DETERMINATION OF SOME PROPERTIES OF COOKING OIL AND ENVIRONMENTAL FRIENDLY TECHNOLOGY TO MAKE A SOAP

ABSTRACT

In this study, we studied the properties of cooking oil and used cooking oil. Saponification value of cooking oil was 188.8 g/ml and saponification of used cooking oil was 197.8 mg/g. After cooking the saponification value is significantly increased. After cooking the relative density and refractive index is significantly increased. It says the cooking oil quality will decrease during the cooking process. The cooking oil can be used can be reprocessed into valuable product, one of which is as a basic ingredient in making soap. This may eventually lessen the environmental pollution and impact economy through sustainable production of soap.

АННОТАЦИЯ

В этом исследовании мы изучили свойства растительного масла и отработанного растительного масла. Значение омыления масла для жарки составило 188.8 г/мл, а значение омыления использованного масла для жарки составило 197.8 мг/г. После варки число омыления значительно увеличивается. После варки относительная плотность и показатель преломления значительно увеличиваются. В нем говорится, что качество растительного масла ухудшится в процессе приготовления. Кулинарное масло можно использовать, его можно перерабатывать в ценный продукт, один из которых используется в качестве основного ингредиента при изготовлении мыла. Это может в конечном итоге уменьшить загрязнение окружающей среды и повлиять на экономику за счет устойчивого производства мыла.

Keywords: The cooking oil, used cooking oil, soap.

Ключевые слова: Кулинарный жир, отработанный кулинарный жир, мыло.

Introduction

Frying is one of the most common methods used for preparation of foods throughout the world. Fast food is termed as a food obtained from restaurants and other catering establishments, where the aim is to provide a fast service and rapid customer turnover at reasonable prices (Sebastian et al., 2014). Cooking oils function as heat transfer medium and contribute to flavor and texture of food in culinary purposes (Yamsaengsung et al., 2008). Fried food quality is a function of oil quality. If the cooking oil is abused or damaged, it affects the texture, taste, and overall flavor perception of the food (Stier, 2013). Salt is used during processing and preserving, and cooking oil is frequently used in food preparation (Ngoan et al., 2002). Repeated use of oils and fats for frying of food brings about many changes in their physical and chemical properties (Bansal, 2013). Consumption of these repeatedly heated oils can pose a serious health hazard (Thrift & El-serag, 2019). Repeated heating of vegetable oils at high temperatures during cooking is a very common cooking practice. Repeated heating of edible oils can generate a number of compounds, including polycyclic aromatic hydrocarbons (PAH), some of which have been reported to have carcinogenic potential (Srivastava et al., 2010). Heating oils and fats for a considerable length of time results in chemical reactions, leading to the aggravation of a free radical processes, which ultimately contributes to atherosclerosis (Anishas et al., n.d.). During the frying, chemical reactions taking place during frying include oxidation, hydrolysis, polymerization, and fission (Li et al., 2008). During this process, many oxidative products such as hydroperoxide and aldehydes are produced, which can be absorbed into the fried food (Taylor et al., 2015). Consumption of repeatedly heated cooking oil has been a regular practice without knowing the harmful effects of use (Venkata & Subramanyam, 2016).  Repeatedly heated cooking oils can generate varieties of compounds, including polycyclic aromatic hydrocarbons, some of which have been reported as carcinogenic. The present review provides additional insights into the polluting features of polycyclic aromatic hydrocarbons produced various cancers via cooking activities in indoor environments (Ganesan et al., 2017). Chemical analysis revealed that repeated heating of oils resulted in changes in fatty acid composition and elevated lipid peroxidation. Degree of saturation of oil is an important factor determining the quality of cooking oils. Unsaturated fatty acids are more susceptible to lipid oxidation than saturated fatty acids and for this reason they are good source of free radicals (Wsowicz et al., 2004). Furthermore, when cooking oil is presented to high temperatures for drawn out stretches of time, it will causes the fatty acid peroxidation process and subsequently pose harmful effect for human health (Venkata & Subramanyam, 2016). Oxidative stress produced by free radicals is associated with the development of atherosclerosis. Oxidative stress is associated with activation of platelets and for the same reason, a role can be assigned for platelets in the cardiovascular events that are related to oxidative stress (Freedman, 2008). The clinical role of oxidative stress in platelet function and thrombosis is not straightforward. Although earlier epidemiological studies found that dietary antioxidant consumption was inversely associated with the development of coronary artery disease, more recent studies of vitamin supplementation have presented conflicting or negative results (Design, 2008). These accumulating data suggest chronic intake of heated cooking oils increases the risk of cancer and cardiovascular diseases (Kamisah, 2014). Accompanying these changes in food consumption at a global and regional level have been considerable health consequences (Kearney & Kearney, 2010). Many consumers and food handlers are not well knowledgeable regarding the damaging effects of overwhelming deep-fried food in repeatedly heated vegetable oil (Kamisah, 2014). Because of the reasons that named in the above, we determined some properties of cooked oil and finding the way environmental friendly technology to make a soap. It is important to determine the repeatedly cooked oil properties to affect massive health improvement.

