Results of research on the determination of a method and a system for on-line non-destructive testing of the quality of naturally white materials are presented. Taking into account analysis of the color properties of the material, two methods are proposed: the first is based on calculation of color indices (whiteness, yellowness, and blue reflectance), and the second is based on comparison of the measured reflectance spectra in appropriately selected wavelength ranges. Practical realization of the second sensing method is described using an optical-fiber color sensor. The testing methods presented can be applied for non-destructive on-line inspection of various color products in different industries.
Marszalec, E., Kopola, H., & Myllylä, R. (1993). Non-destructive testing of the quality of naturally white food products. Sensors and Actuators B: Chemical, 11(1-3), 503 - 509. https://doi.org/10.1016/0925-4005(93)85294-K