阅读说明：本技术 一种藻蓝蛋白快速提取方法 (Method for rapidly extracting phycocyanin ) 是由 黄成潭 潘军 叶蕾 黄敏 于 2021-08-12 设计创作，主要内容包括：本发明涉及蛋白提取技术领域,特别涉及一种藻蓝蛋白快速提取方法。该方法包括如下步骤：将含有微藻的养殖水与蛋白保护剂混合,经第一离心,得到浓缩藻液；将浓缩藻液与细胞冷冻保护剂混合,经反复冻融,得到解冻后的浓缩藻液；将解冻后的浓缩藻液与蛋白保护剂、表面活化剂混合,进行细胞破碎,得到破碎后的藻液；将破碎后的藻液进行第二离心,得到上清液；将上清液与硫酸铵、聚丙二醇混合,搅拌；将搅拌好的料液进行第三离心,得到沉淀；将所得沉淀用乙醇水溶液清洗,经第四离心,将沉淀物进行冷冻干燥。本发明提取方法操作简便快速,成本低廉,获得的藻蓝蛋白纯度高。(The invention relates to the technical field of protein extraction, and particularly relates to a rapid extraction method of phycocyanin. The method comprises the following steps: mixing culture water containing microalgae with a protein protective agent, and performing first centrifugation to obtain concentrated algae solution; mixing the concentrated algae solution with a cell freezing protective agent, and repeatedly freezing and thawing to obtain a thawed concentrated algae solution; mixing the thawed concentrated algae solution with a protein protective agent and a surfactant, and carrying out cell disruption to obtain a disrupted algae solution; performing second centrifugation on the crushed algae liquid to obtain a supernatant; mixing the supernatant with ammonium sulfate and polypropylene glycol, and stirring; performing third centrifugation on the stirred feed liquid to obtain a precipitate; washing the obtained precipitate with ethanol water solution, centrifuging for the fourth time, and freeze drying the precipitate. The extraction method is simple, convenient and quick to operate, low in cost and high in purity of the obtained phycocyanin.)

1. A rapid extraction method of phycocyanin is characterized by comprising the following steps:

mixing culture water containing microalgae with a protein protective agent, and performing first centrifugation to obtain a concentrated algae solution;

mixing the concentrated algae solution with a cell freezing protective agent, and repeatedly freezing and thawing to obtain a thawed concentrated algae solution;

mixing the thawed concentrated algae solution with a protein protective agent and a surfactant, and carrying out cell disruption to obtain a disrupted algae solution;

performing second centrifugation on the crushed algae liquid to obtain a supernatant;

mixing the supernatant with ammonium sulfate and polypropylene glycol, and stirring;

step (6), performing third centrifugation on the stirred feed liquid to obtain a precipitate;

and (7) washing the obtained precipitate with an ethanol water solution, centrifuging the precipitate for the fourth time, and freeze-drying the precipitate.

2. The extraction method according to claim 1, wherein the protein protectant is sodium azide;

step (1), in the culture water containing microalgae, the addition amount of the protein protective agent is 0.1-0.5 mg/L.

3. The extraction method according to claim 1, wherein the rotation speed of the first centrifugation is 5000-10000rpm, and the water content of the concentrated algae solution is 50-70%.

4. The extraction method according to claim 1, wherein the cell cryoprotectant is glycerol;

and (2) adding 5-10g/kg of the cell cryoprotectant into the concentrated algae solution.

5. The extraction method according to claim 1, wherein the repeated freezing and thawing process comprises: freezing at-20 to-10 ℃ for 12 to 24 hours, unfreezing at 10 to 30 ℃ for 6 to 12 hours, and repeating for 2 to 3 times.

6. The extraction method according to claim 1, wherein the surfactant is tween 80 and dow DF104 polyether defoamer;

and (3) in the thawed concentrated algae solution, the adding amount of the protein protective agent is 1-2mg/L, the adding amount of the Tween 80 is 1-5 mL/L, and the adding amount of the Dow DF104 polyether defoaming agent is 1-2 mL/L.

7. The extraction method according to claim 1, wherein the second centrifugation is performed at 2000-3000rpm for 40-60 min.

8. The extraction method according to claim 1, wherein in the step (5), the addition amount of ammonium sulfate is 10 to 15g/L, and the addition amount of polypropylene glycol is 5 to 30 mL/L;

the stirring speed is 500-1000 rpm, and the time is 1-2 h.

9. The extraction method according to claim 1, wherein the rotation speed of the third centrifugation is 5000-10000rpm, and the time is 20-40 min.

10. The extraction process according to any one of claims 1 to 9, wherein the concentration of the aqueous ethanol solution is between 20% and 50%;

the rotating speed of the fourth centrifugation is 5000-10000rpm, and the time is 20-40 min.

