Caracterização fenotípica e performance fermentativa de leveduras dos engenhos produtores de cachaça no estado da Paraíba

Abstract

Yeasts play an essential role in the beverage industry. Sugarcane juice contains a diverse microbiota with an average of 26,000 yeast/mL. For this reason, cachaça production generally uses spontaneous fermentation. Despite the improvement in the quality of cachaça produced in Paraíba, the domain of yeast strains present in these productions remains unknown. This study

evaluated the phenotypic characteristics and fermentation performance of yeasts from cachaça- producing mills in the state of Paraíba. Samples of “pé de cuba” were collected from 13 cachaça

distilleries. The yeasts were purified and isolated by depletion seeding. This was followed by tests for thermal tolerance, assimilation of different carbon and nitrogen sources, resistance to ethanol and acetic acid, hydrogen sulphide production, flocculation, fermentation performance, physico-chemical analysis of the synthetic wine and kinetic evaluation. The data was analyzed by Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA), using the Gower index. The results show that all the strains grew between 15 °C and 37 °C. At 40 °C, only strain 9 did not grow. They all metabolized various carbon sources, although with differences - for example, strain 13 did not use fructose, and only strains 9, 11, 12 and 13 grew on xylose. Tolerance to ethanol varied; strain 5 stood out for maintaining growth even in 20% ethanol. Tolerance to acetic acid was remarkable up to 6%, with strains 9 and 13 maintaining growth even in 10%. Seven yeasts do not produce sulphide. Strains 4, 7 and 11 do not grow on potassium nitrate. Strains 4 and 11 do not grow on sodium nitrite. Strain 4 does not grow on lysine. Seven strains have post-fermentation flocculent characteristics. Six yeasts completed fermentation within 60 hours. Visual changes in the fermented musts were noticed throughout fermentation. Strain 1 showed more than 80% viability. The physicochemical analyses were carried out in duplicate. PCA revealed that strains 1, 3, 4, 6, 8, 12 and 13 differed significantly from strains 2, 5, 7, 9, 10 and 11. Strain 2 had the highest Total Acidity (TA) and Ester (TE) values; strain 5 had the lowest. Strains 1, 3 and 13 proved to be the most efficient in fermentation, with low TA, high Alcohol Content (AT) and higher CO2 loss. Strains 2, 5 and 7 showed greater aromatic capacity, with different profiles. Kinetic analysis revealed that strains 1, 3, 5, 12 and 13 showed the highest specific microbial growth velocities (μ). Strains 1 and 10 showed higher alcohol yields and better carbon conversion. The dendrogram organized the yeasts into four distinct groups. Our findings contribute to a better understanding of the yeasts present in the production of cachaças from Paraíba, seeking to improve the fermentation process, recognizing the regional microbial biodiversity, promoting its fermentation improvement and valuing Paraíba's genetic and cultural heritage.