The influence of myoglobin on the colour of minced pork loin

The influence of the total and chromatic absorbance at wavelengths of 525 nm (A₅₂₅ and A_525p) and 700 nm (A₇₀₀), and the relative content of oxymyoglobin (MbO₂), metmyoglobin (MetMb) and deoxymyoglobin (Mb), on the value of the colour parameters (L*, a*, b*, C* and h°) of minced pork loin, were evaluated. Lightness (L*) depended almost entirely on variation in total absorbance at a wavelength of 525 nm. Redness (a*) depended on the forms of myoglobin and A_525p, while yellowness (b*) depended mainly on the proportions of the reduced form (Mb), the oxygenated form (MbO₂) and the oxidised form (MetMb). Yellowness (b*) significantly increased with a decrease in the relative amount of Mb and an increase in relative amounts of MbO₂ and MetMb, although a greater impact was exerted by fluctuations in MbO₂ than MetMb. Variability of chroma (C*) depended mainly on proportions of the forms of myoglobin. Hue angle (h°) depended primarily on chromatic absorbance at 525 nm (A_525p).