7), bulls with unacceptably high pH (HI, pHu > 5.7), and steers were compared after storage at 15deg.C. HI samples had higher shear forces 120 hours post-slaughter than NOR and steer samples (P < 0.05). Calpastatin and u-calpain activities were higher in the NOR bulls than in steers, but the rates of decline in these activities were more rapid in NOR samples. The activity of u-calpain was low at all times and appeared to be involved in the increased toughness of the HI samples. The activity of m-calpain and the calpastatin : u-calpain activity ratio provided a good prediction of shear force 120 hours post-slaughter in the strip loin (R² = 0.70; P < 0.001). This suggests that calpastatin, u-calpain, and m-calpain all play a role in tenderisation and that on-farm and pre-slaughter management rather than post-slaughter treatment need to be used to decrease the incidence of high pH meat.

Keywords  calpain; pH; tenderness; steer; bull; calpastatin

New Zealand Journal of Agricultural Research, 1999, Vol. 42: 47-54

0028-8233/99/4201-0047 $7.00/0 (c) The Royal Society of New Zealand 1999

PDF file of entire paper: medium quality (537K); (scanned from paper original: notes about this process)

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