Simplified method for calculating colour of honey by application of the characteristic vector method

摘要

A quick and simple method to obtain the colour of honeys with minimum error is proposed. Characteristic vector analysis has been tested and proved to be applicable to the reconstruction of honey reflectance spectra. Expressions for tristimulus values are obtained as function of reflectance measurements at a few wavelengths. Different sets of reflectance were tested (from 3 to 6 wavelengths) showing better results as the number of characteristic vectors (wavelengths) increases. The measures were made both over white and over black backing. Results showed that, when spectrophotometric measurements are made with 10 mm pathlength cells, the determination of reflectance at four wavelengths (443, 530, 554, and 618 nm for white backing; 439, 488, 555 and 636 nm for black backing) is adequate to reconstruct the spectrum and to obtain the tristimulus chromatic characteristics. The black backing measurements showed better results, being 74% and 57% (black and white backing measurements, respectively) the percentage of samples giving colour differences less than 1 CIELAB unit between the calculated coordinates and those obtained from the whole visible spectra.