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Öğe Changes in oxidative stability of selected bakery products during shelf life(Japanese Soc Food Sci & Technology, 2004) Daglioglu, O; Tasan, M; Gecgel, U; Daglioglu, FIn this research, selected bakery products that contain high amount of fat (> 10%) were stored under ambient conditions until the end of shelf life. Changes in oxidative stability and fatty acid composition of the samples including biscuits, crackers, wafer and fruit cake were determined with three months of interval. Free fatty acidity, peroxide value, and Rancimat induction times changed significantly (p < 0.05) in all samples. However, acidity and peroxide values remained under the maximum limits allowed by standarts. Total fat contents ranged from 13.3% (petit beurre) to 27.1% (wafer), and the major fatty acids in the samples were palmitic, stearic, oleic, trans oleic, and linoleic acids. Changes in unsaturated fatty acids which majorly affects the lipid oxidation were insignificant (p > 0.05), and according to the obtained results all samples maintained their oxidative stability throughout shelf life.Öğe Determination of FA composition and total trans FA of Turkish margarines by capillary GLC(Amer Oil Chemists Soc A O C S Press, 2002) Arici, M; Tasan, M; Gecgel, U; Ozsoy, SIn this research, FA composition and total trans FA contents of 16 different brands of margarine (8 hard-type and 8 soft-type) sold in Turkey were determined by capillary GLC method. According to the results, the contents of saturated FA, monounsaturated FA, and PUFA were within the ranges of 23.9-32.3, 44.0-61.9, and 14.2-24.1%, respectively, in hard-type margarines, and 27.0-39.9, 21.0-40.9, and 32.0-53.79%, respectively, in soft-type margarines. Hard-type margarines contained total trans FA concentrations of 20.1-34.3%, whereas softtype margarines contained less than 8.9% total trans FA. C-18:1 trans acid content was within the range of 18.5-29.8% in hard type margarines, and it was significantly higher than the range in soft margarines (0.7-8.1%). C-18:1 trans acid was the in all. or trans FA in all margarines, and C-18:3 trans acid concentrations were less than 0.2%.Öğe Determination of fatty acid composition and total trans fatty acids in cereal-based Turkish foods(Scientific Technical Research Council Turkey, 2002) Daglioglu, O; Tasan, M; Tunçel, BThe fatty acid composition and trans fatty acids of 13 cereal-based foods produced by Turkish companies were analysed by capillary gas-liquid chromatography. The total fat contents of the samples ranged from 1.8 to 37.9%. Traditional Turkish white bread and bulgur had the lowest fat content (1.8% and 2.3% respectively) and wafer the highest (37.9%). The major fatty acids in the samples were C-16:0, C-18:0, trans C-18:1, C-18:1 and C-18:2. Total unsaturated fatty acid contents varied between 49.0 and 80.3% of total fatty acids, and bulgur had the highest percentage among the samples. Except for bulgur, all the samples contained trans fatty acids (weight percentage of methyl esters) ranging from 0.1 to 31.0% of the total. Bulgur did not contain detectable levels of trans fatty acids while white bread and corn chips contained trace amounts: 0.1% and 0.7% respectively.Öğe Determination of fatty acid composition and total trans fatty acids of Turkish biscuits by capillary gas-liquid chromatography(Springer Verlag, 2000) Daglioglu, O; Tasan, M; Tuncel, BIn this research, fatty acid composition and total trans fatty acid contents of six types of biscuit produced by four different Turkish companies were determined by capillary gas-liquid chromatography. Total fat contents of the biscuit samples ranged between 8.5% and 26.0%. The highest fat content was determined in sesame biscuits (average 24.4%) and the lowest in petit beurre biscuits (average 13.5%). Total fat contents varied even for the same type of biscuit as a result of the use of different recipes by each company. The major fatty acids in the samples were C-16:0, C-18:0, trans C-18:1, C-18:1, trans C-18:2 and C-18:2. Depending on the biscuit type, total unsaturated fatty acid contents were between 52.1% and 72.8%. The ranges of total trans fatty acid contents in biscuit types were petit beurre 1.9-29.0%, sesame 15.0-23.1%, baby 3.0-30.5%, oat 17.6-22.4%, cocoa 1.5-22.9% and finger 1.0-24.7%. It is clear from the results that the percentage of trans fatty acids in the total fat content is significant because of the use of hydrogenated vegetable oils in biscuit production.