Combined alkali and hydrothermal pretreatments for oat straw valorization within a biorefinery concept

Bioresource Technology

http://dx.doi.org/10.1016/j.biortech.2016.08.077

The aim of this work was the evaluation of lime pretreatment combined or not with previous step of autohydrolysis for oat straw valorization. Under selected conditions of lime pretreatment, 96% of glucan and 77% of xylan were recovered and 42% of delignification was achieved. Xylose fermentation to ethanol by metabolic engineered Saccharomyces cerevisiae (MEC1133) strain improved the ethanol production by 22% achieving 41 g/L. Alternatively, first step of autohydrolysis (S0=4.22) allowed a high oligosaccharides recovery (68%) and subsequent lime pretreatment attained a 57% of delignification and 99% of glucan to glucose conversion. Oat straw processed by autohydrolysis and lime pretreatment reached the maximal ethanol concentration (50 g/L). Both strategies led to oat straw valorization into bioethanol, oligosaccharides and lignin indicating that these pretreatments are adequate as a first stage within an oat straw biorefinery.

Phenolics production from alkaline hydrolysis of autohydrolysis liquors

CyTA - Journal of Food, 14 (2016) 255-265

http://dx.doi.org/10.1080/19476337.2015.1094516

The objective of this work was to study the release, identification and characterization of phenolic compounds by saponification of non-isothermal autohydrolysis liquors of corn (Zea mays) cobs and Eucalyptus globulus. Corn cobs and E. globulus are lignocellulosic materials with high contents in cellulose and hemicelluloses. Efficient use of these materials can be achieved using autohydrolysis as the first stage of a biorefinery, resulting in a solid phase rich in cellulose and lignin, and a liquid phase containing essentially hemicelluloses-derived compounds and phenolic compounds from the partial solubilization of lignin. This work studied the combination of alkaline hydrolysis and extraction with organic solvents to maximize the amounts of released phenolic compounds since these compounds are interesting for their properties and food applications.