Continuous sodium hydroxide‐catalyzed pretreatment of empty fruit bunches ( EFB ) by continuous twin‐screw‐driven reactor ( CTSR )

BACKGROUND Since extrusion has many desirable characteristics such as high shear, rapid mixing, short residence time, controllable barrel temperature, and adaptability to process modification, the technology has been applied as a viable continuous pretreatment method for empty fruit bunches (EFB). RESULTS Optimized conditions for a continuous twin‐screw‐driven reactor (CTSR) were determined to be 170°C barrel temperature, 1.6% (w/v) sodium hydroxide, 1:8 solid to liquid ratio, and 5 rpm screw rotational speed. Under these operating conditions, 56.55% of lignin and 39.18% of hemicellulose fractions were solubilized from raw EFB, which increases the glucan content in pretreated EFB from 39.25% to 53.60%. After subsequent 48‐h enzymatic hydrolysis of pretreated EFB, the highest digestibility of 92.4% was achieved with an enzyme loading of 30 FPU g−1‐glucan for cellulase and 70 pNPG g−1‐glucan for β‐glucosidase. CONCLUSION CTSR processing has great potential for increasing the efficiency of EFB pretreatment compared with batch pretreatments.