CO2 Extraction Method and Equipment for Astaxanthin

CO2 extraction method for zeaxanthin
Zeaxanthin is also a carotenoid, it can also be prepared as astaxanthin

Astaxanthin

Antarctic krill shell is a good raw material for extracting astaxanthin.

Carotenoids are mainly found in the crustacean of Antarctic krill, the content is about 3 to 4mg/100g chilled samples, which are rich in astaxanthin.

Carotenoids

Carotenoids, whose molecular formula is generally C40H56, are a class of polyene substances that are yellow, orange-red or red.

It is an internationally recognized functional pigment with physiological activity and an important source of vitamin A for humans and animals. It is also a very effective antioxidant with high economic value.

Supercritical CO2 Extraction of Astaxanthin from Antarctic Krill Shells
Supercritical CO2 Extraction of Astaxanthin from Antarctic Krill Shells

Astaxanthin

Astaxanthin is an oxygen-containing derivative of carotenoids and belongs to keto carotenoids. Its free radical quenching activity is 10 times that of β-carotene and 100 times that of vitamin E. At the same time, it has the ability to resist ultraviolet rays, anti-tumor, and improve It has broad application prospects in the fields of food additives, aquaculture, cosmetics and health products, etc. for immunity, enhancing nerve connectivity and improving fertility.

astaxanthin CO2 extraction equipment
astaxanthin CO2 extraction equipment

Extraction Method of Astaxanthin

There are many ways to extract carotenoids, and solvent methods are generally used to extract carotenoids from crustaceans.

When selecting an extractant, while considering the extraction effect, the toxicity of the solvent must also be considered.

Chloroform solvent extraction

Reagents such as chloroform have obvious extraction effects, but are more toxic, volatile, and have carcinogenic risks.

N-hexane solvent extraction

Industrially, solvents such as n-hexane are commonly used to extract carotenoids. These solvents have poor extraction effects and high costs, and are likely to cause oxidative degradation of active ingredients during the extraction process.

Supercritical CO2 extraction

The supercritical CO2 extraction process technology is suitable for the extraction of astaxanthin because of its low temperature, simple operation, high efficiency, no pollution, and strong selectivity.

Astaxanthin Supercritical CO2 Extraction Equipment
700 Bar Astaxanthin Supercritical CO2 Extraction Equipment

Astaxanthin CO2 extraction process

At present, supercritical CO2 fluid extraction of astaxanthin is concentrated in algae and crustacean waste.
The main influencing factors are: sample material characteristics, extraction pressure, temperature, time, CO2 dosage and flow rate, and choice and dosage of cosolvent.
The supercritical CO2 fluid is a non-polar solvent. In the extraction process, adding an appropriate amount of polar co-solvent can effectively improve the solubility and selectivity of astaxanthin.

In the reported experiment, the supercritical CO2 extraction of Antarctic krill astaxanthin was compared with the supercritical CO2 method and the organic solvent method. The experimental results showed that the supercritical CO2 method was significantly better than the organic solvent method.

CO2 Extraction Equipment
CO2 Extraction Process

CO2 extraction process of astaxanthin form Antarctic krill

  • Extraction pressure: 350 bar;
  • Extraction temperature: 60℃;
  • Co-solvent: 1.00mL/g;
  • Extraction time: 3.5h;
  • Yield: 84.41 ±0.57%.
CO2 Extraction Equipment
CO2 Extraction Equipment

Optimization of CO2 Extraction Method of Astaxanthin

Astaxanthin is a weakly polar fat-soluble pigment in Antarctic krill. Adding an appropriate amount of co-solvent during the supercritical CO2 extraction of astaxanthin can effectively improve the solubility and selectivity of astaxanthin in CO2 fluid.
The experimental results showed that the extraction effect of the astaxanthin was significantly improved after the co-solvent was added.

CO2 Extraction Equipment
COsolvent Pump of CO2 Extraction Equipment

Cosolvent dosage

The fixed extraction temperature was 45℃, the extraction pressure was 25MPa, the static extraction was 30min, and the dynamic extraction was 180min. The effect of the amount of cosolvent (0.30-1.00mL/g sample) on the yield of Antarctic krill astaxanthin was investigated.

Under the conditions of constant extraction pressure, temperature and time, the yield of Antarctic krill astaxanthin increases rapidly with the increase of the amount of co-solvent. With the extension of time, the increase rate decreases, and the extraction tends to become saturated. This may be due to the addition of the co-solvent, which changed the density of CO2, significantly changed the polarity of the supercritical CO2 fluid, and formed hydrogen bonds or other specific chemical forces with astaxanthin, greatly increasing the supercritical fluid Solubility in critical CO.

