PRESSING
The harvested oil seeds, such as rapeseed or sunflower seed, are first mechanically cleaned and dried. The cleaned seeds are then crushed in large mills and the crushed seed is pressed in strong screw extrusion or hydraulic presses. This separates the oil from the so-called “cake”. This oil is known as “cold-pressed” or “pressed” oil, depending on the temperature. The oil still in the “cake” is extracted using a solvent. What is left is the almost fat-free meal, which is used as protein-rich animal fodder.
REFINING
The raw oil obtained from the oil seeds is not usually suitable for human consumption. It has a strong colour, is cloudy and has an intense, unpleasant taste and a short storage life. Consumers expect a clear, light, odourless, neutral tasting, all-purpose edible oil. Cold-pressed oils can only be used for very specific applications such as salads, raw foods and suchlike, when these foods are complemented by the typical usually very intense, unique taste.
The refining or cleaning process removes the unwanted components that accompany the raw oil, such as water, gum, colorants, free fatty acids, dirt particles, pesticide residues and unwanted flavourings. The desirable ingredients such as a number of unsaturated fatty acids and vitamin E remain behind.
Refining is carried out in the following stages:
Degumming
The gum and coagulated cell parts (residues from the pressing process) mixed with the oil are removed, as these materials reduce the quality and shelf life of the oil.
Neutralisation
Some oils are washed with an alkali followed by several rinses with fresh water and drying. Free fatty acids (= broken down fat molecules), which are caused by the aging process of the seeds in the field, are washed out along with fibres and gums.
Bleaching
Bleaching is carried out by the addition of earth clay or Fuller’s earth. The porous substance soaks up the coloured components of the raw oil, bleaching it and binding the rest of the impurities. This process is carried out at 90°C under gentle agitation with the exclusion of air. The oil is then filtered to separate out the earth clay.
Winterisation
Winterisation is the process of removing waxes that come from the seed heads of sunflowers and safflowers. The oil is slowly cooled to about 4° C to solidify the wax components. The solidified wax is then removed from the oil by filtering. Winterised oil remains clear and transparent even at low temperatures.
Deodorisation
Air is fully excluded and the oil is now heated to about 220° C and subjected to steam treatment. This refines the oil in a natural, physical manner. The steam removes any remaining impurities, especially unpleasant odours and any pesticide residues. The oil is also cooled in a vacuum.
The end product is a pure, light, mild edible oil with a fine flavour, free of residues. The important unsaturated fatty acids and about 80% of the vitamin E are retained. In top quality oils, the vitamin E content is restored to its original content.
The harvested oil seeds, such as rapeseed or sunflower seed, are first mechanically cleaned and dried. The cleaned seeds are then crushed in large mills and the crushed seed is pressed in strong screw extrusion or hydraulic presses. This separates the oil from the so-called “cake”. This oil is known as “cold-pressed” or “pressed” oil, depending on the temperature. The oil still in the “cake” is extracted using a solvent. What is left is the almost fat-free meal, which is used as protein-rich animal fodder.
REFINING
The raw oil obtained from the oil seeds is not usually suitable for human consumption. It has a strong colour, is cloudy and has an intense, unpleasant taste and a short storage life. Consumers expect a clear, light, odourless, neutral tasting, all-purpose edible oil. Cold-pressed oils can only be used for very specific applications such as salads, raw foods and suchlike, when these foods are complemented by the typical usually very intense, unique taste.
The refining or cleaning process removes the unwanted components that accompany the raw oil, such as water, gum, colorants, free fatty acids, dirt particles, pesticide residues and unwanted flavourings. The desirable ingredients such as a number of unsaturated fatty acids and vitamin E remain behind.
Refining is carried out in the following stages:
Degumming
The gum and coagulated cell parts (residues from the pressing process) mixed with the oil are removed, as these materials reduce the quality and shelf life of the oil.
Neutralisation
Some oils are washed with an alkali followed by several rinses with fresh water and drying. Free fatty acids (= broken down fat molecules), which are caused by the aging process of the seeds in the field, are washed out along with fibres and gums.
Bleaching
Bleaching is carried out by the addition of earth clay or Fuller’s earth. The porous substance soaks up the coloured components of the raw oil, bleaching it and binding the rest of the impurities. This process is carried out at 90°C under gentle agitation with the exclusion of air. The oil is then filtered to separate out the earth clay.
Winterisation
Winterisation is the process of removing waxes that come from the seed heads of sunflowers and safflowers. The oil is slowly cooled to about 4° C to solidify the wax components. The solidified wax is then removed from the oil by filtering. Winterised oil remains clear and transparent even at low temperatures.
Deodorisation
Air is fully excluded and the oil is now heated to about 220° C and subjected to steam treatment. This refines the oil in a natural, physical manner. The steam removes any remaining impurities, especially unpleasant odours and any pesticide residues. The oil is also cooled in a vacuum.
The end product is a pure, light, mild edible oil with a fine flavour, free of residues. The important unsaturated fatty acids and about 80% of the vitamin E are retained. In top quality oils, the vitamin E content is restored to its original content.
