Current Pretreatments of Lignocellulosic Residues in the Production of Bioethanol

Bioethanol production from lignocellulosic residues is an alternative to ensure energy supply required in the coming years and to achieve both environmental and economic benefits; however carbohydrates in lignocellulosic residues are found within a strong reticular network; therefore a pretreatment of the residues is necessary to modify the structure and to have access to carbohydrates and to obtain high yields in bioethanol production. This review discusses the different pretreatments of lignocellulosic residues that can be classified as physical, physicochemical, chemical and biological, with the principal objective to modify the structure of lignin and to permit the release of carbohydrates. Technological development in this topic is recent and the optimization of pretreatments for the production of bioethanol from lignocelullosic residues is needed to be feasible at industrial scale, which is the main objective to reach.