Predominant Yeasts During Artisanal Mezcal Fermentation and Their Capacity to Ferment Maguey Juice

Abstract

Artisanal mezcal is produced by the natural fermentation of maguey juice, which frequently results in a process that becomes stuck or is sluggish. Using selected indigenous starter inoculums of <i>Saccharomyces</i> and non-<i>Saccharomyces</i> yeasts is considered beneficial in overcoming these problems and thereby preserving the essence of the artisanal process. In this work, three hundred and four yeast isolates were recovered from 17 distilleries and then grouped by the ARDRA analysis, their restriction profiles were clustered in 15 groups. Four of them included 90% of all isolates, and these were identified using the sequence of the D1/D2 domain of the large-subunit rDNA. <i>Pichia kudriavzevii, Pichia manshurica, Saccharomyces cerevisiae</i>, and <i>Kluyveromyces marxianus</i> were detected as predominant species. Both species belonging to the <i>Pichia</i> genus were detected in 88% of the distilleries, followed by <i>S. cerevisiae</i> (70%) and <i>K. marxianus</i> (50%). In order to evaluate the fermentative capacity, one strain of each species was assessed in a pure and mixed culture in two culture media, filtered maguey juice (MJ) and maguey juice including its bagasse (MJB). Findings demonstrated that non-<i>Saccharomyces</i> yeast presented better growth than that of <i>S. cerevisiae</i>. <i>K</i>. <i>marxianus</i> PA16 was more efficient for ethanol production than <i>S. cerevisiae</i> DI14. It produced 32 g/L of ethanol with a yield of 0.47 g/g and efficient of 90%. While, <i>P. kudriavzevii</i> produced more ethyl acetate (280 mg/L) than the others species. All fermentations were characterized by the presence of isobutyl and isoamyl alcohol. The presence of <i>K. marxianus</i> in a mixed culture, improved the ethanol production and volatile compounds increased using co-cultures.