How is refined oil processed? An eye opener

No monthly grocery list is complete without “Cooking oils”, you get into a supermarket, a huge space allocated only for refined cooking oils. Almost all the packings are similar with yellow shades, sunflower picture on it.  We will be in hurry to pick and drop the cans in our cart, have we ever thought about the quality of the product? Is the attractive word “Refined/double refined” is creating buying decision? We go to an extent saying oil can be consumed only after refining, It is false. Let’s see how refined oil is processed.

Refined oils like sunflower oil, groundnut oil, canola oil, corn oil, safflower oil are extracted from seeds, the bottle is labeled as “vegetable cooking oil”, which refers to a mixture of various oils based on palm, soybean, corn, etc.

Refined oils are not like Wood pressed/Cold pressed oil”, they undergo several processes before it is on market shelves. Refined edible oil is made using highly concentrated chemicals and mechanical process to extract the oil from the sources. Hence this process removes nutrients which have to be naturally present and makes the final product, which oxidizes easily. The oxidation process makes oil to break down into cancer-causing free radicals within our body. Not only oxidation, additionally refined oils are “Hydrogenated”, this process involves refined oil to be solid at room temperature, this further creates trans fatty acids/unsaturated fatty acids(raises bad cholesterol within our body) and damages the fatty acids(good cholesterols), which are particularly dangerous to human health.

Extracting Refined Vegetable oil - Process

  • Oil seeds such as cotton, soybean, sunflower are collected from plants that have been sprayed with the huge amount of pesticides. Seeds are cleaned, removed dust & dirt and then crushed.

  • The compressed seeds are heated (in a steam bath) at temperatures between 110 degrees to 180 degrees for oil extraction.

  • Roasted seeds are compressed with high volume press, it involves friction & high heat to segregate oil from seed pulp.

  • Here comes one among the dangerous process, seed pulp, and oil is put together in a “Hexane solvent bath” and steamed once again to squash more oil.

  • To separate the oil from seed pulp, the mixture is put through centrifuge and phosphate is included.

  • After solvent extraction, crude oil is split and the solvent is recovered. Now, wait the process haven’t completed yet. This crude vegetable oil will go through further more refining process as given below.


Water degumming: One of the key steps in oil refining process, this eliminates impurities like phosphatides(so called gums) from crude vegetable oil. In this process, water is added to oil to remove phosphatides.

Neutralization: Any pigments, waxes, free fatty acids, phospholipids in the extracted vegetable oil encourage fat oxidation that makes a way to undesirable colours and odours in a final product. These can be treated(removing impurities) with adding soda ash or caustic soda. Hence the impurities will settle down and now refined oils will appear light in colour, less sticky and more capable of oxidation.

Bleaching: To remove “off coloured materials” in oil, bleaching is practiced. Heated vegetable oil is treated with various bleaching agents such as activated clays, activated carbon, fuller’s earth. Most of the impurities are absorbed during bleaching and filtered.

Deodorization: This is the final step in refining vegetable oils, steaming is undergone at 500 degrees or more - extremely high temperature to remove volatiles compounds from oil, which would cause off-tastes and odours.

Now the oil produced is called  “refined vegetable oil” ready to consume by the human, almost all refined oils are adulterated with the huge amount of paraffin oil, glycerin, mineral oil, they are the byproduct of crude oil, which means waste from petroleum. Any oil is not supposed to be filtered nor refined, and by doing so it will become useless.

Hence do not waste your money in buying utter useless oils, completely harmful to our health. It is always wise to choose "chekku ennai”- “Wood pressed/Cold pressed oils”




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