Some people consider that pressed oil is better than refined oil. They think pressed oil is more natural and healthy. However, the refined oil is actually underrated for a long time.
First, the refined oil contains less impurities than pressed oil. Those impurities might make the oil smells better, but they might also make the oil smells worse. The impurities will also effect the color of the oil to make it darker. Besides, there are many impurities that can make the oil more easily to be oxidized, which will reduce the shelf life of the oil. Some impurities are even harmful to health, such as aflatoxin.
Some people are afraid that there are chemical additive in the refined oil. However, with several steps of chemical and physical processing, the additives will be almost totally removed. There are also many standards ruling the contents in the refined oil to ensure the quality and safety.
The refined oil also has a higher yield compared with pressed oil. There are still many residue oil after pressing. In the production of refined oil, the extraction can make use of these oil. As the yield is higher, the price will become relatively lower.
The pressed oil might have some advantages to refined oil, but refined oil has becoming more and more popular now, and it is also playing an important part in food industry. Finally, the qualiified refined oil is never harmful.