以向日葵葉柄為料源之饋料批次式酵素水解生質酒精製程

Bioethanol Production from Sunflower Stalks Based on Fed-Batch Enzymatic Hydrolysis

謝志誠(Jyh-Cherng Shieh) ； 楊哲維(Che-Wei Yang) ； 張思賢(Szu-Hsien Chang) ； 陳韋任(Wei-Jen Chen) ； 劉安琪(An-Chi Liu)

《農業機械學刊》 19卷3期 (2010/09) Pp. 61-74

https://doi.org/10.30062/JAM.201009.0002

摘要

本研究以廢棄之向日葵葉柄為料源，從不同前處理條件中，找出最適酵素水解者為：先以4% NaOH，於固液比1:20、80 rpm、大氣壓及103°C下浸泡180分鐘，再以1 % H2O2，於固液比1:50、85°C、pH11下浸泡45分鐘。前處理後之物料，於基質濃度5%、pH4.5及50°C條件下，以纖維水解脢及葡萄糖苷脢混合之酵素水解72小時，先由葡萄糖產率及成本效益，找出最佳酵素組合（FPU/CBU）及酵素基質比（FPU/g、CBU/g），再討論基質濃度對酵素水解效率之影響。然後，於高基質濃度15%下探討不同模式之饋料批次式酵素水解效率，所得之水解液利用酵母菌Saccharomyces cerevisiae BCRC 21685予以醱酵。結果顯示：最佳酵素組合為FPU/CBU = 21/4.2，最佳酵素基質比為21 FPU/g及4.2 CBU/g，採分批饋入酵素及前處理物者，水解效率最佳，後續醱酵效率亦最佳，所得之葡萄糖濃度及產率分別為31.86 mg/mL，41.86%，比批次式酵素水解者增加13.18%。在未經過排毒及高溫滅菌處理及添加葡萄糖下，不僅可以順利啟動醱酵，並於第18、24小時，獲得理論產率94.31%、94.78%之乙醇，且醱酵24小時後，殘餘之葡萄糖含量低於1%。

關鍵字

向日葵葉柄 ； 生質乙醇 ； 前處理 ； 饋料批次 ； 酵素水解 ； 醱酵

並列摘要

In this work, bioethanol production from wasted sunflower stalks based on fed-batch enzymatic hydrolysis was studied. To reduce cellulose crystallinity and improve the hydrolysis yield, various alkaline and alkaline/oxidative pretreatments were investigated. According to the recovery of glucose after enzymatic hydrolysis of the pretreatment solid, a two-step chemical pretreatment was proposed. It consisted of a first alkaline step ( 4% NaOH, 5% (w/v) solids concentration, 103°C, 80 rpm, and 180 min. ) and a second alkaline/oxidative step ( 1% H202 , 2% (w/v) solids concentration, 85°C, pH 11, and 45 min.). Because of the complex structure of polysaccharides and limitation of individual enzyme, enzymatic hydrolysis was carried out by hybrid enzyme which was a mixture of cellulase from Trichoderma reesei C2730 (Celluclast(superscript ®) 1.5L) and cellobiase from Aspergillus niger (Novozyme(superscript ®) 188). The optimal FPU/CBU and loading of hybrid enzymes were identified as 21/4.2, 21 FPU/g substrate, and 4.2 CBU/g substrate. Further increase in FPU/CBU ratio and enzyme dosage did not increase in the glucose yield based on cost-benefit. The effects of substrate concentration on enzymatic hydrolysis showed that high substrate concentration usually resulted in lower hydrolysis yield. However, raising substrate concentration would lead to high glucose concentration. To overcome the mixing and heat transfer problems occurred due to high substrate concentration, two kinds of fed-batch enzymatic hydrolysis were applied. The proposed fed-batch hydrolysis process was started with a batch hydrolysis containing 5 g/100 mL of substrate concentration and hybrid enzymes with 105 FPU and 21 CBU. After the initial batch, pretreatment solid and hybrid enzyme were added at 6 and 12 h giving a final substrate concentration of 15 g/100 mL. After 72 h of hydrolysis, the glucose concentration and yield reached 31.86 mg/mL and 41.86%, higher than that obtained from the batch process 13.18%. Hydrolysate, without sterilization and detoxification, was then fermented with Saccharomyces cerevisiae BCRC 21685 for 24 h. The final ethanol concentration level reached 15.40 mg/mL, about 94.78% theoretical yield. Glucose residue was less than 1%.

並列關鍵字

Sunflower stalk ； Bioethanol ； Pretreatment ； Fed-batch ； Enzymatic Hydrolysis ； Fermentation