Browsing by Autor "Mats Galbe"

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Arabinosylated phenolics obtained from SO<sub>2</sub>‐steam‐pretreated sugarcane bagasse
(Wiley, 2012) Cristhian Carrasco; Carlos Solano; J. Mauricio Peñarrieta; Henrique Macedo Baudel; Mats Galbe; Gunnar Lidén
Abstract A pentose‐rich hydrolysate fraction obtained by extraction of steam‐pretreated sugarcane bagasse was analysed with regard to dissolved phenolics. The liquid obtained after steam pretreatment (2% SO 2 (w/w) at 190 °C for 5 min) was divided into two parts: one containing dissolved compounds originating from hemicellulose (with xylose as the dominating compound), and the other containing predominantly dissolved compounds originating from lignin. Using nuclear magnetic resonance, the main dissolved compounds originating from lignin were identified as the glycosylated aromatics, 5‐ O ‐( trans ‐feruloyl)‐L‐Arabinofuranose and 5‐ O ‐( trans ‐coumaroyl)‐L‐Arabinofuranose, together with p ‐coumaric acid and small amounts of more common free phenolics such as p ‐hydroxybenzaldehyde, p ‐hydroxybenzoic acid and vanillin. The phenolic compounds were analysed and quantified using reversed‐phase high‐performance liquid chromatography. The findings show that SO 2 steam explosion opened up new degradation pathways during lignin degradation. Copyright © 2012 Society of Chemical Industry
Fermentation of the Straw Material Paja Brava by the Yeast &lt;i&gt;Pichia stipitis&lt;/i&gt; in a Simultaneous Saccharification and Fermentation Process
(Scientific Research Publishing, 2013) Cristhian Carrasco; Henrique Macedo Baudel; Christian Roslander; Mats Galbe; Gunnar Lidén
Paja Brava is a native South American grass with a high carbohydrate content. In the current work, the potential of using this feedstock for ethanol production using a simultaneous saccharification and fermentation (SSF) process with the xylose-fermenting yeast Pichia stipitis (Scheffersomyces stipitis) CBS6054 was investigated. The straw material was subjected to SO2 catalyzed steam pretreatment at 200°C and 5 min residence time, which resulted in a solubilization of pentose sugars (mainly xylose) of 64% with only minor amounts of degradation products. The obtained material, including the pretreatment liquid, was subsequently hydrolyzed and fermented in an SSF process at microaerobic conditions using either a batch or a fed-batch process at a total water-insoluble solids loading of 10%. Overall yields of ethanol based on all available sugars of 0.24 g/g and 0.27 g/g were obtained for batch and fed-batch mode of operation, respectively. The higher yield in the fed-batch process coincided with a higher degree of conversion of the sugars in the liquid medium, in particular of arabinose, for which the conversion was doubled (from 48% to 97%).
<scp>SO<sub>2</sub></scp>‐catalysed steam pretreatment of quinoa stalks
(Wiley, 2013) Cristhian Carrasco; Diego Cuno; Karin Carlqvist; Mats Galbe; Gunnar Lidén
Abstract BACKGROUND Quinoa is a pseudo‐cereal grown predominantly in South America. The quinoa stalks are lignocellulosic residues, which have a limited use today. The objective of the current study was to assess the potential of this material as a source of monosaccharides for fermentation purposes by means of steam pretreatment giving sugars from the hemicellulose part, and enzymatic hydrolysis of the solid fraction obtained. SO 2 catalysed steam pretreatment was carried out with a holding time of 5 min at temperatures between 180 and 220°C. The pretreatment was carried out at two different scales, a small reactor of size 0.5 L and a somewhat larger reactor of size 10 L, to allow comparison of scale effects in the pretreatment. RESULTS The highest xylose yield in the liquid phase, obtained after pretreatment at 210°C, was 80%. In the smaller scale unit, longer residence times were needed. The enzymatic hydrolysis, at an enzyme loading of 15 FPU g ‐1 glucan and a WIS loading of 2%, resulted in a glucose yield of 70% based on the original glucan. The overall sugar yield, including the xylan hydrolysed in the enzymatic treatment, at dilute conditions was 75%. CONCLUSIONS SO 2 catalysed pretreatment of quinoa straw followed by enzymatic hydrolysis gave a relatively good sugar yield. However, the yield obtained was somewhat lower than previously reported for similar materials, such as wheat straw and sugarcane bagasse, steam pretreated with SO 2 . © 2013 Society of Chemical Industry
SO2-catalyzed steam pretreatment and fermentation of enzymatically hydrolyzed sugarcane bagasse
(Elsevier BV, 2009) Cristhian Carrasco; Henrique Macedo Baudel; Johan Sendelius; Tobias Modig; Christian Roslander; Mats Galbe; Bärbel Hahn‐Hägerdal; G. Zacchi; Gunnar Lidén
Steam pretreatment and fermentation of the straw material “Paja Brava” using simultaneous saccharification and co-fermentation
(Elsevier BV, 2010) Cristhian Carrasco; Henrique Macedo Baudel; J. Mauricio Peñarrieta; Carlos Solano; Leslie Tejeda; Christian Roslander; Mats Galbe; Gunnar Lidén