category: food/groceries: cooking fat

Edible oils, vegetable oils

There are many seeds, kernels and fruits containing oil. Oil has been extracted from plants for thousands of years. One of the oldest sources of oil is the fruit of the olive tree. On the Greek island Crete olives were cultivated for the production of oil as early as 3500 BC.

Plants are not the only source for edible oil. Marine animals like whales or herring and the liver of several fish are also used as source for oils rich in unsaturated fatty acids. Pure fish or whale oil is not sold as edible oil though. It is used for the production of margarine and canned fish. Edible oils sold to the end customer are always plant derived. Depending on the used plant and production method they differ in taste and properties.

Crude oil; Production of vegetable oil

For the production of edible oil fruits and seeds containing oil (oleaginous fruits) are washed and crushed between rolls. The crushed pulp is then heated. Chemical solvents are added to wash the oil out. Crude oil is the result of this treatment.

Crude oil is considered to be inedible. It contains impurities that don't look and taste good and let it perish quickly. These impurities are often plant matters and free fatty acids. The oil is refined to separate impurities from the end product. The crude oil is clarified, degummed, bleached and neutralised through several chemical and mechanical processes. The end product does not contain any solids that could settle out during storage. Refined oil is clear and light and considerably more neutral in taste and smell. Valuable unsaturated fatty acids are not destroyed during refinement. Refined oils are well suited for the preparation of warm foods, for example to fry.

Cold-pressed oil is produced through mechanical extraction from the oleaginous fruits and filtration of the oil. Heat generated during extrusion may have negative effects on the quality of the oil. The presses are therefore cooled to ensure full quality. Cold pressed oil is only clarified through filtration in special filters.

Cold-pressed oil is of higher quality, because the gentle production method preserves all valuable properties of the oleaginous fruit. Compared to refined oil, cold-pressed varieties are stronger in taste and colour. Cold-pressed oils are well suited for the preparation of cold foods and salads. It should be used quickly, since it does not contain preservatives and perishes faster than refined oils.

Vegetable oil varieties

Vegetable oils sold to the end customer are derived from one plant or may be a mixture of several plant oils. Where oil is named after a specific plant, it has to be pure and no other oil may be mixed in. Oils mixed from several plants are simply called vegetable oil and mostly sold under a brand name only.

In general mixed vegetable oils are cheaper and have a better heat stability than oils produced from one plant only. They may be used for frying, baking and deep-frying.

Well-known vegetable oils

• cotton seed oil
• diet oil
• safflower oil
• hydrogenated peanut oil
• peanut butter
• peanut oil
• linseed oil
• corn oil
• rapeseed oil
• sesame oil
• sunflower oil
• wheat germ oil
• special oils