Technical Field

The invention relates to the technical field of protein extraction, and particularly relates to a rapid extraction method of phycocyanin.

Background

Microalgae is one of the oldest species on the earth, has rich nutritional ingredients, is widely applied in the fields of livestock husbandry, environmental protection, medicine, cosmetics, food and the like, and is also known as the most ideal and perfect food for human in the 21 st century by world food and agriculture organizations. Meanwhile, microalgae are baits (or baits of baits) for the lifetime or specific development stages of aquaculture animals, and are one of important bases to support the aquaculture industry to a great extent. The nannochloropsis oculata grows rapidly, has small cell particles, is rich in unsaturated fatty acids such as EPA and the like, has comprehensive nutrition and has the characteristic of thicker cell wall. The microalgae is the primary productivity of a water body ecosystem and contains rich nutrient substances such as protein, polyunsaturated fatty acid, carotenoid, vitamin and the like; the microalgae can provide food for aquatic animals, and can absorb redundant substances such as ammonia nitrogen, phosphorus and the like in a water body through photosynthesis to play a role in stabilizing and improving water quality, so that the microalgae is widely applied to the aquaculture industry.

Phycocyanin is an important nutrient component in microalgae, is a photosynthetic auxiliary pigment commonly existing in microalgae cells, and is an open-chain tetra-La compound and a dehydrant protein. It is an important photosynthetic natural pigment in microalgal cells, and in photosynthesis, it can preferentially transfer light energy to photosystems with nearly high efficiency. Many researches show that phycocyanin has biological activities of improving the radiation resistance, oxidation resistance, inflammation resistance, cancer resistance, aging resistance, bacteriostasis, protecting nervous tissues from being damaged, enhancing the immunity of organisms, protecting the liver, immunofluorescence and the like of organisms, and is widely applied to the fields of foods, cosmetics, medicines, molecular probes and the like. Phycocyanin is commonly present in microalgae, and the content of phycocyanin in blunt microalgae is up to 20 percent. It is rich in eight essential amino acids, has great development value in nature, and is one kind of edible and bait protein resource. Phycocyanin has two important uses: the crude product can be used as natural edible pigment (sky blue); secondly, the pure product can be used as a fluorescent molecular probe and is mainly used for early detection and conventional detection of cancers or prepared into a rapid detection kit, and China is totally dependent on import.

Several technical difficulties still exist to varying degrees in the phycocyanin processing process: such as low extraction rate, high cost, unstable properties, etc. These problems often affect the color and efficacy of phycocyanin, affecting the commercial value of the product. At present, more than two crushing means are adopted for the research of the cell wall breaking of algae, such as: although the phycocyanin can be released from the microalgae to a greater extent by combining repeated freezing and thawing with ultrasonic treatment, the method has the disadvantages of complex operation, long time consumption, high energy consumption, high equipment cost and easy degeneration of the ultrasonic treatment protein. The large-scale purification technology of phycocyanin is not mature, and comprises a salting-out method, a chromatography method, a two-aqueous phase extraction and the like. The salting-out method is mild and is easy to concentrate, but the purity of phycocyanin obtained by the method is not high. The large-scale purification technology of phycocyanin mostly adopts a chromatographic purification technology, is easy to amplify and produce in a large scale, and has the problems of expensive chromatographic column packing, harsh purification conditions, difficult recovery and preparation of products and the like. Most phycocyanin extraction researches are still in the laboratory stage at the present stage, and the method is complex, low in yield, low in purity, high in cost and difficult to realize industrialization. The extraction and purification of phycocyanin mainly adopts gel adsorption and ion chromatography, but the operation is complex and needs to be combined with each other for application, which is not beneficial to the purification of phycocyanin.

Disclosure of Invention

In view of this, the invention provides a method for rapidly extracting phycocyanin. The extraction method has simple operation, low cost, and high phycocyanin purity.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a method for quickly extracting phycocyanin, which comprises the following steps:

mixing culture water containing microalgae with a protein protective agent, and performing first centrifugation to obtain a concentrated algae solution;

mixing the concentrated algae solution with a cell freezing protective agent, and repeatedly freezing and thawing to obtain a thawed concentrated algae solution;

mixing the thawed concentrated algae solution with a protein protective agent and a surfactant, and carrying out cell disruption to obtain a disrupted algae solution;

performing second centrifugation on the crushed algae liquid to obtain a supernatant;

mixing the supernatant with ammonium sulfate and polypropylene glycol, and stirring;

step (6), performing third centrifugation on the stirred feed liquid to obtain a precipitate;

and (7) washing the obtained precipitate with an ethanol water solution, centrifuging the precipitate for the fourth time, and freeze-drying the precipitate.

Preferably, the protein protectant is sodium azide.

