Unraveling the mechanism of aroma formation in the maillard reaction of roasted Wuyi rock tea: Focus on furfural, tea pyrrole, and 1-ethyl-1H-Pyrrole

Abstract

The formation mechanisms of key aroma-active compounds in Wuyi rock tea (WRT)—furfural, tea pyrrole, and 1-ethyl-1H-pyrrole, which contribute to its roasted aroma and low sensory thresholds—remain unclear. This study employed the carbon module labeling (CAMOLA) technique to simulate medium-fire roasting conditions (130 °C, 5 h) of WRT, enabling the elucidation of the formation pathways within a theanine-glucose Maillard system. Aroma components were identified using solid-phase microextraction coupled with comprehensive two-dimensional gas chromatography-mass spectrometry. Results showed that the carbon skeletons of furfural and 5-hydroxymethylfurfural were primarily derived from glucose, while the glutamic acid component of theanine also contributed to the formation. The carbon skeleton of pyrrole compounds was entirely supplied by glucose, with the N-ethylamine group originating from the ethylamine moiety of theanine. Epigallocatechin gallate modulated pyrrole formation by promoting the Strecker degradation pathway and altering glucose cleavage patterns. Glucose significantly influenced furfural formation, while theanine played a crucial role in generating tea pyrrole and 1-ethyl-1H-pyrrole. Thus, these compounds can serve as critical indicators for monitoring the roasting process.