N-delta-(5-hydroxy-4,6-dimethylpyrimidine-2-yl)-L-ornithine, a novel methylglyoxal-arginine modification in beer

N-delta-(5-Hydroxy-4,6-dimethylpyrimidine-2-yl)-L-ornithine, or Argpyrimidi ne, was identified and quantified in beer by high-performance liquid chroma tography (HPLC) and coupled gas chromatography-mass spectrometry (HRGC-MS). This novel fluorescent arginine Maillard modification represents the first amino acid modification reported in beer retaining the full backbone of th e original amino acid. Two mechanisms of formation could be verified: the m ajor pathway via methylglyoxal and the minor pathway via 5-deoxypentoses. A rgpyrimidine concentrations, determined in 35 lager-type beer varieties, re ached up to 27 nmol/L and could be positively correlated to beer color and wort content. Within this context, 5-deoxy-D-ribose was identified as a nov el intermediate of the Maillard reaction of maltose by HRGC-MS and independ ent synthesis.