Skip to content

Method for supercritical CO2 extraction of hemp seed oil

Method for supercritical CO2 extraction of hemp seed oil

Hemp seeds→crushing→packing extraction column→pressure extraction-decompression separation→crude oil hydration and degumming→deacidification→decolorization, dewaxing, filtration→deodorization→packaging→refined hemp seed oil

Method for supercritical CO2 extraction of hemp seed oil
Method for supercritical CO2 extraction of hemp seed oil

Specific steps

Supercritical CO2 extraction

Break the dried hemp seeds into pieces

Supercritical CO2 extraction

Put the crushed hemp seeds into the extraction kettle, then turn on the carbon dioxide cylinder, turn on the refrigerator, and adjust the extraction temperature and separation temperature to the set temperature at the same time. Turn on the plunger reciprocating pump to pressurize to the set extraction pressure, separation pressure, and adjust the carbon dioxide flow to the set value.

The extraction is carried out under these conditions, and when the set extraction time is reached, the hemp seed oil is collected from the separation kettle. (Most data show that the conditions for hemp seed oil supercritical CO2 are: pressure 30MPa, temperature 43°C, extraction time 3~4h)

Crude oil refining

Hydration and Degumming

The purpose of hydration is to remove the colloid in the crude oil, which is the pretreatment of alkali refining, decolorization and deodorization.
Because the colloid will decompose and be carbonized at high temperature, which will affect the color and quality of the finished oil.
The filtered crude oil is put into the hydration tank and the temperature is raised first. When the oil temperature reaches 60-75℃, it will be hydrated.

Add 2-3% oil weight and warm salt water at a stirring speed of 60 rpm, and stir for about 30 minutes. When the phospholipid particles are separated from the oil, reduce the stirring speed to 30 rpm and wait until the phospholipid particles are condensed and separated. At this time, the stirring is stopped, and the oil temperature rises to 80-90°C at this time, and the precipitation is transferred to the next process for more than eight hours.


According to the acid value and the amount of oil, find the required concentration and quantity of the lye, and prepare the alkali.
Add the prepared lye in about 10 minutes, and stir for 20-60 minutes at a speed of 60 rpm.
When the oil and soap particles in the emulsion are in a separated state, heat to 65-70°C at a heating rate of 1-1.5°C per minute, and reduce the stirring speed by 30 rpm. About 10 minutes, when the oil and soap particles are clearly separated, stop stirring. Leave it to settle for 6 to 8 hours, and move the lower oil feet to the soap feet pot, leaving the oil in the caustic refining tank.

Heat the purified oil to 70°C, add 65-70°C soft water at 15-30 revolutions and separate stirring speeds. The amount of water added is 8-10% of the oil weight to wash away the soap particles remaining in the purified oil. Let it stand for 1m2 hours, and put away the washing wastewater. If it does not meet the requirements, rewash.


Hemp seed oil has a darker color and is usually decolorized. Under normal circumstances, the amount of decolorizing agent should be minimized to reduce the loss of oil. Vacuum the washed oil into the decolorization tank, and first dehydration in the vacuum decolorization tank, and then under vacuum conditions Add activated clay for decolorization, the decolorization temperature is 95~100℃, and the decolorization time is about 20min.

After the decolorization is completed, the decolorization tank breaks the vacuum and sucks in nitrogen gas to form a certain protective layer on the high-temperature oil surface. The decolorizing oil is carried out alternately by two sheet filters, so that the grease in the decolorizing tank can be filtered at one time, which greatly shortens the filtering time.

The decolorized grease is easily oxidized and rancid. The residual oil in the filter is filtered by nitrogen pressure.

Dewaxing filtration

The wax in hemp seed oil mainly exists in the skin, and it can dissolve in the oil above 40℃, and it will form a precipitate at low temperature. Dewaxing generally adopts low temperature cooling and crystallization method to dewax.


The dewaxing oil is vacuum sucked into the deodorizing tank, the deodorizing temperature is 130~150℃, and the vacuum degree is above 0.093Ma. Deodorization time is 2.~3h. After deodorization, it is cooled to 30℃ under vacuum and nitrogen protection, and then packaged.


Refined hemp seed oil is usually packaged in 10kg plastic drums, filled with nitrogen after the oil is packed, and stored in a sealed airtight. In order to prevent oil oxidation and rancidity during storage and transportation, it is required to add VF when storing under low temperature and dark conditions as much as possible.

Leave a Reply

Your email address will not be published. Required fields are marked *