Use of liquid chromatography quadrupole time-of-flight mass spectrometry and metabolomic approach to discriminate coffee brewed by different methods.

An untargeted metabolomic method based on UPLC-QTOF were used to investigate the differences in coffee brewed by boiled, pour-over and cold-brew methods here. Distinctive separation among the three groups could be seen from principal component analysis and hierarchical clustering analysis. Analysis of variance, fold change and orthogonal projection to latent structures discriminant mode were conducted to find the characteristic potential markers, subsequently, nine potential markers were putatively identified using general chemical databases, and five of them were further confirmed by acquisition of reference standards. This work provides an efficient way for discrimination of coffee brewed by different methods. Interestingly, the result of this work also suggested that the contents of two selected markers, norharman and harman, were higher in the pour-over and boiled methods, compared to the cold-brew method. This content difference were further verified by the quantitative analysis data of commercial coffee samples.