Application of supercritical fluid extraction technology in natural pigments

Summary

When Hong Hailong and other supercritical co2 fluid extraction machine extracted capsanthin, 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.

Liang Ruihong et al. 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 2.5~3h, and the product has good color quality, avoiding the problems of solvent residue extracted by organic solvent. With the continuous development of technology, this 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.

Forewords

In the past ten years, China’s edible natural pigment industry has developed. There are dozens of companies producing natural pigments in the country, and there are dozens of products. However, almost all enterprises adopt traditional production techniques, with poor product quality, low purity, odor and solvent residue, which seriously affect the promotion and application of natural pigments.

Although a small number of manufacturers export natural pigment products, most of them are cheaply supplied to foreign companies by means of semi-finished products such as chili oleoresin, and then advanced separation processes are used abroad, except for impurities and odors, which are sold at high prices. Therefore, how to adopt advanced equipment and processes to improve product quality is an important issue for the future development of natural pigments in China.

Supercritical 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 fluid extraction on natural pigments is described below.

Supercritical fluid 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. .

The application of supercritical fluid extraction in food is mainly for nearly 20 years. In 1974, Zosel first studied the removal of caffeine from coffee by supercritical fluid extraction. In 1978, Hag AG first established an industrialized equipment and process for removing caffeine from coffee beans. 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.

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 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.

supercritical fluid extraction natural pigments

The properties of supercritical CO2 are similar to those of n-hexane and are therefore particularly suitable for the extraction of fat-soluble components. Such as β-carotene, capsanthin, tobacco orange, lutein and so on. In addition, by using different entrainers, the polarity of CO2 can be changed, thereby expanding the extraction range, and extracting more polar pigments such as tea polyphenols, ginkgo flavonoids and the like.

Supercritical 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 extraction of carotenoid pigments

Supercritical fluid extraction of capsanthin

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. Zhao Yaping extracted capsanthin from crushed dried peppers with supercritical CO2.

Capsanthin and chili oil extracted by supercritical CO2 in one process
Capsanthin and chili oil extracted by supercritical CO2 in one process

The optimum extraction conditions were particle size <1.2 mm, pressure 15 MPa, extraction temperature 50 ° C, 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.

Supercritical 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.

Conclusion

Although supercritical fluid extraction of natural pigments has many advantages, China has not yet been widely used in this field. The main reason is that the one-time investment in supercritical equipment is large, and the process of extracting natural pigments is not mature.

However, due to the advantages of supercritical fluid extraction, many manufacturers have already or are preparing to invest in supercritical equipment.

The research on supercritical fluid extraction of natural pigments is a focus of future development. In particular, with the recognition and attention of functional natural pigments, it is believed that supercritical fluid extraction will replace the advantages of traditional solvent species, and many manufacturers have already prepared or are investing in supercritical equipment.

The research on supercritical fluid extraction of natural pigments is a focus of future development. In particular, with the recognition and attention of functional natural pigments, it is believed that supercritical fluid extraction will replace traditional solvent extraction of natural pigments to produce high-purity, high-quality pigment products to meet the needs of use and export.

The best parameters for extraction of natural yellow pigment from spirulina using a supercritical co2 extraction machine:

Pulverization degree: 40 mesh

Extraction pressure:45Mpa

Extraction temperature:45 °C

Extraction time:90 minutes

The best parameters for extraction of zeaxanthin using a supercritical co2 extraction machine:

Pulverization degree: 20 mesh

Extraction pressure:40Mpa

Extraction temperature:40 °C

Extraction time:150 minutes