Simultaneous saccharification and fermentation of Eastern redcedar heartwood and sapwood using a novel size reduction technique

This study investigated the effect of two wood zones (sapwood versus heartwood) and size reduction techniques [Crumbles® (Crumbles® is a registered trademark of Forest Concepts, LLC, Auburn, WA, USA) particles versus ground particles] on wood glucan-to-ethanol yield after acid bisulfite pretreatment and simultaneous saccharification and fermentation (SSF) of Eastern redcedar. SSFs were conducted at 8% solids loading (w/w dry basis) using Accellerase® 1500 at a loading of 46 FPU/g glucan and Saccharomyces cerevisiae D5A for ethanol fermentation. The size reduction technique had no effect on ethanol yield. However, sapwood glucan-to-ethanol yields were significantly greater than heartwood yields. The highest wood glucan-to-ethanol yield of 187 L/dry Mg (95% of theoretical) was achieved with sapwood crumbled particles in 240 h. Ground sapwood, crumbled heartwood and ground heartwood achieved ethanol yields of 89%, 81% and 80% of theoretical in 240 h, respectively. Preliminary mass balances showed 100% glucan recovery with crumbled sapwood and extensive (72%) delignification.