Oil fractionation is a technology method that the different triglycerides are classified by their

different properties.

The basic principle of oil-fat fractionation as below:

Oil-fat is a mixture of various triglycerides. Due to the different types and distribution of fatty acids, the difference in solubility or melting point is formed from each component of triglycerides

under different degrees.

By making use of the differences in the properties of various triglycerides, the corresponding cooling and crystallization conditions are created to make the solid lipids of various properties crystallized and separated from the original solution in a relatively pure state.

The Affecting Factors of Oil-fat Fractionation as below:

①Cooling temperature and cooling rate   ②Crystallization time   ③Stirring speed  

④Auxiliary agent   ⑤Transportation and separation method   ⑥Oil-fat quality

Take rapeseed oil press equipment as an example

1.Hot Pressing: Rapeseed - Cleaning - Frying - Pressing - Filtering - Finished rapeseed oil

The rapeseeds are screened by (aperture of 0.6mm) 30 mesh / inch, so that their impurity content is less than 0.5%. Their moisture content is about 9% after softening, When the rapeseeds are steamed and fried as the oil temperature of 110-120℃ and the moisture content of about 1-1.5%, they can be pressed by the oil press. If use cylindrical frying pan, the rapeseeds can be directly put into it or flat pan after cleaning. But when the rapeseeds are fried up to 110-120℃ after added 2-3% water, they can be out of the pot, and be pressed at once. When hot pressing, it can be judged whether the rapeseeds are fried well by the following method: wipe the rapeseeds with two wooden plates. If the shell and kernel are separated, the color of kernel is deep, then good quality. If the kernel is powdered, too dry. If the shell and kernel are not separated, too wet.

2.Cold Pressing: Rapeseed - Cleaning - Pressing - Filtering - Finished rapeseed oil

When cold pressing, remove the impurities from the rapeseeds, no need a frying pan. The moisture content of the rapeseeds will directly affect the oil production during cold pressing. Therefore, it is very important to judge whether the oil material is dry or wet. Generally, the moisture content of the rapeseeds is controlled at 5-8% before pressing. To judge the moisture content of the rapeseed by local method, you can squeeze a rapeseed with your fingernail. If it’ divided into two pieces with sounds and oil extrusion, the moisture content is appropriate. If powdered, too dry. If flat, too wet.

General Problems during the Oil-Pressing: The oil content of the rapeseeds is up to 33-40%. Generally, there is no abnormal phenomenon in hot pressing as the operation instructions.

If improper the moisture content, abnormal operation or temperature of rapeseed presser when cold pressing, there are phenomena such as slag running, oil return or feeding problems, etc. then the cold pressing treatment of peanut kernel can be referred.