Effect of Slaughter Age on Beef Color Stability during Display of Four Muscles from Japanese Black Steers

Effect of slaughter age (24, 28 and 38 months of age) on beef color stability during display of m. serratus ventralis, m. psoas major, m. semitendinosus and m. longissimus thoracis from Japanese Black steers was studied. Steak samples from muscles were over-wrapped with PVC film and displayed under fluorescent lights at 4C for 12 days. Percentages of metmyoglobin of steak samples were determined at days 0, 3, 6, 9 and 12. The percentage of metmyoglobin of m. psoas major at day 3 of display in the 24 months group was lower (p<0.05) than that in the 38 months group. The percentage of metmyoglobin of m. semitendinosus at day 6 of display in the 38 months group was higher (p<0.05) than that in the other groups. The percentage of metmyoglobin of m. longissimus thoracis at day 3 of display in the 24 months group was lower (p<0.01) than that in the other groups. The percentage of metmyoglobin of m. longissimus thoracis at day 6 (p<0.01), 9 (p<0.01) and 12 (p<0.05) of display in the 38 months group were higher than those in the other groups. Crude fat concentration in m. longissimus thoracis increased (p<0.05) after 28 months of age. -Tocopherol concentration in m. serratus ventralis in the 38 months group was higher (p<0.001) than that in the other groups. In m. psoas major the -tocopherol concentration in the 38 months group was higher (p<0.05) than that in the 24 months group. The -tocopherol concentration in m. longissimus thoracis increased (p<0.001) with age. These results suggested that in spite of increase in both the crude fat and the tocopherol concentrations in m. longissimus thoracis, the beef color stability during display became short with age. (