Preferably, in the step (1), the addition amount of the protein protective agent in the culture water containing microalgae is 0.1-0.5 mg/L.

In the specific embodiment provided by the invention, the adding amount of the protein protective agent in the culture water containing microalgae is 0.2 mg/L.

Preferably, the rotation speed of the first centrifugation is 5000-10000rpm, and the water content of the concentrated algae solution is 50-70%.

In the specific embodiment provided by the invention, the rotating speed of the first centrifugation is 8000rpm, and the water content of the concentrated algae liquid is 58%.

Preferably, the cell cryoprotectant is glycerol;

preferably, in the step (2), the cell cryoprotectant is added to the concentrated algal solution in an amount of 5-10 g/kg.

In the specific embodiment provided by the invention, the adding amount of the cell cryoprotectant in the concentrated algae solution is 10 g/kg.

Preferably, the procedure of repeated freezing and thawing is: freezing at-20 to-10 ℃ for 12 to 24 hours, unfreezing at 10 to 30 ℃ for 6 to 12 hours, and repeating for 2 to 3 times.

Preferably, the program of repeated freeze-thawing is: freezing for 12-24h at the temperature of minus 18 ℃, unfreezing for 6-12h at normal temperature, and repeating for 2-3 times.

In the specific embodiment provided by the present invention, the procedure of repeated freezing and thawing is as follows: freezing at-18 deg.C for 12h, thawing at normal temperature for 6h, and repeating for 2 times.

Preferably, the surface active agent is tween 80 and the dow DF104 polyether defoamer;

preferably, in the step (3), the addition amount of the protein protective agent is 1-2mg/L, the addition amount of the Tween 80 is 1-5 mL/L, and the addition amount of the Dow DF104 polyether defoaming agent is 1-2mL/L in the thawed concentrated algae solution.

In the specific embodiment provided by the invention, in the thawed concentrated algae solution, the addition amount of the protein protective agent is 2mg/L, the addition amount of the Tween 80 is 5mL/L, and the addition amount of the Dow DF104 polyether antifoaming agent is 1 mL/L.

Preferably, the rotation speed of the second centrifugation is 2000-3000rpm, and the time is 40-60 min.

In the specific embodiment provided by the invention, the rotation speed of the second centrifugation is 2000rpm, and the time is 40 min.

Preferably, in the step (5), in the supernatant, the adding amount of ammonium sulfate is 10-15g/L, and the adding amount of polypropylene glycol is 5-30 mL/L;

in the specific embodiment provided by the invention, the adding amount of ammonium sulfate in the supernatant is 10g/L, and the adding amount of polypropylene glycol is 20mL/L

Preferably, in the step (5), the stirring speed is 500-1000 rpm, and the time is 1-2 h.

In the specific embodiment provided by the invention, the stirring speed is 1000rpm, and the time is 1 h.

Preferably, the molecular weight of polypropylene glycol is 1500-.

In a specific embodiment provided by the present invention, the polypropylene glycol has a molecular weight of 1500.

Preferably, the rotation speed of the third centrifugation is 5000-10000rpm, and the time is 20-40 min.

In the specific embodiment provided by the invention, the rotating speed of the third centrifugation is 5000rpm, and the time is 30 min.

Preferably, the concentration of the ethanol aqueous solution is 20 to 50 percent;

preferably, the concentration of the aqueous ethanol solution is 30%.

Preferably, the rotation speed of the fourth centrifugation is 5000-10000rpm, and the time is 20-40 min.

In the specific embodiment provided by the invention, the rotation speed of the fourth centrifugation is 5000rpm, and the time is 30 min.

In the present invention, the microalgae are selected from algae of the phylum cyanophyta, chlorophyta, chrysophyta or rhodophyta. Such as chlorella, nannochloropsis, etc.

The invention provides a rapid extraction method of phycocyanin. The method comprises the following steps: mixing culture water containing microalgae with a protein protective agent, and performing first centrifugation to obtain concentrated algae solution; mixing the concentrated algae solution with a cell freezing protective agent, and repeatedly freezing and thawing to obtain a thawed concentrated algae solution; mixing the thawed concentrated algae solution with a protein protective agent and a surfactant, and carrying out cell disruption to obtain a disrupted algae solution; performing second centrifugation on the crushed algae liquid to obtain a supernatant; mixing the supernatant with ammonium sulfate and polypropylene glycol, and stirring; performing third centrifugation on the stirred feed liquid to obtain a precipitate; washing the obtained precipitate with ethanol water solution, centrifuging for the fourth time, and freeze drying the precipitate. The invention has the technical effects that:

in the invention, sodium azide is used as a protein protective agent, so that protein denaturation and decomposition in a centrifugation process are avoided, and impurities are formed. The glycerol has the cell protection effect, and avoids the formation of large-particle ice crystals in the freezing process and the damage to the protein structure.

