Browsing by Author "Baştürk, A."

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The Effects of Different Storage Temperatures on the Oxidative Stability of Breakfast and Kitchen Margarines
(Centenary University, 2018) Bozkurt, F.; Baştürk, A.
In this study, different brands of breakfast (K1, K2, K3, K4 and K5) and kitchen margarines (M1, M2, M3, M4 and M5) were stored at 4 and 25°C for 12 weeks. During the storage period, samples were taken every 2 weeks and the oxidative stability of the margarines was evaluated by detecting changes in tocopherol contents, peroxide values (PV), thiobarbituric acid (TBA) values, conjugated diene (K232) and fatty acid compositions. In the margarine samples used in the study, it was determined that the initial values were compatible with the label values, but changed depending on the storage temperature and duration. In breakfast margarine samples kept at 4 °C and 25°C, K3 (11.08 meqO2 kg-1) and K4 (70.97 meqO2 kg-1) showed the highest PVs, respectively. In kitchen margarines stored at 4 °C and 25°C, M2 (9.22 meqO2 kg-1) and M1 (27.63 meqO2 kg-1) showed the highest PVs, respectively. The PVs of margarines kept at 4°C remained within legal limits (except K3). The breakfast margarines generally exceeded the legal limit after the 2nd week, and in the kitchen margarines after the 4th week in samples stored at 25°C. K232 and TBA values increased with storage temperature. The breakfast margarine samples showed higher K232 and TBA values than those of kitchen margarines. Margarines had different tocopherol contents which showed decreasing trend depending on increasing temprature and time. As the storage temperature and duration increased, the total saturated fatty acids contents of margarines increased and their total unsaturated fatty acids content decreased. Kitchen margarines showed higher oxidative stability than breakfast margarines due to their higher saturated fatty acids contents. For margarines, storage at 4°C is appropriate, while storage at 25°C led to deterioration after the first week. © 2018, Centenary University. All rights reserved.
Evaluation of the Effects of Different Factors on Oxidation of Soybean Oil by Response Surface Methodology
(Centenary University, 2017) Baştürk, A.; Cavıdoğlu, İ.
In this study, the effects of temperature (30, 50 ve 70 °C), time (0, 10 ve 20 days), concentration of copper and iron ions (0, 0.15 ve 0.3 mg kg-1 oil) and ascorbyl palmitate (AP) (0, 200 ve 400 mg kg-1 oil) on peroxide value (PV), malonaldehyde (MAD) and hexanal (HEX) content of soybean oil under accelerated oxidation conditions have been evaluated by response surface method (RSM). Besides of its rich linoleic acid (C18: 2) content (55.81%), soybean oil had 8.69% linolenic acid (C18: 3). The total tocopherol content of soybean oil was 538.5 mg kg-1 oil. Data obtained showed that temperature and time significantly increased (P<0.05) PV, MAD and HEX content of the samples. AP significantly decreased the formation of peroxides (P<0.05). Samples with copper showed higher PV and HEX values compared to those with iron. In general, the presence of copper and iron did not significantly (P>0.05) affect the oxidation. It’s concluded that temperature and time were the most important parameters affecting soybean oil oxidation (P<0.05). In addition to the reduced number of experimental runs, RSM provided an overall evaluation of the effects of different factors on oxidation parameters. © 2017, Centenary University. All rights reserved.