Effect of yeast harvest moment on a brewing process in beer produced on an industrial scale

Abstract

The aim of this study was to determine the effect of yeast harvest timing on the process performance, total yeast count and the content of volatile components in beer. The experiments were performed on an industrial scale with fermentation and maturation conducted in three fermentation tanks with a capacity of 3800 hl (cylindro-conical tanks – CCT). All processes were carried out using the same technological conditions. The worts were aerated with sterile air and yeast after the second fermentation (third generation) was added. The duration of the maturation phase and the processes of the yeast harvest were conducted at different times (1^st, 4^th and 6^th day) after finishing the primary fermentation process. During fermentation and maturation, changes in the contents of the extract, yeast, and volatile components were investigated. These experiments showed that the use of different times during yeast harvest had a significant impact on the course of fermentation and maturation and impact on the total yeast count during the maturation process and on the amount of volatile components in beer. With a delay in the start of yeast cropping, the content of acetaldehyde and vicinal diketones decreased and the content of esters increased. The timing of the yeast crop significantly influenced the final beer quality.