Formation and characterization of polyphenol-derived red chromophores: Enhancing the color of processed cocoa powders: Part 2

Very recently, we described the formation of (+)-catechin- and (−)-epicatechin-derived polar chromophores by means of a cocoa alkalization process. In this study we focus on the generation of unpolar chromophores using model reactions via Dutching with softer alkaline conditions. UPLC-HR-ESI-TOF-MSe analysis and one-dimensional and two-dimensional NMR spectroscopy led to the unequivocal identification of dehydrodicatechin- and hydroxyxanthene-derived chromophores. The previously unknown 6-C-linked constitutional isomers of C-6′B/C-6D-(2R,3S)-dehydrodicatechin (3, 5) were first described, and furthermore, the dimers dehydrocatechin-C-6′B/C-8D-(2S,3S)-epicatechin (2) and dehydrocatechin-C-6′B/C-6D-(2S,3S)-epicatechin (4, 6) as well as the reddish-colored chromophores 8-C-xanthenocatechin (7), 8-C-xanthenoepicatechin (8), 6-C-xanthenocatechin (9), and 6-C-xanthenoepicatechin (10) were identified as new compounds. A LC-MS/MS method was developed to screen and quantify both classes of chromophores as well as t...