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The optimization guide to the CO2 extraction process of natural pigments

CO2 Extraction of Natural Pigments

The traditional production process to produce natural pigments, with poor product quality, low purity, odor, and solvent residue, seriously affects the promotion and application of natural pigments.

Extraction of natural pigments

Supercritical CO2 Extraction of Capsanthin

Supercritical co2 fluid extraction is an emerging extraction and separation technology for the food industry. Compared with the traditional chemical solvent extraction method, the superiority is that there is no chemical solvent consumption and residual, no pollution, avoiding thermal degradation of the extract at high temperature, protecting the activity of the physiologically active substance, and maintaining the natural flavor of the extract, and the like. The application status of supercritical co2 extraction on natural pigments is described below.

CO2 Extraction

With the continuous development of technology, the co2 extraction method has been combined with high-tech such as chromatography, ultrafiltration, and nuclear magnetic resonance to broaden the application range of supercritical fluid extraction.

When we extracted capsanthin with supercritical CO2, it was found that, except for the higher yield than the organic solvent extraction method, the color price of the product reached 289.3, which was more than three times higher than the organic solvent extraction method.

Studied the supercritical extraction process of Xinjiang comfrey and compared it with the results of organic solvent extraction. The results showed that the supercritical extraction of comfrey pigment contained less impurities, contained more pigment components, and contained higher content. The whole process only takes 1~1.5h, and the product has good color quality, avoiding the problems of solvent residue extracted by organic solvent.

What is supercritical co2 extraction?

Supercritical fluid extraction is an extraction process using a fluid above a critical temperature and a critical pressure as a solvent. The fluid near the critical point not only has a very high solubility for the substance but also the solubility of the substance varies with the pressure or temperature of the system so that it is convenient to selectively extract the separated substance by adjusting the pressure or temperature of the system.


Supercritical Fluid Extraction In food processing, almost all CO2 is used as an extractant. CO2 is not only a strong solvent, it can extract a wide range of compounds in food processing, and is relatively stable, inexpensive, non-toxic, non-flammable, and recyclable. The CO2 production cost is low, and high-purity gas can be obtained without residue. The critical point of CO2 is lower, the criticality is 31.1 ° C, and the critical pressure is 7.38 MPa, so it is especially suitable for extracting volatile and heat-sensitive substances. Compared with the traditional solvent n-hexane, dichloromethane, it has remarkable advantages.


The application of supercritical co2 fluid extraction in food is mainly for nearly 40 years, it was used in the food industry for supercritical fluid extraction. Important milestone. At present, supercritical fluid extraction has been widely used in the extraction and separation of oils, cholesterol, flavors, and fragrances.

CO2 extraction of carotene

In the past, the extraction of carotene mainly uses an organic solvent such as n-hexane, which requires not only the consumption of a large amount of solvent but also the removal of all solvents to avoid toxicity caused by solvent residues. Supercritical CO2 extraction can replace traditional solvent methods and effectively extract carotene. Yu Enping uses supercritical CO2 to extract carotene from seaweed. Using acetone as an entrainer increases the extraction rate.

Supercritical co2 extraction of carotenoid pigments

The co2 extraction process of capsanthin

Extracted capsanthin from crushed dried peppers with supercritical CO2. The optimum extraction conditions were particle size <1.2 mm, pressure 15 MPa, extraction temperature 50 ° C, and flow rate 6 M3 / hr. Purification of capsanthin (containing solvent 10000 mg/kg or more) from red pepper was carried out. The optimum extraction conditions are 18 MPa, 25 ° C, and a flow rate of 2.0 L/min. The residual solvent can be up to 20mg/kg or less.

In the industry, capsanthin is extracted from chili powder by ethanol or n-hexane to obtain capsicum oleoresin. After the pepper capsaicin is isolated, no capsicum oleoresin is obtained, and then the spicy capsaicin is separated to obtain a non-spicy taste. Red oily liquid – capsanthin. Due to the oily nature of capsanthin, the removal of residues (solvents such as n-hexane, etc.) in the solvent-extracted products is difficult to meet the standards of FAO and WHO, which greatly affects their use and export earnings.

CO2 extraction of annatto orange

The effect of supercritical CO2 on the extraction of tobacco orange was studied. The maximum solubility of pure annatto in CO2 is 0.003 mg/g, while the maximum solubility of annatto seed pigment is 0.026 mg/g. The temperature increases the solubility of the pigment in CO2 but does not increase the solubility of the medium pressure at the same temperature. The use of vegetable oil as an entrainer can increase the extraction rate of annatto.

The natural pigment was extracted from the annatto seed with supercritical CO2. The results showed that the extracted pigments were mainly annatto and orange-scented orange. Carmine tree orange is easier to extract than tortoise tree orange. The annatto orange is easier to extract than the alfalfa tree orange. The extraction temperature is 50 ° C and the pressure is 310 bar, which can obtain a higher total pigment yield.

The CO2 extraction process of 2 kinds of natural pigments

Yellow pigment from spirulina

  • Pulverization degree: 40 mesh
  • Extraction pressure:45Mpa
  • Extraction temperature:45 °C
  • Extraction time:90 minutes


  • Pulverization degree: 20 mesh
  • Extraction pressure:40Mpa
  • Extraction temperature:40 °C
  • Extraction time:150 minutes

Here’s a comparison of natural pigments in terms of efficiency, composition, and function between CO2 extracted natural pigments and common extraction methods:


CO2 extraction method offers higher efficiency compared to traditional extraction methods. It is more selective and can extract only the desired pigments while leaving behind unwanted compounds. This results in a higher yield of pure pigments.


CO2 extracted natural pigments contain a higher concentration of pigments compared to traditional extraction methods. They also retain more of the natural compounds and nutrients, such as antioxidants and vitamins, that may offer additional health benefits.


CO2 extracted natural pigments have a wider range of functions compared to traditional extraction methods. They can be used in a variety of applications, such as food and beverage coloring, natural cosmetics, and pharmaceuticals.

Benefits of CO2 Natural Pigments

  1. Environmentally Friendly: Unlike traditional extraction methods that use solvents and chemicals to extract natural pigments, CO2 extraction method does not produce waste or harm the environment. It is a safe and sustainable method of extraction.
  2. Pure and Safe: CO2 extraction method produces pure and safe natural pigments without any harmful solvents or chemicals. This makes it safe for use in a variety of applications, including food and cosmetic industries.
  3. Retains More Nutrients: CO2 extraction method retains more of the natural nutrients of the pigment compared to traditional extraction methods. This results in a more nutrient-dense product that offers additional health benefits.
  4. Better Stability: CO2 extraction method produces pigments that are more stable and resistant to environmental factors such as light, heat, and pH changes. This increases their shelf life and makes them more versatile for use in various applications.

A comparison of CO2 Extraction and Traditional Extraction for extracting Natural Pigments

CriteriaCO2 ExtractionTraditional Extraction
EfficiencyHigher efficiencyLower efficiency
CompositionHigher pigment concentration and more natural compoundsLower pigment concentration and may destroy some natural compounds
FunctionalityWider range of functionsLimited functions