Volatile Compounds Formed from Thermal Degradation of Glucosamine in a Dry System

Glucosamine was pyrolyzed at 200 °C for 30 min under dry conditions. A roasty aroma was obtained. Volatile compounds generated included pyrazines, pyridines, pyrroles, and furans. The most interesting compounds were pyrazines with one or two furyl substituents. They are 2-(2-furyl)pyrazines, 2-(2-furyl)methylpyrazines, 2-(2-furyl)dimethylpyrazines, 2-(2-furyl)acetylpyrazines, and di-2-furylpyrazines. Some of these furyl pyrazines are being reported for the first time. The mechanism of the furan ring formation in polycyclic pyrazine compounds was studied. The furan ring was suggested as a result of the dehydration reaction from the intermediate polyhydroxypyrazines, which were dimerization products of glucosamine. Model reactions were designed to test the proposed mechanism. When fructose and ammonium acetate were heated under the same conditions as the glucosamine pyrolysis, those furyl pyrazines were also generated.