Pretreatment of oil palm frond using hot compressed water: An evaluation of compositional changes and pulp digestibility using severity factors

The influence of reaction temperature (160–200 °C), residence time (45–90 min), and liquid–solid ratio (8–16 v/w) on oil palm frond (OPF) pre-treated with hot compressed water (HCW) was evaluated using severity factors. Effect of the process parameters studied on pulps composition and digestibility were found to be complex. The results revealed that digestibility could not be predicted merely according to composition. Severity factor was correlated with compositional changes and digestibility with good R-squared values at varied liquid–solid ratios (8–16 v/w), but not with overall glucose yield. HCW pretreatment significantly improved the overall glucose yield up to 83.72% with severity of 3.31 and liquid–solid ratio of 8.0 compared to untreated raw OPF which only recorded an overall glucose yield of 30.97%. HCW is therefore an effective method for pretreatment of OPF for glucose recovery.