PART1
What is Astaxanthin
Astaxanthin, also known as variegated alga flavin or astaxanthin, is a terpene unsaturated compounds, the chemical name is 3,3′-dihydroxy-4,4′-diketo-β, β′-carotene, the molecular formula for the C40H52O4. under the conditions of 100kPa, the melting point of 216 ° C, the boiling point of 774 ° C.
Astaxanthin is widely found in animals (e.g., aquatic animals, birds), plants, fungi, algae and bacteria, and is known as the "Red Miracle" for its obvious benefits to human health. Currently, astaxanthin is packaged as health food for sale in the market, with antioxidant, anti-aging, anti-tumors, and cardiovascular disease prevention effects.
PART2
How astaxanthin is produced
1, chemical synthesis method
According to the differences in the synthesis method, astaxanthin synthesis method is divided into two kinds, one is the indirect synthesis method, that is, by the oxidation of other carotenoids; the second is the direct synthesis method, that is, by the commonly used synthesis of carotenoids monomers directly synthesized.
Chemical synthesis of astaxanthin has the advantages of lower production cost, high yield, astaxanthin purity can reach more than 96%, but its synthetic astaxanthin absorption and utilization in organisms is low, stability, safety and antioxidant activity are lower than that of naturally extracted astaxanthin.
2, natural extraction method
Natural astaxanthin mostly exists in marine organisms, natural extraction method is the use of crushed shrimp and crab and other astaxanthin-rich processing by-products, removal of lime, the use of organic solvents and other ways to extract astaxanthin. This method can promote the development of the aquaculture industry and reduce the pollution of waste aquatic by-products on the environment. However, due to the high content of ash and chitin in the crustaceans of discarded shrimp and crab, and the low content of astaxanthin will cause the extraction process to be complicated, and there is the problem of high extraction costs.
The use of yeast, algae and bacteria to produce astaxanthin method is called microbial fermentation. The main strains include unicellular green algae red algae, Chlorella vulgaris, red Fife yeast, sticky red yeast, gum red yeast and Paracoccidioides.
Astaxanthin produced by bioreactor fermentation machine has a well-defined structure, few by-products and is environmentally friendly. However, it is constrained by factors such as low yield, strict cultivation conditions and high cultivation cost. The use of cheap culture raw materials and the selection of high-quality high-yield strains so that they can be applied to industrial production are the key factors in the production of astaxanthin by microbial fermentation.
PART3
Astaxanthin-producing microorganisms
1、Algae
Many algae can produce astaxanthin, such as red algae, chlamydospermum, umbrella algae, naked algae and so on. Red algae are freshwater single-cell green algae, its intracellular astaxanthin mainly to double esterification astaxanthin and single esterification astaxanthin exists, a small amount of free form exists, is the main algae astaxanthin production.
However, the growth time of Robodocs rainier is long, the cultivation conditions are demanding, requiring light, the production site is limited, and astaxanthin exists in thick-walled spores, with a low extraction rate and poor continuity.
2、Bacteria
Astaxanthin is found in a variety of bacteria such as Pseudomonas aeruginosa, Paracoccidioides spp. and Bacteroides lactis. Although the astaxanthin content of most bacteria is much lower than that of algae and red fife yeast, the problem of low bacterial astaxanthin production can be improved by introducing astaxanthin synthesis-related genes into bacteria.
The production of astaxanthin by bacterial fermentation can significantly reduce the production cost of natural astaxanthin, which is important for the future industrial production of astaxanthins.
3. Yeast
Yeast fermentation production of astaxanthin, the main strains used include red Fife yeast, sticky red yeast, marine red yeast and crimson yeast. Red Fife yeast astaxanthin production has the following advantages:
1. Can use a variety of carbon and nitrogen sources to produce astaxanthin.
2. Fast cell growth and reproduction, high density culture can be achieved
3. Short production cycle and low cost
4. Easy to be absorbed by human body, and the extracted yeast can be directly used as feed additives.
The pathway of yeast biosynthesis of astaxanthin is divided into two stages: the first stage is the synthesis of β-carotene; the second stage is the generation of astaxanthin from β-carotene through oxidation and hydroxylation. The synthetic pathway of yeast astaxanthin is as follows:
Synthesis pathway of yeast astaxanthin
PART4
Astaxanthin purification method
1, Astaxanthin wall-breaking processing method
Astaxanthin is an intracellular product, which generally needs to go through the steps of wall-breaking, extraction and purification before it can be extracted from yeast body. Commonly used wall-breaking methods include mechanical method, chemical method, enzymatic method and heat treatment.
Mechanical method is the use of mechanical equipment to tear the cell wall, through the cell osmotic pressure to release inclusions, the main way of ultrasonic crushing method, bead milling method, spray impact crushing method, and high-pressure homogenization method. The operation is simple but easy to cause part of the location of the solution temperature is too high resulting in astaxanthin loss.
Chemical methods mainly include dimethyl sulfoxide method, acid and alkali heating method and organic solvent penetration. The wall-breaking of alkaline extraction and acid digestion requires the consumption of a large amount of alkali and organic acid, which increases the amount of effluent discharge, causes environmental pollution, and the stronger acid and alkali will cause damage to astaxanthin. The use of 5.55 mol/L lactic acid concentration, 30 ℃ crushing temperature for wall-breaking extraction can reduce the damage to astaxanthin.
Enzymatic treatment conditions are mild, the requirements for equipment are low, the process causes less pollution to the environment, and the extracted astaxanthin is more stable than astaxanthin obtained by other methods.
A variety of modern extraction methods have been developed for the extraction of active components, such as pulsed electric fields, high-pressure micro fluidization, ionic liquids and other emerging technologies.
2, Astaxanthin extraction method
Astaxanthin is a fat-soluble substance, soluble in organic solvents insoluble in water, can be extracted using acetone, ethanol, methanol, petroleum ether and other polar organic solvents. Due to the limited extraction effect of a single solvent, so the researchers found that the content of astaxanthin extracted by acid-heat method utilizing a 2:1 mixture of ethyl acetate and ethanol as an extraction solution was significantly higher than that of a single solution.
3, Astaxanthin purification and detection methods
Astaxanthin purification mainly with thin layer chromatography and column chromatography, thin layer chromatography can be used for the simple determination of the composition of the crude extract, column chromatography is the most commonly used purification method because of the inexpensive equipment, the replacement of stationary phases and mobile phases is convenient.
Thin-layer chromatography and column chromatography are suitable for the pre-purification process, and preparative high-performance liquid chromatography (HPLC) can be used for the post-purification process, which can make the purification effect more than 98%, but the preparation cost is higher. In order to quickly determine the amount of astaxanthin production in the experiment, usually use UV-visible spectrophotometry.
PART 5
Concluding remarks
Astaxanthin has a broad development potential, in medicine, cosmetics, health products, feed additives and other aspects have great utilization value and development space.