Rapeseed oil comes from the seeds of rapeseed plants. You clean the seeds before they undergo other processes to extract oil. There are two methods of producing rapeseed oil: one by cold pressing and filtration, the other by applying heat and pressing the seeds. Add a solvent to the remaining solids and wash it off as the oil goes through further refining processes such as cooling, bleaching, and steam distillation.
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Extracting rapeseed oil in cold-pressed or hot-pressed method
The traditional method to extract oil from rapeseed is by cold-pressing. In fact, extracting oil from all types of seeds usually involves cold-pressing. This means that you clean and press the seeds without adding heat and chemicals like solvents. After filtering out the impurities, what remains is only the rapeseed oil. This method retains most of the rapeseeds’ nutrients.
The other method commonly occurs in commercial production and requires multiple processes resulting in a heavily processed rapeseed oil. To start with, heat and press the seeds and add a solvent called hexane to the remaining solids to extract more oil. Then wash the oil by adding caustic soda and spinning it at high speed using a centrifuge to separate the natural impurities. After that, cool the processed oil at low temperatures to thicken the wax and remove it from the oil. Then, finish the process with a bleaching process to lighten the color, and steam injection to remove unwanted odor. The result is processed rapeseed oil ready for packaging.
From rapeseed plant to cooking oil and other industrial oils
Between both rapeseed oil processing types of extraction, the cold-pressed method is healthier since it doesn’t undergo multiple processes such as high-temperature refining and the addition of chemicals. This method, however, can only extract around 70% of the oil from the seeds. Refined or hot-pressed rapeseed oil, in its turn, extracts up to 98% of it. But this process removes some of the nutrients that are naturally present in the seeds.
Rapeseed oil is one of the major vegetable oils available in the world. It comes from rapeseed plants, and these plants are extremely vulnerable to pests and diseases. And, while you need to treat them with fungicides and insecticides to protect it, this may also harm pollinating insects and other wildlife. Alternatives such as palm oil and olive oil require less pesticides for their plants. Palm oil has better yield and has the least amount of chemicals used in growing. But it also requires a huge land area that can cause destruction of natural habitats.
Regulations in rapeseed oil processing
Some rapeseed plants come from genetically modified (GMO) seeds. In European countries, farmers cannot grow most GMO crops. However, countries like US, Canada, Japan, and China allow GMO crops. Another regulation to consider is the amount of erucic acid in the oil. It is a monounsaturated fatty acid which is deemed detrimental to health at high levels. Depending on the country, rapeseed oil is known as “canola oil” when used for cooking. To be safe for this activity, though, the erucic acid level should be around 2% or less. It is also possible to use rapeseed oil for automotive and chemical industry applications such as lubricants and biodiesel.