Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Potential of Deep Eutectic Solvent Pretreatment for Xylooligosaccharides Production From Corncob(01. Izmir Institute of Technology, 2023) Büyükkileci, Ali Oğuz; Büyükkileci, Ali Oğuz; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyEnzymatic hydrolysis of xylan to produce xylooligosaccharides (XOS) requires pretreatment of the feedstock lignocellulosic biomass. The current pretreatments have some disadvantages, such as the use of harsh chemicals, high energy requirements, and impurity generation. This study aimed to develop a greener method for high-purity XOS production based on mild pretreatment of corncob and subsequent enzymatic hydrolysis. Both deep eutectic solvent (DES) and dilute alkali pretreatments provided approximately 65% lignin removal from the corncob, while 80% of the xylan remained in the solid. When corncob was treated with DES at 130 ○C for 2 h, the total XOS yield in the hydrolysis was 44.1%, and the yield of xylotriose and xylobiose (LDP XOS) was 39.7% based on feedstock xylan. Dilute alkali treatment of corncob at 30 oC for 8 h, provided a total XOS yield and LDP XOS yields of 41.6% and 33.4%, respectively. The enzyme was removed from the XOS solution, while most of the LDP XOS was recovered, using the ultrafiltration system with a 10 kDa membrane. Fermentable sugars were produced from the spent solids as a secondary product using cellulase hydrolysis. This study suggested that DES and dilute alkali-based processes can be considered an eco-friendly approach to XOS production. Since XOS was mostly composed of LDP XOS, they can be preferred as food additives.Master Thesis Succinic Acid Production From Lignocellulosic Biomass by Actinobacillus Succinogenes(01. Izmir Institute of Technology, 2021) Büyükkileci, Ali Oğuz; Büyükkileci, Ali Oğuz; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologySuccinic acid is an expensive and high industrial value organic acid that can be used in many industries such as food, cosmetics, chemistry. It can be produced by bacterial fermentation. When cellulose and xylan in the lignocellulosic biomass are hydrolyzed into glucose and xylose with pretreatment process, they can be used as a carbon source in fermentation. This study was designed for the production of succinic acid from pretreated corncob by Actinobacillus succinogenes ATCC-55618. Corncob was pre-treated by organasolv. The cellulose and xylan were hydrolyzed into monomers using commercial enzymes. The optimal enzyme dosages were sought at 50C and pH 5.2, under which conditions pretreated corncob was hydrolyzed for separate hydrolysis and fermentation (SHF). The same test was repeated at 37C and pH 6.8 to find the required enzyme dosages under the simultaneous saccharification and fermentation (SSF). The cellulose and xylan recoveries were 69.2% and 68.8% for SHF, 31.8 % and 41.4 % for SSF. The SHF was conducted using the enzymatic hydrolysate and succinic acid yield was 0.48 g succinic acid/g sugar. In the SSF, the pretreated corncob was used as the carbon source, the succinic acid yields were 0.75 g succinic acid/g sugar. This study shows that corncob treated with organosolv had a potential as carbon source for succinic acid production by A. succinogenes either via SHF or SSF. Although the conditions in the fermentation step were not optimum for the enzyme activity, the SSF was more successful than SHF considering the succinic acid yield on the carbohydrates.