Optimization of Agave cupreata juice fermentation process for mezcal production using statistical experimental design

Abstract

Mezcal is a traditional alcoholic beverage in Mexico obtained from fermentation of juices, coming from mature agave pineapples, and their subsequent distillation, Agave cupreata juice as natural sugar source is the commonly used. This study aims to investigate mezcal production from Agave cupreata juice by optimizing fermentation at flask level temperature; initial content sugar; pH and initial cell concentration, using single strains, factorial fractional design was applied and for fermentation at bioreactor level 2.5 Liters a Simplex centroid design was developed to determine the most appropriate yeast consortium for producing mezcal. The fermentation process was carried out for 52 h with varied input variables, and all the models showed significant p-values for interaction of variance (< 0.05). It was produced at an optimized temperature of 32.5 °C, initial quantity sugar of 14 °Brix, pH of 5.5 and stirring agitation of 150 rpm was found that it is possible to reach ethanol concentration levels of about 5.9, 5.2, 7.3 and 4.9% v/v for S. cerevisiae, C. lusitaniae, K. marxianus and Z. bailii, respectively. Therefore K. marxianus and Z. bailii strains reached the highest production of ethanol. Fermentation broths from the mixture design were distilled and rectified determining alcohol concentration; mixtures of K. marxianus and Z. bailii reached ethanol content in their distillates, about 42.82% v/v. The developed models could predict the quality of mezcal developed from Agave cupreata using a yeast consortium.

Keywords:
Agave cupreata; fermentation; mezcal production; optimization; yeast consortium