MATERIALS AND METHODS

Collection used cooking oil

The used cooking oil samples were collected from local chain restaurant, that locates in Ulaanbaatar Mongolia. We get a sample fresh natural vegetable oil and oil that after cooked 3 times for food frying. Literature reported procedures were employed to do the pretreatment on the collected used cooking oil in order to remove solid, inorganic material and other contaminants from food frying process. It was carried out, first, by heating them at 80°C. The hot oil samples were then allowed to cool to room temperature. Suction filtration was also used to remove the above mentioned impurities and to make used cooking oil suitable for soap preparation (Adane, 2020).

Analyses of physicochemical properties of used cooking oil

Though there are several parameters to evaluate qualities of oils, the two important parameters namely saponification values and total fatty number were considered in this experiment to assess the properties of the collected used cooking oil for soap making.

Determination of relative density of oils

Determination of the density of oil and oil products with a hydrometer is performed in accordance with GOST 3900-85.

Determination of saponification value

The saponification number (value) is defined as the milligrams of potassium hydroxide (KOH) required to saponify 1g of fat or oil. Two grams of the oil sample was weighed into a clean dried conical flask and 25 ml of alcoholic potassium hydroxide (KOH) was added. The flask was heated for an hour with frequent shaking. 1 ml of 1% phenolphthalein indicator was added and the hot excess alkali was titrated with 0.5 mol/L hydrochloric acid (HCl) until it reached the end point where it turned colorless. A blank titration was carried out at the same time and under the same condition. The saponification value was calculated using following equation.

B and S are titration values of blank and sample, respectively, M is the molarity of HCl and 56.1 is the molecular weight of potassium hydroxide.

Determination of total fatty matter

In the present study, determination of total fatty matter was done following a method described in AOCS (ISO, 1975), with slight modifications. The tests were carried out by reacting soaps samples with acid in the presence of hot ethanol and measuring the fatty acids obtained. 10 grams of soap samples was mixed with 150 mL of warm neutralized ethanol and was heated; the soap materials were dissolved. The dissolved solution was then filtered, and the residue was dried in oven at 110°C for 1 h and weighed again. The total fat matter was obtained using following equation:

Where, MC = moisture content and MIA = matter insoluble in alcohol.

Preparation of soap

300 g of the oil was measured into a plastic container. It was warmed in order to quicken the reaction between the alkali and the fat. A calculated amount of NaOH was weighed and a fixed amount of distilled water was added to it to prepare a 0.2 N NaOH solution. And prepared 3 different types of soap. The caustic soda was poured very gradually into it and stirred gently in one direction to enhance through mixing of the solution. The plastic container was insulated with pieces of cloths to prevent the fat from hardening before the soap mix properly. The content of soap consists of 43% of water, 16 % of NaOH and 27% of water.

Results and discussion

Saponification value gives information concerning the character of the fatty acids of the fat- the longer the carbon chain, the less acid is liberated per gram of fat hydrolyzed. The long chain fatty acids found in fats have low saponification value because they have a relatively fewer number of carboxylic functional groups per unit mass of the fat and therefore high molecular weight. Oils with high saponification values such as coconut oil (257.0) and palm oil (199.1) are better used in soap making. Saponification value of cooking oil was 188.8 g/ml and saponification of used cooking oil was 197.8 mg/g (Table 1). After cooking the saponification value is significantly increased. It is comfortable to make better quality soap.

Table 1.

The analysis of cooking oil and used cooking oil

After cooking the relative density and refractive index is significantly increased. It says the cooking oil quality will decrease during the cooking process. Unsaturated fats, which are liquid at room temperature, are considered beneficial fats because they can improve blood cholesterol levels, ease inflammation, stabilize heart rhythms, and play number of other beneficial roles. After cooking the fatty number is increased and trans fatty acid will form in the used cooking oil. Trans fatty acids, more commonly called trans fats, are made by heating liquid vegetable oils in the presence of hydrogen gas and a catalyst, a process called hydrogenation. It is not comfortable for cooking. We made the following 3 types of soap illustrated in Image 1. First one (A) is no additive soap, second one is added coffee sediment (B) and third one is added activated carbon (C). The caustic soda was stirred well using a stirring rod until it blends with the fat.

