The results of sugar reduction concentration was shown in Figure 5. Sugar reduction concentration increased with incubation time until 5 d incubation time then it decreased. The maximum sugar reduction concentration was obtained on 5 d incubation time. It means that before 5 d incubation time, cellulose enzyme converted into glucose and balanced with the yeast performance in converting glucose into alcohol. However, after 5 d incubation time, cellulose enzyme was not working optimally which is showed by the decrease in the sugar reduction concentration. Whereas, at the same time the number of active yeast decreased which is shown by the graph of TPC and OD. It means the amount of glucose converting into alcohol was reduced. Therefore, the SSF process would be more effective if carried out up to 5 d incubation time when yeast and cellulose enzyme in optimum condition.