The quality of an edible oil is not determined by the pressing process alone, several other factors are to be considered. The filtering of the oil is very important. There are essentially three different methods which are illustrated here:
Cold pressing ("cold-pressed edible oil")
The raw material rape is lightly crushed so that the husk opens, it is then pressed in a roller press without warming.
The emerging oil is separated from the solids through a large filter and bottled.
- no vitamins are destroyed, the oil is "purely natural".
- Due to ineffective filtration various impurities, suspended solids as well as also water are still present in the oil. Also the remaining free fatty acids strongly tend towards oxidation, the oil will quickly turn rancid and will only keep for a maximum of 3 months.
- A strong flavour of rape seed remains in the oil. This is not for everyone's taste.
- Use: only for cold food, unsuitable for heating.
Warm pressing with extraction ("refined edible oil")
The seed is crushed, heated briefly to almost 100°C and pressed in a roller press. As a result, the remaining oil from the pressing residue is washed out or so to say extracted with a chemical solvent, usually hexane. The subsequent distillation tries then to separate the solvent residues from the oil. Then purification (=refining) of the oil in a refining plant and separation of the free fatty acids through the addition of alkalis (saponification).
- high oil yield (about 99%)
- because the yield would be so low soy oil and sunflower oil are almost impossible to produce economically without using chemical extraction.
- extensive use of chemicals required.
Warm pressing without extraction as with Rapso
The seed is crushed, heated briefly to almost 100°C and pressed in the roller press. Using refining techniques the oil is then separated from solids and impurities via centrifuges and filters. This is a physical distillation process specially developed by us, through which the free fatty acids can be separated from the oil without the use of chemicals.
- The naturally high content of vitamin E remains.
- By refining (filtering) the oil has a neutral taste and can be kept longer: 1 year after filling.
- Due to our filtering process the oil can be heated (smoking point just over 205 °C). It is therefore suitable for all cooking purposes (salads, roasting, baking, frying, etc.)
- Through our process the oil is tasteless and does not overpower the flavour of the food.
- Pressing without using chemicals results in a lower oil yield (approx. -9%), however the remaining oilcake can be used in organic farming as animal feed and fertilizer.
- lower oil yield
After production completion Rapso is stored immediately next to the oil mill in tall, narrow stainless steel tanks and bottled on site in light-protective glass bottles. Transporting the oil is unnecessary, oxidation is avoided from the beginning.