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Öğe A Chemometric Approach to Assess the Frying Stability of Cottonseed Oil Blends During Deep-Frying Process: I. Polar and Polymeric Compound Analyses(WILEY, 2013) Arslan, Fatma Nur; Kara, Huseyin; Ayyildiz, Hamide Filiz; Topkafa, Mustafa; Tarhan, Ismail; Kenar, AdnanThe main goal of the present study was (i) to determine the formation of degradation products in cottonseed oil (CSO) blends during deep frying process by adsorption and high performance size exclusion chromatography techniques and (ii) to evaluate the impacts of food additives on total polar (TPC) and polymeric compound (PTAG) formation using a chemometric approach. In order to prepare the frying CSO blends; ascorbic palmitate, mixed tocopherols, dimethylpolysiloxane, lecithin and sesame oils were used as additives. To determine the real impacts of additives, a quarter-fraction factorial experimental design with two levels and five factors was used. The changes in TPC and PTAG data were carefully evaluated during 10 h of frying at 170 +/- A 5 A degrees C with normal distribution (ND) graphs and analyzed using a one-way analysis of variance (ANOVA), followed by Tukey's Post-hoc test (alpha = 0.05). The results indicated that the increasing values for TPC and PTAG during the frying processes for all blends, TPC and PTAG contents reached maximum levels of 16.37 and 6.01 % respectively, which are below the limit values stated by official authorities for the quality assessment of frying oils. The ANOVA test results were in good agreement with ND graphs and data indicated that the impact of mixed tocopherols was significant for TPC formation, meanwhile the impact of lecithin and ascorbic palmitate x dimethylpolysiloxane were significant for PTAG formation. Thus, the present study should be considered to be a very useful guide for developing new frying oil formulations based on CSO by using food additives.Öğe Evaluation of Fatty Acid Composition, Tocols Profile, and Oxidative Stability of Some Fully Refined Edible Oils(TAYLOR & FRANCIS INC, 2015) Ayyildiz, Hamide Filiz; Topkafa, Mustafa; Kara, Huseyin; Sherazi, Syed Tufail HussainPresent study includes evaluation of fatty acid composition, tocols profile, and oxidative stability of some fully refined edible oils. Fully refined sunflower, soybean, corn, hazelnut, peanut, and canola oils were analyzed for fatty acids by capillary gas liquid chromatography, tocols by normal phase-high performance liquid chromatography and oxidative stability by rancimat. Free fatty acid, peroxide value, and iodine value of investigated oils were determined by titrimetric methods. Saturated, mono-, and polyunsaturated fatty acids were found to be in the ranges between 2.03-18.58, 23.39-77.26, and 14.39-58.52%, respectively. Tocols and oxidative stability of the investigated oils were found to be in the ranges between 488.88-913.51 mg kg(-1) and 3.05-4.99 h, respectively.Öğe Evaluation of new silica-based humic acid stationary phase for the separation of tocopherols in cold-pressed oils by normal-phase high-performance liquid chromatography(WILEY-V C H VERLAG GMBH, 2015) Ayyildiz, Hamide FilizA new humic acid stationary phase was prepared by immobilizing humic acid onto aminopropyl silica via an amide linkage formation and used, for the first time, for the separation and quantification of the tocopherol compounds in cold-pressed oil samples under normalphase high-performance liquid chromatography conditions. Parameters affecting the chromatographic separation such as mobile phase composition and flow rate were optimized. By evaluating the calculations of capacity factor, asymmetry factor, resolution, selectivity factor, and theoretical plate number, the best separation was obtained with isocratic elution of n-hexane and isopropyl alcohol (99:1% v/v) at a flow rate of 1.0 mL/min. The effluent was monitored by a fluorescence detector set at excitation and emission wavelengths 295 and 330 nm, respectively. All compounds were separated in 20 min. The method was validated according to international guidelines and found to be linear in a wide concentration range, also the mean recovery of the compounds ranged from 97.9 to 99.2%, with a CV less than 2.7% in all cases. The results showed that the developed stationary phase is suitable for the separation and quantification of the tocopherol compounds in real oil samples.Öğe An implementation of central composite design: Effect of microwave and conventional heating techniques on the triglyceride composition and trans isomer formation in corn oil(TAYLOR & FRANCIS INC, 2017) Topkafa, Mustafa; Ayyildiz, Hamide FilizTriglyceride composition and trans fatty acid content of corn oil subjected to microwave and conventional heating were evaluated with the aid of central composite design methodology. Oil samples with and without alpha-tocopherol were prepared on the basis of central composite design and, the effects of the main three factors (temperature, contact time, and the amount of alpha-tocopherol) were tired to investigate 10 at different five levels. Linoleic acid-linoleic acid-linoleic acid content in triglyceride structure of corn oil and the amount of trans fatty acids in the same oils were taken as response values for evaluation of central composite design assays. Based on the response surface, the optimum conditions (at which trans fatty acid formation and the change in the triglyceride composition are minimum) were determined for both heating procedures. The results showed that the increasing of the temperature and contact time increased the trans fatty acid formation and changed triglyceride structure of the oil in both heating techniques, although, the addition of alpha-tocopherol at high concentration caused pro-oxidant effect on triglyceride composition (bad effect), while reducing the formation of trans fatty acid (good effect). The results revealed that the heating 20 treatments caused significant changes in the triglyceride composition and trans fatty acid isomers of unsaturated fatty acids of the oil, while the saturated fatty acid contents did not change substantially. These alterations were much greater in microwave-heated samples (trans fatty acid <= 7.26%) than in Q3 corresponding samples heated in a conventional stove (trans fatty acid <= 0.56%).Öğe New potential humic acid stationary phase toward drug components: Development of a chemometric-assisted RP-HPLC method for the determination of paracetamol and caffeine in tablet formulations(WILEY-V C H VERLAG GMBH, 2016) Topkafa, Mustafa; Ayyildiz, Hamide Filiz; Memon, Fakhar N.; Kara, HuseyinA new humic acid based stationary phase has been used, for the first time, to achieve the separation and quantification of paracetamol and caffeine in pharmaceutical preparations under reversed-phase high-performance liquid chromatography conditions. Central composite design was applied as a powerful tool to optimize the most dominant parameters that influence the resolution of reversed-phase high-performance liquid chromatography, that is, mobile phase composition (acetonitrile percentage in water), flow rate, and column temperature. The optimum conditions were obtained as 21.69%, 1.5 mL/min, and 15 degrees C, respectively, with the aid of a second-order quadratic model and desirability function. Under the optimum conditions, the peaks could be baseline separated within 10 min. For the developed reversed-phase high-performance liquid chromatography method, the linearity was investigated in the concentration ranges of 2-160 mg/mL (R-2 = 0.999) for paracetamol and 2-9.9 mg/mL (R-2 = 0.991) for caffeine. Mean recoveries for paracetamol and caffeine were 95.90 and 95.68%, respectively. The limits of detection and quantification were 4.1 x 10(-4) and 1.3 x 10(-3) mg/mL for paracetamol and 1.6 x 10(-4) and 5.0 x 10(-4) mg/mL for caffeine. The results showed that the new humic acid based stationary phase is very suitable for the separation of paracetamol and caffeine in pharmaceutical preparations and, thus it can be used effectively in the pharmaceutical industry.
