*Editorial* **Pretreatment of Crop Residues for Bioconversion**

**Carlos Martín**

Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden; carlos.martin@umu.se; Tel.: +46-90-786-6099

Decreasing the dependence on fossil resources as raw materials for the production of fuels, platform chemicals, and commodities is an imperative requirement of today's industry and society in order to alleviate the threats related to climate change. Processing lignocellulosic biomass in biorefineries provides an alternative route for producing fuels and most of the chemicals that today are produced from fossil resources. Crop residues are a realistic option of lignocellulosic feedstock for biorefineries considering their large availability, low cost, and renewable nature. The generation of crop residues is increasing as a result of the expansion of the agricultural production necessary to support the increase in the global population. The harvest of cereals [1], other food crops [2], and non-food agricultural products [3] generates large amounts of residues, whose proper management poses huge challenges. Although the environmental impact of disposing crop residues by burning has not been as mediatic as that of industrial and vehicular emissions, its contribution to air pollution is an issue of major significance in many countries [4].

The bioconversion of crop residues via sugar-platform processes, in which polysaccharides are hydrolyzed to sugars for further conversion through microbial, enzymatic, or chemical processing, is a highly promising option for producing fuels and chemicals required for the sustainable development of human society. The enzymatic saccharification of cellulose is a selective approach for deconstructing biomass, but it requires a pretreatment for removing or weakening the barriers causing the inherent recalcitrance of lignocellulosic feedstocks [5]. In spite of the intensive research in the area, pretreatment of crop residues is still an open question. Pretreatment effectiveness is feedstock-dependent [6–8], and further research is required to develop efficient methods enabling the commercial operation of bioconversion processes based on crop residues of different nature.
