Browsing by Author "Tokuşoǧlu Ö."
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Item HPLC-UV and GC-MS characterization of the flavonol aglycons quercetin, kaempferol, and myricetin in tomato pastes and other tomato-based products(University of Silesia, 2003) Tokuşoǧlu Ö.; Ünal M.K.; Yildirim Z.The amounts of three flavonoids, quercetin, kaempferol, and myricetin, in tomatoes (Solanum lycopersicum L.) and tomato-based products produced in Turkey has been determined by reversed phase high-performance liquid chromatography (RPHPLC) with UV detection. The HPLC profiles of five types of tomato, one commercial composite tomato juice, and three types of tomato paste, were obtained after acid hydrolysis and extraction. The presence of the flavonol aglycons was confirmed by gas chromatography with mass spectrometric detection (GC-MS). Tomatoes and tomato-based products contained primarily quercetin, kaempferol, and the minor flavonol myricetin. The total flavonol aglycon content of different varieties of tomato varied from 3.1 to 10.0 mg kg -1 of fresh weight. Tomato juice and tomato salsa were rich in total flavonols, containing 19.8 mg L-1 and 10.5-13.2 mg kg-1, respectively. The method enabled accurate and reproducible quantitative analysis of these flavonols in tomatoes and tomato-based products.Item Simultaneous Differential Pulse Polarographic Determination of Cadmium, Lead, and Copper in Milk and Dairy Products(2004) Tokuşoǧlu Ö.; Aycan Ş.; Akalin S.; Koçak S.; Ersoy N.The contents of potentially toxic elements lead and cadmium and the essential element copper in various milk and dairy products consumed in Turkey were determined by differential pulse polarography (DPP), primarily to assess whether the intakes comply with recommended desired concentrations for essential and permissible levels for toxic elements. A simple and rapid DPP method has been developed for the simultaneous determination of cadmium, lead, and copper in samples. Using the differential pulse mode, half-wave peak potentials as E1/2 were -0.58, -0.40, and -0.07 V for cadmium (Cd), lead (Pb), and copper (Cu), respectively. Marketed formulations of dairy products have been analyzed by calibration and standard addition methods. Recovery experiments were found to be quantitative. The linear domain ranges were 0.00-674.28 μg/L for Cd (R2 = 0.9999), 0.19-2.94 mg/L (p < 0.01) for Pb (R2 = 0.9997), and 0.41-133.46 μg/L for Cu (p < 0.01) (R2 = 0.9999). The studies have shown that the method is a rapid, reproducible, and accurate determination of these elements in milk and dairy products and can be used in the analysis of marketed formulations in the milk and dairy industry.Item The effect of oregano and rosemary essential oils or alpha-tocopheryl acetate on performance and lipid oxidation of meat enriched with n-3 PUFA'S in broilers(South African Bureau for Scientific Publications, 2004) Basmacioǧlu H.; Tokuşoǧlu Ö.; Ergül M.The study was conducted to compare the effects of two essential oils, fed individually or in combination, with alpha-tocopheryl acetate (alpha-TA) on performance parameters and lipid oxidation of broiler meat enriched with n-3 PUFAs. Seven hundred and twenty day-old Hubbard-JV unsexed broiler chicks were used. Treatments included; control: without antioxidant; alpha-TA200: with alpha-TA at 200 mg/kg; OO150: with oregano essential oil (OO) at 150 mg/kg; OO300: with OO at 300 mg/kg; RO150: with rosemary essential oil (RO) at 150 mg/kg; RO300: with RO at 300 mg/kg; OO75+RO75: both OO and RO at 75 mg/kg; OO150+RO150: both OO and RO at 150 mg/kg. The feeding program consisted of a starter diet to 21 d and a grower diet to the end of the trial at 42 d. Both feeds contained 15 g fish oil/kg as the source of n-3 PUFAs. Birds fed alpha-TA200 had significantly higher weight gains at 42 d than those fed OO150, OO75+RO75 and OO150+RO150. However, there were no differences in carcass yield, feed intake, feed conversion ratio or mortality between treatments. Neither essential oil exerted any growth-promoting effect on performance, and there was no interaction between them. Antioxidants retarded lipid oxidation as measured in TBARS, but the effect of each differed according to storage time (0, 3, 6, 9, 12 and 15 d) and meat type (breast or thigh). Alpha-TA200, RO300 