Selection of indigenous Saccharomyces cerevisiae strains for top fermentation beer production

The consumption and production of top fermenting beers in South America and Brazil have great increased in the past years. Despite the great biodiversity and production of traditional alcoholic beverages, all Brazilian craft brewers still depend on imported commercial yeast strains as a result of total lack of information and studies about the use of indigenous strains in brewing. Hence, the costs of buying yeast are high and even more with the greater tendency to produce various beer styles and application of many different strains. From this perspective,this study aimed to selected indigenous South American yeasts able to produce high quality and flavorful top fermented beers. Ninety nine Saccharomyces cerevisiae wild strains, from different regions in South America(from North to South of Brazil, Ecuador and Galapagos Island) all from a variety of niches like environment strains (mainly tree barks) and from different musts of traditional spontaneous beverages with spontaneous fermentation (cachaça, traditional fruit wines, chicha etc.) were tested. Based on the maltose fermentation,20 S. cerevisiae strains from the 99 tested were characterized with its different killer activity and selected to perform top fermented beers in different scales. Preliminary tests were performed on lab scale where it was evaluated the main fermentation parameters (attenuation degree, alcohol production etc.), fermenting sugars (HPLC) and the main aroma compounds (HS-SPME) produced by each different yeast. Based on these results, 12 strains were selected to perform brewing process on pilot scale. The same parameters described were analyzed, together with sensory analysis. Based on physiological aspects, fermentative capacity and production of desirable flavor compounds and final product, were selected yeasts with great potential and one indigenous strain was selected to be tested on an industrial scale, whereas all described parameters were also followed.In cooperation between Universities and Industry, the first beer with indigenous Brazilian yeast was produced in the facilities of a micro-brewery (Grimor Brewery, Brazil) and was released in the market. In addition to the results with high reproducibility as regards of the fermentation parameters and aroma compounds produced, the beer also was very approved by Brazilian consumers. This work showed for the first time the use of Brazilian S. cerevisiae strain as starter in the production of flavorfull top fermenting beer with no prior need for adaptations and attending industrial proportions. This may support and commence the building of an innovative beer yeast bank, which so far does not exist in Brazil and undoubtedly provides a basis for diversified beer brewing. This work encourages the greater autonomy to the sector in increasing expanding in the country, with knowledgeable brewing of cost-effective and flavor-rich new craft beers. The attractive results show undoubtedly a support to Brazilian sector and other yeast dependent countries that can point out the unique and high-valued biodiversity in brewing.status: publishe