Využití kvasinek Kluyveromyces marxianus při fermentaci syrovátky

This thesis is focused on the using of Kluyveromyces marxianus during fermentation of whey. Specifically, this thesis is focused on determining of the lactose decrease during fermentation of whey using two strains of yeast Kluyveromyces marxianus. The process of fermentation was monitored in whey at two concentrations (3 and 5 g-100 g-1) and at three incubation temperatures (20, 28 and 35 °C). The decrease of lactose was measured at de-fined time intervals (0, 24, 48, 72 a 96 h) by HPLC with refractometric detection (HPLCRI). The results showed that the fermentation time and concentration of whey have a considera-ble influence on the fermentation process and the final amount of lactose in the sample. Furthermore, also the temperature of 28 °C appeared to be optimal for the optimal growth of yeast and thus optimal for maximum decrease of lactose in whey. In addition to alcohol fermentation, enzymatic hydrolysis of lactose by -galactosidase was also observed. The enzyme was applied to the whey in two concentrations (1 and 2 g-l-1) and the process of hydrolysis was monitored for 6 hours. Enzymatic hydrolysis of lactose has led to a decrease in lactose and an increase in hydrolytic products, i.e. glucose and galactose. Double concentration of the enzyme was more effective, complete lactose cleavage was achieved after 5 hours of hydrolysis.