The effect of ultrasound on brewing yeast

Abstract

An important task of beer production is to increase the physiological activity of yeast to intensify the fermentation process. Dry top-fermented brewer's yeast Saccharomyces cerevisiae, Fermentis, Safale T-58, France were selected for the investigation. The method of activation of brewer's yeast by ultrasound with a vibration frequency of 44 kHz was studied in the work. Ultrasonic technologies can dramatically intensify the process and improve the finished products quality. The studies were carried out in the laboratory of the Bashkir State Agrarian University on the ultrasonic processing device VGT-800. A yeast suspension was prepared for the study. It was placed in the ultrasonic device and subjected to ultrasonic treatment at a vibration frequency of 44 kHz. During exposure, the temperature was measured every minute from 1 to 20, and 25, 30, 35 min, and the yeast cells survival by the dead cells percentage was studied. It was found out that under the influence of ultrasound, heating of the medium at 1 ° C for 1 min takes place, and the medium reaches the temperature of 57 ° C by the 40th min of treatment. The percentage of dead cells in the treated medium was also studied. At the same time, a pure culture was selected from each sample by plating on wort agar for further research on the safety of acquired properties. Ultrasound-treated yeast served as inoculum at the fermentation stage of beer wort. Fermentation was carried out at a temperature of 22 ° C. Morphological characteristics of yeast were monitored during fermentation: the total number of cells, the number of budding cells, cells with glycogen. When fermenting beer wort, the fermentation activity increased by 36% in experiment 2 during the treatment of sowing yeast with ultrasound for 2 min. The remaining samples differed slightly from the control during the first 72 hours of fermentation and lost their fermentation activity after 80 hours of fermentation. The physicochemical parameters of the finished beer samples were studied on the "Kolos-2" device.