Relação entre a microbiota presente no processo de produção de cachaça e a qualidade físico-química da bebida

Abstract

The alcoholic beverage obtained from the fermentation of sugarcane juice, followed by the distillation, is called cachaça or sugarcane spirit. The cachaça/spirits production process still presents differences and peculiarities among producers, and this difference reflects on the physical-chemical and sensory quality of the beverage produced. Therefore, it is necessary to develop research that contributes to the understanding of the origin of the compounds present in cachaça/spirits and that allows the establishment of criteria for improving processes and the final product. The objectives of this work were to understand the possible pathways of formation of the acrolein contaminant during the production of cachaça/spirits and the correlations with other compounds present in the beverage; identify the microorganisms present in the “pé de cuba” (starter culture) used by cachaça-producing stills through metagenomic techniques; and verify the influence of these microorganisms on the physical-chemical and volatile composition of the cachaça produced and the other fractions of the distillate. Samples of cachaça produced by different processes in all regions of Brazil were collected in retail supermarkets and used to quantify acrolein and evaluate the possible routes of formation of this contaminant based on the correlation with other secondary compounds present in the beverage using principal component analysis. Furthermore, samples of cachaça and the head and tail fractions were collected in cachaça producing stills in Minas Gerais and used for physical-chemical and chromatographic analyses. Microbiological and metagenomic analyses were also performed to identify the microbiome present in the “pé de cuba” samples. The results were interpreted with the aid of statistical tools. It was found that the origin of acrolein in cachaça/spirits is related to the chemical degradation and enzymatic conversion of glycerol, which can be correlated with that of other compounds that also compose the beverage, such as butan-2-ol, propan-1-ol and volatile acids. A great diversity and microbiological richness was observed among the analysed samples of the microbiome that constitutes the “pé de cuba”. Different genera of bacteria, yeasts and filamentous fungi were identified. Lactobacillus was the main bacterial genus identified in all the samples, with a high degree of dominance in relation to the others genera. Other genera identified in all the samples were: Wolbachia, Zymomonas and Acetobacter. Saccharomyces was the main genus among the fungal genera identified, but a great diversity was observed in some samples, with the presence of other genera such as Cladosporium, Geastrumia and Fusarium. The samples of cachaça and the head and tail fractions produced in the stills under study possessed a diversified physical-chemical and volatile composition, which was influenced by the presence of microorganisms that constitute the “pé de cuba”. The main positive correlations were observed between the bacterial genera Komagataeibacter, Bacillus, Lactococcus, Streptococcus with volatile acidity levels; acrolein levels with Bacillus and Lactococcus genera; of butan-1-ol concentrations with the presence of Saccharomyces and Lactobacillus; of Ruminococcaceae UCG−014, Intestinimonas and Alloprevotella bacteria with the concentrations of butan-2-ol and propan-1-ol; the levels of isoamyl and isobutyl alcohols with the genus Pseudomonas; between ethyl carbamate concentrations with the Bradyrhizobium, Lactobacillus and Saccharomyces genera.