Differences Between
Cold Pressed vs Heat Extraction & Solvent Extracted Vegetable Oils
Cold Press (also referred to as Cold Milling)
Cold pressed oil is extracted by squeezing or pressing in a big press, without chemicals. Cold pressing does use low temperature heat, in a heat-controlled environment. To prevent denaturing of the oil seed's protein, temperatures are kept below 158 degrees F (70C). HIgher temperatures can damage or destroy the quality of precious oils. With cold process the oil remaining from seeds, nuts or vegetables has no trace of chemicals and no poisonous trans fatty acids. Cold pressing also maintains more of the oil's nutrients.
Heat Press
Heat pressing increases the yielded quantity of oil, and why cold pressed oils are more expensive than heat pressed oils.
Heat pressing is the application of heat in conjunction with mechanical pressure to extract oil from seeds.
Solvent (Chemical) Extraction
Solvent extraction refers to the process of extracting oil from oil bearing materials by means of solvent. Solvent always use a petroleum by-product, normally Hexane. The process is followed by distillation, to remove the solvent from the extracted oil.
When poisons (insecticides, herbicides, fungicides) are used by agribusiness to grow seed, nut and vegetable oil crops, molecules of those poisons show up in the extracted oil. To fully extract the oils, high heat and a powerful solvent is used, normally hexane. Molecules of hexane is possibly found in commercial oils.
Hexanes are significant constituents of gasoline. They are all colorless liquids at room temperature, with boiling points between 50 and 70 °C, with gasoline-like odor. They are widely used as cheap, relatively safe, largely un-reactive, and easily evaporated non-polar solvents.
Heat extraction can bring whatever poisonous molecules are in the oils to the user. Although these may only be in trace amounts, they can still be poison to the body. The liver will extract some of the poisons as waste with some remaining in the body, being stored in body tissues. These stored poisons do not go away.
Pretreatment of Plant Oils Prior to Extraction
The pretreatment for vegetable oil processing or edible oil processing usually means the working procedures of removing impurities from the vegetable oil materials. These impurities are generally referred to as organic and inorganic impurities. The organic impurities include the stem leaf, cord, chemical fibers, velveteen and their seeds. The inorganic impurities, however, sometimes mean soil, dinas and metal. The vegetable oil processing industry involves; the extraction and processing of oils and fats from vegetable sources. The preparation of raw materials includes; husking, cleaning, crushing, and conditioning. (source)
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