Production of xylooligosaccharides from cotton and tobacco stalk

Comparison of acid and enzymatic hydrolysis of tobacco stalk xylan for preparation of xylooligosaccharides

“…The amounts of produced XOs from 3, 4 and 5 g/100 ml substrate concentrations were similar to each other. In the previous studies performed with cotton stalk and corn cob, similar results were observed and it was speculated that a high concentration of substrate might result in the reduction of water content in the reaction mixture which lowered pentose yield or inhibited the enzyme by the impurities present (Akpinar et al, 2007;Yoon et al, 2006).…”

“…The oligosaccharide syrup permeate obtained from the first ultrafiltration composed of 20 g/100 g >X6, 1 g/100 g X6, 3 g/ 100 g X5, 11 g/100 g X4, 30 g/100 g X3, 34 g/100 g X2 and 1 g/100 g X1 was processed by a second UF having a 3 kDa cut off membrane. The previous study done with the cotton stalks (Akpinar et al, 2007) showed that changing the membrane from MWCO 3 kDa to 1 kDa, did not change the composition in the final permeate and retentate, drastically, but increased the concentration of longer chain oligosaccharides in the retentate. Considering flow rate and ease of work, only membrane of MWCO 3 kDa was used for refining of XOs in this study.…”

“…Since previous studies show that A. niger xylanase produced only small amount of monomer (Akpinar et al, 2007), xylanase from A. niger was used for production of XO and the effects of hydrolysis period, pH, temperature, substrate and enzyme concentrations on XO production were examined. Fig.…”

“…Generally, in lignocellulosic biomass, xylan exists in a xylan-lignin complex and becomes resistant to hydrolysis. Therefore, currently XO production is carried out in two stages: alkaline extraction of xylan from lignocellulosic biomass followed by xylanase hydrolysis having low exoxylanase and/or b-xylosidase activity (Akpinar, Ak, Kavas, Bakir, & Yilmaz, 2007;Akpinar, Erdogan, & Bostanci, 2009b;Chen, Chen, & Lin, 1997;Freixo & Pinho, 2002;Pellerin et al, 1991) or acid hydrolysis (Akpinar et al, 2009a;Sun et al, 2002) of the xylan. Enzymatic hydrolysis does not produce undesirable by-products or high amount of monosaccharides.…”

Xylose Production By Combined Autohydrolysis and Enzymatic Hydrolysis From Tobacco Stalks

“…Kullanılan ezimlerin protein içeriği Bradford Hidrolizasyon grafiklerinden de görüldüğü gibi, enzimin hidrolizasyon hızı 24. saate kadar hızla ilerlemiş daha sonra yavaşlamış ya da azalmaya başlamıştır. Enzim hidrolizinin 24. saaten sonra yavaşlamasının ya da azalmasının nedeni ise; bulunan substrat miktarın tükenmiş olması veya enzimlerin belli süre sonra aktivitelerini yitirmiş olması veya substratla ürünlerin yarışmalı inhibisyona girerek substartların bağlanmasını engellemesi veya ortamda bulunan başka bileşiklerin hidrolizi engellemesi veya substrat miktarının tükenmiş olması olarak yorumlanmıştır [5,29]. Bu nedenle 24 saatlik reaksiyon süresinin daha uygun olduğuna karar verilmiştir.…”