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Öğe Antioxidant efficacy of thymol and carvacrol in microencapsulated walnut oil triacylglycerols(Elsevier Sci Ltd, 2019) Gursul, Sevilay; Karabulut, Ihsan; Durmaz, GokhanAntioxidant efficiency of thymol and carvacrol in walnut oil triacylglycerols (WO-TAGs) was investigated. WO-TAGs alone or fortified with thymol/carvacrol were emulsified with sodium caseinate-lactose mixture. Oxidative stability of freeze dried emulsions was assessed via Rancimat and accelerated oven tests. Bulk WO-TAGs with and without thymol/carvacrol were also tested for comparison. Higher induction periods (IPs) were recorded for encapsulated and antioxidant fortified WO-TAGs compared to non-encapsulated and non-fortified counterparts. IP of thymol included and encapsulated WO-TAGs were found to be 1.5-2 fold higher than that of carvacrol at all concentrations (0.05-0.20%). IP of WO-TAGs was increased dose-dependent manner in the case of thymol and the highest protection was obtained with 0.20% thymol concentration (p < 0.05). Peroxide formation in bulk WO-TAGs fortified with carvacrol showed a slightly higher oxidative stability compared to thymol after 24 d of storage whereas thymol was a bit more effective in encapsulated WO-TAGs.Öğe Antioxidant properties of different extracts of black mulberry (Morus nigra L.)(Tubitak Scientific & Technological Research Council Turkey, 2011) Kutlu, Turkan; Durmaz, Gokhan; Ates, Burhan; Yilmaz, Ismet; Cetin, M. SevketIn vitro antioxidant properties of 3 different extracts of black mulberry (Morus nigra L.) were investigated. Acidified methanol, acidified water, and non-acidified methanol/water solutions were used to prepare extracts. Different solvents caused different protonation on black mulberry anthocyanin structures, which were predicted according to their UV-VIS spectrum. Extracts indicated 2 main peaks at about similar to 280 and similar to 520 nm with different peak areas in their UV-VIS spectrum. The rank of extracts' total phenolic content and reducing power values were both found to be in correlation with their absorbance at similar to 280 nm. Meanwhile the same relationship was observed between DPPH scavenging activity and absorbance values at similar to 520 nm. Acidified extract of black mulberry was higher in beta-carotene prevention and DPPH radical scavenging activity than non-acidified extract. However, non-acidified extract represented a higher reducing power and metal chelating activity, and a higher content of total phenolics.Öğe C18 Unsaturated Fatty Acid Selectivity of Lipases During the Acidolysis Reaction Between Tripalmitin and Oleic, Linoleic, and Linolenic Acids(Springer, 2010) Karabulut, Ihsan; Durmaz, Gokhan; Hayaloglu, Ali AdnanThe C18 unsaturated fatty acid (UFA) selectivity of three immobilized lipases, namely, Lipozyme TL IM from Thermomyces lanuginosa, Lipozyme RM IM from Rhizomucor miehei, and Novozym 435 from Candida antarctica, was determined in acidolysis conducted in hexane. Tripalmitin with a mixture of equimolar quantities of C18 UFAs was used as the substrate. Significantly different incorporation rates were observed for C18 UFAs used (p < 0.05). The highest incorporation was obtained for all three C18 UFAs with Novozym 435 followed by Lipozyme RM IM and Lipozyme TL IM catalyzed acidolysis under default conditions (substrate mole ratio 1:1; temperature 50 A degrees C; reaction time 6 h; enzyme dosage 10%). Incorporation of the equimolar quantities of C18 UFAs was in the order C18:3 > C18:2 > C18:1 which also reflects C18 UFAs preferences of the lipases. The effects of operating variables on incorporation or UFA selectivity of lipases were also investigated. Among the experimental parameters including the mole ratio of fatty acid to triolein, temperature, enzyme dosage, and time on incorporation, the effect of the substrate mole ratio on UFA selectivity was greater than those of the others.