Use of digital images to estimate CIE color coordinates of beef

The objective of this study was to evaluate the use of digital images (DI) to estimate CIE L∗a∗b∗, hue angle and chroma of beef, as compared to a colorimeter (CM). Loin samples from 21 steers finished with high-grain diets were displayed under retail-simulated conditions. Color readings were obtained from 63 cores covering the full spectrum of discoloration in beef. CIE L∗, a∗, and b∗ were measured with a surface-reflectance CM. Red, green and blue (RGB) values were obtained from DI and sequentially transformed to XYZ and CIE L∗a∗b∗ color space. Hue angle and chroma were calculated from a∗ and b∗ values. Regressions of CM on DI for a∗, hue angle and chroma had R2 values of 0.93 and above. Average color difference (ΔEab∗) between the predicted and the actual CM L∗, a∗, and b∗ values for 13 samples that were not included in the regressions was 1.57, below reported thresholds of detection for 50% of observers. Color readings from DI could be used to accurately predict color coordinates measured by CM, especially a∗, hue angle and chroma. Use of digital imaging could become a practical tool to detect changes in beef color and other muscle foods.