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D-Xylose produced from wheat straw b...

Liavoga, Allan Bright.

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D-Xylose produced from wheat straw by acid and enzyme catalyzed hydrolysis, and the purification of xylitol.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	D-Xylose produced from wheat straw by acid and enzyme catalyzed hydrolysis, and the purification of xylitol./
作者:	Liavoga, Allan Bright.
面頁冊數:	180 p.
附註:	Adviser: Paul A. Seib.
Contained By:	Dissertation Abstracts International67-09B.
標題:	Agriculture, Food Science and Technology. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3234503
ISBN:	9780542879111

D-Xylose produced from wheat straw by acid and enzyme catalyzed hydrolysis, and the purification of xylitol.
Liavoga, Allan Bright.

D-Xylose produced from wheat straw by acid and enzyme catalyzed hydrolysis, and the purification of xylitol. - 180 p.

Adviser: Paul A. Seib.

Thesis (Ph.D.)--Kansas State University, 2006.

Xylitol is a valuable sweetener produced by reduction of D-xylose. The objective of this work was to optimize conditions for acid- and enzyme-catalyzed production of D-xylose from wheat straw. Ground straw (10g) was treated with 10 parts of 0.2-0.4 M sulfuric acid at 110-130°C and for 15-45 min or to atmospheric hydrolysis in refluxing 0.75-1.25 M sulfuric acid for 1.5 to 3 h. A maximum of 18-19% of D-xylose and 5% other sugars were found in hydrolyzate when straw was heated in 0.3 M acid at 123°C (5.8 atm) for 28 min or in boiling 1.25 M sulfuric acid for 2.5 h. To release D-xylose enzymically, ground wheat straw was stirred and preheated in 10 parts water at 140, 160, 180 and 200°C for 15, 30 and 60 min in a bench-scale reactor, and the liquid and solid phases separated. The swollen solid phase was mixed with one of five endo-xylanases at optimum pH and temperature, and the liquid phase also was hydrolyzed. The most effective xylanase (T. reesei) gave a total of 17% D-xylose and 5% other sugars from the straw pretreated at 160°C for 1 h. When the T. reesei xylanase (40 IUg-1 dry straw) was reacted directly with unseparated hydrothermally treated straw, 16% of free D-xylose was released with 5% of contaminating mono saccharides. Among these hydrolysis experiments on straw, the one chosen for the production of xylitol was the pressurized hydrolysis in 0.3 M and 123°C for 28 min. The liquid phase containing the sugars was neutralized, treated with activated charcoal and the mineral ions removed. The sugars in the hydrolyzate were reduced by a molar equivalent of sodium borohydride, and sodium and borate ions removed on resin columns. Xylitol (10% of straw weight) with a purity of 95% was obtained by fractional crystallization of the processed mixture. When the processed mixture was fractionated on a strongly basic anion-exchange resin (hydroxide form), 5.0% xylitol crystals were obtained with a purity of 99%.

ISBN: 9780542879111Subjects--Topical Terms:

1017813
Agriculture, Food Science and Technology.

D-Xylose produced from wheat straw by acid and enzyme catalyzed hydrolysis, and the purification of xylitol.
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245 1 0 $a D-Xylose produced from wheat straw by acid and enzyme catalyzed hydrolysis, and the purification of xylitol.
300 $a 180 p.
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502 $a Thesis (Ph.D.)--Kansas State University, 2006.
520 $a Xylitol is a valuable sweetener produced by reduction of D-xylose. The objective of this work was to optimize conditions for acid- and enzyme-catalyzed production of D-xylose from wheat straw. Ground straw (10g) was treated with 10 parts of 0.2-0.4 M sulfuric acid at 110-130°C and for 15-45 min or to atmospheric hydrolysis in refluxing 0.75-1.25 M sulfuric acid for 1.5 to 3 h. A maximum of 18-19% of D-xylose and 5% other sugars were found in hydrolyzate when straw was heated in 0.3 M acid at 123°C (5.8 atm) for 28 min or in boiling 1.25 M sulfuric acid for 2.5 h. To release D-xylose enzymically, ground wheat straw was stirred and preheated in 10 parts water at 140, 160, 180 and 200°C for 15, 30 and 60 min in a bench-scale reactor, and the liquid and solid phases separated. The swollen solid phase was mixed with one of five endo-xylanases at optimum pH and temperature, and the liquid phase also was hydrolyzed. The most effective xylanase (T. reesei) gave a total of 17% D-xylose and 5% other sugars from the straw pretreated at 160°C for 1 h. When the T. reesei xylanase (40 IUg-1 dry straw) was reacted directly with unseparated hydrothermally treated straw, 16% of free D-xylose was released with 5% of contaminating mono saccharides. Among these hydrolysis experiments on straw, the one chosen for the production of xylitol was the pressurized hydrolysis in 0.3 M and 123°C for 28 min. The liquid phase containing the sugars was neutralized, treated with activated charcoal and the mineral ions removed. The sugars in the hydrolyzate were reduced by a molar equivalent of sodium borohydride, and sodium and borate ions removed on resin columns. Xylitol (10% of straw weight) with a purity of 95% was obtained by fractional crystallization of the processed mixture. When the processed mixture was fractionated on a strongly basic anion-exchange resin (hydroxide form), 5.0% xylitol crystals were obtained with a purity of 99%.
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