and combined essential oils (EO) had higher antioxidant effects in breast meat, and OO150+RO150 in thigh meat, than the other treatments with antioxidant at zero time of storage. The ability of natural antioxidants to inhibit lipid oxidation to the end of the storage period was, in decreasing order, combinations of EOs > alpha-TA200 = OO300 = RO150 = RO300 > OO150 in breast meat; and combinations of EOs > RO at both levels > alpha-TA200 = OO150 = OO300 in thigh meat. Combinations of EOs had a greater effect than those fed individually or alpha-TA200 on inhibiting lipid oxidation, and protecting alpha-TA concentration in refrigerated meat enriched with n-PUFAs stored for 15 d. Thigh meat was more susceptible to lipid oxidation than breast meat. The combination of OO and RO, at 150 mg/kg, proved as effective as alpha-TA in retaining the sensory qualities of breast meat after 15 d storage, and was more effective than when these EOs were fed individually or at 300 mg/kg. There is a possible synergistic effect between oregano and rosemary essential oil in preventing lipid oxidation in stored meat enriched with n-3 PUFAs.Item A rapid high performance liquid chromatographic detection of furosine (ε-N-2-furoylmethyl-L-lysine) in pasteurized and UHT milks(2004) Tokuşoǧlu Ö.; Akalin A.S.; Unal M.K.Furosine, generated from the acid hydrolysis of the amadori compound during the early Maillard reaction, is a suitable indicator of the effect of heating treatments on milk quality. Furosine content in pasteurized and UHT milks marketed in Turkey was detected using ion-pair reversed-phase liquid chromatography (RP-HPLC). Calibration study (R2 = 0.9999), analytical method validation and recovery studies (y = 5.315 x + 0.043 (R2 = 0.9998)) gave satisfactory results A wide range of furosine content was found in UHT milks (49.68 ± 0.10 to 213.38 ± 0.07 mg 100 g-1 protein) depending on the heat-treatment intensity. Pasteurized milks had lower content of furosine (3.79 ± 0.01 and 5.88 ± 0.02 mg 100 g -1 protein). The method provides rapid, reproducible and accurate determination of this amadori compound in milk and dairy products and can be utilized as one of the most commonly used quality marker in dairy industry.Item Liquid chromatographic detection of α-, γ-, δ-tocopherols in infant formulas(2004) Akalin A.S.; Tokuşoǧlu Ö.Simultaneous determination of α-tocopherol, γ-tocopherol and δ-tocopherol by reversed-phase liquid chromatography (RP-HPLC) with UV detection in various infant milk formulas sold in Turkey was performed. Analytical method parameters confirmed the quality of the method. Tocopherol isomers in 15 infant formulas ranged from 8.73±0.09 to 27.02±0.06 mg α-tocopherol in 100 g-1, from 1.67±0.04 to 7.28±0.10 mg γ-tocopherol in 100 g-1; from 0.87±0.05 to 1.81±0.03 mg δ-tocopherol in 100 g -1.Item Determination of the phytoalexin resveratrol (3,5,4′-Trihydroxystilbene) in peanuts and pistachios by High-Performance Liquid Chromatographic Diode Array (HPLC-DAD) and Gas Chromatography-Mass Spectrometry (GC-MS)(2005) Tokuşoǧlu Ö.; Ünal M.K.; Yemiş F.The phytoalexin resveratrol (3,5,4′-trihydroxystilbene) in edible peanut (Arachis hypogaea L.) and pistachio (Pistacia vera L.) varieties grown in Turkey was analyzed by high-performance liquid chromatographic diode array and gas chromatography-mass spectrometric detection. trans-Resveratrol in six peanut varieties, five pistachio varieties, and four market samples ranged between 0.03 and 1.92 μg/g. The Çerezlik 5025 peanut (1.92 ± 0.01 μg/g) and Ohadi pistachio genotype (1.67 ± 0.01 μg/g) had significantly higher trans-resveratrol contents. Peanuts contained 0.03-1.92 μg/g (av = 0.84 μg/g) of trans-resveratrol, whereas pistachio contained 0.09-1.67 μg/g (av = 1.15 μg/g). With exposure to UV light for 1 min, trans-resveratrol concentrations of samples ranged from 0.02 to 1.47 μg/g and those of cis-resveratrol from 0.008 to 0.32 μg/g. The occurrence of resveratrol in peanut and pistachio was confirmed by total ion chromatograms (TIC) of bis[trimethylsilyl]-trifluoroacetamide derivatives of resveratrol isomers and comparison of the mass spectral fragmentation data with those of a resveratrol standard. Formation of the cis-isomer in pistachios was higher than in peanuts. © 2005 American Chemical Society.Item