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 °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. Keywords: Serine; glucose; ribose; Maillard; volatile; flavor; roasty; pyrazine; furfuryl; acetol; aldehyde