What Is Astaxanthin?

Astaxanthin is a ketone or carotenoid. It is pink in color, fat-soluble, insoluble in water, and soluble in organic solvents. ^{[1] Also} known as astaxanthin. A red carotenoid found in the shells of crawfish, aquatic animals such as oysters and salmon. It can be combined with proteins in the body to become cyan and blue. ^[2] Especially in the feathers of aquatic animals such as shrimp, crab, fish and birds, it plays a role of color development. ^[1]

Astaxanthin is also known as astaxanthin, astaxanthin. In 1933, a purplish red crystal was extracted from shrimp, crab and other aquatic products, and it was determined that it was a carotenoid closely related to astaxanthin, so it was named astaxanthin. It is widely found in shrimp, crab, fish, bird, certain algae and fungi. As a non-provitamin carotenoid, astaxanthin cannot be converted to vitamin A in animals, but it has the same antioxidant effect as carotenoids. It has the ability to quench singlet oxygen and trap free radicals. -Carotene is more than 10 times higher and more than 100 times stronger than vitamin E. People also call it "super vitamin E". Astaxanthin has been widely recognized for its antioxidant, coloring, and enhancing body immunity. The United States and other countries have been allowed to be used as food additives in production and have broad development prospects as natural food additives. ^[3]

Natural shrimps, crabs, fish and other aquatic substances that humans consume daily are rich in natural astaxanthin. Humans have no adverse reactions and symptoms of poisoning in daily consumption. Therefore, natural astaxanthin is safe for humans and animals. Experiments have also proved that Got this. After a systematic human safety test, a company in the United States took two groups of healthy adults at 19.25mg and 3.85mg daily to take astaxanthin supplements at a dose of 19.25mg and 3.85mg, respectively. After the test, after detailed monitoring and comprehensive analysis, it was orally rich in Haematococcus pluvialis powder with natural astaxanthin has no pathogenic effect or toxic side effect on the human body. However, chemically synthesized astaxanthin, as the synthesis process may be contaminated by other harmful substances, the product also contains a large number of cis isomers, and its bioavailability is reduced. Therefore, chemically synthesized astaxanthin is used in food, feed, and pharmaceuticals. And cosmetic applications are greatly restricted. ^[3]

Astaxanthin Extraction Source

Astaxanthin in nature is derived from algae, bacteria, and phytoplankton. Some aquatic species, including crustaceans such as shrimp and crab, have a red appearance due to long-term consumption of these algae, bacteria, and phytoplankton. They are also used by fish such as salmon and afterburning fish, birds such as flamingo, chicken, and duck. Predators, poultry, and pigments are stored in the skin and adipose tissue to make their skin and feathers red. Therefore, natural astaxanthin can also be obtained from crustaceans, fish, birds, and poultry. ^[4]

Studies have found that many types of algae, such as snow algae, chlamydomonas, euglena, and agaric, contain astaxanthin. The accumulation of astaxanthin by Haematococcus pluvialis can reach up to 4% of the cell dry weight. The total production is higher than other green algae, and it is currently recognized as the best biological source for the production of natural astaxanthin. Because bacteria are affected by their own factors, the use value is low. Phaffia rhodozyma is considered to be the most suitable source of astaxanthin in fungal fermentation production. Extracting astaxanthin from red Phaffia yeast is one of the main ways to produce astaxanthin. ^[4]

H. pluvialiso is a single-celled organism. During the cultivation process, when the nitrogen source is sufficient, it can promote cell growth; when the nitrogen source is lacking, it can stimulate the cells to produce and accumulate astaxanthin in the body. Vegetarian. The production of astaxanthin by Haematococcus pluvialis has the characteristics of fast cell proliferation, simple culture, and easy extraction, and the algae powder can be directly applied to the food and feed industry to reduce costs, so it is considered to have a promising astaxanthin production prospect. Microalgae. Astaxanthin in the excellent Haematococcus pluvialis abroad generally accounts for more than 90% of the total carotenoids, and its production quality is good, and it exists in the esterified form, accounting for 60% to 80% of the total carotenoids. %, A small amount is in free form. However, Haematococcus pluvialis has relatively high growth conditions, long cultivation cycles, and the disadvantages of light and wall breaking to release astaxanthin. ^[5]

Chlorella zofingiensis belongs to the genus Chlorella, which has the characteristics of easy cultivation, fast growth, high temperature resistance and extreme pH, and easy to cultivate outdoors. Its synthetic astaxanthin has some of the advantages of both Phaffia rhodozyma and Haematococcus pluvialis. It can use organic matter such as glucose as a carbon source and energy to rapidly synthesize astaxanthin in the absence of light. The optimum growth temperature and The optimal astaxanthin synthesis temperature is close to room temperature at 24 . The higher the carbon-to-nitrogen ratio, the better the astaxanthin synthesis. Astaxanthin accumulates in the cytoplasm in a large amount in an esterified form, and it is relatively easy to reach a high cell concentration. At the same time, growth and reproduction can be synchronized with the accumulation of astaxanthin. These characteristics help to simplify production equipment, save production time, improve production efficiency, and provide favorable factors for large-scale cultivation. But what needs to be resolved is that the astaxanthin content in chlorella is much lower than the astaxanthin content in Haematococcus pluvialis, which may be caused by a defect in the synthetic pathway. Therefore, at this stage, some people use genetic engineering to regulate the gene expression of key enzymes during astaxanthin synthesis, or introduce exogenous genes to optimize the astaxanthin synthesis pathway of chlorella, which may break through the physiological level and induce conventional production of astaxanthin. Limitations. ^[5]

