Production of Xylooligosaccharides from Napiergrass

• Main Authors: Huei-yi Wu, 吳蕙誼
• Other Authors: 余琬琴
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/h7995k

碩士 === 國立臺北科技大學 === 有機高分子研究所 === 102 === Napiergrass (Pennisetum purpureum) is regarded as a potential energy crop because of its rapid growth and high dry matter productivity. In Taiwan, napiergrass juice also prevails as a functional juice due to its beneficial health effects. The fibrous residue after juice extraction can be converted into various products, including xylooligosaccharides, to increase its value. In this study, the fibrous residue of napiergrass was subjected to a steam explosion (SE) treatment to generate a liquid rich in xylooligosaccharides (XOs). However, the SE liquid also contained water-soluble xylan and various impurities, including organic acids, furfural, hydroxymethylfurfural (HMF). In addition, the SE liquid displayed a brownish color, probably resulted from degraded lignin generated during SE. Therefore, further purification and decolorization is necessary to obtain food-grade XOs. In this work, a XOs purification process integrating enzymatic hydrolysis and cross-flow filtration was developed. Commercially available endoxylanase was introduced into the SE liquid to hydrolyze the water-soluble xylan into XOs, thereby increasing the concentration of XOs. We then employ a series of crossflow filtration with decreasing pore size to decolor and to remove impurities, as well as to achieve concentration of XOs. Microfiltration (0.3 μm) and ultrafiltration (UF) were first used to remove large-sized impurities and to decolor. After that, nanofiltration (NF) was employed to concentrate XO solutions, as well as to remove small impurities such as acetic acid and furans. The commercially available endoxylanase was found useful for improving XO yield. The efficacy of the spiral-wound membrane modules (GE-Osmonics) adopted in the work was also confirmed. The UF membrane (MWCO 3 kDa) was an efficient color remover. The NF membrane (MWCO 150-300 Da) effectively removed acetic acid and furans from the SE liquid, while retaining most of the XOs.