Date

2012-12-31

Author

Çekmecelioğlu, Deniz

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Aim:Hazelnut by-products can be one of the most important types of biomass, as it is an abundant, important agricultural and commercial material in Turkey. At present, two-thirds of the world production capacity of hazelnuts is provided by Turkey, with around 250 thousand tons of hazelnut shells per year produced in the Black- Sea region of Turkey alone. Proximate analysis indicates that hazelnut shells have 43.1% lignin, 27.5% hemicellulose, 24.7% cellulose, 3.4% alcohol-benzene extractives and 1.4% ash which shows that it can be used in bioethanol production after removing lignin. Saccharomyces cerevisiae is one of the most important yeasts that is used in bioethanol production; also the use of xylose-fermenting yeast such as Kluyveromyces marxianus that is able to co- ferment xylose, arabinose and glucose offers an extra opportunity for efficient utilization of hazelnut byproducts. Therefore, the aim of this research is to show the utility of hazelnut byproducts in bioethanol production. Material and Methods: Yeast and culture media: The experiments will be carried out using hexose utilizing Saccharomyces cerevisiae and pentose utilizing Kluyveromyces marxianus kindly provided by Agricultural Research Service (ARS) culture collections. Inoculum preparation: The inocula will be prepared by transferring organism by loop from two days slants to 250 ml Erlenmeyer flasks containing 100 ml of growth medium. The inoculum medium consist of (g l−1) 1.2g KH2PO4, 0.18g Na2HPO4, 10 g yeast extract and 50 gr glucose. The yeasts will be incubated aerobically with a magnetic stirrer (150 rpm) at 30 °C for 24h prior to use. Raw material: Hazelnut shells obtained from a local plant in Giresun province in Turkey. Hazelnut shells milled into fine particles and screened into fractions (1-2 mm) to easy reaction with acid. To reduce water content hazelnut shells were dried in an oven at 100 °C. Delignification of hazelnut shell: To minimize the concentrations of fermentation inhibitors, hazelnut shells will be delignified with % 3 NaOH solution in an autoclave before acid hydrolysis. Acidic hydrolysis: The acid hydrolysis will be conducted for 10-30 min with %1 - %5 H2SO4 and a solid/liquid ratio of 1/5 (w/v). The temperature of hydrolysis will be 90-130 °C. Enzymatic hydrolysis: Substrate mixtures (pretreated hazelnut shell) with different substrate loads (2.5%, 5.0%, 7.5% dw/v) will be brought to pH 4.8 using 50 mM citrate buffer. Viscozyme at various concentrations (1.5 U/g-9.0 U/g dry biomass) will be added to initiate the reaction. Enzymatic saccharification will be performed at 50°C in a rotary shaker at 100 rpm. Reducing sugar concentration in the samples will be analyzed by the DNS method.

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https://hdl.handle.net/11511/59868

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Graduate School of Natural and Applied Sciences, Project and Design