Study of the behavior of some vegetable oils during the thermal treatment (original) (raw)

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.

Comparison of Physical Characteristics between Vegetable and Mineral Oils

2011

This paper presents physical characteristics of vegetable oils which are commercial products. The vegetable oils under consideration in this work are comprised of sunflower oil and rice bran oil. The characteristics of the vegetable oils are found by testing and they are compared with that of the mineral oil according to IEC and ASTM standard. The results show that physical characteristics of the two vegetable oil types, it is found that the vegetable oils under test have satisfactory characteristics comparable with the mineral oil. Therefore, it has high possibility that those vegetable oils can be used for electrical insulation of electrical machines.

Effect of Reheating on Thermophysical Properties of Edible Oil at High Temperature

2016

This paper is focused on the evaluation of thermophysical properties of unheated oil and multiple times heated oils to study the thermal degradation of edible oil which is reheated for very long time and hence assess the quality of reheated oil being used in different first food shops and restaurants. The purpose of this study is to evaluate the changes in different thermophysical properties such as total energy, refractive index and conductivity of reheated edible oils that take place during the reheating of oils, in order to find an easy and cost effective technique for quality testing of edible oils. Study reveals that the refractive index and conductivity of reheated edible oil have increased and the total energy of edible oil has decreased due to reheating at high temperature for long time. Study also indicates that the presence of food contents during the heating of edible oil, affect the thermophysical parameters in some extent.

Physico-chemical characterization for different types of food oils

2017

Lipids are indispensable food components, which in large measure determine the energy value as well the nutritional, biological and sensory qualities. The aim of this paper was to evaluate some of the physicochemical characteristics (total soluble solids (TSS), relative density, viscosity and acidity index) in case of three alimentary oils. The analyzed oil assortments, in these works are soybean, rape and corn oil purchased from the commercial market having different origins. Oils density varies from species to species and at the same oil with the conservation conditions (conservation period, climatic conditions in which the plant has developed). Viscosity gives relevant indication of the degree of oil fluidity. The experimental results showed that the highest value for viscosity was registered in rapeseed oil (38,7088cP) and the smallest in soybean oil (34,0174cP). Rape oil from improved varieties is very good cooking oil for human consumption while soybean oil has a neutral taste...

Comparative study of the thermal properties of Sesame oil and two mineral oils of different viscosity

INGE CUC

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...

COMPARATIVE STUDIES ON PHYSICAL PROPERTIES OF VEGETABLE OILS AND THEIR BLENDS AFTER FRYING

Physical properties of six commonly used oils and three blends consisting of three oils in each blend were studied after three successivefrying of 'poories ' @zed snackpom flattened dough of refined wheat flour). The changes in viscosity, CIE trans-reflectance color and related parameters, UV-Visible spectra and UVspectra of oil samples in solvent system (ch1oroform:methanol; 2:1, v/v) were studied. l%e results showed that viscosity and color of the oils changed to a much higher extent after first firing than subsequent fiyings. The hue angle followed a similar trend. Changes in the UY-spectra in the solvent system indicated an increase in the formation of conjugated compounds after successive fryings. Peroxide values (Pv) also increased after fving. Principal Component Analysis (PCA) plots of the data indicated that among oils examined groundnut oil and soy oil in Combination with other oils were preferred forfrying. Use of small amounts of unrefined oils Cfiltered) such as mustard oil or sesame oil which have a high content of natural antioxidants was beneficial as formation of conjugated compounds and increase in peroxide value was minimized affer successive frying using blended oils.

Comparison of some physicochemical properties of edible vegetable oils available in Al-Najaf, Iraq

International journal of health sciences

This study was conducted at the laboratories of chemistry Department / College of Science/ Al-Nahrain University, Iraq. The primary determinants of edible oils' acceptance, preferred uses, and market value are their purity and stability. Therefore, the goal of this study to measure some of a set physical and chemical properties for four (canola oil, sunflower oil, corn oil and olive pomace oil) before using .The main physico-chemical properties determined for oils were Refractive index(RI), Viscosity (μ), Iodine value (IV) , P-Anisidine value (P-AV) and Peroxide value (PV). The values Refractive index were 1.4721, 1.4735, 1.4730 and 1.4685 respectively .While, viscosity (μ) were 78.44, 60.52, 63.79 and 79.91 cps respectively. IV was 112.75, 109.13, 102.61 and 96.43 (g I2/100g) for the four oils respectively .P-AV were 0.60, 2.59, 0.71 and 2.63 for four oils respectively. PV was 1.98, 2.19, 5.05 and 6.03 (Meq.O2/Kg) respectively. These results showed that the oil samples hav...

Selected Physical Properties Assessment of Sunflower and Olive Oils

Acta Technologica Agriculturae

Presented paper is focused on comparison of certain physical properties of selected vegetable oils. Physical properties, such as density, dynamic, kinematic viscosity and fluidity, were experimentally determined. All experiments were conducted on two samples of vegetable oils: sunflower and extra virgin olive oils with approximate temperature range of 5–32 °C. Density of oils was determined by oscillation method utilizing digital densimeter Anton Paar DMA 4500M at different temperatures. Dynamic viscosity was measured by means of rotational viscometer Anton Paar DV-3P. The rest of rheological parameters were determined on the basis of their definitions. Obtained results are depicted as graphical dependencies of rheological parameters and density on temperature. These dependencies of vegetable oils on dynamic and kinematic viscosity showed decreasing exponential shape, which is in compliance with Arrhenius equation; temperature dependencies on fluidity showed an increasing exponentia...

Thermal and Optical investigation of Corn and Cottonseed as Frying Oils

2015

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 Degradation of Vegetable Oils

Foods

Vegetable oils provide lipids and nutrition and provide foods with a desirable flavor, color, and crispy texture when used to prepare fried foods. However, the oil quality is degraded at elevated temperatures, and thus must be examined frequently because of the damage to human health. In this study, sunflower, soybean, olive, and canola oils were examined, and their properties were measured periodically at different elevated temperatures. The unsaturated triglyceride in oils reacted with the environmental oxygen or water vapor significantly changes in optical absorbance, viscosity, electrical impedance, and acid value. We used defect kinetics to analyze the evolution of these oil properties at elevated temperatures. The optical absorbance, viscosity, and electrical impedance follow the second-order, first-order, and zeroth-order kinetics, respectively. The rate constants of the above kinetics satisfy the Arrhenius equation. Olive oil has the lowest rate of color center and dynamic v...