Animal fat : The left-over meat from the huge corporations is boiled to extract the fat has been used to adulterate present refined oils.
Mineral Oils : Refinery industry produces enormous amounts lower octane transparent mineral oils which cannot be used as (diesel or petrol) fuel. These oils are also slowly finding themselves in the cooking oils.
2. Use of plastic
The cooking oils ( for transportation and for plastic companies business) have been packeted in plastic containers of various kinds till the people use in their kitchens. This process impacts nanoparticles of plastic of various kinds into our bodies and intestines especially where absorption nutrients gets affected due to hydrophobic nature of these adhering nanoparticles of plastic leading to various diseases.
3. The companies use lot of chemicals and high temperature and pressure in the industrial process to extract oils, stabilize oils and transport oils. These are of course dangerous for human health.
Then How do you make cooking oils
Our ancestors were extracting oils using bulls driving the Wooden Ghanis oils thus extracted were natural and safe for human consumption. When you extract this way, oil does not get heated. Bull driven wooden ghani oils are extracted at NTP ( normal temperature and pressure).
Now a days some companies produce oils in the name of cold pressed oils in wooden Ghanis but use machines (RPM being high) to maximize extraction but sacrificing the quality (NTP) is not maintained due to high pressures generated by machines (high RPM).