Abstract:

The identification of volatile compounds generated from the Maillard reaction of L-ascorbic acid and L-cysteine
under different water content conditions was performed using headspace solid-phase microextraction-gas chromatographymass
spectrometry (HS-SPME-GC-MS). Sixty-two volatile compounds were identified, including thiophenes, sulfurcontaining
heterocyclic compounds, thiazoles, thiols, furans and thioethers. Meanwhile, 23 thiophenes and 13 sulfurcontaining
heterocyclic compounds were the major volatile compounds in the Maillard reaction products. The effect of water
content on the generation of volatile compounds was investigated. The results showed that water content had significant
effect on the formation of sulfur-containing heterocyclic compounds and thiophene compounds, but had little effect on
other volatile products. Among these sulfur-containing heterocyclic products, two isomers of 3,5-dimethyl-1,2,4-trithiolane
and 4,6-dimethyl-1,2,3,5-tetrathiane had the maximum concentration when the water content was 55%. The concentration
of two isomers of 2,4,6-trimethyl-1,3,5-trithiolane decreased with increasing water content, and 3-methyl-1,2,4-trithiane
had a minimum level at the water content of 45%. However, thiophene products, such as thiophene, 2-methylthiophene,
thieno[3,2-b]thiophene, 2-methylthieno[2,3-b]thiophene and 2-methyl-3-thiophenethiol reached a maximum level at the
water contents of 75%, 55%, 85%, 65% and 15%, respectively.

Key words: Maillard reaction, ascorbic acid-cysteine, water content, thiophene, sulfur-containing heterocyclic compounds