Using sap obtained from the inner part of the trunk, ethanol fermentation was carried out with S. cerevisiae Kyokai no. 7. Regardless of the addition of polypepton and yeast extract, the yeast rapidly fermented glucose in the sap into ethanol. A representative ethanol fermentation profile of the sap, without addition of nutrients, is shown in Fig. 2. Fermentation was almost complete after 12 h and glucose was thoroughly consumed after 24 h. Meanwhile, the minor sugar components in the sap medium, i.e., sucrose, fructose, and galactose initially found at 4.2 g/L, 2.6 g/L, and 0.6 g/L, respectively, were not
detected by HPLC after 24 h. The amount of ethanol produced corresponded to 94.2% of the theoretical yield calculated based on consumption of glucose, sucrose, fructose, and production rate and yield were comparable to the reference fermentation on YPD medium (Fig. 2), indicating that oil palm sap has sufficient nutrients to support ethanol fermentation by S. cerevisiae, and does not contain inhibiting substances.galactose.