title: Composition of beer by 1H NMR spectroscopy: effects of brewing site and date of production.
abstract: A principal component analysis (PCA) of 1H NMR spectra of beers differing in production site (A, B, C) and date is described, to obtain information about composition variability. First, lactic and pyruvic acids contents were found to vary significantly between production sites, good reproducibility between dates being found for site A but not for sites B and C beers. Second, site B beers were clearly distinguished by the predominance of linear dextrins, while A and C beers were richer in branched dextrins. Carbohydrate reproducibility between dates is poorer for site C with dextrin branching degree varying significantly. Finally, all production sites were successfully distinguished by their contents in adenosine/inosine, uridine, tyrosine/tyrosol, and 2-phenylethanol, reproducibility between dates being again poorer for site C. Interpretation of the above compositional differences is discussed in terms of the biochemistry taking place during brewing, and possible applications of the method in brewing process control are envisaged.
authors.affiliation: CICECO and QOPNAA, Department of Chemistry, Campus Universitário de Santiago, University of Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Cláudia
authors.initials: C
authors.lastname: Almeida
authors.forename: Iola F
authors.initials: IF
authors.lastname: Duarte
authors.forename: António
authors.initials: A
authors.lastname: Barros
authors.forename: João
authors.initials: J
authors.lastname: Rodrigues
authors.forename: Manfred
authors.initials: M
authors.lastname: Spraul
authors.forename: Ana M
authors.initials: AM
authors.lastname: Gil
mesh_terms: D000241:Adenosine / Q000032:analysis; D001515:Beer / Q000032:analysis*; D003912:Dextrins / Q000032:analysis; D004777:Environment; D019344:Lactic Acid / Q000032:analysis; D009682:Magnetic Resonance Spectroscopy; D019289:Pyruvic Acid / Q000032:analysis; D015203:Reproducibility of Results; D013997:Time Factors; D014443:Tyrosine / Q000032:analysis; D014529:Uridine / Q000032:analysis
chemical_list: D003912:Dextrins; D019344:Lactic Acid; D014443:Tyrosine; D019289:Pyruvic Acid; D000241:Adenosine; D014529:Uridine