Effects of grilling on luteolin (3′,4′,5,7-tetrahydroxyflavone) content in sweet green bell pepper (Capsicum annuum)(Asian Network for Scientific Information, 2007) Durucasu I.; Tokuşoǧlu Ö.The content of luteloin in green bell pepper (Capsicum annuum) produced in Turkey were determined by RP-HPLC with DAD detection. The luteloin (3′,4′,5,7-Tetrahydroxyflavone) content of green pepper samples were 46.00±0.76 mg kg-1 f.w. (average). The alterations of luteloin concentrations with heating process (grilling, közleme) and the loss of luteloin amount were also determined. Luteolin contents of grilled peppers were found as 29.96±0.96 mg kg-1 f.w. The method was objective and reproducible for accurate detection of luteloin in green pepper and other pepper varieties. © 2007 Asian Network for Scientific Information.Item Fatty acid and conjugated linoleic acid profiles of infant formulas through direct transesterification of acyl lipids(Codon Publications, 2007) Tokuşoǧlu Ö.; Durucasu I.; Akalin A.S.; Serin E.; Akşit S.Fatty acid (FA) values, including C8:0, C10:0, C12:0, C13:0, C14:0, C16:0, C18:0, C18:l t, C18:l c, C18:2, C18:2 CLA, C20:0, C18:3 and C22:0, in sixteen infant formulas were determined through direct transesterification of acyl lipids with sodium methoxide by capillary gas chromatography. Total FA values ranged from 250.25-256.06 mg/g sample and the conjugated linoleic acid (CLA) (cis-9, trans-11 octadecadienoic acid) values were 1.41-2.02 mg/g sample (p<0.01) in the infant formulas. The total saturated fatty acid, monounsaturated fatty acid and polyunsaturated fatty acid values were also obtained. The C18:3 (linolenic acid (n-3)) values were 0.63-0.88 mg/g sample, whereas the C18:2 (linoleic acid (n-6)) values ranged from 35.64-35.82 mg/g sample. FA standard mix including CLA had linear calibration curves through the origin (R2 = 0.9999). The precision of the analytical method was (using C13:0, methyl tridecanoate, as internal standard) within the 95% confidence limits and the mean recoveries determined for individual fatty acids in infant formulas varied from 99.8 to 100%.Item Catechins and methylxanthines in twenty-three black tea infusions by HPLC: Correlations with astringency(Codon Publications, 2008) Tokuşoǧlu Ö.; Ünal M.K.; Balaban M.Ö.Simultaneous detection of flavanols [catechin (C), epicatechin (EC), epigallocatechin (EGC), epicatechingallat (ECG), epigallocatechingallate (EGCG)], gallic acid (GA), theogalline, methylxanthines (caffeine, theobromine, theophylline) were performed on 23 black tea infusions. A hypersil-ODS column (4.6 mm I.D. × 250 mm) with methanol: distilled water: formic acid (19.5:80.2:0.3, v:v:v) as a mobile phase was used for optimizing the RP-HPLC separation (R2=0.9997). Total flavanols varied from 1.423 to 12.051 mg 100 mg-1 whereas EGCG was the major catechin in all of the infusions (0.356-5.972 mg 100 mg -1) (p<0.01). Caffeine levels were high (4.002-8.657 mg 100 mg -1) followed by theobromine and theophylline (p<0.01). Black tea contained 0.134-1.392 mg/100 mg of GA, and 0.156-1.241 mg 100 mg-1 of its ester theogalline. An 8-member trained sensory panel judged black tea infusions for astringency. The correlations between the total catechins and astringency (y= 1.675+6.631 In X) (R 2=0.9551) were extremely high at the 95 percent confidence level (X=total catechin, y=astringency) and total interactions on astringency were obtained.Item Conjugated linoleic acid (CLA). Cis 9, trans 11 and trans 10, cis12 isomer detection in crude and refined corn oils by capillary GC(2008) Tokuşoǧlu Ö.Conjugated linoleic acids (CLAs) exhibit protective effects against various types of cancer and heart diseases. With the newly developed capillary gas chromatographic method (GC), c/s9, trans11 and trans10, cis12 octadecadienoic acid isomers of CLA (C18:2) were determined in crude and refined corn oils as qualitative and quantitative measurements . Cis 9, trans11 C18:2 (c9, t11 CLA) was the major CLA isomer in both oils. It was found that c9, f11 CLA was 0.62% of the total lipid in crude oil and 1.24% of the total lipid in refined oil. Using the refining process, the total CLA was 1.38% whereas that of crude corn oil was 0.62%. An approximate 2.2 fold increase in the total CLA was found in refined oil (n = 9) (p < 