VIEW ARTICLE    DOI: 10.1094/ASBCJ-35-0191

Nuclear Magnetic Resonance Spectroscopy of the Aromatic Region of Beer Extracts. Guy Belleau and Miroslav Dadic, Molson Breweries of Canada Limited, Montreal, Quebec H2L 2R5. J. Am. Soc. Brew. Chem. 35:0191, 1977.

The aromatic (benzenoid) components of beer comprise such important constituents as polyphenols, aromatic amino acids and peptides, and aromatic alcohols. The impact of these substances on beer quality is well established, particularly in connection with its colloidal and flavor stability. The application of nuclear magnetic resonance (NMR) spectroscopy to the investigation of the beer aromatic components is suggested due to a low-field resonance of such compounds vs. the resonance of other major beer constituents. The extracts of the aromatic beer constituents suitable for the NMR analysis are prepared using ethyl acetate. Deuterated methanol is used as the NMR solvent and the spectra are recorded both at 500 Hz and with the expansion of 50 Hz and a sweep offset of 380 Hz. The chemical shifts of the major aromatic components, as well as their integration values, are recorded for various types of beer, both fresh and aged. The forcing (heating at 60° C) kinetics of beer is established as a possible parameter for its fingerprinting as to the type and age. A novel method for an approximate determination of the monomeric catechins in beer extract, using the NMR, has been developed as an additional parameter in beer fingerprinting and quality monitoring.

Keywords: Aromatic (benzenoid) beer components, Beer fingerprinting, Ethyl acetate extracts, Monomeric catechins, Nuclear magnetic resonance (NMR).