Fermentative characterization of producers ethanol yeast from Agave cupreata juice in mezcal elaboration

 

E. Pérez, J.C. González-Hernández, M.C. Chávez-Parga and C. Cortés-Penagos

 

 

Conventional and unconventional yeast strains possess the ability to produce ethanol under different operating and nutritional conditions showing different yields in biomass and ethanol production. In the present work, the kinetics of biomass and ethanol productions were studied at flask and bioreactor levels during the fermentation of Agave cupreata juice. The established variables in a Box-Behnken design were: type of yeast, sugars concentration and temperature (at flask level). At biorreactor level, aeration and agitation were studied by using a factorial experimental design. The response variables evaluated in each test were biomass, ethanol and pH. Volatiles compounds (methanol, ethanol and higher alcohols) were quantified in the distilled fermented must by gas chromatography. It was found that the temperature-sugars interaction was the most significant factor influencing the ethanol concentration. Kluyveromyces marxianus yielded the highest ethanol concentration (12.46% v/v) at 12 °Brix and 28 °C, in bioreactor level, with agitation of 150 rpm and aeration of 0.1 vvm. The fermented must was distillated containing methanol and ethanol concentrations of 1.89% and 47.75% respectively.