Characterization of the aromatic composition of some liquid foods by nuclear magnetic resonance spectrometry and liquid chromatography with nuclear magnetic resonance and mass spectrometric detection

This paper describes the first application of NMR spectroscopy and LC-NMR/MS to the direct analysis of the aromatic composition of beer, grape juice and a wine phenolic extract. NMR spectroscopy provides non-invasive information on the overall aromatic profile and enables the identification of some compounds. However, a more comprehensive assignment is hindered by the low peak intensity and strong signal overlap in the low-field spectral region, as well as by the inherent lack of scalar coupling information for many aromatic compounds present. LC-NMR/MS can overcome these problems and is shown to aid significantly in the identification of aromatic compounds composing all samples analyzed. Some examples are the identification of several cinnamic acids (e.g. p-coumaric, trans-coutaric and trans-caftaric) in grape juice, the identification of 2-phenylethanol, tyrosol and tryptophol in beer and the detection of phenolics such as catechin, epicatechin, trans-resveratrol, tyrosol and caffeic acid in the wine extract.