The CO2 extraction process of linseed oil from linseed meal

Flax seed extract

The oil content of flax seed is over 35%. Flaxseed oil is rich in alpha-linolenic acid. Actually, it is identified with 13 kinds of fatty acids including 4 kinds of saturated fatty acid and 9 kinds of unsaturated fatty acid ( linolenic acid 49.05%, oleic acid 22.34%, linoleic acid 13.73% ).

Notes: The alpha-linolenic acid in soybean oil was 7.8%, and the alpha-linic acid in peanut oil was 1.5%, and the alpha-linolenic acid in rice bran was only 1.1%.

Deep Sea Fish Oil Vs. Flax Seed Oil

flaxseed oil vs fish oil In the global market, deep sea fish oil has always been the main supplement of n-3 fatty acids. But long-term use of fish oil has the risk of Vitamin A and vitamin D poisoning, vitamin E intake imbalance, and high cholesterol. Besides, the sea resources reducing and the fish oil price keeps rising. Fish oil is getting difficult to accept by consumers.
The main source of n-3 fatty acids is alpha-linolenic acid. So developing flax seed oil which is rich in alpha-linolenic acid, sufficient in resources, and low in price is definitely a promising project with great economic value.

Other Kinds of Flaxseed Extracts

Except for oil products, there are also other kinds of extracts processed from flax seeds, such as flax gum, lignans, and flax protein.

Flaxseed Gum

Flaxseed gum is a new type of natural plant colloid extracted from flaxseed. It exists in the flaxseed shell with content of 10~15%. Flax gum is one of the best sources of soluble dietary fiber. As a good alternative to pectin, agar, Arabic gum, and seaweed glue, flaxseed gum can also be used as a thickening agent, adhesive, stabilizer, emulsifier, and foaming agent in the food processing industry.

Lignans

Lignans is a kind of phytoestrogen. Lignans are widely existed in plants and foods, especially whole grains and beans. Flaxseed has the highest content of lignans (0.7% ~ 2%), which is 75 ~ 800 times higher than other food. Lignans help inhibit estrogen and tumor proliferation. It has a therapeutic effect on hyperlipidemia and acute coronary heart disease and also has oxidation resistance and anti-aging effect.

Supercritical CO2 extraction of linseed oil from linseed meal
The CO2 extraction process of linseed oil from linseed meal

The CO2 extraction method for linseed oil

First, the flax meal is crushed, then a certain amount is weighed it into the material cylinder, and the kettle is covered. After reaching the experimental setting parameters, cyclic extraction. Discharge once every half an hour until no product is discharged.

Determine the oil content of linseed meal→crush the linseed meal→weigh and incorporate it into the kettle→supercritical CO2 extraction→separation→linseed oil.

CO2 Extraction Process of linseed oil

  • Pulverization degree:60 mesh
  • Extraction pressure: 30 MPa
  • Extraction temperature: 50°C
  • Separation pressure I: 14 MPa
  • Separation I temperature: 45°C
  • Separation pressure II: 8 MPa
  • Separation II temperature: 40°C
  • Extraction time: 180 min

Effects of pressure, temperature, and time on extraction efficiency

Pressure

According to the best parameters for supercritical extraction of flaxseed in the past (plus references, sample basis), we carried out supercritical extraction of flax meal under pressures of 20Mpa, 25Mpa, and 30Mpa. That as the pressure increases, the extraction rate also increases. At 30Mpa and 50°C, the extraction can reach 14.8% for 3 hours, and the yield is 92.5%. This is because the dissolving power of supercritical CO2 is related to its density. As the pressure increases, the density of supercritical CO2 increases, and the dissolving power also increases, so more linseed oil can be dissolved.

Temperature

To study the effect of temperature on the supercritical extraction of linseed oil in linseed meal, we conducted experiments at 40℃, 45℃, and 50℃ under the pressure of 30MPa. The data obtained after 3 hours of extraction, that as the temperature increases, the extraction rate of linseed oil also increases. When the temperature rises from 45°C to 50°C, the extraction rate increases by 3.8%, which is a more obvious increase. This is also related to the increase in the density of supercritical CO2.

Time

In order to study the effect of extraction time on the extraction rate, we extracted at 20MPa, 25MPa, and 30MPa for 3 hours respectively. The extraction rate at 50°C is the highest under different pressures. Therefore, the effect of extraction time on the extraction rate of linseed oil at 50°C will be investigated next. That no matter what the extraction pressure is, the extraction rate of linseed oil increases with time. At 20 MPa and 25 MPa, the increase in the first 2 hours is faster than the increase in the last 1 hour; and at 30 MPa, The rate of increase in the first two hours and the next hour is basically the same. It can be seen that at the beginning of extraction, because the extract contains more solutes and is easily taken out by supercritical CO2 dissolution, the amount of extraction is greater and the rate is faster; in the second half of the time, As the concentration of the solute in the extract decreases, the amount taken out by the supercritical CO2 dissolution is reduced, and the rate is also lower.

About the CO2 Extraction Rate

The supercritical CO2 extraction method is used to extract the linseed oil in the linseed meal.

At 30MPa, and 50℃, the extraction rate can reach 14.8% for 3 hours, and the yield is 92.5%. The linseed oil in the linseed meal is almost completely extracted On the basis of the original pressing, the extraction rate of linseed oil in linseed was increased by about 9%.

Analysis

After analysis, the content of α-linolenic acid in the linseed oil obtained by supercritical CO2 extraction of linseed meal is about 52%, which is 7 percentage points higher than the 45% of the traditional pressing method.

Effect of storage conditions

Under the same storage conditions, a month later, the content of α-linolenic acid in the linseed oil extracted by supercritical CO2 was 50.2%, a small decrease, while the traditional squeezing method was only about 40%, a large decrease, which was a great loss to the manufacturer.

The advantages of supercritical CO2 extraction technology are fully reflected here, and it has great market application prospects in linseed oil extraction.