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Öğe COMPARISON OF BIODIESEL PRODUCTIVITIES OF DIFFERENT VEGETABLE OILS BY ACIDIC CATALYSIS(Assoc Chemical Eng, 2011) Sagiroglu, Ayten; Isbilir, Sebnem Selen; Ozcan, Hakki Mevlut; Paluzar, Hatice; Toprakkiran, Neslihan M.Biodiesel has become a subject which increasingly attracts worldwide attention because of its environmental benefits, biodegradability and renewability. Biodiesel production typically involves the transesterification of a triglyceride feedstock with methanol or other short-chain alcohols. This paper presents a study of transesterification of various vegetable oils, sunflower, safflower, canola, soybean, olive, corn, hazelnut and waste sunflower oils, with the acidic catalyst. Under laboratory conditions, fatty acid methyl esters (FAME) were prepared by using methanol in the presence of 1.85% hydrochloric acid at 100 degrees C for 1 h and 25 degrees C for 3 h. The analyses of biodiesel were carried out by gas chromatography and thin layer chromatography. Also, biodiesel productivities (%) were determined on basis of the ratio of ester to oil content (w/w). The biodiesel productivities for all oils were found to be about 80% and about 90% at 25 and 100 degrees C, respectively. Also, the results showed that the yield of biodiesel depended on temperature for some oils, including canola, sunflower, safflower Os, but it was not found significant differences among all of the oil types on biodiesel productivities.Öğe Investigation of inhibition kinetics of various plant extracts on polyphenol oxidase enzyme from Paulownia Tomentosa and binding mechanism by molecular docking(Elsevier, 2024) Cesko, Cengiz; Arabaci, Gulnur; Paluzar, Hatice; Ozguven, Serap YilmazPolyphenol oxidase/tyrosinase enzyme, which contains binuclear copper clusters play an important role in melanogenesis and enzymatic browning. Therefore, its inhibitors can be attractive in cosmetics and medicinal industries as depigmentation agents and also in food and agriculture industries as antibrowning compounds. Our aim in this study is to find natural plant extracts that will inhibit the polyphenol oxidase enzyme. The inhibitory effects of Verbascum thapsus, Tanacetum vulgare, Solanum nigrum and Datura stramonium herbal plant extracts obtained from Kosovo on the polyphenol oxidase enzyme activity were investigated. Polyphenol oxidase from the Poulownia tomentosa plant was purified using the three-phase purification method. It is determined that T. vulgare extract showed the most effective inhibitory effect with 0.43 mg/mL IC50 value. In order to explain and support the binding mechanism of the best inhibitor extract, the phenolic content of the T. vulgare extract was determined by LC-MS/MS and the mechanism of the inhibitory effect was explained by performing a molecular docking study for the phenolic compounds it contained at the highest rate.Öğe Investigation of the effects of pesticides on 'Jonagold' apple (Malus x domestica) polyphenol oxidase enzyme activity(Tubitak Scientific & Technological Research Council Turkey, 2023) Cesko, Cengiz; Gashi, Sami; Arabaci, Gulnur; Paluzar, Hatice; Durmishi, Berat; Bruci, Era; Vllasaliu, FjollaIn this study, the effects of a number of commonly used pesticides on the activity of the polyphenol oxidase (PPO) enzyme from pesticide-free and pesticide-applied 'Jonagold' apples were comparatively evaluated. Substrates 4-methylcatechol, pyrocatechol, pyrogallol and L-tyrosine were used to determine the substrate specificity of the PPO enzyme obtained from apple. According to the results, on the contrary, PPO enzyme from 'Jonagold' apple did not show any activity against L-tyrosine substrate which is a monophenolic substrate, the enzyme had high affinity against 4-methylcatechol, pyrocatechol and pyrogallol which are di and tri phenolic substrates. Km values of PPO enzyme obtained from pesticide-free apples against 4-methylcatechol, pyrocatechol, and pyrogallol substrates were determined as followed 0.27 mM, 2.27 mM, and 0.37 mM, respectively. Vmax values were found as 0.133 mM/min, 0.081 mM/min, and 0.051 mM/min. Optimum pH values were found to be 4.5 for 4-methylcatechol, 7.0 for pyrocatechol, and 7.5 for pyrogallol. Optimum temperature values were determined as 40 degrees C for 4-methylcatechol, 