Image 1. The soap made from used cooking oil, (A) is no additive soap, (B) is soap with coffee sediment, (C) is soap with activated carbon

Sum up, it needs to make cooking oil to valuable product.

Conclusion. The cooking oil can be used can be reprocessed into valuable product, one of which is as a basic ingredient in making soap. This may eventually lessen the environmental pollution and impact economy through sustainable production of soap.

References:

1. Adane, L. (2020). Preparation of Laundry Soap from Used Cooking Oils : Getting value out of waste. 15(1), 1–10. https://doi.org/10.5897/SRE2019.6649
2. Anishas, C., Idris, C., Sundram, K., Faizal, A., & Razis, A. (n.d.). Effect of Consumption Heated Oils with or without Dietary Cholesterol on the Development of Atherosclerosis. https://doi.org/10.3390/nu10101527
3. Bansal, G. (2013). Standard Methods Review of Rapid Tests Available for Measuring the Quality Changes in Frying Oils and Comparison with. Critical Reviews in Food Science and Nutrition, February 2013, 37–41. https://doi.org/10.1080/10408390802544611
4. Design, S. (2008). Vitamin e supplementation and cardiovascular events. The New England Journal Of Medicine.
5. Freedman, J. E. (2008). T RANSLATIONAL T HERAPEUTICS AT THE P LATELET V ASCULAR I NTERFACE A CME-Certified Activity Oxidative Stress and Platelets. https://doi.org/10.1161/ATVBAHA.107.159178
6. Ganesan, K., Sukalingam, K., & Xu, B. (2017). Impact of consumption of repeatedly heated cooking oils on the incidence of various cancers- A critical review. 8398(September). https://doi.org/10.1080/10408398.2017.1379470
7. Kamisah, Y. (2014). Repeatedly Heated Vegetable Oils and Lipid Peroxidation. May. https://doi.org/10.5772/46076
8. Kearney, J., & Kearney, J. (2010). Food consumption trends and drivers Food consumption trends and drivers. August. https://doi.org/10.1098/rstb.2010.0149
9. Li, Y., Ngadi, M., & Oluka, S. (2008). Quality changes in mixtures of hydrogenated and non-hydrogenated oils during frying. 1523(May), 1518–1523. https://doi.org/10.1002/jsfa
10. Ngoan, L. T., Mizoue, T., Fujino, Y., Tokui, N., & Yoshimura, T. (2002). Dietary factors and stomach cancer mortality. 37–42. https://doi.org/10.1038/sj.bjc.6600415
11. Sebastian, A., Ghazani, S. M., & Marangoni, A. G. (2014). Quality and safety of frying oils used in restaurants. FRIN, 64, 420–423. https://doi.org/10.1016/j.foodres.2014.07.033
12. Srivastava, S., Singh, M., George, J., Bhui, K., Saxena, A. M., & Shukla, Y. (2010). Genotoxic and carcinogenic risks associated with the dietary consumption of repeatedly heated coconut oil. 1343–1352. https://doi.org/10.1017/S0007114510002229
13. Stier, R. F. (2013). Special Feature Ensuring the health and safety of fried foods. 956–964. https://doi.org/10.1002/ejlt.201300180
14. Taylor, P., Choe, E., Min, D. B., Choe, E., & Min, D. B. (2015). Foods Chemistry and Reactions of Reactive. February 2013, 37–41. https://doi.org/10.1080/10408390500455474
15. Thrift, A. P., & El-serag, H. B. (2019). Burden of Gastric Cancer. Clinical Gastroenterology and Hepatology. https://doi.org/10.1016/j.cgh.2019.07.045
16. Venkata, R. P., & Subramanyam, R. (2016). Evaluation of the deleterious health effects of consumption of repeatedly heated vegetable oil. Toxicology Reports, 3, 636–643. https://doi.org/10.1016/j.toxrep.2016.08.003
17. Wsowicz, E., Gramza, A., Hêœ, M., Jeleñ, H. H., Korczak, J., Maecka, M., Mildner-szkudlarz, S., & Rudziñska, M. (2004). Oxidation of lipids in food. 13(48 61), 87–100.
18. Yamsaengsung, R., Rungsee, C., & Prasertsit, K. (2008). Simulation of the heat and mass transfer processes during the vacuum frying of potato chips. 30(1), 109–115.