Degradation of Maize Hulls with Water in a Flow Reactor

Abstract

Maize hull hemicelluloses can be extracted almost quantitatively by simple water treatment ("prehydrolysis") in a flow reactor at 165-180°C. Severe decomposition of pentosans is thus avoided. Concomitant solubilized starch can be separated from hemicelluloses by degradation with glucoamylase as was shown on an analytical scale. The obtained xylan (yields around 25%) is partly depolymerized and about 50% of original arabinose present in the side chains are split of. Nevertheless the isolated p r o d g , which is well soluble in water, is still highly branched and shows a DP, of 37 t o 54. Abbau von Maisschalen mit Wasser in einem Strbrnungsreaktor.Die Hemicellulosen von Maisschalen konnen durch einfache Behandlung mit Wasser bei 165-180°C (.,Vorhydrolyse") in einem Stromungsreaktor fast quantitativ ohne gravierende Zersetzung der Pentosane isoliert werden. Ebenfalls geloste Starke kann durch enzymatischen Abbau mit Amyloglucosidase von den Hemicellulosen abgetrennt werden, wie in analytischem MaRstab gezeigt wurde. Das in Ausbeuten um 25% erhaltene Xylan ist teilweise depolyrnerisiert und erhalt nur noch etwa 50% der urspriiglich in den Seitenketten vorhandenen Arabinose. Gleichwohl ist das isolierte ProduktLas sehr gut wasserloslich ist, noch stark verzweigt und weist einen DP, von 37-54 auf.

A Comparison between Hot Liquid Water and Steam Fractionation of Corn Fiber

“…Apparently, the pentosans are protected during the pretreatment of biomass while in the form of oligomers. Köll et al also found that the majority of hemicellulose in corn fiber solubilized with hot liquid water (165−180 °C for 60 min) was in the polymeric form (70%), although the pentosan recovery was not reported.…”

“…In addition, acetic acid is formed from the partial deacetylation of hemicellulose, and this acid may catalyze the hydrolysis reactions. The hemicellulose is also depolymerized. , For example, an initial, mild (180 °C, 1 h) water extraction (“prehydrolysis”) has long been used to selectively remove most of the hemicellulose from pine before chemical pulping. , Complete removal of the hemicellulose from hardwoods and herbaceous materials, without significant degradation, was achieved by Mok and Antal using higher temperatures (200−230 °C) for 15 min and less. Lignin is also partially depolymerized and solubilized during treatments with hot water. − Complete delignification is not possible using hot liquid water alone, in part because of recondensation of soluble components originating from lignin.…”