Öğe Effects of microwave and conventional baking on the oxidative stability and fatty acid composition of puff pastry(Amer Oil Chemists Soc A O C S Press, 2000) Daglioglu, O; Tasan, M; Tuncel, BThe effects of microwave and conventional baking on the fatty acid and trans fatty acid compositions of puff pastries, which contain high amounts of hydrogenated fat, were investigated. In addition, free fatty acids, peroxide value, and induction time for oxidative stability by the Rancimat method have been compared for microwave- and conventionally baked puff pastries. The data indicate there were considerable changes in acidity, peroxide value, and Rancimat induction time in both microwave- and conventionally baked samples. Although the content of saturated fatty acid such as palmitic and stearic and the ratio of saturated to unsaturated fatty acids did not change significantly, an apparent increase was determined in trans oleic acid levels by both baking methods. In addition, a significant decrease in linoleic acid content of the samples was found by microwave baking.Öğe Fatty acid composition of traditional fermented and unfermented Turkish corn bread with the emphasis on trans fatty acids(Springer-Verlag, 2003) Daglioglu, O; Tasan, MDietary fat continues to be a major research priority because of its association with heart disease, cancer and other chronic diseases. On the other hand emerging data suggest that trans fatty acids may raise blood levels of low density lipoprotein cholesterol to much the same extent as saturated fatty acids. In this research cis and trans fatty acid composition of unfermented and fermented corn bread as well as flour used in the recipe, and dough samples were determined. Unfermented bread samples were made of corn flour, and fermented breads were made of corn flour-wheat flour mix (1/1) by the traditional straight dough method. Samples, including flour, dough and bread, were analysed by capillary gas-liquid chromatography for their fatty acid compositions. According to the results obtained, unfermented and fermented bread dough have the same fatty acid composition as the flour used in the recipe. Dough fermentation did not effect the fatty acid composition of corn bread. However, fatty acid composition changed slightly in the baked bread. The levels of palmitic, stearic and oleic acid increased, and those of linoleic, linolenic, arachidic and eicosenoic acids decreased, compared to flour and dough. Trans linolenic acid was also detected in both unfermented and fermented corn bread at a level of 0.1%. Slight changes in the fatty acid composition and formation of trans linolenic acid were a result of baking temperature.Öğe Total and individual tocopherol contents of sunflower oil at different steps of refining(Springer, 2005) Tasan, M; Demirci, MThe contents of total and individual tocopherols of sunflower oils at different stages of industrial chemical and physical refining processes were determined by high-performance liquid chromatography (HPLC). According to the results, total and individual tocopherol contents gradually decreased until the end of the refining processes. The average losses of total tocopherol content during the chemical and physical refining processes were found to be 30.2% and 35.5%, respectively. The steam distillation stage of the physical refining process caused greatest overall reduction (average 24.6%) in total tocopherol content. In contrast to the physical refining process, the degumming-neutralizing stage in the chemical refining process caused greatest overall reduction (average 14.7%) in total tocopherol content. An additional average loss of 11.0% occurred during deodorizing in the chemical refining process. In both chemical and physical refining, the bleaching stage caused similar effects. The physical refining process caused higher loss in the total and individual tocopherol contents when compared with the chemical refining process. The conditions of the refining processes should be carefully evaluated to reduce the loss of tocopherols.Öğe Trans FA in sunflower oil at different steps of refining(Wiley, 2003) Tasan, M; Demirci, MThe contents of total trans FA of sunflower oils at different stages of refining processes were determined by capillary GLC. The contents of 18:1, 18:2, and 18:3 trans acids were 0.22 +/- 0.03, 2.31 +/- 0.23, and 0.03 +/- 0.01%, respectively, in physically refined sunflower oils, and 0.05 +/- 0.01, 0.69 +/- 0.26, and 0.02 +/- 0.01%, respectively, in chemically refined sunflower oils. The total trans FA contents drastically increased at the end of the physical refining process. The total trans FA contents of chemically refined sunflower oils were <1%. Because of the high temperature applied in the last stage of physical refining, the content of total trans FA was higher than in chemically refined sunflower oils. The last-stage conditions should be carefully evaluated to reduce the formation of trans FA during physical refining.
