Effect of Reheating on Thermophysical Properties of Edible Oil at High Temperature (original) (raw)
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Effect of heating time on the physicochemical properties of selected vegetable oils
Arabian Journal of Chemistry, 2021
The determination of oil physicochemical properties is a useful strategy to monitor oil quality to avoid the use of potentially toxic oil. It is relevant in determining the physical and chemical changes that oil undergo during heating. In this work, the effect of prolong heating time from 1-7 h on the physicochemical properties of soybean oil, palmolein oil, groundnut oil and palm kernel oil was examined. Properties such as specific gravity, viscosity, saponification value (SV), iodine value (IV), free fatty acid and peroxide value (PV) were studied to evaluate the compositional quality of oils. Results revealed that heating at the different times did not have any significant effect on the physicochemical properties of the oils. There was however, significant differences of the physicochemical properties on the oil types. Results further reveal that based on the peroxide value, soybean oil was the most stable oil out of the four oils studied while palm kernel oil was found to be the least stable oil; as the stability of palm olein oil was found greater than that of groundnut oil.
Determination of Some Physical Properties of Selected Edible Oils in Nigeria
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Edible oils are commonplace in table food, snacks and industrial food products. This inclined the study in this research work which is aimed at investigating the physical properties of the oils and their varying effect on their electrical conductivity, to determine their edible viability and shelf –life. The effect of increased temperature on the viscosity of the oil was studied. Also the electrical conductivity versus power supply through the oil and also the cooling property of the oil were studied using calorimetry experiment. The results show a typical trend of variation in the electrical conductivity and viscosity (dependent variables) and temperature and power supply (independent variables). The electrical conductivity of the oils was found to be increasing with temperature and the viscosity was decreasing with temperature. This is in agreement with earlier postulation. I therefore recommend that it is better to keep edible oils at temperature below 40C so as to maintain accep...
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Thermal stability and kinetic parameters of commercial edible oils were investigated by non-isothermal thermogravimetry/derivative thermogravimetry (TG/DTG). Kinetic parameters were calculated by integral and approximation methods. Results obtained indicated that these parameters were dependent on composition of fatty acids, being influenced by the presence of natural and artificial antioxidants. According to the thermogravimetric curves, the following thermal stability sequence was suggested: corn > sunflower > soybean > rice > soybean + olive > sunflower + olive > canola > olive; while the activation energy indicated the following stability order: sunflower > corn > soybean > rice > soybean + olive > canola > sunflower + olive > olive.
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Structural characterization of edible oils after thermal treatment was made by (FTIR) spectroscopy. Olive, corn and sunflower oil samples were thermally treated at three consecutive cycles. Each cycle consisted of heating at the boiling point for 8 h, followed by cooling at room temperature for 16 h. At the end of each cycle the characteristics of oils were studied by FTIR spectroscopy and standard methods. Study of FTIR spectra of the treated oils revealed that the heating of oils caused significant changes in the intensities of their bands and produced shifts in the position of specific bands such as 3008 cm−1 and 1745 cm−1. The level of oil oxidation during different heating period was followed by the absorbance ratio at 3530/3472 cm−1. Additionally, the absorbance ratio 2853/3008 cm−1 was used as a measure of degree of unsaturation. The thermal heating of oils produced an initial decrease in the specific absorbance ratios which could be attributed to the reduction of unsaturated...
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The purpose of this study is to examine the heating effect on some food oils, we have selected two of the commonly used in cooking and frying in Sudan, namely; the Corn and the Cottonseed. For this purpose we studied the change occurred in some of the physical properties. These are: the refractive index, viscosity, density and the specific heat capacity According to the results obtained a slight change was noticed in the refractive index and the density of the oils, while there was a remarkable increase in the coefficient of viscosity. The measurements were repeatedly recorded before and after boiling the oils in a period of five days for. The results revealed that boiling of the oils change their physical properties.
Thermal Diffusivity Measurements in Edible Oils using Transient Thermal Lens
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Time resolved thermal lens (TL) spectrometry is applied to the study of the thermal diffusivity of edible oils such as olive, and refined and thermally treated avocado oils. A two laser mismatched-mode experimental configuration was used, with a He Ne laser as a probe beam and an Ar+ laser as the excitation one. The characteristic time constant of the transient thermal lens was obtained by fitting the experimental data to the theoretical expression for a transient thermal lens. The results showed that virgin olive oil has a higher thermal diffusivity than for refined and thermally treated avocado oils. This measured thermal property may contribute to a better understanding of the quality of edible oils, which is very important in the food industry. The thermal diffusivity results for virgin olive oil, obtained from this technique, agree with those reported in the literature.
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Introduction: In recent years the research and development of biolubricants from vegetable oils has increased to minimize the impact on the environment of petroleum derivatives. Objective: In this work, there was realized a comparative study of the thermal properties of the oil of Sesame with those of two mineral oils, of medium and high viscosity (360 and 255), which were free of additives. Method: The characterization of the three oils was performed using the technique of infrared spectroscopy (FT-IR) and physical properties such as kinematic viscosity, density, thermal and oxidative properties were determined by the analysis of Differential Calorimetry Scanning (DSC). Results: The sesame oil had a pour point of – 14.67 ° C, lower temperature than for mineral oils of 255 and 360, (– 4.29 ° C and – 6.89 ° C, respectively). The high content of unsaturated fatty acids (84.86%) could be responsible for this behavior. The oils were stable to temperatures near to 250 °C and with nitroge...
A Study of Heating Effect on the Structural and Optical Absorbance of Olive Oil
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In this study, the number of times of heating of olive oil was studied. For the different refineries, the study was conducted using a temperature of 300K and for several times to determine the validity of the olive oil which is used for frying purposes after it was used for more than once times. It was found that there were significant changes in the behavior of the photophysical behavior like absorption and emission; there are changes in the nature and composition of the olive oil molecule, which makes it not useful for human use. The number of heating times was ten. The heating times also showed significant changes in the nature of the oil, such as color, taste, density, and smell.