A comparison of the Maillard reactivity of proline to other amino acids using pyrolysis-molecular beam mass spectrometry

Maillard chemistry, or the low temperature condensation of amino acids and carbohydrates, is shown to be relevant to the practical regime of biomass pyrolysis and leads to dramatic changes in low-temperature volatile products and residual solid structure. Mixtures of amino acids and glucose were subjected to a two-temperature heating sequence (5 min each at 170 and 325 °C) and the volatile products analyzed by molecular beam mass spectrometry. Significant volatile yield was observed from the mixtures at 170 °C where neither amino acids nor glucose generated volatile material in the time frame studied. Proline was the most active of the amino acid studied.Volatile products at low temperature included the diketopiperazine, which were generated in higher yields than from proline alone. Also generated were Maillard condensation such as 1-(1′-pyrrolidinyl)-2-propanone. These products were also generated at 325 °C, but in addition, the mass spectra included evidence for the direct formation of nitrogen-containing aromatics. These observations are discussed in relation to known Maillard chemistry. [Copyright &y& Elsevier]