Efficient ethanol production from separated parenchyma and vascular bundle of oil palm trunk

► Oil palm trunk was separated into parenchyma (PA) and vascular bundle (VB). ► Starch from PA was efficiently converted to ethanol. ► Alkali-pretreatment using NaOH provided high enzyme digestibility for trunk fibers. ► HSS-SSF using separated oil palm trunk fiber is a useful fermentation strategy. For efficient utilization of both starchy and cellulosic materials, oil palm trunk was separated into parenchyma (PA) and vascular bundle (VB). High solid-state simultaneous saccharification and fermentation (HSS-SSF) using 30% (w/v) PA, containing 46.7% (w/w) starch, supplemented with amylases and Saccharomyces cerevisiae K3, produced 6.1% (w/v) ethanol. Subsequent alkali-pretreatment using sodium hydroxide was carried out with starch-free PA (sfPA) and VB. Enzymatic digestibility of 5% (w/v) pretreated sfPA and VB was 92% and 97%, respectively, using 18 FPU of commercial cellulase supplemented with 10U of Novozyme-188 per gram of substrate. Likewise, HSS-SSF using 30% (w/v) alkali-pretreated sfPA and VB, with cellulases and yeast, resulted in high ethanol production (8.2% and 8.5% (w/v), respectively). These results show that HSS-SSF using separated PA and VB is a useful fermentation strategy, without loss of starchy and cellulosic materials, for oil palm trunk.