The propagation of the yeast Saccharomyces cerevisiae was optimized using a Taguchi parameter design (TPD) L9(3 4) to produce bioethanol from an amylaceous material. The response factor selected was the specific growth rate of the yeast as calculated from the slope of the linear portion of its growth curve (neperian log cell concentration versus time). The reason is that the greater this rate, the higher the number of viable cells in the fermentation broth capable of ethanol production. The control factors selected were the initial amount of inoculum in the medium, the amount of glucose, the temperature, and the shaking speed which are the chemical and physical variables that most affect the growth behavior of this yeast. The noise factor selected was the initial peptone concentration in the medium. Statistical analysis and factorial split-plots indicate that the factor that most affected the response was the inoculum concentration (50.79% contribution), followed by the glucose concentration (25.22%), and shaking speed (14.79%). The contribution of temperature to the response variable was small (2.85%). This result was independent of the uncontrolled variation in the percentage of peptone in the sample…