This work examined changes in color that can be explained solely on the basis of the total myoglobin content and the relative proportions of deoxymyoglobin, oxymyoglobin (OMb) and metmyoglobin (MMb) during storage of meat. Meat color was evaluated for L*, a*, b*, C* and h ab . Total pigment content was measured from the reflex attenuance at 525 nm (A 525 ). The relative proportions of each pigment was determined using two different methods: the Krzywicki method based on the reflex attenuance values at 473, 525, 572 and 700 nm and the KS method based on K/S ratios of the absorption and scattering coefficients (K/S) 474 7 (K/S) 525 , (K/S) 572 7 (K/S) 525 and (K/ S) 610 7 (K/S) 525 . The study was performed on beef (Longissimus lumborum) samples measured after 1, 4 and 7 days of exposure to air. Result revealed that L* values can be fully explained by A 525 alone. C* and a* were well explained by those parameters related to OMb content. The other color parameters depended on pigment forms. The KS method gave better results. The parameters related to MMb content were relevant to classify samples according to the time of exposure to air. In any case, information provided by color and pigment parameters were complementary to each other.

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Color of 33 commercial red wines and fivecolor reference wines was measured in the same conditions in which visual color assessment is done by wine tasters. Measurements were performed in the two distinctive regions, center and rim, which are the regions assessed by wine tasters when the wine sampler is tilted. Commercial wines were classified into five color categories using the color specifications in their taste cards. The five color categories describe the spread of red hues found in red wines from the violet to brown nuances. The performance of CIELAB color coordinates in terms of their ability to reproduce the observed classification has been established using discriminant analysis. The CIELAB hue angle, h ab , measured in the rim, where wine thickness is of the order of few millimeters, gives the best results classifying correctly 71.1% of the samples. Classification results are not significantly improved when additional color coordinates are considered. Moreover, DE* color differences with color reference wines do not provide good classification results. The analysis of reference and commercial wines supports the fact that hue is the main factor in the classification done by wine tasters. This is reinforced by the linear correlation found between h ab in the rim and the wine age (R 2 ¼ 0.795) in accordance with the fact that wines change their hues from violet to brown tints with ageing.

Two procedures based on reflectance (R) measurements to calculate the proportions of deoxymyoglobin (DMb), oxymyoglobin (OMb) and metmyoglobin (MMb) in meat are recommended by the American Meat Science Association (AMSA). One uses the K/S ratios (K and S are the absorption and scattering coefficients) and the other method (Krzywicki 1979) uses the reflex attenuance A=log (1/R). Both methods were compared in: a) synthetic sets of two pigment mixtures and b) 15 samples of beef Longissimus Lumborum measured after 24 h, 4 and 7 days of exposure to air. It was found that K/S and Krzywicki methods gave different values of pigment proportions. However both methods exhibited a high linear correlation (R 2 =0.8733 in DMb, R 2 =0.9771 in OMb and R 2 =0.9390 in MMb, p<0.0001). This makes them equivalent for statistical analysis based on differences in pigment proportions.