J. Nig. Soc. Phys. Sci. 3 (2021) 469–476 Journal of the Nigerian Society of Physical Sciences Effects of Repeated Frying on Physical Properties of Cooking Oil obtained from Wurukum Market in Makurdi Metropolis, Benue State, Nigeria. T. Daniela,1,∗, F. Eriba-Idokoa, J. O. Tsora, S. T. Kungur1, E. O. Enokelaa, F. Gbaoruna, E. C. Hembac, A. A. McAsule1, N. S. Akiiga1, P. O. Ushie1 aDepartment of Physics, Benue State University, Makurdi bDepartment of Physics, College of Education, Katsina-Ala, Benue State cDepartment of Physics, Federal College of Education, Pankshin, Plateau State dDepartment of Physics, Federal University of Agriculture, Makurdi, Benue State eDepartment of Physics, Faculty of Physical Sciences, Cross River University of Technology, Calabar Abstract The viscosity, density and specific gravity of different brands of cooking oil samples locally sourced for in Makurdi have been measured with respect to change in temperature. The viscosity of the different brands of cooking oil was measured with the instrumentality of Brookfield Viscometer. The density and specific gravity were evaluated using the mass of the sampled oil obtained with the help of the density bottle. The result showed a pattern of rapid decrease in viscosity with increase in temperature for the oil samples, while density decrease is observed to be almost linear with increase in temperature for all samples. Amongst the sampled cooking oils, palm kernel showed the least viscosity of 8.6 Pascal-second when measured at 45.200C. This illustrates that palm kernel oil has a relatively low viscous nature at 45.200C as compared to other samples used in this work. DOI:10.46481/jnsps.2021.298 Keywords: Cooking Oil, Frying, Brookfield Viscometer, Viscosity and Temperature Article History : Received: 30 June 2021 Received in revised form: 04 September 2021 Accepted for publication: 14 September 2021 Published: 29 November 2021 c©2021 Journal of the Nigerian Society of Physical Sciences. All rights reserved. Communicated by: Edward Anand Emile 1. Introduction Cooking oils are vital ingredients for preparing most of ev- eryday food in many parts of the world and in particular, they are known to be rich sources of beneficial dietary nutrients that contribute to human health [1-2]. Palm trees, Olive plants, ∗Corresponding author tel. no: +234(0)8167598988 Email address: terver.daniel@yahoo.co.uk, tdaniel@bsum.edu.ng (P. O. Ushie) cocoa-nut trees, groundnut and soybean plants are few exam- ples of plants whose seeds and fruits can be processed in order to extract various kinds of cooking oils that are mostly con- sumed on daily basis in this part of the world. These plants are widely cultivated in different parts of the country of which Be- nue State being the Food Basket of the Nation [3-4] produces these on a high commercial scale [3]. The production of cook- ing oils can be done by pressing or crushing the plant seeds or fruits before extracting the oil. These processes are either lo- cal or modernized depending on the equipment used and their 469 Daniel et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 469–476 470 availability. Some are further refined by application of heat to remove unwanted component(s), while others are marketed without further refining. Out of the total production of cook- ing oils, 75 % is used for direct cooking of day-to-day meals both for frying and non-fried meals. The remaining 25 % is be- ing used in industries as local sources for production of other industrial commodities such as biscuits, detergents etc. [5-6]. Food frying involves immersing the food to be fried (such as sliced pieces of yam, plantain, potatoes, fish, beans cake etc.) completely in a bath of hot oil under the supply of heat (though not necessarily with a defined quantity of heat) for a particular period of time until the immersed food turns yellowish in na- ture. The hot cooking oil usually processes the food during the frying process by dehydrating the food moisture content lead- ing to both chemical and physical changes in the food thereby reducing its mass and making it porous and crispy. Frying usu- ally affects the characteristics taste, texture and the color of the food [7]. Food frying can be used for food preservation and food processing. The quantity of heat supplied affects both the chemical and the physical