VOLATILE COMPOUNDS GENERATED FROM THERMAL INTERACTION OF GLUCOSE AND ALLIIN OR DEOXYALLIIN IN PROPYLENE-GLYCOL

Alliin and deoxyalliin, the two important nonvolatile flavor precursor s of garlic, were reacted with and without glucose in propylene glycol , respectively. The reactions were accomplished in a closed sample cyl inder at 180 degrees C for 1 h. The volatile compounds generated were isolated and analyzed by GC and GC-MS. A considerable amount of allylt hio-containing and cyclic sulfur-containing compounds were found in de oxyalliin systems. No allylthio-containing compounds and only a small amount of cyclic sulfur-containing compounds were found in alliin syst ems. Some pyrazines were identified from both alliin and deoxyalliin m odel systems even in the absence of glucose. Propylene glycol was prop osed to participate in the formation of some pyrazines. More thiophene s were generated in deoxyalliin model systems than in aIIiin model sys tems, while more thiazoles were generated in alliin model systems than in deoxyalliin model systems.