Effect of added μ-calpain and post-mortem storage on the mechanical properties of bovine single muscle fibres extended to fracture

• Published in: Meat science Vol. 66; no. 1; pp. 105 - 112
• Main Authors: Christensen, M, Young, R.D, Lawson, M.A, Larsen, L.M, Purslow, P.P
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 2004; Elsevier
• Subjects: Beef; Biological and medical sciences; Food industries; Fundamental and applied biological sciences. Psychology; Meat and meat product industries; Mechanical properties; Post-mortem storage; Proteolysis; Single muscle fibres; Tensile test; μ-calpain; Post-mortem storage; Proteolysis; Tensile test; Mechanical properties; Beef; μ-calpain; Single muscle fibres; Enzyme; Cysteine endopeptidases; Postmortem; Meat product; Calpain; Stored food product; Tensile property; Muscular fiber; Peptidases; Quality; Hydrolases; μ-calpains
• ISSN: 0309-1740; 1873-4138
• DOI: 10.1016/S0309-1740(03)00025-1

The effects of μ-calpain and post-mortem storage on the strength of single muscle fibres were investigated. During the 10 min of incubation at pH 7.5, μ-calpain became evenly distributed throughout the fibre. μ-Calpain-incubation resulted in thinner ( P <0.001) Z-lines and reduced ( P <0.001) the strength of the fibres compared to controls. These results demonstrate that μ-calpain is capable of mechanically weakening the muscle fibres. Post-mortem storage of meat for 10 days at 2 °C weakened ( P <0.001) the muscle fibres compared to 24-h fibres. The presence or absence of Ca 2+ affected fibre stiffness. Fibres incubated at pH 7.5 in 100 μM Ca 2+ were less stiff than fibres incubated in 200 μM EGTA. Breaking stress and strain were not affected by Ca 2+. We hypothesise that Ca 2+ causes conformational changes in some of the load-bearing proteins, which alters their initial resistance to extension, but does not affect the breaking strength of the fibres.