properties of the cooking oil. For in- stance, extreme supply of temperature to cooking oil is a factor that lead to increase in acid value in oils [8]. High acid value in- dicates high free fatty acid, which in turn, causes oil to become rancid [9] and ingestion of acids especially trans- fatty acids appears to increase blood cholesterol, in particular low-density lipoproteins to high-density [6]. High levels of low lipoproteins in the blood have been linked to arteriosclerosis, a disease of the heart that can cause stroke, heart attack [10-11] and other serious health problems as a re- sult of cholesterol deposits that form plaques on the inner sur- faces of the arteries obstructing blood flow [8]. This causes a disease called arteriosclerosis. Due to increasing awareness on the health implications of bad cholesterols in diet, most people now prefer to purchase vegetable oils with low density lipopro- teins [12]. It has been demonstrated that free fatty acids, change of color, smoke point, iodine values, total polar materials, in- terfacial tension, density, cloud point, pour point, flash point, boiling range, freezing point, refractive index, foaming prop- erties and viscosity are indicators used to determine the qual- ity of cooking oils [13-16]. This is to say that: frying of food may bring out the aroma, enhance the flavor and texture com- bination which is very desirable for consumption, making fried foods one of the most popular food products [17]. Conversely, when cooking oils are stored for a long time, excessive recy- cling or exposed to excessive heat, oil degradation occurs [18- 19], and by-products are produced [20]. Elevated temperatures, especially temperature above the smoking point of the oil, will cause significant change in its quality due to the chemical and physical reactions [21]. Some by-products of oil degradation have adverse effects on human health [7, 20, 22]. Previous studies have revealed the effect and health risks as- sociated with eating fried food [7-8, 23-25]. Also, other several researchers have focused on effect of temperature on physical properties of cooking oil at high temperature up to and above their smoking points [9-10, 17, 24, 26], without taking into ac- count however, how repeated use of the same cooking oil for deep frying affects these properties. Our present study focused on the effect of repeated frying on some physical properties of cooking oil purchased from local markets in Makurdi, Benue state. Uniquely in this work, we maintain a minimal tempera- ture (temperature well below the smoking point temperature of each cooking oil) [10, 17, 22] in the frying process, using the same cooking oil repeatedly for frying of yam and potatoes for several days while keeping track of the changes in some of the physical properties of each cooking oil on a daily basis. Addi- tionally, the motivation for this work was further honed by the limited availability of data on the physical properties of cook- ing oils in North Central, Nigeria. Also owing to the fact that Benue State is classified as the Food Basket of the Nation in Nigeria, information on the physical properties of oils with re- spect to changes in temperature will further call for high quality breeds of seedlings for farmers that could mitigate these short changes in the long run. 2. Physical Properties of Cooking Oil The physical properties of cooking oils are free fatty acids, change of color, smoke point, iodine values, total polar mate- rials, interfacial tension, density, cloud point, pour point, flash point, boiling range, freezing point, refractive index, foaming properties and viscosity [13-16]. However, the physical proper- ties of cooking oil measured in this work included the viscosity, density and specific gravity based on availability of instrumen- tation and other requirements. 