PREPARATION OF SACCHAROMYCES CEREVISIAE SC90 INOCULUMS FOR FERMENTATION PROCESS USING SUGARCANE MOLASSES

Abstract

Yeast (Saccharomyces cerevisiae) is an important microorganism used in the food, beverage and energy industries. Thailand is a major source of refined sugar whose major byproduct is molasses, which is fermented into several products using S. cerevisiae. The preparation of the yeast inoculum can affect successful fermentation, therefore the aim was to test preparation methods of S. cerevisiae SC90 inoculum in order to optimize its effectiveness in fermentation of molasses. Three different inoculum preparation methods were studied as follows: Method 1) preparation of step 1 and step 2 in YPD medium, Method 2) preparation of step 1 in YPD medium and step 2 in molasses medium and Method 3) preparation one step in the molasses medium. Inoculum preparation using the Method 1 spent the longest period followed by the Method 2 and the Method 3, respectively. While the highest viable cells was shown in the inoculum prepared using the Method 2 followed by the Method 3 and the Method 1, respectively. The efficiency of inoculum prepared using different methods was evaluated by fermentation in the bioreactor containing molasses medium. The results showed that cells can grow immediately without lag period when the process inoculated with inoculum from the Method 2 and the Method 3. Furthermore, about two times higher cell viability and shorter total process time were achieved comparing to the process inoculated with inoculum from the Method 1. The developed method, the Method 3, could reduce the time and step for inoculum preparation with high efficiency of inoculum. Therefore, the Method 3 may an appropriate method for application in the fermentation industry using molasses.