Abstract: Alkylpyrazines formed by the Maillard reaction between alanine (Ala) and 2,3-butanedione (2,3-BD) were identified and quantified by high performance liquid chromatography (HPLC). Kinetic models for six alkylpyrazines were established to understand the mechanism of the formation of pyrazines. A total of eight alkylpyrazines were identified, including five methylpyrazines and three ethylpyrazines. The results showed that the formation of alkylpyrazines had a good correlation with reaction temperature and time, and was favored by alkaline conditions. The formation of dimethyl pyrazines (DMPs) and ethylpyrazines (EP) followed a first-order kinetic model, while the formation of the other pyrazines fitted well to a zero-order kinetic model. Among the eight alkylpyrazines, the activation energy for the formation of 2-ethyl-5-methylpyrazine (EP-5-MP) was the lowest (3.310 6 kJ/mmol).

Key words: α-dicarbonyl compounds; alkylpyrazines; kinetic model; Maillard reaction; flavor