Key meat flavour compounds formation mechanism in a glutathione–xylose Maillard reaction

The formation mechanism of meat flavours formed from a glutathione–xylose Maillard reaction was studied using a group of model reactions with [13C5] xylose/xylose (1:1), heated at 132 °C for 90 min. Volatiles, especially the aroma-active compounds, and non-volatiles were analysed respectively with GC-O-MS and LC-TOF-MS. Analysis of the mass spectra showed that furfural, 2-furfurylthiol and thiophene were 13C5-labelled and hence stem from xylose, whereas 2-methyl-3-furanthiol, 2-methyl-thiophene and 2-pentyl-thiophene, which showed similar formation patterns with only unlabelled compounds, may be from thiamine and/or cysteine carbons. In the process of Maillard reactions, GSH can be capable of cleaving in the position of glutamyl and cysteinyl, and then form 5-oxoproline or pyroglutamic acid (PCA), cysteine, and Cys-Gly dipeptide, which can form cyclic (Cys-Gly).