Study on increasing production efficiency of xylooligosaccharides and establishing a continuous separation system
2005
Hochschulschrift
Zugriff:
93
This study was to investigate the method of increasing xylooligosaccharides (XOS) production by enzymatic degradation of corn cob xylan (CCX), including using the mixture of α-L-arabinofuranosidase and Pulpzyme HC and isolating XOS by activated charcoal affinity chromatography and ultrafiltration. An enzyme reactor linked with a tangential flow filtration system was also established for continuous production of purified XOS with a certain degree of polymerization. The results of solubility measurement showed that the solubility of xylans in aqueous CCX suspensions reached 62.6% after heating at 121 oC for 1 h, approximately double those at 25 oC. For the 121 oC-dissolved samples, hydrolysis with Pulpzyme HC (pH 7.0, 50 oC for 2 h) alone or after with previous debranching with α-L-arabinofuranosidase (pH 4.0, 40 oC for 2 h) gave the total yield of xylobiose (X2) and xylotriose (X3) as approximate 20%. If the above two enzymes were concomitantly applied at pH 5.5 and 50 oC for 2 h, the total yield of X2 and X3 would increase to 28.6%, indicating that using the multiple enzymes simultaneously could enhance the efficiency of XOS production. After ultrafiltration through molecule weight cut off 10, 5 and 1 kDa membranes, crude XOS solutions without any enzyme deactivation and centrifugation process could recover the oligosaccharides with DP < 7 to 14%. If separation on activated charcoal affinity chromatographic column was used instead, the XOS recovery was 11-12%, where X2 composition may dominate in 5% or 20% EtOH eluent (depending on the source of activated carbon). For the continuous production and separation system of XOS, the separation on the xylan hydrolyzates under the condition of 0.5% substrate concentration, pH 7.0 and 5%(enzyme activity 22.1 kU) Pulpzyme HC at 45 oC for 2 h could resulted in a theoretically maximal XOS yield of 4.64%. Enzyme activity (about 650 U) could maintain for at least six hours. However, a greater substrate or enzyme concentration caused a lower remaining enzyme activity and did not help to increase the XOS recovery. Conclusively, the optimal condition for the lab-scale continuous production of XOS studied was suggested: 0.5% substrate concentration, pH 7.0, and hydrolysis with 5%(enzyme activity 22.1 kU) Pulpzyme HC at 45 oC.
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Study on increasing production efficiency of xylooligosaccharides and establishing a continuous separation system
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Autor/in / Beteiligte Person: | Tien), James(Yii-Jen ; 田以正 |
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Veröffentlichung: | 2005 |
Medientyp: | Hochschulschrift |
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