Total glucose yield as the single response in optimizing pretreatments for Elaeis guineensis fibre enzymatic hydrolysis and its relationship with chemical composition of fibre

In this study, a new approach viz. total glucose yield (TGY) was used as the single response for the optimization of various pretreatments of oil palm (Elaeis guineensis) empty fruit bunch (EFB) fibre through response surface methodology. TGY was calculated by multiplying the enzymatic saccharification yield and pretreatment solid recovery yield. The optimum condition of each pretreatment was calculated based on the estimation model built and then verified experimentally. The optimum conditions for water, acid and alkali pretreatments were 170 °C for 30 min, 120 °C for 45 min in 2.0% (v/v) H2SO4 solution and 110 °C for 45 min in 3.0% (v/v) NaOH solution, respectively. Based on chemical composition analysis, although both the water and alkali pretreated EFB fibres exhibited more than 99% of the cellulose was converted into glucose, water pretreated fibre achieved the highest TGY, as it retained higher recovered glucose content. This study also verified that the use of TGY on the basis of original fibre weight was more appropriate than the enzymatic saccharification yield in the optimization study of biomass pretreatment, as it also considered the loss of the cellulose during pretreatments.