It is also reported that chlamydomonas, euglena, acetabularin, etc. also contain a certain amount of astaxanthin. ^[5]

Astaxanthin extraction method

Currently, astaxanthin is produced in two ways: chemical synthesis and natural extraction. Chemically synthesized astaxanthin is not only expensive, but also has significant differences from natural astaxanthin in terms of molecular structure, biological functions, application effects, and biosafety properties. In addition, the extraction of natural astaxanthin gradually dominated. ^[4]

As the research on astaxanthin extraction methods continues to progress, the astaxanthin production process has been continuously optimized and upgraded, especially in terms of astaxanthin separation and purification. At present, there are two main types of natural astaxanthin production methods: biological fermentation and extraction from crustacean processing waste. The specific separation and purification processes include alkaline extraction, fat dissolution, organic solvent extraction, supercritical extraction, enzymolysis, microwave treatment, and the like. ^[4]

A typical process for extracting astaxanthin by animal crust supercritical extraction is as follows ^[4] :

Shrimp shell crushing dilute acid treatment washing to neutral drying loading supercritical static extraction supercritical cycle extraction collection saponification liquid chromatography analysis and purification packaging frozen storage ^[4]

The process for extracting astaxanthin from Red Fife Yeast is: ^[4]

Red Phaffia yeast activation inoculation fermentation centrifugal collection of bacteria drying wall breaking treatment extraction concentration analysis and extraction of astaxanthin ^[4]

It should be pointed out that the calcareous content in animal carapace will affect the production of astaxanthin. The production conditions of animal carapace extraction method are demanding, the production cost is high, the yield is low and the product purity is not high. Therefore, only a few countries currently use this technology to produce astaxanthin. The yield of astaxanthin extracted from Phaffia rhodozyma is high, but there may be problems such as residues and concentration of pollutants during the extraction process. ^[4]

Natural Astaxanthin Extract

Extracting astaxanthin from aquatic product processing waste is widely used. While creating economic benefits, this method can reduce the color of production and processing wastewater and reduce pollution. Commonly used alkaline extraction, oil-soluble method, organic solvent method and Critical CO ₂ extraction and so on. ^[5]

(1) Alkali extraction

The alkaline extraction method is to dissolve CaCO ₃ in the crustacean shells of processed fishery products with acid, separate the astaxanthin bound to the protein with alkali (NaOH + Na ₂ CO ₃ ), and then dissolve the protein in it to obtain astaxanthin. Prime purpose. The alkaline extraction method consumes a large amount of acid and alkali, and its wastewater has serious environmental pollution, and the astaxanthin is oxidized into bright red astaxanthin when it is processed at high temperature in an alkaline environment. Therefore, the alkaline extraction method is not shrimp. It is astaxanthin or other degradation products of astaxanthin. In recent years, there have been few reports on the research of alkaline extraction. ^[5]

(2) Oil-soluble method

Astaxanthin's molecular structure makes it good fat-soluble and has good heat stability in oil, so oil is used as a solvent, extracted by oil and then purified. The fat used in this method is mainly edible fats and oils, the most common being soybean oil. It is best to control the oil temperature below 80 ° C during extraction. Higher oil temperature will also affect the stability of astaxanthin, and the amount of oil directly affects astaxanthin. Extraction efficiency and purification after extraction can be performed by chromatography. ^[5]

This method has the characteristics of product safety and high extraction efficiency, but the extract is not easy to separate from oil with high boiling point, and the oil containing pigment after extraction is not easy to concentrate, so the product concentration is not high. For further separation and purification, molecular distillation and other processes are required. The cost of separation is higher. ^[5]

(3) Organic solvent method

The organic solvent is used to extract astaxanthin, and the extraction agent with a low boiling point is selected for extraction. The extract is evaporated to obtain a high concentration of astaxanthin oil. The distillation technology can also recycle and recycle the solvent. Common organic solvents are acetone, ethanol, ether, petroleum ether, dichloromethane, chloroform, n-hexane and the like. Different solvents have different extraction effects. It was found in the research that acetone had the best extraction effect, while ethanol had the worst. In order to improve the extraction efficiency, a reduced pressure reflux extraction method is adopted, and the extraction temperature is preferably controlled at about 60 ° C. Organic solvent extraction can use extraction and reflux extraction methods. The extraction method can be divided into single tank multiple repeated extraction and Soxhlet extraction method; the former is the sample is placed in the homogenizer extraction. After the astaxanthin concentration reaches equilibrium, the extract is released, and then the solvent is added for the next extraction, which is repeated many times until the astaxanthin is completely extracted in the raw material; the latter is an improved single-pot multiple repeated extraction, which has the advantage of continuous use Fresh solvents are used for extraction. The maximum concentration difference between the extractant and the raw material is always maintained, which speeds up the extraction speed and improves the extraction rate. The final concentration of the extracted liquid is higher. ^[5]

