calpastatin and Rigor-Mortis

This study was conducted to determine whether the application of high pressure processing (HPP) could prevent the process of rigor in fresh pork and to identify the physical and chemical changes occurring in the meat that are responsible for this effect. Pressure (0-400 MPa) and time (10 min) were applied to the pork loin and enzyme samples. The effects of treatment on shear force, myofibrillar fragmentation, enzyme activity and meat texture were measured. The results showed that, compared with untreated samples, HPP treatment inhibited the occurrence of rigor in pork. The myofibrillar fragmentation indices of HPP treated samples were higher than those of control samples and increased linearly with increasing pressure. Application of HPP prevented the process of rigor at 0-300 MPa, reduced calpain activity and markedly decreased calpastatin activity, resulting in an increase of total calpains. Above 300 MPa, the mechanical action of pressure led to continuous prevention of rigor.

Topics: Animals; Calcium-Binding Proteins; Calpain; Food Handling; Humans; Muscle, Skeletal; Myofibrils; Pressure; Red Meat; Rigor Mortis; Stress, Mechanical; Swine

Baseline research on the toughness of Egyptian goose meat is required. This study therefore investigates the post mortem pH and temperature decline (15 min-4 h 15 min post mortem) in the pectoralis muscle (breast portion) of this gamebird species. It also explores the enzyme activity of the Ca(2+)-dependent protease (calpain system) and the lysosomal cathepsins during the rigor mortis period.. No differences were found for any of the variables between genders. The pH decline in the pectoralis muscle occurs quite rapidly (c = -0.806; ultimate pH ∼ 5.86) compared with other species and it is speculated that the high rigor temperature (>20 °C) may contribute to the increased toughness. No calpain I was found in Egyptian goose meat and the µ/m-calpain activity remained constant during the rigor period, while a decrease in calpastatin activity was observed. The cathepsin B, B & L and H activity increased over the rigor period.. Further research into the connective tissue content and myofibrillar breakdown during aging is required in order to know if the proteolytic enzymes do in actual fact contribute to tenderisation.

Topics: Animals; Calcium-Binding Proteins; Calpain; Cathepsins; Egypt; Female; Geese; Humans; Hydrogen-Ion Concentration; Male; Meat; Pectoralis Muscles; Rigor Mortis; Stress, Mechanical; Temperature

This study describes the changes taking place during rigour in springbok (Antidorcas marsupialis) Longissimus thoracis et lumborum (LTL) and Biceps femoris (BF) muscles. Samples from six male and six female springbok were snap-frozen at 2, 3, 5, 8, 12, 18, 24 and 30h post-mortem (PM) and the pH, calpains I, II and calpastatin activities and cathepsins B, BL and H activities were determined. The temperature was also recorded. Significant third-order interactions were found for the pH and temperature, with the female LTL cooling more rapidly and acidifying slower than the other samples. Female muscles were at risk of developing cold-shortening and all the samples cooled more rapidly than recommended for cattle or sheep. Cathepsin BL activity increased PM, likely due to the degradation of the lysosomes. Calpains I, II and calpastatin activity declined during rigour, indicating that the calpains were activated early PM. Gender and muscle had a significant effect on calpain and cathepsin activity.

Topics: Animals; Antelopes; Calcium-Binding Proteins; Calpain; Cathepsins; Chemical Phenomena; Female; Food Quality; Food Storage; Hydrogen-Ion Concentration; Isoenzymes; Male; Meat; Mechanical Phenomena; Muscle, Skeletal; Proteolysis; Refrigeration; Rigor Mortis; Sex Characteristics; South Africa; Stress, Physiological; Stress, Psychological

Beta agonists used as growth enhancers are known to affect the aging potential of beef muscle negatively. On the other hand, procedures like electrical stimulation could accelerate rigor and the aging process. In this study, 20 out of 40 young steers received no beta agonist (C), the remaining twenty steers received a beta agonist (zilpaterol hydrochloride) (Z) for the 30 days prior to slaughter followed by 4 days withdrawal. After slaughter carcasses were split, the left side electrically stimulated (ES) and the right side not stimulated (NES). Samples were aged for 3 or 14 days post mortem. Parameters included Warner Bratzler shear force (WBSF), myofibril filament length (MFL), sarcomere length and calpastatin and calpain enzyme activity. Zilpaterol resulted in increased (P<0.001) WBSF mainly due to an increased (P<0.001) calpastatin activity. ES improved tenderness (P<0.001) in general by early onset of rigor triggering the activity of calpains. ES also reduced the calpastatin activity (P<0.001), which partially countered the effect of high calpastatin activity on the aging potential of Z loins. ES can therefore be implemented to improve meat tenderness in zilpaterol supplemented steers, although steers without zilpaterol will still have an advantage in final tenderness.

Topics: Adrenergic beta-Agonists; Animal Feed; Animals; Calcium-Binding Proteins; Calpain; Cattle; Electric Stimulation; Food Technology; Male; Meat; Muscle Proteins; Muscle, Skeletal; Myofibrils; Rigor Mortis; Sarcomeres; Stress, Mechanical; Trimethylsilyl Compounds

This study was conducted to evaluate the effects of electrical stimulation (ES) on rigor mortis development, calpastatin activity, and tenderness in anatomically similar avian muscles composed primarily of either red or white muscle fibers. A total of 72 broilers and 72 White Pekin ducks were either treated with postmortem (PM) ES (450 mA) at the neck in a 1% NaCl solution for 2 s on and 1 s off for a total of 15 s or were used as nonstimulated controls. Both pectoralis muscles were harvested from the carcasses after 0.25, 1.25, and 24 h PM and analyzed for pH, inosine:adenosine ratio (R-value), sarcomere length, gravimetric fragmentation index, calpastatin activity, shear value, and cook loss. All data were analyzed within species for the effects of ES. Electrically stimulated ducks had a lower muscle pH at 0.25 and 1.25 h PM and higher R-values at 0.25 h PM compared with controls. Electrically stimulated broilers had a lower muscle pH at 1.25 h and higher R-values at 0.25 and 1.25 h PM compared with controls. Muscles of electrically stimulated broilers exhibited increased myofibrillar fragmentation at 0.25 and 1.25 h PM, whereas there was no such difference over PM time in the duck muscle. Electrical stimulation did not affect calpastatin activity in either broilers or ducks; however, the calpastatin activity of the broilers did decrease over the aging time period, whereas that of the ducks did not. Electrical stimulation decreased shear values in broilers at 1.25 h PM compared with controls; however, there was no difference in shear values of duck muscle due to ES at any sampling time. Cook loss was lower for electrically stimulated broilers at 0.25 and 1.25 h PM compared with the controls, but had no effect in the ducks. These results suggest that the red fibers of the duck pectoralis have less potential for rigor mortis acceleration and tenderization due to ES than do the white fibers of the broiler pectoralis.

Topics: Animals; Calcium-Binding Proteins; Chickens; Ducks; Electric Stimulation; Food Technology; Hydrogen-Ion Concentration; Lactic Acid; Muscle Fibers, Fast-Twitch; Muscle, Skeletal; Postmortem Changes; Poultry; Rigor Mortis