With the increase of the amount of co-solvent, the sample extraction is almost saturated, and the corresponding solubility increase effect becomes slower. Therefore, 1.00mL/g is selected as the best co-solvent amount for supercritical CO2 extraction of Antarctic krill astaxanthin.

CO2 Extraction Equipment
CO2 Extraction Equipment

Extraction Temperature

The fixed extraction pressure was 25MPa, static extraction was 30min, dynamic extraction was 180min, and the amount of co-solvent was 1.00mL/g sample. The effect of extraction temperature (40~65℃) on the yield of Antarctic krill astaxanthin was investigated.

Under the condition that the extraction pressure, time and the amount of co-solvent do not change, the yield of Antarctic krill astaxanthin increases with the increase of the extraction temperature, reaching the maximum value of 81.34±1.37% at 60℃, exceeding 60 At ℃, the yield of astaxanthin decreased slightly.

In the process of supercritical CO2 extraction, increasing the temperature increases the diffusion coefficient of the material, which is beneficial to extraction, and at the same time reduces the density of the supercritical fluid, so that the solubility of the material is reduced and the extraction is not conducive to extraction.

Therefore, the yield depends on the interaction between the density of the supercritical fluid and the diffusion coefficient of the substance after the temperature changes.

When the temperature is lower than 60℃, the yield increases with the increase of temperature, which is dominated by the increase of the diffusion coefficient of the substance;
Above 60°C, the yield decreases with increasing temperature, which is dominated by the decrease in the density of the supercritical fluid.
In addition, astaxanthin is a heat-sensitive substance, too high extraction temperature can easily lead to degradation and inactivation of activity. Therefore, 60℃ was chosen as the most suitable extraction temperature for the supercritical CO2 extraction of Antarctic krill astaxanthin.

CO2 Extraction Equipment
CO2 Extraction Equipment

Extraction pressure

The fixed co-solvent dosage was 1.00mL/g sample, the extraction temperature was 60℃, the static extraction was 30min, and the dynamic extraction was 180min. The influence of pressure change from 20-40MPa on the yield of Antarctic krill astaxanthin was investigated.

Between 20-40MPa, the yield of Antarctic krill astaxanthin increases with the increase of pressure, and reaches the maximum at 35MPa
84.41±0.57%.

This is mainly because as the pressure increases, the density of the supercritical CO2 fluid increases, which increases the solubility of the fluid, while the mass transfer distance between molecules decreases, and the mass transfer efficiency between astaxanthin and CO2 fluid increases, which is beneficial to Extraction of astaxanthin.

After more than 35MPa, the packing density between the particles is too large, reducing the contact area of ​​astaxanthin and the CO fluid and the extraction channel, and the best extraction effect is not achieved, so the yield is slightly reduced.

In addition, the increase in pressure leads to higher instrument requirements, an increase in experimental costs, and an increase in unsafe factors. Therefore, 35MPa was selected as the most suitable extraction pressure for supercritical CO2 extraction of Antarctic krill astaxanthin.

CO2 Extraction Equipment
CO2 Extraction Equipment

Summarize

The optimum process conditions for supercritical CO2 extraction of Antarctic krill astaxanthin are as follows: extraction pressure is 35MPa, extraction temperature is 60℃, co-solvent dosage is 1.00mL/g, extraction time is 3.5h, and the yield of astaxanthin reaches 84.41. ±0.57%.

CO2 Extraction Equipment
CO2 Extraction Equipment

Astaxanthin supercritical CO2 extraction equipment Technical Indicators 

ConfigurationParameter
Extraction vesselVolume: customized according to customer requirements, generally 100ml-1000l
Working pressure: 35MPa-100MPa adjustable
Working temperature: room temperature -85℃ adjustable
3 extraction vessels recommended for production equipment
SeparatorVolume: Configured according to the volume of the extraction kettle, generally 50ml-800l
Working pressure: 10MPa-30MPa adjustable
Working temperature: room temperature -85℃ adjustable
Recommend 3 separation kettles
Working pressure: 16MPa
Gas storage tankVolume: According to the overall plan configuration, generally 10l-6000l
Working pressure: 9.9MPa
PumpCO2 high pressure pump and carrier pump, with adjustable flow and pressure
Production equipment equipped with 2 high-pressure pumps
Heat Exchange SystemWorking pressure: 35MPa-100MPa
Working temperature: adjustable from room temperature to 90℃
Refrigeration system5℃-10℃
Security systemThe high pressure pump and the inlet and outlet of all containers are equipped with overpressure protection device, the safety interlocking device is connected with the PLC control system and the safety valve to ensure the safety of the system

Photo of Astaxanthin Supercritical CO2 Extraction Equipment

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