以台灣櫸製備木寡糖與奈米纖維素

Abstract

本研究透過化學及機械預處理等方法搭配酵素水解，以台灣原生植物台灣櫸為原料，製備兩種高經濟價值之纖維素衍生物：奈米纖維素及木寡糖。由於奈米材料之優異機能及再生性等綠色永續材料特性，奈米纖維素在應用上具高度潛力。木寡糖可作為腸道系統的益生原達到腸胃保健之功效，同時因其五碳醣的結構，不造成熱量負擔。 首先，將原物料進行高強度碎磨之機械預處理，接著經過鹼萃反應提取出木聚醣，隨後以酒精沈澱、酒精沈澱複合膜過濾以及膜過濾這三種方式純化木聚醣，最後以10、30、50 IU/mL 三種酵素劑量進行水解，找出較佳的純化方法、酵素劑量及水解時間。結果發現，酒精沈澱的純化方式之醣回收率最佳，高達91.14 %，但是在木寡糖收率的部分，奈米膜過濾所得的木聚醣在酵素水解的階段產率較高，為59.20 %。 生產奈米纖維素部分，將探討鹼萃及機械預處理對產率的影響。結果發現，兩種預處理對於奈米纖維素的生產效率皆有提升，最佳的反應條件為：機械磨碎及鹼萃處理後，透過64 %wt硫酸水解30分鐘，可以得到粒徑約154 ± 40 nm、Zeta電位-40.7 mV且產率為37.1 %的奈米纖維素溶液。

In this study, chemical and mechanical pretreatments were used in combination with enzyme hydrolysis to produce two kinds of valuable cellulose derivatives from Taiwan Zelkova which is a native species in Taiwan. Nanocellulose has great potential for application because of attractive properties in nanoscale and renewable. Xylooligosaccharides (XOS) could act as probiotic for the intestinal system and don’t cause any caloric burden. First, the raw materials will be mechanically pretreated with high-strength crushing to obtain the powder Taiwan Zelkova, then the xylan will be extracted by alkaline extraction, and then three kinks of purification systems including ethanol-precipitation, ethanol-precipitation plus ultrafiltration and nanofiltration will be conduct. The final enzyme hydrolysis was performed at 10, 30, and 50 IU/mL enzyme dosages. As a result, the sugar recovery rate of the ethanol precipitation was the best noted as 91.14 %, and the yield of xylooligosaccharides of nanofiltration was highest for enzyme hydrolysis, which was 59.20 %. In nanocellulose production phase, the effects of alkali extraction and mechanical pretreatment on production of nanocellulose will be discussed. The results showed that the two pretreatments all improved the production efficiency of nanocellulose. The optimal results of nanocellulose preparation were -40.7 mV zeta (ζ) potential, particle size 154 ± 40 nm and yield 37.1 % with 30 min hydrolysis.