Volatile compounds generated in serine-monosaccharide model systems

The model Maillard reactions of serine-ribose (S-R) and serine-glucose (S-G) were studied. The reactions were conducted in a pH 8 aqueous solution at 160 degrees C for 2 h. Three times more volatiles were generated in the S-R system than in the S-G system, and in total, 37 compounds were identified in the two reaction systems. Some novel pyrazines were formed in both reaction solutions. In the serine-ribose system, the identified pyrazines were 2-(2-furfuryl)pyrazine, 2-(2-furfuryl)-5(and 6)-methylpyrazine, and 2-(2-furfuryl)-3,5-dimethylpyrazine, In the serine-glucose system, 2-[5-(hydroxymethyl)-2-furfuryl]-3,5-dimethylpyrazine was the only identified bicyclic pyrazine compound. To confirm the formation of these pyrazine compounds, they were prepared in a model reaction involving acetol, ammonium acetate, and corresponding aldehydes. In such model reaction systems, we also prepared 2(2-thienylmethyl)-3,5(and 3,6)-dimethylpyrazine and 2-(2-pyrrylmethyl)3,5(and 3,6)-dimethylpyrazine. Mass spectra of some compounds were reported for the first time.