10 degrees C for pyrocatechol, and 50 degrees C for pyrogallol. Km values for PPO enzyme activity obtained from pesticide-treated apples against 4-methylcatechol, pyrocatechol, and pyrogallol substrates were 0.98 mM, 3.94 mM, and 0.37 mM, Vmax values were 0.08 mM/min, 0.02 mM/min, and 0.034 mM/min. Optimum pH values were found to be 7.0 for 4-methylcatechol and pyrocatechol and 7.5 for pyrogallol. Optimum temperature values were determined as 50 degrees C for 4-methylcatechol, 30 degrees C for pyrocatechol, and 40 degrees C for pyrogallol. Overall, the results showed that the PPO enzyme from pesticide-free apples had higher activity than pesticide-treated apples. The effects of metals and storage stability on PPO enzyme activity were also investigated. The results reveal that pesticide use affects PPO enzyme activity. The obtained data bring to light new pesticide functional features of great interest in the medicinal, agro-chemical and environmental circles.Öğe A NOVEL BIOSENSOR BASED ON Lactobacillus acidophilus FOR DETERMINATION OF PHENOLIC COMPOUNDS IN MILK PRODUCTS AND WASTEWATER(Taylor & Francis Inc, 2011) Sagiroglu, Ayten; Paluzar, Hatice; Ozcan, Hakki Mevlut; Okten, Suzan; Sen, BurhanDifferent branches of industry need to use phenolic compounds (PCs) in their production, so determination of PCs sensitively, accurately, rapidly, and economically is very important. For the sensitive determination of PCs, some biosensors based on pure polyphenol oxidase, plant tissu, e and microorganisms were developed before. But there has been no study to develop a microbial phenolic compounds biosensor based on Lactobacillus species, which contain polyphenol oxidase enzyme. In this study, we used different forms of Lactobacillus species as enzyme sources of biosensor and compared biosensor performances of these forms for determination of PCs. For this purpose, we used lyophilized Lactobacillus cells (containing L. bulgaricus, L. acidophilus, Streptococcus thermophilus), pure L. acidophilus, pure L. bulgaricus, and L. acidophilus-and L. bulgaricus adapted to catechol in Lactobacilli MRS Broth. The most suitable form was determined and optimization studies of the biosensor were carried out by using this form. For preparing the bioactive layer of the biosensor, the Lactobacillus cells were immobilized in gelatin by using glutaraldehyde. In the study, we used catechol as a substrate. Phenolic compound determination is based on the assay of the differences on the respiration activity of the cells on the oxygen meter in the absence and the presence of catechol. The microbial biosensor response depends directly on catechol concentration between 0.5 and 5.0 mM with 18 min response time. In the optimization studies of the microbial biosensor the most suitable microorganism amount was found to be 10 mg, and also phosphate buffer (pH 8.0; 50 mM) and 37.5 degrees C were obtained as the optimum working conditions. In the characterization studies of the microbial biosensor some parameters such as substrate specificity on the biosensor response and operational and storage stability were examine. Furthermore, the determination of PC levels in synthetic wastewater, industrial wastewater, and milk products was investigated by using the developed biosensor under optimum conditions.Öğe Production and characterization of lipase from Penicillium aurantiogriseum under solid-state fermentation using sunflower pulp(Taylor & Francis Ltd, 2021) Paluzar, Hatice; Tuncay, Didem; Aydogdu, HalideSolid-State Fermentation (SSF) defined as a system in which the growth of microorganisms occurs on a moist solid substrate, shows tremendous potential in applications of microbial enzyme production as a low-cost, low-energy option. In this work, the production of lipase from Penicillium aurantiogriseum by using SSF was investigated. For this purpose, the sunflower pulp, an agro-industrial by-product, was utilized as a solid substrate in the SSF method. The optimization and characterization studies for lipase extract were performed by using the p-nitrophenyl palmitate (pNPP) (C16) as substrate. The lipase activity was found as 29.6 +/- 0.11 U/mg protein at optimum conditions (50 mM of Tris-HCl buffer, pH 7.0, 40 degrees C). In thermal stability assay, the catalytic activities of lipase which are kept