Avaliação de métodos de baixo custo para conservação de leveduras cervejeiras

Abstract

Yeast is a key ingredient for brewing and its reuse within the brewing industry is of extreme importance. The objective of this work was to develop and evaluate a viable and low cost method for reuse and maintenance of the strains. The study was carried out using strains from “Fermetis”, a national manufacturer, where beer was produced on a pilot scale, aiming at imitating the industrial process and later re-using post-fermentation yeasts. The yeasts were washed and isolated at a stage which contained only living and healthy yeasts. The strains preserved in the refrigerator started from a viability between 86 and 91% and after six months the viability decreased to about 60 to 65%, except for the US-05 yeast that better withstand the cold conditions, maintaining its viability in 76,5% for the present study. The freezing was not very efficient since most of the yeasts did not withstand the severe conditions. The reason behind this is that glycerol was added to the yeast in its stationary phase and the alcohol present in the solution became a cryosensitising agent. Thus, based on the results of this experiment, brewers and microbreweries will be able to maintain and reuse yeasts with a simple method that represents a large economy in brewer industry.