Optimization of fermentation to enhance ethanol production from palmyra sap (borassus flabellifer) using Saccharomyces cerevisiae

Ethanol is widely needed in various field such as for making food and beverages, pharmaceutical products, personal care and cosmetics, as well as for medical and laboratory purposes. Palmyra is an agricultural product which is abundant in Indonesia, especially in the coastal and tropical area of East Java. Legen is known as traditional drinking juice from fresh palmyra sap. It has high sugar content which reaches 10-15%, that potential for ethanol raw material.In the present study, Palmyra sap has been fermented in a batch-wise fermentor using Saccharomyces cerevisiae in a working volume of 100 ml for 80 hours. The optimum independent variables for the fermentation of palmyra sap such as pH, initial inoculum, and sugar concentration have been investigated based on the experimental design by central composite design (CCD) recommendation in response surface methodology (RSM). The result of the experiment at the optimum condition and theoretical prediction obtained yield ethanol of 0.2221 (g/g) and 0.2368 (g/g), respectively.The highest ethanol yield using Saccharomyces cerevisiae was 0.2368 (g/g) obtained at pH 4.77, inoculum concentration of 12,740,970 (cell/ml)/(g.l ^-1 ), and sugar concentration of 110 g.l ^-1 . The P-value of interaction of variance was < 0.005, indicated that the interaction effect was significant.