Öğe ?-carotene rejection mechanism from organic medium by using activated carbon produced from waste biomass apricot(Taylor & Francis Inc, 2017) Akmil-Basar, Canan; Durmaz, Gokhan; Karabulut, Ihsan; Onal, YunusThe present paper deals with the study of adsorption of beta-carotene in tetrahydrofuran solution on activated carbon. Activated carbon was prepared from apricot waste, which is a by-product of apricot processing by means of chemical activation with ZnCl2. BET surface area of activated carbon was measured to be 1060m(2) g(-1). The effect of adsorption time, percentage of activated carbon in beta-carotene solution, and beta-carotene concentration on adsorption efficiency was also determined. Results were analyzed by the Langmiur, Freundlich, Dubinin-Redushkevich (D-R), Temkin, Frumkin, Harkins-Jura, Halse, Henderson, and Henry isotherms with linearized correlation coefficient. The characteristic parameters for each isotherm have also been determined. The kinetics of beta-carotene adsorption has been discussed by the pseudo-first-order model, the pseudo-second-order model, the Elovich equation, the intraparticle diffusion model, the Bangham equation, and the modified Freundlich equation. Three error analysis methods of residual mean square error (RMSE), chi-square statistic ((2)), and the average percentage error (% APE) have been used.Öğe ?-Carotene Stability and Some Physicochemical Properties of Apricot Juice Powders Obtained by Using Maltodextrins with Different Dextrose Equivalents(Wiley-V C H Verlag Gmbh, 2020) Arslan, Tamer; Durmaz, GokhanIn this study, apricot juice powders (AJPs) are obtained via freeze-drying using different maltodextrins (MDs) as carrier agents. The Hacihaliloglu cultivar, which is the most common variety in Turkey, is used as an apricot sample. Three different MDs: low (4-7), medium (13-17), and high (17-20) dextrose equivalence (DE) are used as the carrier agent. The powders obtained are subjected to accelerated oxidation at 55 degrees C, and the stability of beta-carotene in the AJPs is determined. Some physicochemical properties, such as the glass transition temperature, microstructure, bulk density, color, moisture, solubility, degree of caking, and hygroscopicity, are also determined. The results show that after a 20 day period of oxidation, the remaining beta-carotene in the control sample is 24% of the initial value, whereas for low, medium, and high DE MD samples, it is measured to be 47%, 60%, and 57% of the initial concentration, respectively. There is no significant difference in the content of surface carotenoids between the control and the samples with added MD. In contrast, according to other quality attributes like hygroscopicity, caking, moisture content, and solubility, the best results are obtained from the low DE MD sample.Öğe Changes in oxidative stability, antioxidant capacity and phytochemical composition of Pistacia terebinthus oil with roasting(Elsevier Sci Ltd, 2011) Durmaz, Gokhan; Gokmen, VuralThe effect of roasting on oxidative stability, antioxidant capacity and the content of antioxidant phytochemicals in Pistacia terebinthus oil was investigated. Oils were extracted from P. terebinthus fruits roasted at 180 degrees C for 0-40 min. Roasting was found to cause an increase in the passage of phenolic compounds to the oil whereas the level of tocopherols, lutein and beta-carotene was decreased. Antioxidant capacity and oxidative stability of P. terebinthus oil increased with roasting. As an indicator of the presence of Maillard reaction products in oil, hydroxymethylfurfural (HMF) level and colour intensity was measured and found to increase with increasing roasting time. Fatty acid composition was not affected significantly by roasting. (C) 2011 Elsevier Ltd. All rights reserved.