The chemical extraction process uses chemicals such as "vegetable oil extraction solvent" to fully soak the raw oil. The oil is then extracted at temperatures exceeding 120-130°C. The oil is then processed into edible oil through processes such as degreasing, degumming, dehydration, decolorization, deodorization, and deacidification. Numerous chemical agents are used throughout this process to transform the crude oil into a clarified, finished product.

The key advantages of chemical extraction are its high oil yield and low production costs. Li Li, former vice president of China Agricultural University and professor of food engineering, explained that the extraction method allows the raw oil to be fully compressed, leaving very low oil residues, less than 1%. This high oil yield, especially the ability to extract more oil from oilseeds with low oil content, is the most important reason for choosing chemical extraction. However, the extraction process not only uses chemicals, which leave trace chemical residues, but also destroys the bioactive substances and nutrients in the oil.

Chemical extraction is a common method used worldwide to produce edible oil. It's used in countries and regions with strict food safety standards, such as Japan, the United States, and the European Union. Over 80% of edible oil manufacturers use extraction. "However, long-term research and practice worldwide have proven that current residue standards are reliable, and reputably produced extracted oil is completely safe for consumption."

High-end oils such as peanut oil and olive oil are suitable for cold pressing.

Cold pressing is a production process known as "physical pressing." The temperature is typically between 60 and 80°C, preserving the oil's active ingredients and nutrients. Many manufacturers claim that cold-pressed oil is all-natural, avoiding the adverse effects of traditional high-temperature pressing. The finished cold-pressed oil retains the oil's natural flavor and color, preserving its active ingredients. Crucially, physical pressing uses no chemicals, resulting in no chemical residues and protecting nutrients like linoleic acid, unsaturated fatty acids, and vitamin E. However, the oil yield is low.

However, most oils are not suitable for cold pressing. Refining is essential to remove the beany flavor of soybean oil, the acrid flavor of high-erucic acid rapeseed oil, the gossypol toxin in cottonseed oil, and aflatoxins from spoiled oils. Sesame oil and fragrant peanut oil also require hot pressing to achieve their fragrant aroma. Therefore, cold pressing, known as "physical pressing," is currently primarily used in China for high-end oils such as peanut oil, olive oil, nut oil, and sesame oil. Wang Junzi, Secretary-General of the China Vegetable Oil Industry Association, believes that from a safety and environmental perspective, pressed oil, because it retains its original nutrients and offers a purer quality, meets the public's pursuit of health and environmental protection.

Expert Opinion

Both pressing methods must comply with relevant standards.

Is cold-pressed oil truly healthier than extracted oil? Not necessarily! Cold-pressed oil raw materials must be carefully selected. Otherwise, due to the varying maturity of the raw materials and the presence of harmful substances (such as aflatoxins in moldy oil), residual oil in pipelines, storage tanks, and filters can become rancid, easily causing the filtered oil's peroxide value to increase and produce an unpleasant odor. Professor Wang Xingguo, Vice President of the China Oils and Fats Professionals Association and Professor of the School of Food Science at Jiangnan University, stated, "Regardless of the process, the resulting oil is still crude oil (also called crude oil), which generally contains substances harmful to the human body and cannot be consumed directly. Refining is required to further remove these harmful substances."