2.1. Viscosity Viscosity is an important physical property of a fluid system including cooking oil being a function of shear rate, tempera- ture, pressure, moisture content, concentration and flow rate. It differs from fluid to fluid because they are made of different particles with different forces of attraction between them. Ex- amples of these fluids can be engine oil, honey, cooking oils and water. It is important to note that the viscous forces are called into play as soon as fluid flow starts. If the external force caus- ing the flow are constant, the rate of flow becomes constant and a steady state is attained with the resisting viscous forces equal to the applied force. The viscous force stops the flow when the applied force is removed. Viscosity can be expressed in two dis- tinct forms known as dynamic viscosity (η) and the kinematic viscosity (ν). They are mathematically expressed respectively as according to [27] as, ηoil = τ γ &νoil = ηoil ρoil (1) where τ is the shear stress, γ is the shear rate and ρoil is the oil density. The viscosities of the oil samples used in this work are measured using the Brookfield viscometer. 2.2. Density The density of cooking oil influences its absorption as it af- fects the drainage rate after frying and also the mass transfer rate during the cooling stage of frying. The density of a sub- stance is the property that describes the amount of matter that is 470 Daniel et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 469–476 471 packed in a small space. It is measured throughout industry to gain insight into the purity, concentration, quality and behavior of substance. The density of cooking oil is expressed mathe- matically as [13, 27] ρoil = moil νoil (2) where ρoil is the oil density in g/cm3. moil is the mass of the oil in gram and νoil is the oils volume in cm3. 2.2.1. Specific Gravity Specific gravity is an important parameter in cooking oil be- cause of its correlation with cetane number, heating value and storage time. The greater the specific gravity of oil, the higher its energy content. The specific gravity of cooking oil was ob- tained using the equation 3 [13]; Specific Gravity = ρoil+bottle −ρbottle ρwater+bottle −ρbottle = ρoil ρwater (3) 3. Materials and Method 3.1. Geology of Area of Study Makurdi metropolis doubles as the state capital of Benue State in Nigeria and also serves as the headquarters of the Makurdi Local Government Area with the geographical coordinates 7.73o N and 8.53o E [28-29]. In 2016, Makurdi and its environs had an estimated population of about 365,000 persons [30]. The town is divided by the River Benue into the North and South Banks, which are connected by two bridges of about 1 km long each. Due to the fact that Makurdi is located in the valley of River Benue [29, 31], it experiences a temperature fluctuation of between 21−37o C in the year [30, 32]. Within the Makurdi metropolis, there are five major markets namely: Wurukum, Wadata, Makurdi Modern, International, North Bank and the High-level Markets which are the major trade centers for soy- beans, groundnut, shea nut, millet, sorghum, rice, maize, yams, tomatoes, water melon, and other seedlings at various quanti- ties etc. The markets and other features of Makurdi town are as shown in Figure 1. Benue state is predominantly an agricultural area special- izing in both cash and subsistence crops [30]. The vegetation is mainly savanna [32] with the southern part of the state char- acterized by forests, thus, fertile for growing palm trees, con- sequently, ranking Benue State among producers of palm oil in Nigeria. However, the oil samples used in this work were purchased from Wurukum market due to the proximity to the University Research Laboratory. 3.2. Sample Collection The cooking oil samples used in this work include ground- nut oil, palm oil, coconut oil, olive oil, palm kernel oil and soybeans oil. They were purchased from Wurukum market - a major market in Makurdi metropolis that is situated few me- ters away from the Benue State University, Nigeria. While Figure 1. Map of Makurdi Metropolis, Ministry of Lands and Survey, Benue State showing Wurukum Market [33]. the soybeans oil was purchased at the Seraph company along Makurdi - Gboko Road, Makurdi, Benue state. All the oil sam- ples were moved to the Research Laboratory in the Department of Physics, Benue University Makurdi, Nigeria in plastic bot- tles, where they were properly labelled and stored at a room temperature for two days before experiment. 