Degradation Products Formed from Glucosamine in Water

• Published in: Journal of agricultural and food chemistry 1998-03, Vol.46 (3), p.1129-1131
• Main Author: Shu, Chi-Kuen
• Format: Article
• Language: English
• Subjects: AMINO SUGARS; Carbohydrates with 4, 5, 6, ... C atoms, dissacharides and oligosaccharides; Carbohydrates. Nucleosides and nucleotides; CHEMICAL DEGRADATION; CHEMICAL REACTIONS; Chemistry; DEGRADATION; Exact sciences and technology; FLAVOUR COMPOUNDS; IDENTIFICATION; Organic chemistry; Preparations and properties; QUANTITATIVE ANALYSIS; WATER
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf970812n

An aqueous solution of glucosamine hydrochloride was heated to 150 °C for 5 min under different pH conditions. The reaction product mixture obtained was analyzed by GC/MS. It was found that the major products formed were furfurals, especially at pH = 4 and 7. At pH = 8.5, additional flavor components were generated, including pyrazines, 3-hydroxypyridines, pyrrole-2-carboxaldehyde, furans, acetol, and several other compounds. Of the components identified, it is worthwhile to note the formation of pyrazine and methylpyrazine as major components at pH = 8.5. It is proposed that a retro-aldol condensation plays an important role in the formation of the intermediates, α-aminoacetaldehyde (I) and α-amino propanal (II). As a result, self-condensation of I generates pyrazine and combination of I and II generates methylpyrazine. In addition, it is also interesting to note the formation of 3-hydroxypyridines and pyrrole-2-carboxaldehyde. It is suggested that both groups of compounds are derived from furfurals. As the ammonia is liberated from glucosamine, it initiates the ring-opening of furfurals to form 5-amino-2-keto-3-pentenals. Intramolecular condensations of these intermediates between the amino group and the carbonyl groups lead to the formation of 3-hydroxypyridines and pyrrole-2-carboxaldehyde. Keywords: Glucosamine; retro-aldol condensation; α-amino acetaldehyde; α-amino propanal; GC/MS