Kvasny Prum. 2010; 56(5): 226-233 | DOI: 10.18832/kp2010028

Evaluation of pitching yeast by advanced methods.Peer-reviewed article

Martin SLABÝ, Josef ŠKACH, Jaromír FIALA
1 Výzkumný ústav pivovarský a sladařský, Lípová 15, 120 44 Praha 2
2 Ústav kvasné chemie a bioinženýrství, Vysoká škola chemickotechnologická v Praze, Technická 5, 166 28 Praha 6

Changes in the physiological state of yeasts during repeated pitching under different fermentation conditions were studied. Traditional Czech strains kept in the culture collection of the Research Institute of Brewing and Malting (RIBM) were tested. The control parameters for the primary fermentation were maximum temperature and pressure. The pressure is dependent on the concentration of carbon dioxide. The physiological condition of yeasts was evaluated by means of flow cytometry based on the content of trehalose and glycogen in the cell and by the determination of the acidification power (AP) of the yeasts. It was found that the yeast strains tested reacted to changing conditions in different ways. The methods used for the study of the physiological conditions also show important information about glycogen production. No significant relationship between the results obtained and the fermentation process was found, when characterizing by the speed of extract reduction between the 48th and the 96th fermentation hour and the time of fermentation needed for an attenuation difference of 8-10 %.Changes in the physiological state of yeasts during repeated pitching under different fermentation conditions were studied. Traditional Czech strains kept in the culture collection of the Research Institute of Brewing and Malting (RIBM) were tested. The control parameters for the primary fermentation were maximum temperature and pressure. The pressure is dependent on the concentration of carbon dioxide. The physiological condition of yeasts was evaluated by means of flow cytometry based on the content of trehalose and glycogen in the cell and by the determination of the acidification power (AP) of the yeasts. It was found that the yeast strains tested reacted to changing conditions in different ways. The methods used for the study of the physiological conditions also show important information about glycogen production. No significant relationship between the results obtained and the fermentation process was found, when characterizing by the speed of extract reduction between the 48th and the 96th fermentation hour and the time of fermentation needed for an attenuation difference of 8-10 %.

Keywords: yeast strain, primary fermentation, trehalose, glycogen, acidification power test, flow cytometry

Received: December 10, 2009; Accepted: March 26, 2010; Published: May 1, 2010 

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