The higher is the oil viscosity, the slower is the oil drainage. 11. [4] The main reactions involved in this process are starch gelatinization, protein denaturation, aromatizing, and coloring via Maillard reactions, rapid cooking, and texture and flavor development. Similar trends to previous studies [18,20,22] were observed in the current study using a different assembly. of vegetable oils (crambe, rapeseed, corn, soybean, milk- of each vegetable oil, and for the purity and the manufac- weed, coconut, lesquerella) and eight fatty acids in the turers of the fatty acids used in the experimental pro- range from Cg to CZZ The viscosity measurements were cedures. [35] The , and were calculated as the sum of the corresponding property for each fatty acid present in the oil weighted with its correspondent molar fraction; was calculated using Eq. The surface tension data was also modeled using the predicted density values obtained from the Rackett equation and fitting them in the Eötvös equation. According to the data, the Eötvös equation has a higher accuracy of prediction of surface tension between 60–100°C, as the error was less than five percent in this temperature range for all five oils. In the current study, viscosity was found to have a power law relation of the second degree with temperature (Eq. Overall, the Eötvös equation overestimates the surface tension value at lower temperatures (23 and 40°C) and underestimates the surface tension at higher temperatures (140–200°C). [22], Miller et al. Viscosity as a function of temperature was modeled using the modified Andrade equation (Eq. Statistical analysis showed significant effect (p < 0.05) of temperature and oil type on the surface tension values. e absolute viscosity of uids is an important property needed in uid ow and heat transfer unit operations. Absolute Viscosities of Vegetable Oils at Different Temperatures and Shear Rate Range of 64.5 to 4835 s −1. Eötvös constant () is the measure of entropy of the surface and its value was calculated using the method of least squares. [5–7] Frying also causes changes in the flavor and stability of oils by hydrolysis, oxidation, and polymerization. [22] measured viscosities of vegetable oils from room temperature up to maximum of 130°C using a glass capillary viscometer. Same Eötvös constant values could be used to fit the data for all oils studied with one equipment. Figure 6. Deep fat frying is one of the oldest and the most commonly used techniques to process foods, which involves submerging a food in hot oil (150–200°C) for a short period of time until it reaches a safe minimum internal temperature. 3) developed by Spencer and Danner [31] which estimates the molar volume of a saturated pure liquid (): Eq.\ 3, where is in , is the critical temperature (), is the critical pressure (), is the ideal gas constant (), is the Rackett parameter which is unique to each compound, and is the reduced temperature (). Figure 2. The viscosity values are similar to those obtained by Noureddini et al. Density and surface tension decreased linearly with increasing temperature, whereas the viscosity decreased exponentially. (6); however, when it was higher, Eq. For the purpose of this study, was assumed negligible, was determined to be 8.58 cm3, and equal to 0.01 cm3. Table 1. Molecular weight, critical temperature, and critical pressure of five vegetable oils. [ 20 ] , and Noureddini et al. The objectives of this study are to determine and mathematically model surface tension, density and viscosity of commonly used food oils at high temperatures. Table 6. Decane was purchased from TCI America (Portland OR, USA). Surface tension values of five vegetable oils from room temperature to each oil’s smoke point determined using a KRÜSS goniometer. The density () was calculated using the following equation: Eq.\ 1, where is the buoyancy, is the volume of the reference object, is the surface tension effect between the liquid and the wire, and is the volume of immersed wire. Absolute viscosities of the different vegetable oils at different temperatures (experimental and published). The torque of each sample at different temperatures was recorded at different shear rates. Measurements were performed from 23 ± 1°C to the oils’ smoke point at intervals of every 20°C. Stainless steel wire (diameter: 0.76 mm) was bought from Hobart Welders (Northern Tool; Raleigh NC, USA). Measurements were performed in triplicate and data was analyzed using Minitab 17 (Minitab Inc., State College PA, USA). Correlation of Fatty Acid Composition of Vegetable Oils with Rheological Behaviour and Oil Uptake, Mechanism and Reduction of Fat Uptake in Deep-Fat Fried Foods, Influence of Oil Temperature on Convective Heat Transfer during Immersion Frying, Factors Affecting Oil Uptake in Tortilla Chips in Deep-Fat Frying, Modelling Oil Absorption during Post-Frying Cooling: II: Solution of the Mathematical Model, Model Testing and Simulations, Temperature-Dependent Viscosity Correlations of Vegetable Oils and Biofuel–Diesel Mixtures, Densities of Vegetable Oils and Fatty Acids, Temperature Dependence of Density and Viscosity of Vegetable Oils, Viscosities of Vegetable Oils and Fatty Acids, Effect of Repeated Frying on the Viscosity, Density and Dynamic Interfacial Tension of Palm and Olive Oil, A Different Perspective to Study the Effect of Freeze, Air, and Osmotic Drying on Oil Absorption during Potato Frying, Interfacial Tension Measurement of Oil-Water-Steam Systems Using Image Processing Techniques, Viscosity and Heat Transfer Coefficients for Canola,Corn, Palm, and Soybean Oil, Quality Control in the Use of Deep Frying Oils, Emissions of Volatile Aldehydes from Heated Cooking Oils, Improved Equation for Prediction of Saturated Liquid Density, Density Estimation for Fatty Acids and Vegetable Oils Based on Their Fatty Acid Composition, Thermodynamic Interpretation of the Eötvös Constant, Effects of Temperature, Time and Composition on Food Oil Surface Tension, Saturated Liquid Molar Volumes. Viscosity of soybean, canola, corn, peanut and olive oil was measured using a viscometer from room temperature to 200°C (Table 6). [32] presented a variation of Eq. Crude oil viscosity as function of gravity - Viscosity at 20°C/68°F and 50°C/122°F for more than 120 crudes is shown as function of specific gravity@15°C/60°F Drag Coefficient - The drag coefficient of … Comparison between density experimental values of A) Canola oil, and B) Soybean oil and their corresponding predicted values by the modified Racket equation. 5). The oil type influenced the density and viscosity of oil, but did not affect surface tension. Eq.\ 10. where is the oil kinematic viscosity (), is the temperature (), , and are correlation constants which are calculated using the method of least squares.