Influence of early postmortem protein oxidation on beef quality1

Abstract

The objective of this study was to examine the effect of early postmortem protein oxidation on the color and tenderness of beef steaks. To obtain a range of oxidation levels, the longissimus lumborum muscles (LM) from both strip loins of 20 steers fed either a finishing diet with vitamin E (1,000 IU per steer daily, minimum of 126 d [VITE]; n = 10 steers) or fed the same finishing diet without vitamin E (CON; n = 10 steers) were used. Within 24 h after slaughter, the LM muscle from each carcass was cut into 2.54-cm-thick steaks and individually vacuum packaged. Steaks from each steer were assigned to a nonirradiated group or an irradiated group. Steaks were irradiated within 26 h postmortem, and were aged at 4°C for 0, 1, 3, 7, and 14 d after irradiation. Steaks from each diet/irradiation/aging time treatment were used to determine color, shear force, and degree of protein oxidation (carbonyl content). Steaks from steers fed the VITE diet had higher (P < 0.01) α-tocopherol contents than steaks from steers fed the CON diet. Immediately following irradiation, steaks that had been irradiated had lower (P < 0.05) L* values regardless of diet. Irradiated steaks, regardless of diet, had lower a* (P < 0.05) and b* (P < 0.01) values than nonirradiated steaks at all aging times. Carbonyl concentration was higher (P < 0.05) in proteins from irradiated steaks compared to nonirradiated steaks at 0, 1, 3, and 7 d postirradiation. Immunoblot analysis showed that vitamin E supplementation decreased the number and extent of oxidized sarcoplasmic proteins. Protein carbonyl content was positively correlated with Warner-Bratzler shear force values. These results indicate that increased oxidation of muscle proteins early postmortem could have negative effects on fresh meat color and tenderness. ABSTRACT: The objective of this study was to examine the effect of early postmortem protein oxidation on the color and tenderness of beef steaks. To obtain a range of oxidation levels, the longissimus lumborum muscles (LM) from both strip loins of 20 steers fed either a finishing diet with vitamin E (1,000 IU per steer daily, minimum of 126 d [VITE]; n = 10 steers) or fed the same finishing diet without vitamin E (CON; n = 10 steers) were used. Within 24 h after slaughter, the LM muscle from each carcass was cut into 2.54-cm-thick steaks and individually vacuum packaged. Steaks from each steer were assigned to a nonirradiated group or an irradiated group. Steaks were irradiated within 26 h postmortem, and were aged at 4°C for 0, 1, 3, 7, and 14 d after irradiation. Steaks from each diet/irradiation/ aging time treatment were used to determine color, shear force, and degree of protein oxidation (carbonyl

Postmortem protein degradation is a key contributor to fresh pork loin tenderness

“…The rate of activation and autolysis of calpain-1 could impact the amount of protein degradation by calpain-1. Calpain-1 activity is inhibited as pH declines from pH 7 to pH 6 and below (Carlin et al, 2006;Bee et al, 2007) or by oxidative conditions (Rowe et al, 2004a;Chen et al, 2014). Postmortem pH decline data are not available for these loins, but if differences in pH decline actually existed, they could potentially explain the differences in proteolysis exhibited between classification groups in this study.…”

Dietary leucine improves flesh quality and alters mRNA expressions of Nrf2-mediated antioxidant enzymes in the muscle of grass carp ( Ctenopharyngodon idella )

“…Cellular metabolism and other processes occurring in muscle tissue give rise to formation of reactive oxygen species (ROS) (Rowe et al, 2004). Exceeding ROS can interact with both lipids and protein, causing oxidative damage .…”

Food restriction and refeeding in lambs influence muscle antioxidant status

“…This means that the metabolic stress created by food restriction followed by refeeding was not sufficient to modify the oxidation level of proteins in animals at slaughter. Consequently, in our study, an alteration of protein oxidation during the compensatory growth process in vivo cannot be responsible for an altered protease activity during meat aging in animals undergoing compensatory growth (Maltin et al, 2003;Rowe et al, 2004a and2004b). However, proteins (and hence the proteases) still undergo oxidation during maturation, its intensity being highly dependent on the antioxidants present in the muscles and meat (Martinaud et al, 1997;Mercier et al, 1998;Rowe et al, 2004a).…”

“…Increased proteases oxidation reduces the functional properties of these proteases and decreases their efficiency in the meat protein maturation process (Rowe et al, 2004a and2004b). Consequently, it can be hypothesized that some in vivo oxidation processes in the muscles may have an impact on the enzymes activities and protein structure both in vivo and post mortem (Stadtman and Levine, 2000).…”