Yeasts population in fermented sotol must, fermentative capacity and the higher alcohols production potential of isolated yeasts (e-Latin Food 2020)
Sotol is a Mexican alcoholic beverage obtained from the distillation of fermented sotol plants (Dasylirion spp.) juices. It is naturally fermented by autochthonous yeasts, which play an important role in the flavor formation of alcoholic beverages. This study aimed to identified yeasts population of fermented sotol, evaluation of the fermentative capacity, and higher alcohols production potential of isolated yeasts to contribute to the understanding of the play role the yeasts in the natural fermentation to produce this spirit. Isolated yeasts were identified by 5.8S-ITS-RFLP analysis. Saccharomyces cerevisiae and four non-Saccharomyces yeast species, including Pichia kudriavzevii, Pichia kodamaea, Schizosaccharomyces pombe and Candida glabrata were detected. Two autochthonous yeast species: S. cerevisiae (LTS12) and P. kudriavzevii (LTS8) were selected to evaluate their performance profile in terms of growth, sugar consumption, ethanol and higher alcohols production in mixed culture inoculated in synthetic medium, sotol (Dasylirion spp.) and maguey (Agave angustifolia) juices. The results indicated that the growth of mixed culture was favored in maguey and sotol juices. In these natural musts, fermentations finished after 120 h (5 days), the yeasts consumed most of the sugars (≥96%), while in synthetic medium only less than 50% of the sugar was consumed (57.58±0.25 g/L of residual sugar) after 384 h (16 days), so it is considered as a stuck fermentation. Mixed culture had a great fermenting potential in maguey juice with an ethanol yield of 0.33 g ethanol/g substrate and a higher efficiency (65%) than that of sotol juice (51.54%) and synthetic medium (41.89%). Fermented sotol and maguey juices were characterized by higher amount of 2-phenylethanol (42 and 70% of peak area), a higher alcohol that contribute to the floral attributes of the alcoholic beverages. This higher alcohol was produced mainly by P. kudriavzevii as evidenced in the experiment of pure cultures in synthetic medium (supplementary material). Findings suggest that the alcoholic yield, fermentation efficiency and higher alcohol production depend on the nature and composition of the culture medium. These results suggest that the co-culture of S. cerevisiae LTS12 with P. kudriavzevii LTS8 could be an alternative to ferment sotol and maguey juices.
Keywords: Culture media, higher alcohols, indigenous yeasts, Pichia kudriavzevii, sotol.