Contribution of postmortem muscle biochemistry to the delivery of consistent meat quality with particular focus on the calpain system

Abstract

Tenderness has been repeatedly reported as the most important quality aspect of meat. However, a number of studies have shown that a significant portion of retail meat can be considered tough. As a consequence, a significant consumer segment is willing to pay a premium for guaranteed tender meat. However, apart from measuring the shear force, there is no reliable method to predict tenderness. Most of the branded meat programs therefore attempt to ensure eating quality by controlling some of the factors that affect tenderness. Meat tenderness is determined by the amount and solubility of connective tissue, sarcomere shortening during rigor development, and postmortem proteolysis of myofibrillar and myofibrillar-associated proteins. Given the effect of postmortem proteolysis on the muscle ultrastructure, titin and desmin are likely key substrates that determine meat tenderness. A large number of studies have shown that the calpain proteolytic system plays a central role in postmortem proteolysis and tenderization. In skeletal muscle, the calpain system consists of at least three proteases, μ-calpain, m-calpain and calpain 3, and an inhibitor of μ- and m-calpain, calpastatin. When activated by calcium, the calpains not only degrade subtrates, but also autolyze, leading to loss of activity. m-Calpain does not autolyze in postmortem muscle and is therefore not involved in postmortem tenderization. Results from a number of studies, including a study on calpain 3 knockout mice, have shown that calpain 3 is also not involved in postmortem proteolysis. However, a large number of studies, including a study on μ-calpain knockout mice, have shown that μ-calpain is largely, if not solely, responsible for postmortem tenderization. Research efforts in this area should, therefore, focus on elucidation of regulation of μ-calpain activity in postmortem muscle. Discovering the mechanisms of μ-calpain activity regulation and methods to promote μ-calpain activity should have a dramatic effect on the ability of researchers to develop reliable methods to predict meat tenderness and on the meat industry to produce a consistently tender product.

Kinetics of colour and texture changes of beef during storage

“…Meat texture is generally difficult to evaluate using physico-chemical tests, as texture depends on the state and interactions of different muscle components, especially myofibrillar and connective tissues (Campo et al 2000; Koohmaraie and Geesink 2006).…”

Influence of vitamins A, D3 and E status on post-mortem meat quality in steers under winter housing or pasture finishing systems

“…Post-slaughter proteolytic activity is -E-mail: tyler.turner@lmv.slu.se 1141 a natural enzymatic-induced tenderising process involving the breakdown of cross-linkages between muscle myofibrillar proteins. The biochemistry involved during the postslaughter tenderisation process has been reviewed by Koohmaraie and Geesink (2006).…”

“…Although m-and m-calpain share many similar characteristics in growing animals, evidence has indicated that only m-calpain is extensively involved in post-mortem proteolysis of bovine tissue (Koohmaraie and Geesink, 2006). This finding was based on the observed post-mortem m-calpain reduction in bovine muscle, whereas m-calpain was stable (Koohmaraie et al, 1987).…”

“…Post-slaughter proteolytic activity is -E-mail: tyler.turner@lmv.slu.se 1141 a natural enzymatic-induced tenderising process involving the breakdown of cross-linkages between muscle myofibrillar proteins. The biochemistry involved during the postslaughter tenderisation process has been reviewed by Koohmaraie and Geesink (2006).Calpains consist of a group of proteolytic proteins that are activated in the presence of calcium. Two proteins, m-and m-calpain, have been identified as the most likely candidate proteases responsible for myofibrial degradation and protein turnover in growing animals (Goll et al, 1998).…”

“…The estimated calcium concentration required to achieve halfactivity has been shown to be in the range of 3 to 50 mM and 400 to 800 mM for m-and m-calpain, respectively (Goll et al, 1998). The calcium requirement for the calpains to reach half-activity has been shown to be reduced during autolysis (Dayton, 1982).Although m-and m-calpain share many similar characteristics in growing animals, evidence has indicated that only m-calpain is extensively involved in post-mortem proteolysis of bovine tissue (Koohmaraie and Geesink, 2006). This finding was based on the observed post-mortem m-calpain reduction in bovine muscle, whereas m-calpain was stable (Koohmaraie et al, 1987).…”