Simplified measurement of virgin olive oil color by application of the characteristic vector method

There are several simplified methods to measure the color of virgin olive oils. However, their reliability is questionable, as they provide errors that sometimes can be considerable. A new method to calculate color coordinates and objective chromatic parameters in the color region of these olive oils is proposed with the aim of overcoming these objections. The method is a simplification of the original method proposed by the Commission Internationale de l'Eclairage (CIE), based on the measurement of the complete visible spectrum, from 380 to 770 nm. The characteristic vector analysis provides new equations to calculate tristimulus values as functions of these transmittance values based on a reconstruction of oil transmission spectra measuring from three to six wavelengths. The results show that color differences exist between the color coordinates of the experimental samples and those obtained by means of the proposed method. For more than 90% of the samples, the difference was smaller than three CIELAB units when equations based on four or more wavelengths were used.