Avaliação da eficiência da levedura Saccharomyces cerevisiae (W-34/70) reaproveitada na produção de cerveja

Abstract

Beer represents a constant growing market in Brazil, mainly in the branch of specialty beers with a greater variety of styles and tastes. Being the fermentation performed by yeast, a very important process in the influence of the final product, this project aimed to analyze the physical-chemical composition and the microbiologic growth of the biomass during the fermentation of a Pilsner beer craft brewed in the Parana Federal Technology University lab, reusing subsequent yeast for 3 fermentations. After the preparation of the beer wort, 3 samples of the same brew where separated to be subjected to fermentation, Wort A, B and C, aiming the subsequent reuse of the yeast strain Saccharomyces cerevisiae (W-34/70). Microbiological analyzes were performed by direct plate counting, Brix of the wort during fermentation and the determination of the ethanol content at the end point of fermentation by gas chromatography. The microbiological results were close to expectations in relation to the literature, with a graph expressing a growth peak in the middle of fermentation and consequent reduction of the concentration of cells near the end of the process. However, for the physical-chemical results, the values obtained indicated an increase in the concentration of soluble solids, being an unsatisfactory result for concise conclusion of the data. For the result of ethanol, it was observed within the three fermentation results compatible with the yeast count. Although the Wort C shows higher quantity of CFU/g, a lower alcohol production in relation to the alcohol in Wort A and B, indicating a possible decrease in vitality of yeast for its reuse.