title: Ethanol yield and volatile compound content in fermentation of agave must by Kluyveromyces marxianus UMPe-1 comparing with Saccharomyces cerevisiae baker's yeast used in tequila production.
abstract: In tequila production, fermentation is an important step. Fermentation determines the ethanol productivity and organoleptic properties of the beverage. In this study, a yeast isolated from native residual agave must was identified as Kluyveromyces marxianus UMPe-1 by 26S rRNA sequencing. This yeast was compared with the baker's yeast Saccharomyces cerevisiae Pan1. Our findings demonstrate that the UMPe-1 yeast was able to support the sugar content of agave must and glucose up to 22% (w/v) and tolerated 10% (v/v) ethanol concentration in the medium with 50% cells survival. Pilot and industrial fermentation of agave must tests showed that the K. marxianus UMPe-1 yeast produced ethanol with yields of 94% and 96% with respect to fermentable sugar content (glucose and fructose, constituting 98%). The S. cerevisiae Pan1 baker's yeast, however, which is commonly used in some tequila factories, showed 76% and 70% yield. At the industrial level, UMPe-1 yeast shows a maximum velocity of fermentable sugar consumption of 2.27g·L(-1)·h(-1) and ethanol production of 1.38g·L(-1)·h(-1), providing 58.78g ethanol·L(-1) at 72h fermentation, which corresponds to 96% yield. In addition, the major and minor volatile compounds in the tequila beverage obtained from UMPe-1 yeast were increased. Importantly, 29 volatile compounds were identified, while the beverage obtained from Pan1-yeast contained fewer compounds and in lower concentrations. The results suggest that the K. marxianus UMPe-1 is a suitable yeast for agave must fermentation, showing high ethanol productivity and increased volatile compound content comparing with a S. cerevisiae baker's yeast used in tequila production.
authors.affiliation: Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Michoacán, México.
authors.forename: Arnoldo
authors.initials: A
authors.lastname: López-Alvarez
authors.forename: Alma Laura
authors.initials: AL
authors.lastname: Díaz-Pérez
authors.forename: Carlos
authors.initials: C
authors.lastname: Sosa-Aguirre
authors.forename: Lourdes
authors.initials: L
authors.lastname: Macías-Rodríguez
authors.forename: Jesús
authors.initials: J
authors.lastname: Campos-García
mesh_terms: D027882:Agave / Q000737:chemistry / Q000378:metabolism* / Q000382:microbiology; D000434:Alcoholic Beverages / Q000382:microbiology*; D050260:Carbohydrate Metabolism; D000431:Ethanol / Q000032:analysis / Q000378:metabolism*; D005285:Fermentation; D005516:Food Microbiology; D007716:Kluyveromyces / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000378:metabolism*
chemical_list: D012335:RNA, Ribosomal; C065096:RNA, ribosomal, 26S; D000431:Ethanol