- 學位論文
利用蒸爆技術與酵素水解自狼尾草生產木寡糖之研究
Enzymatic production of xylooligosaccharides from napier grass xylan extracted using steam explosion
摘要
狼尾草具有生長快速、生產力高與耐高溫等特性，因此被視為有潛力之理想能源作物，在台灣除作為牧草的用途外，其汁液也有做為健康食品相關之應用，經榨汁後之狼尾草渣若經適當的處理程序，可生產具經濟價值之木寡糖。 本研究使用鹼性蒸煮爆碎法對狼尾草渣進行前處理，於蒸爆程序中添加碳酸鈉可降低雜質的生成(糠醛和甲基糠醛)，經蒸爆處理後使可溶性木聚醣溶於液體中，後續則結合酵素水解之方法，利用市售木聚醣酶進行水解反應，以得到低聚合度的木寡糖，研究中將探討pH值、酵素劑量對木寡糖濃度和單糖濃度的影響。同時與傳統的鹼液萃取法得到之木聚醣比較水解效率間的差異。 研究結果顯示，所使用之木聚醣內切酶在pH值5以下的環境有較良好的水解效率，而酵素劑量大於175 U時，其水解效率已無明顯增加，在考量調整蒸爆液pH值所需的化學藥劑量與酵素成本，選擇pH 5、87.5 U做為水解條件。鹼液萃取法的水解效率在24小時的水解時間內，木寡糖濃度明顯低於鹼蒸爆法，儘管加長水解時間有得到更高濃度的可能性，但增加的寡糖量過少不符合時間成本。
並列摘要
Napiergrass (Pennisetum purpureum) is regarded as a potential crop because its rapid growth rate and high dry matter productivity. In Taiwan, napiergrass juice prevails as a functional juice due to its beneficial health effects. In addition, the residual fiber could be subjected to suitable treatment to increase its economic value, such as production of xylooligosaccharide. In this research, the alkaline steam explosion was used to extract xylan from napiergrass. However, the extracted xylan had a high degree of polymerization. The xylan was degraded via enzymatic hydrolysis to produce xylooligosaccharides. The commercial endo-xylanase was used for decreasing the production of monosaccharide. The effect of pH value and enzyme dosage on xylooligosaccharide production was investigated. Furthermore, the enzymatic hydrolysis result of xylan from alkaline extraction would be investigated. The result showed that if the pH value was lower than 5, the hydrolysis efficiency would be better. When the cost of chemical and enzyme were considered, the ideal hydrolysis conditions were pH 5 with enzyme dose 87.5 U. For comparison of hydrolysis efficiency between alkaline steam explosion and alkaline extraction, the former was preferred due to its higher yield of xylooligosaccharides.