(4) Supercritical CO ₂ extraction method

Supercritical fluid extraction technology is to use the special properties of critical fluids, contact the solid or liquid mixture to be separated under high pressure conditions, adjust the operating pressure and temperature of the system, extract the required substances, and then reduce the pressure or increase the temperature. Reduce the density of the supercritical fluid and separate the extracts. ^[5]

The product obtained by supercritical CO ₂ extraction has the advantages of high purity, less solvent residue, and no toxic side effects. Compared with other methods, this method can avoid degradation of astaxanthin, obtain high-quality products, and can effectively extract astaxanthin However, due to the large initial investment in equipment and high production technology requirements, there are still some difficulties in large-scale industrial production. ^[5]

In addition to the methods described above, some people have used enzymes to extract astaxanthin, selected a better flocculant to recover the protein and astaxanthin, and then used acid protease and neutral protease to hydrolyze the protein and isolate the shrimp. Penicillin; there is a compound process that combines alkaline method and organic solvent method to extract astaxanthin. However, the extraction of astaxanthin from scraps of aquatic products is subject to various constraints, such as the hygiene issues of the scraps, the environmental problems of production, the contamination of the extracts, the impact of changes in the astaxanthin content of the waste raw materials on the extraction costs, and Chitin, ash, and humidity in the raw materials all limit the extraction of astaxanthin. ^[5]

(5) Production of redhead yeast

Astaxanthin was first discovered in Phaffia rhodozyma in 1976. Phaffia yeast belongs to the genus Rhodopsomyces of the basidiomycete class. It is the only natural astaxanthin-producing yeast. Approved by the FDA in 2000 for food additives. The red-headed yeast is mainly single cells, sometimes forming pseudohyphae, and the reproduction method is asexual reproduction of buds, without sexual reproduction. The cells are not only rich in protein, lipids, vitamins, but also contain a large amount of unsaturated Fatty acids and various astaxanthin precursors grow at temperatures ranging from 0 to 27 ° C. Of the more than 10 carotenoids produced by wild yeast, astaxanthin is the largest component, accounting for 40% to 95% of the total carotenoids. ^[5]

Red hair yeast has become an excellent strain for industrial production of astaxanthin. The characteristics of astaxanthin production are: red hair yeast does not require light, can use multiple sugars as carbon sources for fast heterotrophic metabolism, and has a short fermentation cycle. , The production speed is fast, can achieve high-density culture in the fermenter, and the single cell protein of the bacteria can be used as bait and feed additives after pigment extraction. ^[5]

In addition, some people use red yeast yeast isolated from vineyard soil to produce astaxanthin by mutants obtained by UV and EMS mutagenesis. Some people also isolated a deep red yeast (Phadotoralarubra) from Bulgarian yogurt. Yeast isolated from Antarctic sea ice also has the ability to synthesize astaxanthin, which may become a new way to obtain astaxanthin. ^[5]

Chemical Synthesis of Astaxanthin

The conversion of -carotene to astaxanthin requires the addition of two keto groups and two hydroxyl groups. Chemical synthesis is difficult and the products are mostly cis-structures, while most of the astaxanthins required for biosynthesis are trans-structures. The synthesis of astaxanthin can be completed through multiple steps of chemical and biocatalytic reactions. The biocatalysis is to determine the stereo configuration of the intermediate carbon atoms or the substitution position of oxygen atoms in the synthesis process. The main precursor of chemical synthesis is ( S) -3-acetoxy-4-oxo--iononone, which is an asymmetric hydrolysis of (R) -terpene alcohol acetate by different microorganisms, which is then extracted, refluxed and redistributed. The resulting product is processed by crystallization and other techniques. This precursor material is converted into a Wittig salt containing 15 carbon atoms through the reaction. Finally, two Wittig salts are reacted with a dialdehyde containing 10 carbon atoms to produce astaxanthin. This process is very complex and difficult to synthesize. Only a few companies in the world industrially produce astaxanthin by chemical synthesis, and the synthetic trans-astaxanthin is expensive. ^[5]

Astaxanthin other methods

In addition to two methods of producing astaxanthin, such as natural extraction and chemical synthesis, -carotene in bacteria, protozoa, and crops can also be used as precursor substances, and the enzymes that synthesize astaxanthin can be transferred to the corresponding through transgenic technology. Astaxanthin is synthesized in crops. But at present, this method of producing astaxanthin is only in experimental research. ^[5]