Leveduras não convencionais isoladas a partir de colmeia de abelhas sem ferrão e seu potencial fermentativo visando a produção de cerveja

Abstract

Saccharomyces cerevisiae is the most widely used yeast species in fermentation processes. However, there is an increasing use of non-conventional yeasts, due to their potential in the production of flavors in simple culture or in co-fermentation and in the production of low-alcohol beverages. A favorable place for prospecting these yeasts would be the pollen of stingless bees stored in their nests (hives), which undergoes a fermentation process carried out by bacteria and yeasts. Thus, pollen yeasts from four species of stingless bees with potential for use in simple fermentation or co-fermentation of maltose were isolated and selected for the production of differentiated or low-alcohol beers. Yeast isolation was carried out using three different culture media and the selection of isolates was carried out through qualitative tests of maltose fermentation potential, flocculation and resistance to high concentrations of maltose and glucose. The best performing isolates were submitted to molecular identification using the ITS1/ ITS4 and LR0R/LR6 primer pairs. Some isolates were submitted to simple fermentation and co-fermentation at 12°C and 20°C, in which the cell viability, consumption of reducing sugars and alcohol content were verified. Subsequently, the influence of temperature, initial concentration of yeasts and must was verified by using two rotational central composite planning, in which the same variable responses as in the test fermentations were verified. Ten morphotypes were isolated and sixteen isolates (some with duplicate morphotypes) were submitted to qualitative tests. Of these isolates, seven were submitted to molecular identification (10C, 13H, 6G, 50M, 4I, 53C and 27K) and resulted in three different species (Hanseniaspora opuntiae, Wickerhamomyces anomalus and Kodamaea ohmeri). H. opuntiae and W. anomalus were submitted to fermentation and co-fermentation, in which it was observed that these species in simple fermentation at both temperatures showed better results regarding cell viability than Saccharomyces. However, they had lower consumption of sugars and alcohol content than these Saccharomyces. The best consumption of sugars from these two species was observed at the lowest temperature. The co-fermentations indicated that Saccharomyces species impacted the cell viability in both species, but resulted in an increase in sugar consumption and alcohol content, especially at higher temperature. The low alcohol production in simple fermentation was confirmed by DCCRs, in which W. anomalus had the highest production (1.60%), which can be increased, according to DCCRs, using higher temperature and initial wort concentration. Therefore, these main results indicate two possible uses for H.opuntiae and W. anomalus, their use in the production of beverages with low alcohol content, or their use in cofermentations for flavor increase quantified in DCCR1 of H.opuntiae and presented sweet and floral aromas.