How is salad oil made?

Find out the English name again. Salad oil is salad oil, salad oil, but salad oil is also welcome. Just figure out what salad oil is.

Salad oil is called salad oil or vegetable oil in Taiwan Province province, salad oil in Chinese mainland and salad oil in Hongkong. Refers to high-grade edible oil, which is used as cold salad and seasoning oil. It tastes good and will remain clear and transparent after being put in the refrigerator for several hours. General refined blending oil, such as corn oil plus rapeseed oil, or corn oil plus soybean oil can be used as salad oil. The mainland has strict standards for salad oil, and now there are many mustard seed salad oil, rapeseed salad oil and soybean salad oil. All the above are refined salad oil. As for sesame oil, it is very fragrant in our country. It can be eaten raw, cold or salad oil, but sesame oil has not been refined.

The process of oil refining is by no means simple in food technology. At present, the industry mainly uses the methods of squeezing and extracting to prepare vegetable oil, or uses the method of squeezing first and then extracting to get oil. Oil seeds with less oil content are mostly extracted by leaching or preloading leaching. For those with high oil content, such as peanuts, sesame seeds are mostly extracted by pressing.

Squeezing oil is to squeeze oil from squeezed materials with an oil press. For example, in the oil mills in Chinese mainland or in Hong Kong before, the heat-treated peanuts or sesame seeds were put into a screw oil press to extract D oil, then filtered and bottled for sale. The remaining residue is called oil meal. These "fragrant peanut oil" belong to "crude oil", that is, unrefined oil containing colloid, free fatty acid, water, aflatoxin and other impurities. However, if the peanuts are carefully selected and there is no mildew and deterioration, these raw oils are edible, but they are not easy to deteriorate due to many impurities.

Extraction of oil by leaching is to soak and wash the oil with organic solvent, so that the oil is dissolved in the solvent to obtain a mixture of solvent and oil, and then heat and evaporate to volatilize the solvent, leaving the oil. For example, soybean is softened and crushed, made into thin slices, soaked in "hexane" organic solvent commonly known as "light gasoline", and the leached solution is mixed oil of soybean oil and gasoline, and then heated and separated according to the different boiling points of soybean oil and light gasoline. The soybean oil taken out is also crude oil, and the recovered light gasoline is recycled.

These leached crude oils are inedible without refining. Because light gasoline is toxic, besides 90% hexane, there are carcinogens such as benzene and toluene. In addition to selling "fragrant peanut oil", we rarely see oil companies publicize how to do their products, for fear of affecting sales.

In fact, we have been eating oil extracted by leaching for a long time. Europe and America have used this method for decades. If the refining technology is high, it should be no problem for health to control the residual amount of organic solvents within tens of parts per million (PPM), but if the factory equipment is poor, the technology is insufficient, the government supervision is not in place, or the factory is full of tricks, it will be difficult.

There is less residual oil in leaching residue and more residual oil in pressing residue. Therefore, some factories use pressing to get crude oil first, and then extract the remaining oil from the cake to improve efficiency. This is called preloading leaching.

Refining is to remove impurities from crude oil, and the process is very complicated. Simply put, the process includes filtering suspended impurities, degumming, deacidification, decoloration, deodorization and dewaxing. In the deodorizing process, the organic solvent is removed by high-temperature vacuum steam distillation. Of course, it can't be completely removed, and trace residues are inevitable.

The oil sold in Hong Kong now doesn't explain how to do it. Luzhou-flavor peanut oil, sesame oil and millet oil are all extracted by pressing, while soybean oil is mainly leached. As for rapeseed oil, cottonseed oil and mustard rapeseed oil, most of them are extracted by pre-pressing, while ordinary peanut oil is extracted by pressing or pre-pressing.

Finally, olive oil, which is also salad oil, is obtained by pressing.