The pretreatment of nipa sap to improve the efficiency of ethanol fermentation was investigated. The ability of the pretreatment to increase fermentable sugars and yeast cells in the sap, and the suitability of nipa sap for fermentation was assessed. Effects of pH, temperature and duration of the pretreatment were studied, and response surface models were created for reducing sugar, total sugar, and yeast cell yields. Temperature was the most important pretreatment variable, followed by pH value, for all the outputs modeled. The maximum cell yield of 829% (from 0.7×105 to 6.5×105 CFU/mL) was achieved with a pH of 5.3 at 44 °C for 21 minutes. These conditions gave a total sugar yield of 39% (from 266 to 369 g/L) and a reducing sugar yield of 422% (from 36 to 188 g/L). The fermentation of pretreated and non-pretreated saps was compared, and it was found that the pretreatment increased fermentation efficiency.
