| dc.description |
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 . |
|