One of the commonly used items in our kitchen is oil. In many homes refined cooking oil is widely used. In this article, let us try to understand how oil is refined and what are the effects of using refined cooking oil.
Where does our cooking oil come from?
The most commonly used refined vegetable-based oils include sunflower oil, rice bran oil, palm oil, canola or rapeseed oil and soybean oil.
The generic cooking term “vegetable oil” refers mainly to a blend of a variety of oils often based on palm, corn, soybean or sunflower oils.
How is oil refined?
1. Most oils are made from plant seeds and the seeds are dried, husked, cleaned and crushed.
2. The crushed seeds are heated to temperatures up to 200 C, to start the oil extraction process.
3. The seeds are further put through high volume press which uses high temperatures to press the oil from the seed pulp.
4. To increase the oil output from the seed, the seed pulp along with oil is put through a hexane solvent, which is a by-product from crude oil refining.
5. Further, the oil at this stage goes through a 3-stage process of degumming, neutralisation and bleaching. In this process, the oil is treated with caustic soda and bleached to get the pure silky oil.
6. In the last step, steam at high pressure and temperature is passed over the oil to remove any odours.
The output that one gets after the above steps is called as refined oil.
Why is the refinement done?
The refinement is done primarily to increase the shelf-life of the oil that can last for years. Also these days consumers prefer non-sticky lighter oil that has a see-through effect to say.
Ill-effects of Refined Oils
The refined oil after going through so much of processing is devoid of any nutrients that were originally present. Many in the industry refer to the refined oils as “Plastic Fats”.
The ill-effects include:
1. Refined oils have significantly high levels of Omega-6 polyunsaturated fatty acids that are harmful to our body. It needs to be in balance with Omega -3. Refined oils contain Omega-6 to Omega-3 in the ratio of 120:1, which is dangerous to health.
2. Refined oils have high amounts of trans-fat, which cause multiple diseases. The same trans-fat is also present in large quantities in packed foods like biscuits.Trans fat is known to increase bad LDL cholesterol, triglycerides and insulin levels and reduces beneficial HDL cholesterol. Trans fats also trigger cancer, diabetes, immune dysfunction, obesity and reproductive problems.
3. Refined Oils when repeatedly reused at high-temperature releases free-radicals that remain in our body and are cancer causing. A high consumption of oxidised polyunsaturated fatty acids (PUFAs), which are found in most types of vegetable oil, may increase the likelihood that postmenopausal women will develop breast cancer.
In summary, while the harmful effects of using refined oils may vary between sunflower oil, canola oil or palm oil it is pretty conclusive that the way refined oil is manufactured gives a clear signal that the refined oil is bad for health. In fact in the past decade in India, a strong correlation is found between the increase in diabetes/cardiovascular diseases and increased used of refined vegetable oil.
What is the best oil then?
Oils need to be cold-pressed or wooden pressed in order to ensure that the nutrient qualities of oil are not lost.
Amongst all oils, the best oil that is harmless to health is unrefined Sesame oil. Sesame oil contains Vitamins A, E, D & K in optimal proportion and contains high amounts of calcium (7 times more than found in milk). Also, it contains phosphorous that is required for absorption of calcium. Sesame oil can last for a long time without getting spoilt and is one of the reasons used in pickles to increase the shelf life. Sesame oil in Ayurveda is suggested as a remedy for hypertension and it does not increase cholesterol or triglycerides.
The next best oil is unrefined ground nut oil that has a high smoking point and is well suited for frying. On same lines would be mustard oil which is more prominently used in North India but it generates heat within the body when compared with groundnut oil and hence is suited for colder climes.
Unrefined coconut oil in limited quantities is also good for health but it is high in saturated fat and cannot be used for those who are high on cholesterol.
Next time when you touch oil look for its stickiness, which is the main quality of oils. Any oil that claims to be non-sticky and transparent is not good for your health.
Trivia – Do You Know?
50 years ago paint and varnishes were made of soy, safflower and linseed oils. Developments in the chemical industry made it easier and cheaper to make paint from petroleum. As a result, the seed oil industry had loads of crop, which were eventually given to farmers to make their pigs fatter with less food! The same crops today ended up on our plate as well.
Check out this interesting video on the process of Refined Oil Manufacturing.