The hue and the chroma values depict the actual colour of the
object that is measured (Fig. 1) and thus give a better description
of the colour changes. The chroma values decreased (P < 0.0001)
in all the packaging treatments over time, indicating a decrease
in the vividness of the colour of the meat. The treatments differed
significantly from one another on all of the sampling days, except
on day 8 where the overwrap and the N_MAP did not differ. The
hue angle increased significantly in all three treatments over time,
indicating an increase in browning. The O_MAP increased the most
from 40.22 ± 1.08 to 60.69 ± 3.25, the overwrap from 44.85 ±
1.00 to 58.63 ± 2.81 and the N_MAP increased the least from
41.00 ± 1.58 to 48.19 ± 1.39 over 10 days. The gradual increase
in the hue angle observed in the N_MAP is indicative of slower oxidation
due to the low concentrations of oxygen (±3%) in the packaging
(Mancini & Hunt, 2005). The hue values for the O_MAP and
the overwrap remained stable for the first 4 days, while the myoglobin
was in an oxygenated state (oxymyoglobin) presenting a
cherry red pigment. The hue then began to increase as the myoglobin
was oxidised and converted to metmyoglobin (brown). The
chroma values support the hue values, indicating that the N_MAP
remained dull, while the O_MAP and the overwrap were initially
bright red and gradually became a dull brown colour as the myoglobin
was oxidised.