According to whether the materials are heat treated before pressing, pressing can be divided into hot pressing and cold pressing. Using cold pressing technology to make oil is to avoid overheating and excessive chemical treatment of oil, so that the quality of refined oil and cake can be improved accordingly, such as the taste and appearance of oil, and the natural characteristics of oil can be maintained, so as to avoid producing harmful substances when processing oil at high temperature.
As far as possible, the physiological active substances in the oil are retained, and the cake protein after oil processing can be more fully utilized. First-class pressing refers to the grade of physical pressing technology. According to the relevant national standards, most edible oils (such as soybean oil, corn oil and peanut oil) are divided into first, second, third and fourth grades according to the quality from high to low.
The higher the grade of edible oil, the higher the refining degree. Take olive oil as an example. First-class pressed olive oil, also known as VIRGIN, means the purest olive oil. Only this kind can be used on the skin, and of course it can also be eaten.
But for cold pressing, a lot of alkali should be added when pressing, in order to deacidify. This will have an impact on the skin, and can't be used for beauty. It can only be eaten.
Excuse me, what is the difference between pressing and cold pressing edible oil?
Pressing is a unit operation to separate liquid phase from liquid-solid two-phase mixture by mechanical compression force. Squeezing technology is mainly used in oil industry and juice making of fruits and vegetables. Cold-pressed oil-making technology is a kind of oil-making technology, which directly presses the oil without embryo rolling or steam frying at room temperature to 65 degrees Celsius by a low-temperature oil press to obtain oil and cake with nutritional value and unchanged molecular structure.
The pressing oil extraction process is simple, with few supporting equipment, strong adaptability to oil varieties, flexible production, good oil quality, light color and pure flavor. However, after pressing, the cake has high residual oil, high power consumption and easy loss of parts. Cold-pressed oil production is a physical method, which pressurizes without raising the temperature, and has no effect on the nutrients of oil.
At the same time, this process not only has the general characteristics of ordinary oil-making process, but also can improve the quality of oil, avoid the production of trans fatty acids, oil polymer and other harmful substances in oil due to high-temperature processing, and retain the active substances in oil.