3.3. Measurement of Viscosity The viscosities of the different brands of cooking oils were measured using the Brookfield Viscometer. Brookfield viscome- ters employs the well-known principle of rotational viscometry; which measures viscosity by sensing the torque required to ro- tate a spindle at constant speed while immersed in the sample fluid. The torque is proportional to the viscous drag on the im- mersed spindle, and thus to the viscosity of the fluid. The con- tinuous rotation of the spindle allows uninterrupted measure- ments to be made over long periods of time depending on the fluid properties. The viscosities of each of the six (6) samples of the cooking oil (at room temperature) without frying, were measured using the Brookfield viscometer at room tempera- ture. The measurements for each oil sample were performed and recorded as shown in Table 1. 5. 00 mL of groundnut oil was poured in a frying pan and heated up to a temperature of 120o C . A tuber of yam and six (6) tubers of potatoes were sliced, poured into the frying oil and allowed to fry well enough for human consumption. The frying process for all the six (6) brands of oil was carried out almost concurrently. During the frying process, the temperature of the frying oil was maintained at a temperature below the smoking point of the oil. At the end of each frying, the oil was allowed to cool before taking the viscosity measurement at a constant tem- perature every day for five (5) consecutive days. Viscosity for each oil sample was measured and plotted as shown in Figure 2. Again, while varying the temperature of each oil sample each consecutive day for five days, their viscosity was measured and recorded as shown in Table 2. The same variety of yam and 471 Daniel et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 469–476 472 Figure 2. Viscous change measured at constant temperature per day after recy- cled usage of cooking oils for frying of yams and potatoes potatoes with the same cooking oils were repeatedly used in all the five days in the frying process. 3.4. Determination of Oil Density To obtain the densities of the oil samples, we use the den- sity bottle to measure the mass and volume of each oil sample before evaluating their corresponding densities using equation 2. To do that, we first of all measure the mass of the dry and empty density bottle using the electronic weighing balance and its volume was evaluated using equation 4 as expressed V olume = mwater − mbottle ρwater −ρair (4) The result of equation 4 is substituted for the volume of oil in equation 2 and the results for the densities of the cooking oils are recorded as shown in Table 3. 3.5. Experimental Results In this section, the results that were gotten in the various investigations of the physical properties considered in this study are duly presented and discussed as shown below 4. Discussions 4.1. Viscosity The results for the viscosity of soybean oil, groundnut oil, olive oil, coconut oil, palm kernel oil and palm oil measured at room temperature without frying are presented in Table 1 and plotted as in Figure 3. While Table 2 presents the results of viscosity of the sampled cooking oils measured each day after frying of sliced yams and potatoes repetitively for five consec- utive days at varying temperature. From Table 1, the viscosi- ties ranged from 61 mPa.s to 111 mPa.s with palm oil having the highest viscosity of 110.96 mPa.s and the lowest value is reported in palm kernel oil as 61.12 mPa.s. This is clearly de- picted in Figure 3. The result for soybeans at 24o C. is 96.82 Figure 3. Viscosity of cooking oil samples without frying and measured at room temperature Figure 4. Viscosity versus temperature of cooking oil samples after repeated frying of yams and potatoes for five successive days 472 Daniel et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 469–476 473 Table 1. Viscosity (Pas−1) of cooking oil sample without (that is, at room temperature) frying. Oil sample Viscosity (Pas−1) Temperature (0C) Soya beans 96.82 23.90 Groundnut 104.27 23.10 Olive 68.62 22.70 Coconut 64.26 24.10 Palm Kernel 61.12 23.60 Palm Oil 110.96 23.20 Table 2. Viscosity (Pas−1) of cooking oils used for frying yams and potatoes for five consecutive days. Viscosities of oil Samples (pas−1) Days Temperature (0C) Soya beans Groundnut Olive Coconut Palm Ker- nel Palm Oil Day 1 24.50 60.00 52.61 65.67 50.91 65.27 70.21 Day 2 32.30 48.30 41.34 50.26 34.32 46.32 50.57 Day 3 37.30 31.52 28.21 38.92 27.21 35.78 38.26 Day 4 41.20 33.20 21.25 23.24 19.46 18.45 28.92 Day 5 45.20 14.31 11.21 12.36 10.52 8.6 18.61 Table 3. Densities, ρ(g/cm3), of the cooking oil at different temperature