0.01). The alteration in CLA could be used as a quality indicator for the refining process due to the contrubution of CLA to polyunsaturated fatty acids. Analytical method validation, calibration (R 2 = 0.9999) and recovery data [y = 2.782x + 0.046 (R2= 0.9999)] were performed (p < 0.01).The proposed Chromatographic procedure could be used for vegetable oil quality control.Item Retinol and α-tocopherol concentrations in breast milk of Turkish lactating mothers under different socio-economic status(2008) Tokuşoǧlu Ö.; Tansuǧ N.; Akşit S.; Dinç G.; Kasirga E.; Özcan C.Retinol and α-tocopherol levels in breast milk of Turkish mothers under different socio-economic status were investigated. Mature milk samples were collected from 92 lactating mothers living in Izmir and in Manisa, cities of Turkey, who were at 60-90 days of the lactating period. Socio-economic, anthropometric, and dietary data were collected by means of a questionnaire. The body mass index was used to determine the nutritional status. The retinol and α-tocopherol contents of breast milk were determined by high-performance liquid chromatography; the concentration of α-tocopherol was 9.84 μg/ml whereas retinol levels were 81.5 μg/100 ml. The questionnaire survey was used to determine the level of these vitamins in the daily ration of the women. No significant differences were found in terms of milk retinol and α-tocopherol levels for the variables income, educational level and mothers' body mass index.Item High hydrostatic pressure effects on mold flora, citrinin mycotoxin, hydroxytyrosol, oleuropein phenolics and antioxidant activity of black table olives(2010) Tokuşoǧlu Ö.; Alpas H.; Bozoǧlu F.High hydrostatic pressure (HHP) as a non-thermal technology is an effective tool for microbiologically safe and shelf-stable fruits. Mycotoxin citrinin (CIT) is a toxic secondary metabolite, especially produced from filamentous fungus Penicillium citrinum and is also produced by other species of Penicillium, Aspergillus, and Monascus that are able to develop on olive after harvest, during brine and storage of olives. Nutritional benefits of olive fruit are mainly related to phenolics such as hydroxytyrosol, oleuropein and antioxidative effects. With HHP application of olives, total mold was reduced to 90% at 25 °C whereas it was 100% at 4 °C based on Rose-Bengal Chloramphenicol Agar (RBCA). Total Aerobic-Mesofilic Bacteria load was reduced to 35-76% at 35 ± 2 °C based on the Plate Count Agar (PCA). Citrinin load was reduced to 64-100% at 35 ± 2 °C. 2.5; 10; 25; and 100 ppb of spiked citrinin in sample were degraded as %56; %37; %9; and %1.3, respectively. 2.5 ppb and less citrinin contamination in table olive were degraded more (56%). Total phenolics were increased to 2.1-2.5-fold after HHP (as mgGA/100 g). Hydroxytyrosol in olives increased on average 0.8-2.0-fold whereas oleuropein decreased on average 1-1.2-fold after HHP (as mg/kg dwt). Antioxidant activity values varied from 17.238 to 29.344 mmol Fe2+/100 g for control samples whereas 18.579-32.998 mmol Fe2+/100 g for HHP-treated samples. HHP could be used in the olive industry as non-thermal preservation. © 2009 Elsevier Ltd. All rights reserved.Item The proximate composition and quality characteristics in artichoke (Cynara scolymus L.) varieties developed with clonal selection(WFL Publisher Ltd., 2013) Başay S.; Tokuşoǧlu Ö.The standard varieties of artichoke (Cynara scolymus L.) from populations of the Bayrampaşa and Saki{dotless}zi{dotless} varieties were developed by using a vegetative clonal selection method. This research project was conducted at two different locations and the resulting second lineage for Bayrampaşa and the second lineage for Saki{dotless}z were found to be the best standard varieties based on the evaluation of the quality parameters. In bract leaves and fruit heads of new developed artichoke varieties, analytical quality characteristics including moisture (%), ash (%), total sugar, invert sugar, sucrose, total fat level and total protein content were analysed to determine the proximate composition. Besides, the well-developed varieties were commercially registered as Saki{dotless}z, Bayrampaşa, Şebnem and Şimşek names by the Atatürk Horticulture Research Institute, Ministry of Agriculture and Rural Affairs.