Reflectance at 610 nanometers estimates oxymyoglobin content on the surface of ground beef

This research evaluated the utility of direct (K/S 610÷K/S 525) and indirect (100%-% deoxymyoglobin+% metmyoglobin) methods for estimation of oxymyoglobin (OMb) on the surface of ground beef. Direct estimation was highly correlated to visual color scores (r=-0.93), indirect determination of OMb (r=0.98), and % metmyoglobin (r=-0.98). Since indirect OMb was based partially on % deoxymyoglobin, which was poorly correlated to visual color scores, the accuracy of the subtraction method may be limited. Both direct and indirect methods produced similar variability when estimating OMb. All calculations for pigment forms produced outliers, which were adjusted to 0 and 100% to more precisely represent surface pigment concentrations. This work suggests that the K/S 610÷K/S 525 method is accurate and repeatable and can be used to quantify surface OMb concentration and discoloration of ground beef.