Chemical composition and volatile compounds in the artisanal fermentation of mezcal in Oaxaca, Mexico

Abstract

The differences among the several varieties of mezcal produced in Mexico, besides the Agave species, consist essentially in the individuality of the traditional methods used in the elaboration or fermentation process. Therefore, it is necessary to understand the artisanal fermentation processes and to make clear the factors and management practices that have an influence on the chemical composition. Two mezcal artisanal factories of Agave angustifolia Haw. under two fermentation seasons were investigated in Oaxaca, Mexico. Volatile compounds were analyzed using a gas chromatograph and a capillary column HP-FFAP. Reference standards were used for the identification and quantification of volatile compounds. Samples were successfully separated, and the main volatile compounds identified corresponded to ethyl acetate, ethanol, methanol, 3-methyl-1-butanol, propanol, 2-methyl-1-propanol, and acetic acid. The chemical composition of the artisanal fermentation process differs significantly from factory to factory, season to season, and the interaction between the factories in which the fermentation process takes place and the seasons. Addition of ammonium sulfate reduces the fermentation time and affects significantly the production of ethanol, propanol and butanol, but decreases the methanol, ethyl acetate, and acetic acid production, and this practice is more convenient in fall than in spring. Key words : Fermentation, ammonium sulfate, volatile compounds, higher alcohol, gas chromatography, mezcal.