Bioethanol from the Portuguese forest residue Pterospartum tridentatum – An evaluation of pretreatment strategy for enzymatic saccharification and sugars fermentation

Under the current energy scenario, the development of alternatives to fossil fuels, like bioethanol from lignocellulosic materials, is highly relevant. Therefore it is important to search and study new raw materials and to optimize the different steps that lead to bioethanol production. In this work, acid diluted pretreatment was optimized considering the release of sugars. Under the optimal conditions, the reducing sugars yield was of 293.4 mg/g of dry biomass in liquid fraction. The tested pretreated samples of Pterospartum tridentatum that presented a higher glucose yield in enzymatic saccharification where those that were subject to a pretreatment at 180 °C for 75 min with 2.75% (w/w) of sulfuric acid when using a biomass/liquid ratio of 2.25 g/10 mL leading to a maximum yield of glucose that was 92% of the theoretical maximum. From the fermentation of filtrates it was possible to obtain a maximum ethanol yield of 0.26 g ethanol/g total sugars, without previous detoxification.