Investigation of fast hot compressed water pretreatment of oil palm fronds for fermentable sugar production

Oil palm fronds, the lignocellulose waste material produced from palm oil plantation, was subjected to the pretreatment in hot compressed water for sugar production. In this study, the influence of fast hot compressed water (15 minutes holding time) was investigated at temperature 170, 190 and 210 °C in a batch autoclave. After hot compressed water process, the products were separated into solid residue and liquid fraction by filtration. The chemical composition and color change of the oil palm frond residues after pretreatment were evaluated by Fourier Transform infrared (FTIR) spectroscopy and CIELAB parameters. The solid residue was further submitted to hydrolysis for fermentable sugar production using a commercial enzyme. The relative changes in the intensity of FTIR spectra bands indicate that hot compressed water deconstructed the structure of palm oil frond by removing hemicellulose. The fast hot compressed water of oil palm frond resulted in color changes to the darkness because of the lignin modification. Enzymatic hydrolysis yield that 50.5% (b/v) fermentable sugar can be produced after 48 h saccharification process on pretreated at 190 °C for 15 minutes, suggesting that the hot compressed water pretreatment of oil palm frond can be considered as inexpensive, simple and environmentally friendly pretreatment methods.