obtained after repeatedly frying yams and potatoes for five days. Density of Oil Samples (g/cm3) Temperature (0C) Soya beans Groundnut Olive Coconut Palm Kernel Palm Oil 20.0 0.900 0.900 0.910 0.870 0.880 0.920 40.0 0.890 0.860 0.880 0.860 0.860 0.890 60.0 0.880 0.850 0.860 0.860 0.850 0.870 80.0 0.840 0.830 0.840 0.850 0.840 0.850 100.0 0.810 0.820 0.840 0.820 0.830 0.820 Table 4. Specific gravities of the cooking oil at different temperature obtained after repeatedly frying yams and potatoes for five days consecutively. Specific Gravity of Oil Samples Temperature (0C) Soya beans Groundnut Olive Coconut Palm Kernel Palm Oil 20.0 0.903 0.903 0.913 0.873 0.883 0.883 40.0 0.893 0.832 0.883 0.863 0.853 0.873 60.0 0.883 0.842 0.863 0.853 0.842 0.873 80.0 0.842 0.853 0.842 0.863 0.832 0.893 100.0 0.812 0.822 0.842 0.822 0.832 0.822 473 Daniel et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 469–476 474 Figure 5. Density of different brands of cooking oil against temperature ob- tained after repeated frying of yams and potatoes for five successive days. Figure 6. Specific gravity of different samples of cooking against temperature for five successive days obtained after repeated frying of yams and potatoes mPa.s. This value is far higher when compared to [26] and [34] which are 60 mPa.s at 20o C and 57.1 mPa.s at 22o C re- spectively. While the result of [34] is a theoretical prediction that was modelled mathematically using the Andrade equation, [2]6 is contrarily an experimental result measured with the use of MCR301 Rheometer - a device that employ the principle of rotational viscometery which is similar to the Brookfield vis- cometer used in this work. However, the large disparity of about 36.8 mPa.s in this result and [26] is not only due to the tem- perature difference of 4o C but largely because, the viscome- ters were operated at different shear rate, which corresponds to the rate of spindle rotation in oil solution per minute (RPM). The Brookfield viscometer was operated at a shear rate of 60 RPM while the rheometer as in [26] was operated at 750 RPM. Whereas, higher shear rate corresponds to higher spindle speed in oil solution [35] and thus, lower viscosity measurement as observed in this result. The results in Figure 2 shows that, vis- cosity decrease as the number of days of recycled use of the same oil to fry sliced yams and potatoes increases continually for five successive days. The viscosity of palm oil for instance decreased from 70.21 mPa.s in day 1 to 50.57 mPa.s in day 2 to 38.26 mPa.s in day 3 to 28.92 mPa.s in day 4 to 18.61 mPa.s in day 5. Since the viscosity of a solution is dependent on the intermolecular forces and the interaction within its molecules, the continuous decrease in viscosity after each repeated frying is because, continuous application of heat to the oil each day for five days results in continuous breakdown of the oil layers. This breakdown weakens the intermolecular forces and the bond en- ergies of oils molecules that restrict molecular rotational motion of the viscometer spindle within the oil solution, and therefore, lower viscosity is recorded as the number of days of repeated frying increase. The results plotted in Figure 4 reveal a steady linear decrease in viscosity as the temperature of the cooking oils increases. A similar trend was observed for olive oil, palm oil and soybean in [27], and in coconut oil and soybean as in [14]. We observed that palm oil has the highest viscosity for all the five-oil follow by olive oil and groundnut oil while the oil with least viscosity is palm kernel. 4.2. Density and Specific gravity The density and specific gravity of cooking oil varied sig- nificantly with change in temperature as shown in Tables 3 and 4 respectively. A general trend of decrease in these two physi- cal properties of cooking oils were observed in Figures 5 and 6 as temperature increases from 20o C to 100o C. This decrease in the density of the cooking oil with increased temperature was also observed [13, 27, 34] and same trend being applicable for specific gravity [10, 13, 36]. The decrease in density and spe- cific gravity of the oils due to increase in temperature lead to breakdown of the oils structure. This causes the mass of the oils to reduce as frying progresses even though the volume or the quantity of this oil that was