Öğe Characterisation of Pomegranate Juices from Ten Cultivars Grown in Turkey(Taylor & Francis Inc, 2009) Cam, Mustafa; Hisil, Yasar; Durmaz, GokhanPomegranate juices obtained from ten pomegranate cultivars of Turkey were analysed for their sugars, organic acids and the other quality parameters including pH, total soluble solids, and titratable acidity. Statistically significant differences were determined among the cultivars for parameters analysed. Citric acid was the predominant acid of all the cultivars studied. Cultivar Zivzik, one of the most popular cultivar in Turkey, showed best scores for total soluble solids (16.9 0.06 Brix), glucose (84.18 0.42 g/l) and fructose (83.34 0.81 g/l). Pomegranate juices were classified into three groups according to principal component analysis and cluster analysis.Öğe Combined effects of cultivar, extraction technology, and geographic origin on physicochemical traits of Moroccan olive oil as revealed by multivariate analysis(Academic Press Inc Elsevier Science, 2024) Sakar, El Hassan; Aalam, Zakarya; Khtira, Adil; Uluata, Sibel; Durmaz, Gokhan; Gharby, SaidThis study aimed at evaluating physicochemical traits of olive oil ('Haouzia' and 'Moroccan Picholine') according to extraction technologies (ETs: super-pressure SP, 2-phase 2 P, and 3-phase 3 P) across eight climatically contrasted Moroccan agroclimatic areas (AA). Our samples were classified as extra virgin olive oil (EVOO), whose traits varied (p < 0.05) among ETs, cultivars, and AA. EVOO from SP had high records of basic indices, most phytosterols, and trans fatty acids (TFA) due to partial oxidation during extraction, while continuous ETs (2 P and 3 P) displayed a better oil quality as demonstrated by routinely measured parameters. 'Haouzia' had the greatest saturated (SFA), monounsaturated (MUFA), polyunsaturated fatty acids (PUFA), and TFA. However, it had a lesser stability revealed by a low MUFA/PUFA and oleic/linoleic (O/L) as compared to 'Moroccan Picholine'. Arid climatic areas had the highest palmitoleic, oleic acid, MUFA, MUFA/PUFA, and O/L and therefore the best oil stability as compared to the remaining agroclimatic areas. These variations were confirmed by principal component analysis, cluster analysis, and artificial neural networks. Important simple and multiple regression models with strong correlations were highlighted among the studied variables. In conclusion, environmental conditions have a key role to be considered when assessing olive oil quality and authenticity.Öğe Comparing DPPP fluorescence and UV based methods to assess oxidation degree of krill oil-in-water emulsions(Elsevier Sci Ltd, 2021) Uluata, Sibel; Durmaz, Gokhan; McClements, D. Julian; Decker, Eric A.In this study, lipid oxidation evaluation methods were compared for a krill-oil-in-water emulsion system. With this aim, thiocyanate and DPPP (diphenyl-1-pyrenylphosphine) fluorescence methods were comparatively examined to determine primary oxidation products. 2-thiobarbituric acid reactive substances (TBARS), hexanal and propanal formation were also monitored as secondary oxidations products. All oxidation experiments were performed via both auto-oxidation at 45 degrees C and light-riboflavin induced photooxidation at 37 degrees C. The results have shown that thiocyanate method was not suitable to measure lipid hydroperoxides by the both in auto- and photo-oxidation systems. On the other hand, fluorescence intensity of samples containing the DPPP probe increased during incubation period which indicates the formation of lipid hydroperoxides could be detected via this method. TBARS, hexanal and propanal concentrations also increased during storage period and the formation kinetics of secondary oxidation products was confirmed that the DPPP fluorescence method was accurate and reliable at different environmental conditions.Öğe Comparing physical stability of ultrasound and Pickering emulsion fortified with vitamin D(Wiley, 2022) Uluata, Sibel; Avci, Seymanur; Durmaz, Gokhan[Abstract Not Available]Öğe Determination of Lipid Hydroperoxides in Oil-in-water Emulsions Using by a Novel Technique.