Optimization of a Culture Medium for the Production of Saccharomyces cerevisiae using Glucose Syrup and Corn Steep Liquor

Saccharomyces cerevisiae is the dominant yeast in the bakery industry used throughout the world. One of the most widely used sources of carbon for the bread yeast culture medium is molasses. In recent years, due to the expansion of the fermentation industries and the increased demand for carbon and nitrogen sources in these industries, and the shortage of raw materials and their high cost, the possibility of using by-products produced in food industry factories has been considered.

In this study, the use of corn steep liquor as the nitrogen source and glucose syrup as the carbon source has been studied. The amount of biomass production and yeast activity was measured in the form of carbon dioxide gas production and sugar consumption in separate tests. In all treatments, the fermentation time was 16 hours, and stirring on a shaker was at 30 °C and 150 rpm.

At the optimized point, where the amount of the glucose syrup and corn steep liquor was 12.82 mL/100 mL and 4.31 mL/100 mL, respectively, the amount of produced CO2 increased about 12.5%, and the time of rising of the dough reduced from 25 to 14 minutes showing a significant progress.

To replace the carbon and nitrogen sources in the yeast culture medium, the factors and their levels were selected from previous studies. Because of the shortage of sugar beet molasses, which has recently appeared in Iran's fermentation industry, we tried to introduce two cheap but still valuable replacements, for both the carbon and nitrogen sources. The result showed that using glucose syrup and corn steep liquor is not only feasible but also better than the conventional sources.