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BACKGROUND: The objective of this work was to study the post-mortem evolution of potential biomarkers (µ-calpain activity and proteolytic profile) of meat tenderisation in bovine longissimus dorsi (LD) muscle from several biotypes coming from two beef breeds (‘Asturiana de los Valles’ and ‘Asturiana de la Montana’) and showing different levels of muscular hypertrophy (mh/mh, mh/+, + /+). RESULTS: LD samples were taken at 2, 12, 24 and 48 h and 3, 7, 14 and 21 days post-mortem. The presence of muscular hypertrophy produced a faster rate of pH decline, faster exhaustion of µ-calpain activity and earlier occurrence of proteolytic changes. Changes in the electrophoretic pattern of some peptides from sarcoplasmic (glyceraldehyde-3-phosphate dehydrogenase) and myofibrillar (troponin T and troponin I) muscle extracts within the first 24 h significantly correlated with meat toughness and allowed accurate discrimination of meat products into two groups: (1) fast tenderising meat, coming from mh-biotypes, and (2) late tenderising meat, from normal (+/+) biotypes. CONCLUSION: Early monitoring (within 24 h after slaughter) of selected biomarkers in LD muscle allowed accurate prediction of ultimate meat toughness and could be used in the meat industry as a tool for early classification of beef into fast and late tenderising meat. Copyright © 2012 Society of Chemical Industry

Double-muscled syndrome in cattle improves meat tenderness. However, the nature of the proteolytic processes associated with this phenomenon remains unknown. The aim of this study was to monitor changes in the activity of cathepsins (B, B + L, D and H) during meat aging and their gradual release from lysosomes to the cytosol in the longissimus muscle of yearling bulls of two breeds from northern Spain (Asturiana de los Valles and Asturiana de la Montana) showing three genotypes for muscular hypertrophy (mh/mh, mh/+ and + / +). The data showed that the pattern of cathepsin activity during meat aging paralleled variations in tenderness in the different genotypes studied. Maximal cathepsin D activity and minimal cathepsin H activity were recorded during meat aging times ranging from 3 to 21 days. The activities of cathepsins B and B + L were lower than that of cathepsin D at the established time points (3, 7, 14 and 21 days post-slaughter). The role of these enzymes in the activation of cathepsin D is discussed. All cathepsins showed similar action patterns, with high levels early on in the aging process and lower levels at later times. This pattern depended on the genotype and was significantly faster (P≤0.05) in meat from mh/mh animals, intermediate in meat from mh/+ animals and slower in meat from normal (+/+) animals of both breeds. Copyright © 2006 Society of Chemical Industry

The objective of this work was to study the post-mortem evolution of potential biomarkers (µ-calpain activity and proteolytic profile) of meat tenderisation in bovine longissimus dorsi (LD) muscle from several biotypes coming from two beef breeds ('Asturiana de los Valles' and 'Asturiana de la Montaña') and showing different levels of muscular hypertrophy (mh/mh, mh/+, + /+).LD samples were taken at 2, 12, 24 and 48 h and 3, 7, 14 and 21 days post-mortem. The presence of muscular hypertrophy produced a faster rate of pH decline, faster exhaustion of µ-calpain activity and earlier occurrence of proteolytic changes. Changes in the electrophoretic pattern of some peptides from sarcoplasmic (glyceraldehyde-3-phosphate dehydrogenase) and myofibrillar (troponin T and troponin I) muscle extracts within the first 24 h significantly correlated with meat toughness and allowed accurate discrimination of meat products into two groups: (1) fast tenderising meat, coming from mh-biotypes, and (2) late tenderising meat, from normal (+/+) biotypes.Early monitoring (within 24 h after slaughter) of selected biomarkers in LD muscle allowed accurate prediction of ultimate meat toughness and could be used in the meat industry as a tool for early classification of beef into fast and late tenderising meat.