Scientists from Wageningen University (Netherlands) report the optimization of pretreatment conditions for wheat straw using maleic acid. The findings are published in the open access journal, Biotechnology for Biofuels. Pretreatment is usually the first step in the production of "second generation" bioethanol from lignocellulosic biomass, like wheat straw. It is done "to disrupt the lignin-carbohydrate matrix and to facilitate enzymatic cellulose hydrolysis by improving cellulose accessibility to cellulolytic enzymes". The use of sulfuric acid (a strong inorganic acid) in combination with heat, is a common acid-based preatreatment method. However, some of the sugars produced by this method are converted by a side reaction, into compounds that inhibit ethanol fermentation. Maleic acid (an organic acid) reportedly avoids this undesirable side reaction. A statistical approach via Response Surface Methodology was used. A Central Composite Design was set up with the following process design variables: maleic acid concentration, temperature and pretreatment time. The response factors were: (1) glucose benefits (defined in the paper), (2) xylose benefit (defined in the paper), (3) cost of unrecoverable maleic acid, (4) cost of sodium hydroxide used for neutralization after acid treatment prior to enzymatic hydrolysis, (5) cost arising from furfural formation, (6) heating costs. The process was shown to achieve "almost complete conversion of wheat straw glucan and xylan". Details of the study and full access to the paper can be obtained at the Biotechnology for Biofuels website (URL above)..