Adaptation of free and immobilized brewery years during attenuation if highly concentrated hopped worts.

Abstract

The attenuation of highly concentrated hopped worts by means of non-stressed or stress-adapted yeast was compared in this work. As the yeast adaptation is very dependent on the genetic base of the yeast strain and its physiological state, the results of the study can be considered as a representation of possible behavior of solely brewery yeast. The use of non-stressed cells for attenuation of highly concentrated hopped worts led to the accumulation of trehalose in cells during the fermentation process. If, however, some cells, previously exposed to higher stress, were used for the wort attenuation, the intracellular trehalose dropped. These conclusion were confirmed both for free and immobilized yeast. During the attenuation of highly concentrated hopped wort the free and immobilized yeast, previously exposed to stress achieved higher speed of ethanol formation than the non-stressed yeast. In mutual comparison of beers no marked difference was observed in the process of fermentation of 12 or 24 % hopped worts by means of either stressed or non stressed yeast resulted, notwithstanding, in a considerably shorted time necessary for the fermentation of a 24 % hopped wort.(In Czech, English summary only)

Keywords

• immobilized brewery years
• beer
• stress
• trehalose
• very high gravity