Refined edible oil refers to the refined oil obtained by decoloration, degumming, dehydration and deodorization. Dewaxing is a process in edible oil refining process, and its purpose is to improve the quality, nutritional value and industrial utilization value of oil. So do all refined edible oils need dewaxing?

Not all refined edible oils need dewaxing. ‌
The principle of dewaxing is to separate wax with high melting point from oil by cooling, and then separate it from oil by filtration or centrifugal separation, so as to improve the quality and storage stability of oil. For some edible oils, such as first-class soybean oil and rapeseed oil, dewaxing process is usually needed in the production process, because most of the wax contained in these oils comes from the seed coat and germ of the oil, and the wax has a high melting point, which will crystallize at low temperature, affecting the quality and storage stability of edible oils. However, linseed oil, for example, does not need to be dewaxed separately if the oil temperature is lower than 45℃ by low temperature pressing process.

The process of oil dewaxing usually includes the following steps:

1. Cooling: First, the oil is cooled to a low temperature, usually below 0℃, which depends on the type of oil and the melting point of wax. The process of cooling makes wax begin to crystallize.

2. Crystallization: At low temperature, wax will gradually form larger crystalline particles. In order to promote the formation of crystals, slow cooling and slow stirring can be adopted, which is beneficial to the formation of crystal nuclei and the growth of crystals.

3. Filtering or centrifugal separation: When the wax is fully crystallized, the crystallized wax is separated from the oil by filtering or centrifugation. Filtration usually uses equipment such as plate-and-frame filter or filter paper, while centrifugal separation uses centrifuge.

4. Heating: Finally, the dewaxed oil is heated to normal temperature to restore it to liquid state for subsequent processing and use.

Generally speaking, whether refined edible oil needs dewaxing depends on the type of edible oil, processing technology and expected product quality.