Investigation of the reaction between ammonium sulfide, aldehydes, and alpha-hydroxyketones or alpha-dicarbonyls to form some lipid-Maillard interaction products found in cooked beef

Aqueous reaction mixtures containing alpha-dicarbonyls (2,3-butanedione or 2,3-pentanedione) or alpha-hydroxyketones (1-hydroxypropanone, 1-hydroxy-2-butanone, or 3-hydroxy-2-butanone), alkanals (C-4-C-10) and ammonium sulfide were heated at 140 degrees C for 30 min. Among the products formed were 3-thiazolines and thiazoles with C-3-C-9 alkyl substituents in the e-position and methyl or ethyl in positions 4 and/or 5. Similar compounds have recently been reported in cooked beef, and their presence in the reaction mixtures confirmed the proposed route of formation, in cooked beef, from the reaction of lipid-derived aldehydes with dicarbonyls, ammonia, and hydrogen sulfide produced via the Maillard reaction. Trialkylpyridines, which had been observed in cooked beef, were also formed by the reaction of three molecules of aldehyde with one of ammonia. The mass spectra of all of these compounds are reported.