Formation of flavor components by the reaction of amino acid and carbonyl compounds in mild conditions

This work describe products of reactions between four a-dicarbonyl. compoun ds (diacetyl, pentan-2,3-dione, glyoxal, and methylglyoxal) or two cr-hydro xy ketones, (acetoine and acetol) and amino acids present in wines. The res ults shows the formation of odorous products or strong-smelling additives r esulting from the Maillard and Strecker reaction in a primarily aqueous med ium;, at low temperature and low pH (similar to pH 3.5) of the wine. GC/FID , GC/FPD, GC/NPD and GC/MS techniques were used. The olfactive characterist ics of the products are described. In the presence of sulfur amino acids an d in particular cysteine, many products were formed with a heterocycle prod uction such as pyrazines and methylpyrazines, methylthiazoles, acetylthiazo les, acetylthiazolines, acetylthiazolidines, trimethyloxazole, and dimethyl ethyloxazoles. These various compounds present odors of sulfur, cornlike, p ungent, nut, popcorn, roasted hazelnut, toasted, roasted, and ripe fruits. The chemical conditions of the model reactions are specified. The influence of temperature and pH ori the reactions in the presence of cysteine were a lso studied.