| dc.description.abstract | The primary objectives of this research were to characterize the involvement of
lactate dehydrogenase (LDH) in color stability of physiologically different bovine
muscles, and to investigate the influence of lactate enhancement on the myoglobin redox
state of bovine muscles. In experiment 1, three different bovine muscles; Longissimus
lumborum (LD), Semimembranosus (SM), Psoas major (PM) were (n=7 respectively)
cut into steaks, and displayed for 7 days. Instrumental color, LDH-B, LDH isozyme
expression, and NADH were measured. In experiment 2, strip steaks (n=8) were cut into
half, and one side was injected with oxamate (LDH inhibitor), and the other was injected
with water. Surface color, LDH, and NADH were measured after 10 days. In
experiment 3, the three bovine muscles (n=10) were enhanced with solutions containing
lactate and/or phosphate. Steaks were stored and displayed for 14 days. Instrumental
color, LDH-B, total reducing activity (TRA), and NADH were measured. In experiment
4, fifteen beef strip loins were divided individually into four equal sections, and one of six treatments containing phosphate and/or calcium lactate with or without irradiation
(2.4 kGy) randomly assigned to each loin section (n=10). Steaks were packaged in highoxygen
modified atmosphere package, irradiated, stored in the dark at 1°C for 14 days.
Instrumental color, TRA, lipid oxidation, and NADH were measured.
LD remained the most red, whereas PM was most discolored. LD had a
significantly higher level of LDH-1 responsible for LDH-B activity as compared to SM
and PM. Consequently, LD had a higher LDH-B, and more NADH (p < 0.05).
Inclusion of oxamate inhibited LDH-B, decreased NADH, and consequently discolored
more. Potassium lactate enhancement led to more NADH through elevated LDH flux
and subsequently increased (p < 0.05) color stability of LD and PM throughout display.
Loins with calcium lactate/phosphate maintained the most stable red color during display.
Calcium lactate/phosphate in loins increased NADH concentration, TRA, and were the
least oxidized over display. These results confirm the involvement of LDH in meat
color stability through replenishment of NADH. Lactate enhancement promotes meat
color stability by providing superior antioxidant capacity and increased reducing activity
of myoglobin by elevating NADH concentration. | en |
