Soybean oil, also known as soy oil, is a vegetable oil made by crushing soybean – a leguminous plant native to East Asian countries. In countries of Far East, it has been used to prepare famous recipes, such as “tofu”, “miso,” “tempeh,” and soy sauce. India is the largest importer of crude soy oil in the world. It meets its domestic demand by imports from Argentina and Brazil and then refining it at refineries located at eastern and western coast of the country.
In India, soybean is grown in the states of Andhra Pradesh, Rajasthan, Madhya Pradesh and Maharashtra. The domestic production stood at just 1.44 million metric tonnes but imports are of 15 million metric tonnes in 2019.
Though not a tradition Indian cooking oil, soybean oil is fast becoming a popular cooking replacement, mainly because it is relatively cheaper and better marketed than other edible oils.
Composition and Properties of Soybean Oil
Soybean oil is mainly composed of fatty acids-both saturated and unsaturated fatty acids. Unsaturated fatty acids are good for heart and contribute to development of good cholesterol (HDL). These are close to 80% of total fatty acid composition in this oil.
Alpha-linoleic (omega-3) fatty acids play an integral role in heart health, fetal development, brain function and boosting immunity.
Linoleic (omega-6) fatty acids are also good for health but one has to be careful in taking these in right amounts in diet.
Soybean oil also contains a large amount of lecithin which is an important constituent of all organs of the human body and especially of the nervous tissue, the heart and liver. It lends strength to the body.
Fatty acid composition of the soybean oil is given in chart below…
|Saturated Fatty Acid||Stearic Acid||4.0%|
|Monosaturated Fatty Acid||Oleic Acid||22.6%|
|Polyunsaturated Fatty Acid||Alpha-linoleic (omega-3)||7.0%|
Soybean oil has high smoke point of about 230°C. This makes it a good cooking oil for high-heat cooking applications like roasting, baking, frying, and sautéing.
Health benefits of Soybean oil
This oil is rich in unsaturated fatty acids which contribute to good cholesterol (HDL). So, people having high bad cholesterol (LDL) cholesterol levels can trade their high saturated fatty acid oils with soy oil to reduce LDL and total cholesterol levels. This way it does not accumulated in arteries and you keep a healthy heart.
2/7. Healthy for bones
One of the benefits of soybean oil is that it is good for bone strength and its development. Presence of Vitamin K is soy oil plays an important role in regulating the bone metabolism and in synthesising proteins, such as osteocalcin, which help in maintaining bone mass.
Soy oil has isoflovids called phytoestrogen which has characteristics similar to estrogen. Estrogen is essential for keeping the bones healthy and strong. Soybean oil is said to be good for post-menopausal women because they have low oestrogen levels and the oil can supply it.
3/7. Good for Skin
Soybean oil is rich in vitamin E, linoleic acid, isoflavones and antioxidants which makes it a good anti-inflammatory agent. So, it protects against the inflammation caused by ultraviolet rays, skin damage, acne and atopic dermatitis.
It is believed that the black soybean oil prevents development of ageing marks in post-menopausal women because it contains antioxidants.
4/7. Good for Hair
Soybean oil nourishes hair with amino acids and keratin-like molecules. Therefore, hair are strengthened from the roots. It also helps in attaining shiny hair.
5/7. Good for Brain
The presence of unsaturated fatty acids in the oil leads to making of omega-3 fatty acids such as DHA and EPA and omega-6 fatty acids as well. These show neuro-protective characteristics and can help prevent cognitive and degenerative diseases such as Alzheimer’s disease.
6/7. Strengthens body
Soya bean oil contain lecithin which helps in absorption of fat soluble vitamins. This works to strengthen the tissues and organs of body.
7/7. Helps in certain cancer types
Soybean oil has various phytosterols, the compounds that have anticancer and antioxidant properties. Also, phytoestrogen present in soy oil is able to maintain estrogen levels and prevent risk of breast and colon cancer in women.
Using Soybean Oil in cooking
1/3. Soybean oil has a neutral taste which makes it suitable for bakery products where the flavour of prepared eatables is to be retained.
2/3. It is used to prepare margarine to impart tenderness in baked products and also to make wafers, crusts, etc. crispier.
It is also used in salad dressings and sauces.
3/3. Due to high smoking point, it can be used for high temperature cooking such as frying and sautéing.
Soybean Oil Adulteration
Soybean oil consumption in cooking has increased in India due to its relatively cheaper price than other edible oils. Due to rising demand and short supply, adulteration is done to generate more profits. Adulteration may be done with the corn oil.
This adulteration of soybean oil with corn oil can be detected with carbon stable isotope technique. Using this method both partial and complete adulteration can be checked.
It should be noted that this adulteration of soya bean oil cannot be tested at home.
Side effects of using Soybean Oil
If you are consuming foods which are fried in soybean oil too much, then you are adding omega 6 fatty acid (Linoleic Fatty Acid) to your diet beyond the correct limits, which is not a healthy practice and it can lead to a number of health issues.
1/7. High Omega-6 intake is believed to be one of the major reasons for people to become obese because the ideal ratio of omega 6 to omega 3 acid (1:1) gets distorted. Americans have been found to intake in ratio of 10:1 or even more.
2/7. Obesity, in turn, can lead to Type 2 diabetes. It is believed to interfere in secretion of insulin and in insulin resistance.
3/7. Another potential bad effect of obesity is development of non-alcoholic fatty liver disease (NAFLD) because of the improper functioning of liver that fails to breakdown all fat.
4/7. If the soybean oil is partially hydrogenated, then it produces trans-fats in large amount. These are linked to a number of metabolic disorders and heart diseases.
5/7. Another potential side effect or drawback of using soy oil is that it can destroy lymphocyte and neutrophil, two important immune cells which leads to reduction of immunity in people.
6/7. People allergic to birch pollen or soybean products in general, might also be sensitive to soybean oil.
7/7. Consumption of soybean oil is seen to be associated with hindrance to proper functioning of thyroid gland. More research is needed. People with hypothyroidism condition should take soybean oil only under medical advice because it can interfere with medicine taken for it.
Extraction of Soybean oil
It is important to note that the mechanical processes are not generally used for soybean oil extraction because of lower yields and comparative expensiveness.
For this reason the solvent extraction process is generally used. Soya beans are first dried and then de-hulled by cracking. The beans are separated from the hull and heated to 75°C to coagulate the soy proteins. Thereafter, the oil is extracted from it using hexane as solvent which is later removed by evaporation. Other insoluble impurities present in the oil are removed using filtration process and soluble impurities are removed using other processes.
After purification of the oil, it is hydrogenated to make it more stable but it produces trans-fats and more saturated fatty acids while reducing the unsaturated fatty acid component.
Hydrogenation reduces the formation of free radicals due to lipid oxidation. It shall be known that due to high levels of linoleic acid, the oil remains susceptible to lipid oxidation and has to be hydrogenated before being used in certain applications.