The shake flask (SF) system has been a common reaction system for laboratory scale assessment of enzymatic saccharification of lignocellulosic biomass. The enzymatic saccharification of lignocellulosic biomass involves the use of enzymes (such as cellulases or hemicellulases) to convert the carbohydrate polymers (mainly cellulose and hemicellulose) into simple sugars for bioethanol fermentation. In the SF system, solid lignocellulosic biomass is usually size-reduced to particle size, and suspended in water with added enzyme treatment. When the solids loading of the particle-sized biomass is very high, the SF system may no longer be effective because the shaking (mixing) intensity may not be sufficient to keep the high-solids suspension in a homogeneously agitated state. Effective, homogeneous mixing allows better contact of the solids with the enzymes and result in higher reaction rates. Scientists from the National Bioenergy Center of the National Renewable Energy Laboratory (NREL) (United States) developed a roller bottle reactor (RBR) system which can provide better mixing compared to SF systems. Experiments using the RBR system under a broad range of experimental conditions showed that it can work well for a variety of pretreatments and enzyme systems. A relatively low amount of mixing input can mitigate mass transfer limitations which can often occur at high solids loading. The full paper can be accessed in the open-access journal, Biotechnology for Biofuels..