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download articleEdible Oils
Article index
 | Current trends | |
| 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.
Current trends
18.5 million tons of oil were produced from plants in 2004. Demand will rise quickly due to this oil's additional advantage as a substitute for mineral oil.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.
Constituents, processing, origin
Edible oil contributes unsaturated fatty acids to people's diet. The recommended daily intake of these fatty acids is 10 grams. Oils contains vitamins E, D, K and A. In particular, vitamin E is important as an antioxidant. Since these oil constituents are very sensitive, the process must be controlled very precisely. A large number of products, for example palm oil, must be processed directly after harvesting in order to prevent spoilage. This leads to very harsh conditions for the plantations which are often located in inhospitable areas close to the Equator. Since harvesting is a seasonal business, the installed machines must be able to readily cope with these burdens on production and the difficult climatic conditions.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.
Types of edible oil
Commercial edible oils come from one specific plant or are a mixture of several plant oils. If oils have a specific plant name, they must stem from the pure unmixed oil of this plant. Mixed oils are called table oil, edible oil or vegetable oil. Mixed oils are mostly sold under a brand name. References to the utilized plant oils are only permissible if their type and proportion are shown on the label.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.
The best-known edible oils include:
- 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.
Pressed or beaten: Differences in oil quality
Cold-pressed or cold-beaten oil is obtained solely through pressing and subsequent filtering of the oil fruits. Pressing of the oil fruits may produce heat which has an unfavorable effect on the quality of the oil. The oil press is therefore cooled to ensure high-quality oil. The oil is only cleaned in special filter systems.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%.
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