COMPARISON OF THE VOLATILE COMPOUNDS FORMED FROM THE THERMAL-REACTION OF GLUCOSE WITH CYSTEINE AND GLUTATHIONE

Sulfur-containing amino acid, cysteine, and tripeptide, glutathione (gamma-Glu-Cys-Gly), were reacted with glucose in an aqueous medium. Each reaction solution was adjusted to pH 7.5 and heated for 1 h at 180-degrees-C. A roasted sesame and cooked-rice-like aroma with strong sulfur notes was observed for both reaction masses. A total of 62 compounds including 7 furans, 8 carbonyls, 10 thiazoles, 19 thiophenes, 10 pyrazines, and 6 cyclic polysulfides were identified by GC and GC/MS. Most of them can be accounted for by well-known chemical reaction mechanisms. In the reaction system of glucose and cysteine, more sugar-amino acid interaction products were formed, and the major product was 3,5-dimethyl-1,2,4-trithiolane. In contrast, for the reaction of glucose and glutathione, carbonyls and furans dominated quantitatively, and 5-methylfurfural was found as the most abundant product. They were derived from the thermal degradation of glucose. The degradation of cysteine alone produced the greatest amount of volatile compounds compared with the interaction of either 2,4-decadienal or glucose. However, when glutathione reacted with 2,4-decadienal, the volatile production increased dramatically and decreased again when reacting with glucose.