used in frying at the initial place may still be the same 474 Daniel et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 469–476 475 5. Conclusion This work has shown that the thermal (heat) properties of different oils determine their superiority over others when sub- jected to the same amount of weather conditions. Based on the results obtained from research, temperature had a signifi- cant effect on all three physical properties (viscosity, specific gravity and density) of oils measured. Oil type was shown to have a significant effect on viscosity, density and specific grav- ity. A general trend for all the properties decreased with in- creased temperature as can be seen from Figures 4 to 6. The effect of temperature on the viscosity for all the vegetable oils show a linear relationship for all temperatures used in this work. Although [34] reported non-linear decrease in viscosity at very high temperature above 100o C. This is an indication that tem- perature had significant effect on viscosity of vegetable oils. Oil that has been used repeatedly for so long at high temperatures are not advisable for human consumption because its qualities such as the viscosity, density, specific gravity etc have been re- duced. Density decreased linearly with increased temperature whereas specific gravity decreases almost linearly in compari- son with the other physical properties measured in this work. 6. Acknowledgment We wish to appreciate the Head of the Department of Physics, Professor Frederick Gbaorun for allowing this experiment to be conducted in the laboratory of the Department. The authors also wished to thank all the Laboratory staff of the Department of Physics for their assistance during measurement and data anal- ysis as well as interpretations and discussions of the results ob- tained. Lastly, the authors are grateful to God for a good life that all of them are enjoying and the wisdom to conduct this research. References [1] N. Morgan, “Food consumption: world vegetable oil consumption ex- pands and diversifies”, Food Rev. (1993) 26. [2] E. Ike, “The study of viscosity-temperature dependence and activation en- ergy for palm oil and soybean oil”, Glob. J. Pure Appl. Sci. 25 (2019) 209. Available at https://doi.org/https://dx.doi.org/10.4314/gjpas.v25i2.11. [3] S.K. Upev, L. Haruna, D.Y. Giroh, “Analysis of resources use efficiency among soybean (glycine max) farmers in Gboko Local Government Area of Benue State”, Nigeria., Glob. J. Agric. Sci. 15 (2016) 57. [4] List of Nigerian States’ name. Retrieved on June 4, 2021 from Wikipedia. [5] USDA FAS, Global Market Analysis: Oilseeds, World Market and Trade, (2021) 1. [6] P. Shankar, S. Ahuja, A. Tracchio, “Coconut oil: a re- view”, Agro Food Ind. Hi Tech. 24 (2013) 62. Available at https://www.researchgate.net/publication/264157941. [7] N.K. Andrikopoulos, G. Boskou, G.V.Z. Dedoussis, A. Chiou, V.A. Tzamtzis, and A. Papathanasiou, “Peer review quality assessment of frying oils and fats from 63 restaurants in Athens, Greece”, Food Serv. Technol. 3 (2003) 4. Available at https://doi.org/10.1046/j.1471- 5740.2003.00064.x. [8] V. Sodano, R. Riverso, F. Scafuto, “Investigating the intention to reduce palm oil consumption”, Qual. - Access to Success. 19 (2019) 500. Avail- able at https://www.researchgate.net/publication/323759111. [9] H.A. Mudawi, M.S.M. Elhassan, A.M.E. Sulieman, “effect of frying process on physicochemical characteristics of corn and sunflower oils”, Food Public Heal. 4 (2014) 181. Available at https://doi.org/10.5923/j.fph.20140404.0. [10] N. Idun-acquah, G.Y. Obeng, E. Mensah, “Repetitive use of veg- etable cooking oil and effects on physico-chemical properties - case of frying with redfish (Lutjanus fulgens)”, Sci. Technol. 6 (2016) 8. https://doi.org/10.5923/j.scit.20160601.02. [11] F. Soriguer, G. Rojo-Martinez, M.C.. Dobarganes, “Hypertension is re- lated to the degradation of dietary frying oils”, Am. J. Clin. Nutr. 78 (2003) 1092. [12] A. Lapointe, C. Couillard, S. Lemieux, “Effects of dietary factors on ox- idation of low-density lipoprotein particles”, J. Nutr. Biochem. 17 (2006) 645. [13] R. Kumar, S. Chandra, V. Kumar, V. Chaudhary, “Physico-chemical study of edible and composite edible oil”, Int. J. Agric. Eng. 12 (2019) 129. Available at https://doi.org/10.15740/HAS/IJAE/12.1/129-135. [14] M.A. Boda, P.N. Bhasagi, A.S. Sawade, R.A. Andodgi, “Analy- sis of kinematic viscosity for liquids by varying temperature”, Int. J. Innov. Res. Sci. Eng. Technol. 