*2.1. Materials*

Oil palm empty palm fruit bunch (OPEFB) was obtained from a palm oil industry in Medan, Indonesia. It was sun-dried to achieve 7% moisture content. The dried OPEFB was then milled using a cutting mill (Retsch SM 100, Haan, Germany) using a screen with a pore size of 300 µm and resulted in the following particle size distribution: 44.24% of >500 µm; 17.96% of 250–500 µm; 23.81% of 100–250 µm; and 13.99% of 63–125 µm. The composition of OPEFB is presented in Table 1. The enzyme cocktail Cellic®® Ctec3 (Novozymes, Bagsværd, Denmark), with a cellulase activity of 222 filter paper units (FPU) /mL, was used for the hydrolysis of a mixture of glucan- and hemicellulosic compounds-rich fraction. The chemicals used were sulfuric acid, D-glucose, L-arabinose, D-maltose, D-xylose, and D-galactose from Sigma-Aldrich, and pure ethanol (100%) and glacial acetic acid from Scharlau.

**Table 1.** Composition of oil palm empty palm fruit bunch (OPEFB).


\* A nitrogen-to-protein conversion of 6.25 was used.
