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 Pretreatment Methods for Valorization of Hazelnut Pruning Wastes(Izmir Institute of Technology, 2016) Doğru, Kevser; Büyükkileci, Ali Oğuz; Büyükkileci, Ali Oğuz; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyTurkey is the world leader in hazelnut production and a large amount of residues is produced during its harvesting and processing. So far, the residues of hazelnut production had no economic value and usually burned in the fields. Obtaining valuable products such as ethanol from hazelnut pruning waste (HPW) can add value to those. Ethanol produced by microorganisms via fermentation is a promising alternative biofuel. Ethanol has been produced for a long time from sugary substances, while lignocellulosic biomasses (LCBs) are interesting alternative to fossil fuel based resources in order to have a sustainable production process. Liquid hot water (LHW) treatment is one of the pretreatment processes necessary to facilitate enzymatic hydrolysis of cellulose into glucose before ethanol fermentation. Organosolv is similar to LHW treatment except that ethanol-water mixture is generally used is the liquid part instead of only water. LHW could remove the hemicelluloses from the lignocellulosic matrix to some extent, while adding H2SO4 improved the hemicellulose removal. Organosolv was effective on removal of lignin as well as of hemicellulose. Acid catalysis improved the hemicellulose solubilization in organosolv, like in LHW treatment. After acid catalyzed organosolv, cellulose content of the HPW was increased to 67.91%. This sample was hydrolyzed with a conversion efficiency of 87.32%. Hydrolysate containing 60.63 g/L glucose was used as the medium for ethanol production using Saccharomyces cerevisiae. At an 83.49% theoretical yield, 22.2 g/L ethanol was obtained after 6 h. These results demonstrated that hazelnut pruning waste has potential to be used as a feedstock for ethanol production.