(Wiley, 2021) Uluata, Sibel; Durmaz, Gokhan; McClements, David; Decker, Eric[Abstract Not Available]Öğe The Effect of Apricot Added Sports Drink on Cardiac Mitochondrial Dysfunction in High Intensity Exercising Rats(Wiley, 2023) Ozer, Muhammed Yusuf; Duzova, Halil; Gul, Mehmet; Arslan, Ozge; Elmas, Furkan; Koc, Ahmet; Durmaz, Gokhan[Abstract Not Available]Öğe Effect of refining on bioactive composition and oxidative stability of hazelnut oil(Elsevier Science Bv, 2019) Durmaz, Gokhan; Gokmen, VuralIn this study, the effect of refining process on the content of phytochemicals, antioxidant capacity and oxidative stability of hazelnut oil was investigated. The oil samples were taken at the consecutive steps of hazelnut refining process and analyzed for some compositional properties along with the antioxidant capacity and oxidative stability. The results have shown that, carotenoid content of the hazelnut oil was decreased during the refining process. The main carotenoids of hazelnut oil were found to be lutein and zeaxanthin and these compounds were lost completely during bleaching step of the refining. On the other hand, phenolic compounds and tocopherols were also partly removed from hazelnut oil to a degree. Loses in antioxidant compounds caused a clear decrease in antioxidant capacity measured in either the oils or polar extract of oils. Oxidative stability of the oil samples was measured by Rancimat method and it was found that neutralization caused an increase in oxidative stability compared to the crude oil. However, deodorization step caused a slight decrease in oxidative stability probably as a result of partial removal of tocopherols at this stage.Öğe Effects of sodium selenite on some biochemical and hematological parameters of rainbow trout (Oncorhynchus mykiss Walbaum, 1792) exposed to Pb2+ and Cu2+(Springer, 2008) Ates, Burhan; Orun, Ibrahim; Talas, Zeliha Selamoglu; Durmaz, Gokhan; Yilmaz, IsmetThis study was carried out to understand the preventive effect of selenium (Se4+) on heavy metal stress induced by lead and copper in rainbow trout (Oncorhynchus mykiss). Variation in glutathione peroxidase (Se-GSH-Px) and superoxide dismutase (SOD) activity, and in malondialdehyde (MDA) levels in liver, spleen, heart, and brain tissues of rainbow trout after 72 h of exposure to Pb2+ and Cu2+ were investigated in the presence and absence of Se4+. In the presence of Se4+, Se-GSH-Px activity and SOD activity were found to be higher and MDA levels were lower compared with in its absence. Hematological parameters were also determined and it has been observed that total leukocyte count (WBC), mean cell volume (MCV), and mean cell hemoglobin (MCH) were increased and erythrocyte number (RBC), hemoglobin (Hb), and hematocrit value (Hct; P < 0.05) were decreased in fish exposed to heavy metals in the absence of selenium. Selenium presence recovered hematological parameters to normal levels. In the light of our findings, it could be stated that Pb2+ and Cu2+ lead to dramatic changes in biochemical and hematological parameters and selenium caused these parameters to converge to control levels when it was administered concurrently with these heavy metals.Öğe Fatty Acid Selectivity of Lipases during Acidolysis Reaction between Oleic Acid and Monoacid Triacylglycerols(Amer Chemical Soc, 2009) Karabulut, Ihsan; Durmaz, Gokhan; Hayaloglu, Ali AdnanWith the aim of determining the fatty acid (FA) selectivity of lipases, a mixture of oleic acid and monoacid triacylglycerols (TAGs) including tricaproin (T6), tricaprylin (T8), tricaprin (T10), trilaurin (T12), trimyristin (T14), tripalmitin (T16) and tristearin (T18) was used as the substrate in acidolysis performed in hexane. Three immobilized lipases, namely, Lipozyme TL IM from Thermomyces lanoginosus, Lipozyme RM IM from Rhizomucor miehei and Novozym 435 from Candida antarctica, were used as