Wheat Straw Autohydrolysis: Process Optimization and Products Characterization

Abstract

Wheat straw was subjected to autohydrolysis treatments in order to selectively hydrolyze the hemicellulose fraction. The effects of temperature (150-240 degrees C) and non-isothermal reaction time on the composition of both liquid and solid phases were evaluated and interpreted using the severity factor (log R0). The operational conditions leading to the maximum recovery of hemicellulose-derived sugars were established for log R0 = 3.96 and correspond to 64% of the original (arabino)xylan with 80% of sugars as xylooligosaccharides. Under these conditions, a solubilization of 58% xylan, 83% arabinan, and 98% acetyl groups occurred. Glucan was mainly retained in the solid phase (maximum solubilization 16%), which enables an enrichment of the solid phase to contain up to 61% glucan. Delignification was not extensive, being utmost 15%. The yields of soluble products, including sugars, acetic acid, and degradation compounds, such as, furfural, 5-hydroxymethylfurfural furfural obtained suggest the fitness of liquid stream for fermentation purposes or to obtain xylooligosaccharides with potential applications in food, pharmaceutical, and cosmetic industries.

Fractionation of Hemicelluloses and Lignin from Rice Straw by Combining Autohydrolysis and Optimised Mild Organosolv Delignification

“…The hydrolysis of xylan increased with temperature and attained large values above 200 ºC, for which more than 70% of the initial xylan was solubilised. A similar trend was obtained in other autohydrolysis studies using rice straw, corn straw, and wheat straw (Carvalheiro et al 2009;Moniz et al 2013Moniz et al , 2014.…”

“…One potential strategy is to carry out in a first step the hydrolysis of the hemicellulosic fraction by hydrothermal processing (autohydrolysis) before further processing. This is an effective and selective pre-treatment enabling a high production of soluble hemicellulosic oligosaccharides from the liquid phase and a high recovery of cellulose and lignin in the solid phase (Carvalheiro et al 2009;Moniz et al 2013).…”

Valorization of Leucaena leucocephala for energy and chemicals from autohydrolysis

“…Polysaccharides were fairly moderately degraded (0.100-1.075% in combination) relative to previously reported values for the studied operating ranges [51][52][53]. Both compounds only increased appreciably above the medium temperature and time conditions.…”

Pre-treatment and extraction techniques for recovery of added value compounds from wastes throughout the agri-food chain

“…The addition of CO 2 to the hydrothermal medium resulted in a higher yield of xylose oligomers in comparison to water-only reactions at optimal reaction conditions. 135 Pang et al studied various methodologies such as butanediol, ammonia, H 2 O 2 , hot lime water, NaOH and scCO 2 to process raw cornstalk. Among the technologies investigated, butanediol and scCO 2 allowed the extraction of 77% of the hemicelluloses from cornstalk, and in the case of CO 2 , it occurred without coextraction of lignin.…”