The Effect of Lactose, Protein and Zinc on Biotechnological Characteristics of Cheese Whey Using Kluyveromyces Yeasts

Background: In the last decade, the volume of cheese and cheese-based production has been growing steadily. This study aimed to determine the effect of lactose, protein and zinc on biotechnological characteristics of cheese whey using Kluyveromyces yeast.Methods: The yeast strains Kluyveromyces lactis Y-2037, Y-2035 and Kluyveromyces marxianus Y-2042 were cultivated using a laboratory fermenter and orbital shaker thermostat for 72 hours at 34°C. To assess the differences related to whey composition, we changed the concentration of lactose, protein or zinc ions. Main characteristics of the investigations were yeast growth rate, lactose processing, ethanol production and fermentation efficiency.Results: Yeast strains converted lactose from 82.7% to 89.9% and produced ethanol from 17.1 to 20.9 g-1 L-1 with a fermentation efficiency of 74.9-91.6%. The substrate feeding increased the lactose processing and ethanol production by 1.58-1.66 and 1.44-1.54 times, respectively. With a high initial lactose concentration in whey, an improvementin bioconversion rates, and ethanol production were observed with an increase by 1.87-2.02 times.Conclusion: Cultivation in a low-protein environment as shown to worsen the biotechnological characteristics of fermentation. High concentrations of zinc ions contributed to an increase in the efficiency of the lactose conversion to ethanol too; while the percentage of processed lactose increased by 3.1-5.1%, and fermentation efficiency increased to 14.5%. ‎