biocatalyst. The effects of operating variables including the mole ratio of oleic acid to monoacid TAG, temperature, enzyme dosage and reaction time on incorporation were also investigated. Significantly different incorporation rates were obtained for different TAGs used (P < 0.05). Incorporation of oleic acid into TAGs except tricaproin and tricaprylin was higher for all the TAGS with Lipozyme TL IM catalyzed reactions than those of other two enzymes tested. Incorporation of oleic acid decreased as the acyl chain length of FA in the TAG increased with Novozyme 435 catalyzed acidolysis. Compared to the other substrate mixtures, the highest incorporation was observed for oleic acid and tricaproin mixture with three lipases tested. It was shown that the FA selectivity of the lipases is strongly dependent on the acyl chain length of FA in a TAG.Öğe Freeze-dried ABTS•+ method: A ready-to-use radical powder to assess antioxidant capacity of vegetable oils(Elsevier Sci Ltd, 2012) Durmaz, GokhanA new approach to 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulphonate) (ABTS(center dot+)) assay was conducted. ABTS(center dot+) radical solution in water was obtained by using classical method of incubating ABTS with potassium peroxodisulphate. The resulting radical solution was freeze-dried and tested for its radical efficiency by comparing freshly prepared ABTS(center dot+) (FP-ABTS) via using standard antioxidants. A high correlation was observed between the results obtained from FP-ABTS and freeze-dried ABTS (FD-ABTS) assays. When it was stored in the freezer. FD-ABTS powder was found to keep its initial activity to a great extend over one month. For the measurement of antiradical capacity of oil samples. FD-ABTS was dissolved in methanol and diluted to desired concentrations with a chloroform-methanol mixture. Linearity and accuracy of the method was confirmed by measuring the antiradical capacity of stripped sunflower oil spiked with different concentrations of standard antioxidants. Antiradical capacity of 22 oil samples including some commonly consumed vegetable oils was also tested by the FD-ABTS method. (C) 2012 Elsevier Ltd. All rights reserved.Öğe Hazelnut skin powder: A new brown colored functional ingredient(Elsevier Science Bv, 2014) Ozdemir, Kubra S.; Yilmaz, Cemile; Durmaz, Gokhan; Gokmen, VuralHazelnut skin arises as a by-product in the roasting process of hazelnuts. This study aimed to investigate the potential of its utilization as a brown colored functional ingredient. Chemical composition analyses revealed that hazelnut skin is a very rich source of dietary fibers (67.7%) and phenolic compounds (233 mg GAE/g). Its oil fraction (14.5%) was found to contain very high amounts of tocopherols (2.77 mu g/g) and oleic acid (75.2%). After defatting, coarse and fine hazelnut skin powders were obtained by low and high shear homogenization. High shear homogenization was performed at different pressures (10, 20 and 30 ksi) for different pass cycles (1, 3, 5 and 10). The powder samples were analyzed for particle size distribution, color, individual phenolic compounds, total phenolic content, and total antioxidant capacity. A desirable low micron particle size for the hazelnut skin for incorporation into food formulations was achieved by means of high shear homogenization, meanwhile there was no significant change in phenolic composition and antioxidant capacity. (C) 2014 Elsevier Ltd. All rights reserved.Öğe Mulberry Seed Oil: a Rich Source of ?