The difference between crude oil and refined oil
Crude oil refers to the primary oil that has not been refined from vegetable oils (the main component is a mixture of triglycerides (commonly known as neutral oil); it also contains non-glycerol substances, collectively referred to as impurities). Due to the simple processing technology, this oil contains many impurities, is easily oxidized and deteriorated, and is not suitable for long-term storage. The edible oil squeezed out using the screw press is also treated as a crude oil without being treated by the crude oil refining equipment.
Refined oil refers to the refining of wool oil through the refining equipment of wool oil. The refined edible oil should meet the quality standards set by the state, mainly because the water, impurities, acid value and peroxide value of the oil meet the quality set by the state. Standard; and not easy to rancid and deteriorate, but is conducive to storage, does not produce a large amount of soot when cooking; such oil is a refined edible oil.
The difference between wool and refined oil is mainly due to the different processing techniques of crude oil and refined oil.
1. Crude oil processing technology
Crude oil refers to the primary oil that has not been refined from vegetable oil. If the oil is pressed by a screw press, the spiral rotation of the screw shaft causes the spiral to shrink as the lead is reduced or the diameter of the root circle is gradually increased, so that the volume of the pressing space is continuously reduced and the pressing effect is generated; The squeeze cage is squeezed out and the residue is pressed into a crumb cake, which is continuously discharged from the end of the press shaft. Spiral oil press press oil extraction can be divided into three stages, namely feeding (pre-pressing) section, main pressing (oiling) section, forming cake (heavy pressure draining) section, and the pressed oil is not hairy. Oil refining equipment processing, belonging to wool oil.
2. Refined oil processing technology
- mechanical method: including precipitation, filtration, centrifugal separation, mainly used to separate some of the peptizing impurities used in mechanical impurities suspended in oil;
- chemical methods: mainly including acid refining, alkali refining, in addition, There are also lipidation, oxidation, etc., acidification is treated with acid, mainly to remove pigments, peptized impurities, alkali refining is treated with alkali, mainly to remove free fatty acids, oxidation is mainly used for decolorization.
- physical and chemical methods: mainly include hydration, decolorization, steam distillation, etc., hydration mainly removes phospholipids, decolorization mainly removes pigments, and steam distillation is used to remove odor substances and free fatty acids.
- The oil is refined through refining. The water, impurities, acid value and peroxide value of the oil meet the quality standards set by the state, and it is not easy to be rancid and deteriorated. It is advantageous for storage, does not produce a large amount of soot during cooking, and maintains the flavor of oil.
