Relationships among Calcium-Dependent Protease, Cathepsins B and H, Meat Tenderness and the Response of Muscle to Aging

Abstract

This study was conducted to compare the relative importance of Ca-dependent protease (CDP) and cathepsins B and H to meat tenderness and changes in tenderness in response to postmortem cooler aging. Charolais bulls (n = 8) and steers (n = 7) were slaughtered at 15 mo of age, and total activities of CDP-I (a protease with neutral pH optimum that requires micromolar amounts of Ca for activity) and cathepsins B and H (lysosomal proteases with acidic pH optima) were determined within 1 h. Shear-force values were obtained after 1 , 3, 6, 9 and 14 d of aging. Data were pooled when analysis of variance revealed no differences between bulls and steers. Initial shear force was correlated (r = -.71, P < .lo, n = 7) to CDP-I activity (only seven animals sampled for CDP-I), and the overall change in shear force (d 1 t o d 14) was correlated to cathepsin B (r = .59, P < .05, n = 15). Most of the aging response occurred between d 3 and d 6 (41.6%), and changes in shear force during this period were related to total activities of cathepsins B and H (r = .44, .64, respectively, P < .05). Collectively, cathepsins B and H accounted for 35 and 58% of the variation in shear force change between d 1 to d 1 4 and d 3 to d 6, respectively. These data suggest that CDP-I helps to establish initial (d 1) meat tenderness but that cathepsins B and H are responsible for the tenderization that occurs during aging. By manipulating live animal growth and postmortem handling, it might be possible t o control meat tenderness through the actions of these enzyme systems.

Quantifying the aging response and nutrient composition for muscles of the beef round

“…Advancements in histological technology, including the electron microscope, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and western blotting, enabled further research in the area of postmortem muscle proteolysis (Bandman and Zdanis, 1988). Even though postmortem proteolysis presumably accounts for 30 to 40% of postmortem tenderization (Goll et al, 1997), most studies agree that proteolytic degradation has a minimal effect on muscle within the first 72 hours postmortem (Goll et al, 1964;Calkins and Seideman, 1988;Koohmaraie, 1994). Myofibrillar proteins maintain the structural integrity of myofibrils; thus, proteolysis of these proteins should result in loss of myofibrillar integrity and improved tenderness (Koohmaraie, 1996).…”

“…In general, most meat is more tender after 7 to 10 days of postmortem aging, than it is the day after slaughter . Calkins and Seideman (1988) found that a majority (81.1%) of the aging response occurred during the first six days postmortem, with 4% of tenderness increase occurring between 6 and 9 days, and the remaining 14.9%…”

“…Cathepsin activity is believed to be limited to frozen tissues or aging above temperatures of 16°C, with cathepsins L, H, and B being responsible for the majority of degradation, respectively (Goll et al, 1983). Because lysosomal enzymes, primarily cathepsins, have an affinity for acidic environments, it may be possible for cathepsins to continue proteolytic activity after day 1 postmortem, when muscle pH has decreased (Calkins and Seideman, 1988). Cathepsin B and H activity was found to be strongly correlated to a decrease in shear force between 3 and 9 days postmortem in 15 bulls and steers analyzed for proteolytic activity (Calkins and Seideman, 1988).…”

“…Because lysosomal enzymes, primarily cathepsins, have an affinity for acidic environments, it may be possible for cathepsins to continue proteolytic activity after day 1 postmortem, when muscle pH has decreased (Calkins and Seideman, 1988). Cathepsin B and H activity was found to be strongly correlated to a decrease in shear force between 3 and 9 days postmortem in 15 bulls and steers analyzed for proteolytic activity (Calkins and Seideman, 1988). No correlation was found between the activity of either cathepsin and the change in shear force between 1 and 3 days postmortem, indicating that other enzymatic processes were more active during that time.…”

Assessment of Postmortem Aging Effects on Texas-style Barbecue Beef Briskets

“…Research has shown that tenderness is 1 of the 3 most important factors in beef eating quality (Legako et al, 2016), and can be improved through postmortem aging (Calkins and Seideman, 1988, Doty and Pierce, 1961, Eilers et al, 1996, Smith et al, 1978. Although most researchers have conducted studies on tenderness for "middle meats" and muscles from the round, there has been limited work evaluating the postmortem aging effect on other muscle groups such as those comprising the brisket.…”