Supercritical CO2 Fluid Extraction of Edible Natural Pigment (2)

Three supercritical CO2 extraction methods for capsanthin and capsaicin

Capsanthin is a natural red dye of the xanthophyll class of carotenoids. As a food coloring, it has the E number E160c(i). Capsanthin is the main carotenoid in the Capsicum annuum species of plants including red bell pepper, New Mexico chile, and cayenne peppers (Capsicum annuum) and a component of paprika oleoresin. Capsanthin is also found in some species of lily. Among other carotenoids, capsanthin is considered to have the greatest antioxidant capacity due to the presence of eleven conjugated double bonds, a conjugated keto group, and a cyclopentane ring. Read More: Capsanthin Wikipedia

Red peppers contain capsanthin and capsaicin.

• Capsaicin can be made into anti-tumor and analgesic drugs, and it is very tight in the international market.
• Capsanthin belongs to carotenoid pigments, including capsanthin, capsorubin, zeaxanthin, β-carotene, etc.

Characteristics of capsanthin

• Capsanthin has bright colors and various hues;
• 1:15 soluble in edible ethanol;
• It turns red when the additional amount is 15000;
• Orange at 1/8000;
• Yellow at /12000.

Application of capsanthin

• Capsanthin is one of the most widely used natural pigments and is widely used in food, medicine, cosmetics, daily necessities, and other fields.
• Capsanthin has no side effects on the human body, so the international regulation of ADI (human daily intake) is “unrestricted”, and it has been produced abroad for a long time. Especially the United States, Britain, Canada, Japan, and other countries are in a leading position. Japan’s annual output is 260t, accounting for 1.1% of its domestic natural pigment market demand.

In recent years, China has also attached great importance to the development and utilization of capsanthin. Capsicum is widely cultivated in various places, and the raw materials for preparing capsanthin are quite abundant. However, the extraction process still needs further research.

Method of extraction

The traditional extraction method of capsanthin: The traditional extraction methods of capsanthin are an oil-soluble method and a solvent method, and the general process adopts a two-step method:

• Step 1 – Extraction: First extract the plants with an organic solvent to obtain a paste-like viscous liquid (commonly known as extract or oleoresin);
• Step 2 – Refining: Extraction with organic reagents, all soluble components in plants are dissolved, in addition, to using pigments and aroma components, there are also various impurities, especially tar, spicy, and other peculiar smells. Refining is to remove the peculiar smell from the extract or oleoresin, that is, to deodorize.

Traditional refining method: The traditional refining method is to use strong alkalis, strong acids, and salt for washing. This method has a long process and high cost, and it is easy to bring in heavy metal ions. Strong alkalis will also destroy some pigments and affect the color tone. Later, there were many improved methods, but in general, there were problems such as complex processes, low product purity, peculiar smell, and high solvent residue.

3 Methods of Supercritical CO2 extraction of Capsanthin and Capsaicin

At present, the domestic and foreign research work on the extraction of capsanthin and capsaicin by supercritical CO2 fluid mainly includes two aspects: the direct extraction of capsanthin and capsaicin and the refining of capsicum oleoresin.

In the supercritical CO2 extraction process, there are three commonly used methods for supercritical CO2 fluid extraction of capsanthin and capsaicin.

Method 1: Segmented Extraction

CO2 extraction process: Dry the chili until the water content is below 20%, crushing the particle size to 40-60 mesh, then put the chili powder into the extraction kettle, close the valve of the second-stage separation kettle, open the valve of the first-stage separation kettle, keep the extraction temperature at 35°C, and extract The pressure is 10MPa, the temperature of the first-stage separation tank is 60°C, and the pressure is 5MPa. After 3~4 hours of extraction, the pressure of the extraction pot is raised to above 12MPa, the extraction temperature is adjusted to 45°C, the valve of the first-stage separation tank is closed, and the second-stage separation tank is opened. For the kettle valve, the separation conditions are the same as the first-stage separation kettle, dynamic extraction for 3~4h, close all valves, reduce pressure, and collect the product. The first-stage separation kettle is the crude product of capsaicin, and the second-stage separation kettle is slightly spicy. of capsanthin.

Principle of CO₂ separation: The principle of separation is that the pressure in the extraction kettle is high and the density of CO2 is high, the extracted substance is dissolved in CO2, and the extracted substance in the separation kettle is separated from CO2 due to a sudden drop in pressure and solubility. Capsaicin and capsanthin have different solubilities in supercritical CO2 fluid. Capsaicin has a high solubility and can be dissolved in high-pressure supercritical CO2 fluid; capsanthin has a small solubility and can only be dissolved in high-pressure supercritical CO2 fluid. Therefore, under low pressure, the capsaicin is first extracted and the capsanthin is retained in the extraction kettle. After the capsaicin is extracted, the pressure is increased to extract the non-pungent capsanthin.

Method 2: One-time extraction and two-stage separation method

CO2 extraction process: Put chili powder in the extraction kettle, open the valves of the first and second separation kettles, keep the extraction conditions of 45°C and 25MPa in the extraction kettle, maintain the separation conditions of 60°C and 12MPa in the first separation kettle, and keep the separation conditions of the second stage separation Keep the separation conditions of 60°C and 5MPa in the kettle, extract dynamically for 3~4 hours, release the pressure, close the valve, and collect the product. The first-stage separation kettle contains slightly spicy capsanthin, and the second-stage separation kettle contains capsaicin. Crude products.

Principle of CO₂ separation: The principle of extraction and separation is that under high pressure, both capsaicin and capsanthin are extracted, and the mixture of capsaicin and capsicum oleoresin is separated out first due to the decrease in pressure, density, and solubility of capsanthin in the first-stage separation kettle. Deposited in the separation kettle; while capsaicin is still dissolved in CO₂, in the second-stage separation kettle, the pressure is further reduced, capsaicin is precipitated, and the two achieve separation.

Method 3: Continuous Segmented Extraction

First, extract the capsicum oleoresin under high pressure, then add suitable fillers and the mixed filler of capsicum oleoresin. , you can get the crude product of capsanthin and capsaicin without a spicy taste. If only to obtain capsicum oleoresin, it should be extracted under high pressure, close the second-stage separation kettle, and maintain the separation condition of the first-stage separation kettle at 60°C and 5MPa to obtain high-quality capsicum oleoresin.

Comparison of three methods and subsequent treatment process

The pepper red pigment obtained by the third method is of the best quality and has no spicy taste;

However, the capsanthin obtained by the first and second methods has a slightly pungent taste. If it is applied to the field of cosmetics, it needs to be processed to remove the pungent taste of the capsicum extract.

Remove the spicy taste of chili extract

• Method 1: adopting the method of supercritical CO2 fluid extraction to continuously extract capsanthin, the extraction conditions, and separation conditions are the same as the third method and can obtain non-pungent, high-quality capsanthin and a trace amount of crude product of capsaicin:
• Method 2: use a solvent to remove the pungent taste of the capsicum extract, add an appropriate amount of 15% NaOH to the capsanthin to react capsaicin with NaOH, destroy the capsaicin and remove the pungent taste of the capsicum extract, and then use a suitable extraction method Capsanthin is extracted by solvent, concentrated and enriched, and the solvent is recovered to obtain high-quality capsanthin.