More Accurate Determination of Acid-Labile Carbohydrates in Lignocellulose by Modified Quantitative Saccharification

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• 作者：Geoffery Moxley ; Y.-H. Percival Zhang
• 刊名：Energy & Fuels
• 出版年：2007
• 出版时间：November 2007
• 年：2007
• 卷：21
• 期：6
• 页码：3684 - 3688
• 全文大小：176K
• 年卷期：v.21,no.6(November 2007)
• ISSN：1520-5029

文摘

Production of biofuels and biobased products from lignocellulosic materials is an emerging industry. Quantitative saccharification (QS) is a widely used method for determining carbohydrate composition in lignocellulosic materials. The NREL methods (versions 1996 and 2006) involve a primary hydrolysis in 72% w/w sulfuric acid at 30 °C, converting polysaccharides into oligosaccharides, and a secondary hydrolysis in 4% w/w sulfuric acid at 121 °C, converting all oligosaccharides to monomeric sugars. Because some polysaccharides are degraded during the harsh hydrolysis processes, a sugar control set of monomeric sugars was run in parallel, and the correction coefficients of monomeric sugars were used to compensate the polysaccharide degradation. This assumption may be invalid because polysaccharide and monosaccharide sugars have different degradation rates, especially for acid-labile carbohydrates. Here we propose a modified quantitative saccharification involving a primary hydrolysis (72% sulfuric acid, 30 °C, 1 h), followed by a secondary hydrolysis (4% sulfuric acid, 121 °C, 1 h, for glucose, galactose, and mannose) and a parallel secondary hydrolysis (1% sulfuric acid, 121 °C, 1 h, for xylose and arabinose). The weaker secondary hydrolysis can decrease degradation of acid-labile xylose by ~4.4-fold. The data of acid-labile hemicellulose carbohydrates for all of the five tested lignocellulosic materials from herbs to hardwood to softwood suggest that the current QS protocol results in a 4.2%–9.1% overestimation of xylan contents. Such statistically significant overestimation is attributed to theoretical errors from the methods’ assumption.