Leveduras Saccharomyces sp. E Não-Saccharomyces de potencial cervejeiro isoladas de frutos do cerrado

Abstract

The production and consumption of craft beers have grown a lot in Brazil in recent years and this has encouraged the search for national inputs, as wild yeasts, for the preparation of the drink, but little is known about their use in production, this makes the producer a dependent on imported commercial yeast strains. Therefore, the objective of this study was to isolate wild yeasts of fruits in the Cerrado and submit them to a beer production process in pure malt, compared to a commercial S-33 Ale yeast (widely used in the market), under the same conditions. The strains were isolated in BDA medium and transferred to YPD PLUS medium which underwent the stress test in 5, 7.5, 10, 12 and 15% ethanol PA, spectrophotometry and subsequent plating for verification of cell biomass and number of viable colonies. Afterwards, have undergone a test fermentation in eppendorf in the Middle containing glucose with concentration transfers starting from 2, 4, 8 and 12o Brix. So, one could select 4 strains that behaved significantly in the process of tolerance to ethanol as well as standard glucose fermentation to beer, which is 12oBrix. Soon, the samples were replicated in Sabouraud liquid medium for obtaining sufficient cell mass to inoculate the wort brewed. Later, the lines were transferred to the wort 12o Brix and so proceeded to the primary fermentation for 22 days at a constant temperature of 18o C. Constant measures were made of pH, density, volatile acidity, and turbidity. The results showed that Fermentation capacity was slow with initial low Brix reduction with increased faster at the end of fermentation alcohol content ranging from 1.91 - 3.9%, highlighted the lineages the control and the sample 18 I as the production of ethanol. The pH remained 4.6, within the standard for beers. On the other hand, as the values of volatile acidity, turbidity, and showed that all samples were nonstandard, however, one cannot infer that are not palatable, without sensory analysis. It was observed in most samples fruity aroma, characteristic in beers like Ale, two samples were out of this pattern. The level of bitterness was at 46.1 IBU, just above the established, but acceptable to the style. In General, the isolation methods were effective and promising results, aiming at the improvement in subsequent steps.