Work

Unraveling the formation mechanism of 3-methylindole from tryptophan in the glucose-mediated Maillard reaction: a combined ReaxFF MD, DFT, and experimental study

Year: 2026

Type: article

Abstract: 3-Methylindole is a concentration-dependent aroma compound, and its formation mechanism in the tryptophan-glucose Maillard reaction is crucial for flavor regulation but remains incompletely elucidated. Using gas chromatography-olfactometry-mass spectrometry (GC-O-MS), 3-methylindole was identified as a key odor-active compound (OAV > 1). Reactive molecular dynamics (ReaxFF MD) and density functional theory (DFT) revealed a sequential pathway involving nucleophilic addition, Amadori rearrangement, dehydration, decarboxylation, and Strecker degradation, and characterized 16 transition states and their activation energies, indicating a net endothermic reaction. Pyrolysis-gas chromatography–mass spectrometry (Py-GC–MS) detected methylglyoxal and indole-3-acetaldehyde as key intermediates, whose temperature-dependent concentration trends supported the proposed pathway. Differential scanning calorimetry (DSC) further confirmed the multi-stage endothermic behavior, consistent with the DFT results. This study proposes a complete formation mechanism of 3-methylindole, providing a theoretical basis for indole-type flavor generation and a methodological framework for studying volatile compounds in complex thermally processed food systems.

Source: Food Chemistry X

DOI: 10.1016/j.fochx.2026.104719