2.6. Measurement of pigment NO-Heme
The concentration of cooked meat pigment NO-Heme was
measured according to the method described by Hornsey (1956). All
the procedures were carried out under anaerobic condition within a
fume hood in a dimmed roomilluminated by aweak red light (ca.1.04
lx) at room temperature (ca. 20 C). All solvents were deoxygenated
by flushing with a streamof nitrogen gas.Minced samples (10 g each)
fromcooked beef patties without storage (day 0) or stored for 9 days
were each mixed with 40 mL of acetone and 3.2 mL of water. The
mixture was stirred intermittently for 5 min then centrifuged
(1000g, 5min). The absorbance of the supernatantwasmeasured at
a 540 nm against the acetone/water blank. The NO-Heme concentration
in the sampleswas calculated by the formula: NO-Heme (mg/
kg) ¼ A540 290. The test was done on triplicatemuscle samples for
each pea protein treatment. The reduction rate of NO-Heme
decomposition was calculated as the concentration difference (mg/
kg) between 9th and 0th day samples divided by the concentration of
the 0th day sample then multiplying by 100.