Aroma compounds generated from L-ascorbic acid and L-methionine during the Maillard reaction

Aroma compounds from the Maillard reaction of the L-ascorbic acid and L-methionine system were investigated. The mixture was heated while stirring at 142+/-2 degrees C for 2 h in an oil bath at five different pH values (5, 6, 7, 8, or 9). Analysis of the reaction mixture was performed by headspace-SPME-GC-MS technique, and further use of LRI. 27 Components, comprising 11 pyrazines, 5 thiophenes, 6 aliphatic S compounds, 4 furans (non-S-containing) and 1 phenol, were identified. The studies showed that furans (non-S-containing), 4-hydroxybenzo[b]thiophene and 2,3,5-trithiahexane were formed mainly at acidic pH. In contrast, higher pH values could promote the production of pyrazines, acylthiophenes, 2-(isopropylthio)thiophene, methyl butanedithioate and 2,4-di-tert-butylphenol. The effect of pH on the formation of other compounds did not follow a consistent pattern.