at 40, 50 and, 60 degrees C in a water bath for 1 h, were calculated as 100%, 60.48 +/- 1.3%, 32.67 +/- 0.2%, respectively. Also, the enzyme lost rapidly its activity within 15 min at 70 degrees C. The kinetic data, K (m) and V (max) , were determined as 0.17 mM and 2.9 mu M/min, respectively. Also, 10 mM of Ba+2 ion had a slight activating effect (15%) showed on lipase. Lipase kept about 50% of its activity at 4 degrees C at the end of the 30 days. The hydrolytic activities of lipase for commercial olive oil and sunflower oil were found as 3.52 +/- 0.1 U/mg and 3.90 +/- 0.12 U/mg, respectively. The SSF method had obvious potential for the sustainable and cost-effective production of lipase from P. aurantiogriseum. Also, these results confirmed that the sunflower pulp could be used as an alternative substrate to produce enzymes in SSF conditions.Öğe Production of high quality biodiesel from sunflower soapstock acid oil as novel feedstock: Catalyzed by immobilized pancreatic lipase(Wiley, 2024) Paluzar, HaticeEdible refined oils, which are utilized as raw materials in biodiesel production, have been replaced by by-products (acid oil, fatty acid, deodorized distillate, and soapstock distillates) obtained from the vegetable oil refining industry, in recent years. This study aims to investigate the production of high quality biodiesel fuel in accordance with the standards (TS EN and ASTM) from sunflower soapstock acid oil. This feedstock was donated by an oil factory in the Thrace region, Turkey. Esterification reaction was performed by immobilized enzyme. For this, immobilization was carried out by covalent binding of pancreatic lipase in glutaraldehyde activated chitosan and optimum immobilization conditions were determined. The activity of the immobilized lipase and the retained activity were found to be 65.69 U/mu g and 61.8%, respectively (pH: 7.5, 37 degrees C). The Km (Michealis constant) and Vmax (maximum velocity of an enzymatically catalyzed reaction) values of the immobilized enzyme were found to be 5.1 mmol/L and 48.6 U/min/mg protein, respectively. The immobilized enzyme was employed as a biocatalyst for esterification of sunflower soapstock acid oil. Notably, an impressive yield of 75.6% was attained under the conditions of a 1:5 molar ratio of soapstock acid oil to methanol, with 10 wt% immobilized lipase as the catalyst, and a reaction temperature of 45 degrees C for 36 h. The resulting biodiesel exhibits fuel characteristics that meet the standards outlined in TS EN 14214:2012 + A2 and ASTM D6751-02. Experimental design for immobilization of lipase enzyme on chitosan, production of sunflower soapstock acid oil, production of biodiesel by immobilized lipase catalysis.imageÖğe Sunflower oil deodorizer distillate as novel feedstock for biodiesel production and its characterization as a fuel(Springer Heidelberg, 2023) Kulaksiz, Burcu Diger; Paluzar, HaticeAn economical way to reduce oil consumption and environmental problems in fuel production is the production of biodiesel from by-products and waste materials. By-products from the vegetable oil refining industry such as soap stock, acid oil, and fatty acid distillates are suitable for biodiesel production. In this study, biodiesel production was made using deodorizer distillate, which is the last step of the sunflower oil refining stage. Sunflower oil deodorizer distillate (SODD) obtained from oil facilities in Thrace region, and it was examined whether the fuel characteristics of the produced biodiesel comply with EN 14214 and ASTM D6751 standards. Biodiesel production from SODD was based on acidic catalysis method. H2SO4 was used as catalyst and methanol as alcohol. Catalyst amount, methanol to SODD ratio, reaction temperature and reaction time parameters were studied and optimum conditions were determined. As a result of the studies, the highest biodiesel yield was obtained in 1 wt% H2SO4, 12:1 methanol to SODD ratio, 65 degrees C reaction temperature, and 9-h reaction time. Biodiesel achieved 98.98% methyl ester concentration and 94.32% biodiesel yield. In addition, comparison of fuel properties of synthesized biodiesel with ASTM D6751 and EN 14214 showed well-matched values. Our study thus recommends SODD as a non-edible potential feedstock for biofuel production and industrial purposes.
