Cold pressed oils retain their nutritional value, flavor, aroma that are otherwise damaged by heat treatment. They contain anti-oxidants that help fight free radicals harming our body cells. Rich in vitamins, most cold pressed oils have anti-inflammatory and healing properties. They are a good source of oleic acid that can help you boost your immune system and hence preferred as cooking oils. However, it is advisable to cook these oils on low heat since they lose their nutritional value once you expose them to high temperatures.
Cold pressed oils are extracted through moderate pressure which are organic from seeds, nuts and even vegetables, exactly how our ancestors extracted it 1000 of years ago. Cold pressed oil refers to a method of oil extraction where the oilseeds are crushed and pressed (without using heat) to extract oil. These oils are more nutritious to our body than the highly refined oils and plus enhance the taste of our food if used in cooking. The entire process involves pressure and no heat and that is what makes this oil healthier than any other form.
Most of seeds oils cannot yield oil through natural extraction techniques. Some manufactures produce oil with using chemical treatment and refining techniques to remove residues of chemicals from refined oils.
Refined oils could have harmful effect on health because of chemical methods are used for the extraction of them.
The typical industrial or commercial oil extraction process begins by using a mechanical extractor for pressing the constituents followed by chemical extraction. Today solvent extraction is standard in the vegetable oil industry.
The process of refined oil extraction:
The mechanical extractor presses the oil seeds for example – sesame, rapeseed, peanut, sunflower, mustard, or coconut pieces ground into coarse meal to provide more surface area to be pressed.
Heat the coarse meal in very high temperatures (up to 270°C) to start the oil extraction process.
The mixture of oil and seed pulp is then chemically processed with a hexane solvent (produced by refining crude petroleum oil) to extract any residual oil from the pulp.
This resulting mixture is then put through a centrifuge and phosphate is used to separate the oil from the seed residues.
The extracted oil plus solvent mixture is then subjected to the next processes: degumming, neutralization, washing.
During degumming process water is added. This reaction with water results in hydrated phosphatides, which can be separated by decantation or by centrifuges.
During neutralization process the resulting product from the above steps contains fatty acids, phospholipids, pigments, waxes, etc. These impurities are removed by using caustic soda (sodium hydroxide) or soda ash (sodium carbonate). The refined oil is lighter in color, less viscous and easily prone to oxidation.
Bleaching is done to remove off colored materials. Bleaching agents are used in this process.
To remove volatile compounds which cause off odors and taste in the final product is applied pressurized steam at very high temperatures 260°C (500F). This process is called deodorization and that is why refined oils called deodorized.
This process of refined oil production kills all the nutrition. This chemical process yields oil that is very unhealthy, but very consistent in terms of color, smell, odor and shelf life. When you take a natural food product and expose it to multiple chemical processes, how can it be natural and healthy?