EXTREME TEMPERATURES FOR ENZYMATIC ACTIVITY OF BAKING YEAST

Abstract

The effect of cryostatic temperatures -17 and -30 °C to zymase and maltase activity and lifting force of baking yeast was determined. Baking yeast Saccharomyces cerevisiae strains KD, LD, K7 and LK-22 were the objects of research. Yeast biomass has been cultivated in malting wort, and then isolated by centrifugation. And then biomass was frozen during 3 hours. Insignificant decrease in zymase activity of yeast strains LD, KD and K7 compared to controls was observed at temperature -17 °C. Fermentation activity of yeast strains LK-22 and KD was reduced at the temperature of -30 °C, but fermentation rate of glucose by yeast strains K7and LD was satisfactory. Yeast strain LK-22 has the lowest cryostatic stability, strain LD - the highest. Maltase activity of all investigated yeast strains after freezing at -17 ° C is higher compared to controls. The maltase activity was highest in yeast strain LD, and the lowest – in yeast strain LK-22. Maltase activity of all investigated yeast strains was reduced when the cryostatic temperature was -30 °C. After holding temperature at -17 °C lifting force all investigated yeast strains was lower than in the control samples and significantly higher than at -30 °C. Cryostatic of baking yeast at temperatures of -17 °C and -30 °C provides satisfactory preservation of their technological properties. Yeast strain LD has better technological properties and cryopreservation stability than other investigated strains.