The extraction of oil and fat for food has always been an important part of human nutrition and culture. There is evidence that oil fruits such as poppies, rape and flax were cultivated as far back as the Neolithic period. The first oil mills appeared in the Minoan culture in 3500 B.C while Chinese sources from 2800 B.C. already mentioned soy and hemp as oil plants.
|Constituents, processing, origin|
|Types of edible oil|
|The best-known edible oils include:|
|Pressed or beaten: Differences in oil quality|
The rapid growth in the population in Europe in the 18th and 19th centuries was due solely to the industrial extraction of oils from plant seeds. Edible vegetable oil is one of the nutritional foundations on which western civilization is historically based.
The world's most important oil seeds are now the soy bean, palm fruit, rape, sunflower, cottonseed and maize. Sunflowers, rape and maize are primarily cultivated, processed and consumed in Europe. Olives are also processed, but on a rather small scale compared with other fruits, and are intended for direct consumption.
Oil can not only be extracted from plants, but also from marine animals such as whales, herring or the liver of other fish. This oil is rich in unsaturated fatty acids. However, it is not sold commercially as a pure fish oil or waltran for use as an edible oil. For this reason this will not be mentioned any further.
Mixed oils are normally cheaper and more heat resistant than oils from a single plant. They can be easily used for all kitchen processing methods such as frying, baking or deep frying.
- Cottonseed oil
- Dietary edible oil
- Thistle oil
- Peanut fat
- Peanut oil
- Linseed oil
- Maize oil
- Rapeseed oil
- Saflor oil
- Sesame oil
- Sunflower oil
- Special oils
- Wheatgerm oil
Edible oils can be produced either through cold pressing (up to 40°C) or hot pressing with extraction from the oil seeds or fruits.
The fruits and seeds from which the oil is extracted (oil fruits) are first cleaned and then crushed in rollers. The mush created during this process is then normally heated. The addition of chemical solvents finally "washes" the oil out of the heated mush, thus producing the raw oil.
The raw oil contains unwanted substances which make it cloudy and spoil it, and may have a negative effect on taste. These substances include plant residues, sludge, slime and free fatty acids. In order to separate these substances from the oil, it is refined. During refining, different chemical and mechanical processes are used to clean, de-lime, de-acidify and de-color the raw oil and free it from unwanted odors. The edible oil thus produced is stable, which means that no solid constituents settle during storage. Refined oil is also clear and light, and has a much more neutral taste and smell than untreated raw oil. Refining has no adverse effect on the valuable polyunsaturated fatty acids. Refined oils are suitable for the preparation of warm meals in the kitchen, e.g. for frying.
The quality of cold-pressed oil is very high since all the valuable substances originally contained in the oil fruit are preserved due to the gentle production method. Cold-pressed oil is characterized by a strong taste and intensive color. It can be called "natural" or "naturally pure". Cold-pressed oil is suitable for the preparation of cold meals and salads. Since it does not contain any preservatives, it should be used up quickly. Cold-pressed oil is not suitable for frying. From an ecological viewpoint, cold pressing uses less energy but only has a yield of between 10% and 30%. By comparison, hot pressing uses a great deal of energy but has a yield of 99.5%.