Analysis of bitter fractions of roasted coffee by LC-ESI-MS -- new chlorogenic acid derivatives

Chlorogenic acid lactones were identified as important compounds of the bitter methanol fraction of the roasted coffee fractionation. Seven chlorogenic acid lactones were identified in the methanol fraction, with 5 of them identified for the first time in roasted coffee. Sensory tasting revealed bitterness of the lactones at 19 ppm (in aqueous solution). Schrader et al. (1996) quantified lactone contents (3-CQL + 4-CQL) at 120 ppm. Therefore, it can be assumed that these compounds do have an impact on the perceivable coffee bitterness. Furthermore, chlorogenic acid methylesters were identified via LC-ESI-MS (HPLC electrospray ionization mass spectrometry) analysis. Structural identification of the isomers is still ongoing.