| Year |
2010 |
| Abstract |
The objective of this study was to examine the occurrence of microstructural changes in aged Longissimus dorsi (LD) muscle from Norwegian Red Cattle, and to investigate how these changes relate to pH decline, calpain and calpastatin activities, and tenderness (Warner-Bratzler shear force; WBSF). Samples of the LD muscle from 403 Norwegian Red (NRF) dual purpose bulls were collected over a 4-year period and analysed for muscle pH, protease activity and WBSF. Microstructural analysis of fibre-fibre detachment, muscle fibre-perimysium detachment, contracted muscle fibres and fractured muscle fibres were performed on a subset of 50 animals. The occurrence of fractured muscle fibres was negatively correlated to WBSF and calpastatin activity and positively correlated to the ratio of μ-calpain and calpastatin activity, strongly indicating that these fractures are important in the development of meat tenderness and that they are a result of calpain-mediated proteolysis. On the contrary, detachments between individual muscle fibres and between muscle fibres and perimysium did not play an important role in determining variation in LD tenderness in these animals. Moreover, both pH decline and what is considered a normal ultimate pH range in beef were positively correlated to calpastatin activity and WBSF and negatively correlated to fractured muscle fibres. Thus, an accelerated muscle pH decline and a low ultimate pH seem to increase calpain-mediated proteolysis, causing fractures in muscle fibres and thereby giving rise to more tender meat. |
| Reference |
Veiseth-Kent, E., Hollung, K., Ofstad, R., Aass, L., Hildrum, K.I. 2010. Relationship between muscle microstructure, the calpain system and shear force in bovine Longissimus dorsi muscle. Journal of Animal Science, Vol 88, pp 3445-3451. |
| Publisher |
Journal of Animal Science, |
Eva Veiseth-Kent
Kristin Hollung
Ragni Ofstad
