Determination of Carotenoids of Tomato Fruits of Different Colors

Abstract A method for the determination of the composition of carotenoids of tomato fruits of different colors is proposed using a combination of spectrophotometry and chromatography. An explanation of the elution order of mono-cis-isomers of lycopene under the conditions of reversed-phase chromatography on traditional “monomeric” reversed C18-phases is proposed for the first time. It was found that, for prolycopene, (7Z, 9Z, 7'Z, 9'Z)-lycopene, which is responsible for the orange color of fruits, there is an almost imperceptible transition in normal examination in the vibronic structure of the electronic absorption spectrum with the lowest energy, λmax(1) = 486.2 nm. The main carotenoids of tomato fruits of different colors were determined: trans-lycopene and its cis-isomers for fruits of red and pink colors, protolycopene and other carotenes preceding its biosynthesis for fruits of orange color, and the carotenoid composition of yellow tomatoes significantly differing from that of tomatoes of first two colors by a considerable accumulation of lutein. For the quantitative assessment of the concentration of carotenoids with different chromophores, a calculation system ensuring the determination of the contribution of each of the components of complex mixtures was proposed.