4 (2015) 1951. Available at https://doi.org/10.15680/IJIRSET.2015.0404020. [15] A.J. Bolton, G. Koutsianitis, “The effect of temperature on the surface tension of sap of thuja plicata heartwood”, J. Wood Fiber. 12 (1980) 3. [16] A. Ayoola, P. Anawe, M. Ojewumi, R. Amaraibi, “Comparison of the properties of palm oil and palm kernel oil biodiesel in relation to the degree of unsaturation of their oil feedstocks”, Int. J. Appl. Nat. Sci. 5 (2016) 1. [17] A.M. Biliaed, M.A. Ahmed, M.M. Okasha, O.M. Alwakdi, A.M. Ho- moud, “The effects of frying on the thermal behaviour of some vegetable oils”, Int. J. Agric. Res. Rev. 4 (2016) 529. [18] C.M.C. Laranjeira, C.S.E. Ventura, S.M.C.S. Bermejo, S.P.T.A. dos San- tos, M.F. da S.P. Ribeiro, D.M.G. de O.L.B. de Lima, M.O.I. Henriques, “Used food oils: physical-chemical indicators of quality degradation, FOODBALT 40 (2017) 154. https://doi.org/10.22616/foodbalt.2017.040. [19] E. Choe, D.B. Min, “Chemistry of deep-fat frying oils”, J. Food Sci. 5 (2007) 77. [20] F. Aladedunye, R. Przybylski, “Frying performance of canola oil triacyl- glycerides as affected by vegetable oils minor components”, J. Am. Oil Chem. Soc. 89 (2011) 1. [21] F. Pedreschi, “Fried and Dehydrated Potato Products”, Adv. Potato Chem. Technol. (2009) 319-337. [22] M. Ghidurus, M. Turtoi, G. Boskou, P. Niculita, V. Stan, “Nutritional and health aspects related to frying”, Rom. Biotechnol. Lett. 15 (2010) 5675. [23] L.G. Chuffa, F.R. Vieira, D.A.F. Silva, D.M. Franco, Soybean Seed Oil: Nutritional Composition, Healthy Benefits and Commercial Applica- tions”, Seed Oil, Nova Science Publishers, Inc., Estadual Paulista, 2015, 1-23. [24] J. Mlcek, H. Druzbikova, H. Valasek, J. Sochor, T. Jurikova, M. Borkovo- cova, M. Baron, S. Balla, “Assessment of total polar materials in fry- ing fats from czech restaurants”, Ital. J. Food Sci. 27 (2015) 160. https://doi.org/10.14674/1120-1770/ijfs.v182. [25] R.N. Prasada, “A study on cooking oil consumption on various health markers in rural population of Coimbatore”, India, Int. J. Biomed. Res. 7 (2016) 179. Available at https://doi.org/10.7439/ijbr. [26] E. Rukke, R.B. Schà 14 ller, “Viscosity of a selection of edible oils and blends of oils at different temperatures”, Annu. Trans. Nord. Rheol. Soc. 25 (2017) 287. [27] R. M. Davies, “Effect of the temperature on dynamic viscosity, density and flow rate of some vegetable oils, J. Sci. Res. Eng. Technol. 1 (2016) 14. [28] The World Gazetteer”. Archived from the original on 9 February 2013, World Gazet. [29] A.M. Chinenyeze, J.B.N. Ozibo,”Geology of parts of Gboko and Makurdi local government area” , Int. J. Geol. Min. 3 (2017) 71. [30] Makurdi — Location, Facts, Population”. Encyclopedia Britannica, Re- trieved on 7th Match, 2021 [31] C. A. Kogbe, A. Tokarski, D. Osijuk, D.E. Wonzy, “Geology of the Makurdi Sheet 251 in the Middle Benue Valley, Nigeria”, Occas. Pub. No. 5 Dept. Geol., Ahmadu Bello Univ. Zaria, Niger. 5, 1978. [32] I.O. Agbede, P. Smart, “Geotechnical Properties of Makurdi Shale and Effects on Foundations”, Niger. J. Technol. 26 (2007) 63. [33] K.F. Aov, I. Okon, C. G.Njoku, K.A. Thaddeus, S.A. Iorkua, T. Olorun- dami, I.J. Lekam, “Spatial Analysis of Crime Incidents in Makurdi Metropolis, Benue State, Nigeria”, in Proceedings of 58th Assoc. Niger. Geogr. Annu. Conf., Nasarawa State Univ. Keffi, Nasarawa State , Niger., 475 Daniel et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 469–476 476 2017. [34] S.N. Sahasrabudhe, V. Rodriguez-martinez, M.O. Meara, B.E. Farkas, S.N. Sahasrabudhe, V. Rodriguez-martinez, M.O. Meara, “Density, vis- cosity, and surface tension of five vegetable oils at elevated tempera- tures: measurement and modeling”, Int. J. Food Prop. 20 (2017) 1965. https://doi.org/10.1080/10942912.2017.1360905. [35] B.E. Laboratories, Brookfield Dial Viscometer Operation Instructions, Brookfield engineering laboratories, inc. 11, Commerce Boulevard, Mid- dleboro, MA 02346-1031 USA. [36] M.S. Sarjadi, T.C. Ling, M.S. Khan, “Analysis and comparison of olive cooking oil and palm cooking oil properties as biodiesel feedstock”, J. Phys. Conf. Ser. 1358 (2019) 1. Available at https://doi.org/10.1088/1742- 6596/1358/1/012007. 476