-Tocopherol(Springer, 2015) Yilmaz, Mehmet Ali; Durmaz, GokhanIn the present study, mulberry seed oil (MSO) samples obtained from seeds of different mulberry varieties as well as concentrated mulberry juice production waste (mulberry pomace) were investigated. Radical scavenging capacity, tocopherol and total phenolic content of MSO were determined. It was observed that MSO contain unique amounts of delta-tocopherol varying between 1645-2587 mg kg(-1) oil depending on the variety. The secondary tocopherol homologue was gamma-tocopherol within a concentration range of 299-854 mg kg(-1) oil. MSO exhibited a very high antioxidant capacity varying in the range of 1013-1743 and 2574-4522 mg alpha-tocopherol equivalents (alpha-TE) per kg of oil for 2,2-diphenyl-1-picrylhydrazyl (DPPH) and freeze-dried 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (FD-ABTS) radical cation assays, respectively. Both antioxidant capacity and total phenolic content were higher for mulberry pomace oil compared with the seed oils. Fatty acid composition of MSO was also determined, and linoleic acid was found to be the primary fatty acid (66-80 %).Öğe Pressurized liquid extraction of phenolic compounds from Anatolia propolis and their radical scavenging capacities(Pergamon-Elsevier Science Ltd, 2011) Erdogan, Selim; Ates, Burhan; Durmaz, Gokhan; Yilmaz, Ismet; Seckin, TurgayPropolis samples from important honey producing locations of Anatolia namely; Bingol (BG), Rize (RZ), Tekirdag (TK) and Van (VN), were evaluated for their antiradical capacities, total phenolic contents and individual phenolic compounds which was recovered by means of pressurized liquid extraction (PLE). Several extraction parameters of PLE such as; temperature, pressure, solvent type, extraction time and cell size were investigated for their effects on the extraction performances. The results showed that, 40 C. 1500 psi, Ethanol:water:HCl; (70:25:5, v/v/v) containing 0.1% tert-butylhydroquinone (tBHQ) as solvent, three extraction cycles within 15 min, and a cell size of 11 mL was the most favorable PLE operating conditions. Results of the tests performed to designate the success of the polyphenol analysis showed that the recovery was in the range of 97.2% and 99.7%. Major phenolic compounds in all samples were found to be gallocatechin (GCT), catechin (CT). epicatechin gallate (ECTG), caffeic acid (CA), chlorogenic acid (ChA), and myricetin (Myr). ChA level of BG propolis was 4.5, 3 and 23 times higher than that of RZ, TK and VN region, respectively. Antiradical tests showed that all propolis samples have superior antiradical capacities up to 500 mg Trolox equivalent activity per gram of extract. (C) 2011 Elsevier Ltd. All rights reserved.Öğe Proximate analysis and fatty acid, mineral and soluble carbohydrate profiles of some brown macroalgae collected from Turkiye coasts(Walter De Gruyter Gmbh, 2023) Yucetepe, Aysun; Aydar, Elif Feyza; Okudan, Emine Sukran; Ozcelik, Beraat; Durmaz, GokhanIn this study, the fatty acid, carbohydrate, and mineral profiles and proximate composition of Halopteris scoparia, Padina pavonica, Zanardinia typus, Cladostephus spongiosum, Sargassum vulgare, and Sargassum acinarium brown macroalgae collected from Turkiye seas were determined. According to the results, the ash and total carbohydrate contents of all macroalgae ranged from 20.79 to 53.49% in dry weight (dw) and from 15.32 to 55.13% dw, respectively. Their protein, lipid and crude fiber contents changed between 4.22 and 9.89% dw, 0.25 and 0.90% dw, and 12.28 and 16.01% dw, respectively. Palmitic acid (29.36-48.55% dw) and oleic acid (8.92-20.92% dw) were at the highest levels in all brown macroalgae. In addition, they included prominent levels of saturated fatty acids (51.87-69.56% dw of total fatty acid content). Magnesium (6.97-18.78 mg/kg dw), potassium (1.34-3.78 mg/kg dw), iron (1.27-8.24 mg/kg dw), and manganese (63.10-252.23 mu g/kg dw) were found to be the major minerals. The main soluble carbohydrates of macroalgae were found to be mannitol (1149.99-8676.31 mg/kg dw), glucose (368.78-1305.59 mg/kg dw), myo-inositol (225.96-956.78 mg/kg dw), fructose (137.05-689.21 mg/kg dw), and sucrose (189.55-328.06 mg/kg dw). This study revealed that brown macroalgae are particularly rich in potassium, magnesium, iron, manganese, and zinc and they may have potential for use in the food industry.
