The optimum ethanol content results were supported by the data of yeast activity (TPC and OD) and sugar reduction concentration which conducted on pre and post SSF incubation. In this process, yeast activity was determined with TPC and OD which showed on Figure 4. The TPC graphic has similarity with standar graphic of yeast activity [10,11] consisting of log phase, stationary phase and lag phase. Based on the TPC graphic, the log phase was estimated on 3 d to 5 d incubation time, the lag phase on 5 d to 7 d and the stationary phase on 4 d to 6 d incubation time. The OD graphic showed that the number of yeast increases with incubation time. Although on 5 d to 7 d incubation time showed an increased yeast number, but did not show increased yeast activity because the inactive yeast was also calculated in the OD graphic. Based on the combination of TPC and OD results, the optimum results of yeast activity was obtained on 4 d to 6 d incubation time.