In the step (2), the hard cell walls of the microalgae can be damaged by repeatedly freezing and dissolving the microalgae, so that the homogenization and crushing efficiency is better facilitated.

And (3) in the step (3), Tween 80 and the Dow DF104 polyether defoaming agent form a mixed surfactant, and phycocyanin can be separated out from the supernatant by combined use.

The combined use of ammonium sulfate and polypropylene glycol in step (5) can separate out phycocyanin dissolved in the supernatant to form a particle precipitate.

Residual ammonium sulfate, polypropylene glycol and other impurities can be washed away by adopting an ethanol water solution in the step (7), so that the purity of the phycocyanin is improved.

Through the multi-step simple and rapid extraction and purification operation of the invention, the purity of the lyophilized phycocyanin dry powder can reach 99%, the protein capture rate is 87%, and the protein activity is 98%.

Detailed Description

The invention discloses a rapid extraction method of phycocyanin, which can be realized by appropriately improving process parameters by referring to the contents in the field. It is expressly intended that all such similar substitutes and modifications which would be obvious to one skilled in the art are deemed to be included in the invention. While the methods and applications of this invention have been described in terms of preferred embodiments, it will be apparent to those of ordinary skill in the art that variations and modifications in the methods and applications described herein, as well as other suitable variations and combinations, may be made to implement and use the techniques of this invention without departing from the spirit and scope of the invention.

The method for rapidly extracting the microalgae phycocyanin provided by the invention specifically comprises the following steps:

1. adding sodium azide into cultured microalgae (microalgae, Chlorella, Nannochloropsis oculata, etc.) at an amount of 0.1-0.5 mg/L. And then, carrying out centrifugal separation on the microalgae liquid by using a disc type centrifuge, and extracting algae somatic cells to form concentrated algae liquid. The rotation speed of the centrifuge is 5000 plus 10000rpm, and the water content of the separated algae liquid is 50-70 percent.

2. Adding glycerol (100% purity, 5-10g/kg concentrated algae), stirring, and freezing at-18 deg.C for 12-24 hr.

3. Thawing the frozen concentrated algae solution at normal temperature for 6-12 h.

4. Repeating the second step and the third step for 2-3 times.

5. Adding sodium azide (the addition amount is 1-2mg/L), tween 80 (the addition amount is 1-5 mL/L) and Dow DF104 polyether defoaming agent (1-2mL/L) into the thawed concentrated algae solution, uniformly mixing, and placing into a homogenate breaker for cell disruption.

6. And (4) centrifuging the crushed algae liquid at a low rotation speed of 2000-3000rpm for 40-60 min by using a disc centrifuge, collecting supernatant and removing precipitates.

7. Adding ammonium sulfate solid (10-15 g/L) and polypropylene glycol (5-30 mL/L), and stirring for 1-2 h.

8. And (3) centrifuging the stirred material liquid at a high rotation speed of 5000 plus 10000rpm for 20-40 min by using a disc centrifuge, and collecting the precipitate.

9. And (3) cleaning the precipitate with 30% ethanol solution, centrifuging again at the rotation speed of 5000-10000rpm for 20-40 min, and collecting the precipitate.

10. Freeze drying the precipitate to obtain phycocyanin freeze-dried powder.

The reagents or apparatus used in the present invention are commercially available.

The invention is further illustrated by the following examples:

example 1

1. The cultured marine chlorella (algae density: 800 ten thousand cells/mL) is added with sodium azide at a dosage of 0.2 mg/L. And then, carrying out centrifugal separation on the microalgae liquid by using a disc type centrifuge, and extracting algae somatic cells to form concentrated algae liquid. The rotation speed of the centrifuge is 8000rpm, and the water content of the separated algae liquid is 58 percent.

2. Adding glycerol (100% purity, 10g/kg concentrated algae), stirring, and freezing at-18 deg.C for 12 hr.

3. Thawing the frozen concentrated algae solution at normal temperature for 6 h.

4. Repeat the second step and the third step 2 times.

5. Adding sodium azide (the addition amount is 2mg/L), tween 80 (the addition amount is 5 mL/L) and the Dow DF104 polyether defoaming agent (1mL/L) into the thawed concentrated algae solution, uniformly mixing, and placing into a homogenate crusher for cell crushing.

6. And (3) centrifuging the crushed algae liquid at a low rotation speed of 2000rpm for 40min by using a disc centrifuge, collecting supernatant, and removing precipitates.

7. To the collected supernatant, ammonium sulfate solid (added amount: 10g/L) and polypropylene glycol (added amount: 20mL/L) were added, and the mixture was stirred for 1 hour.

8. And (4) centrifuging the stirred feed liquid at a high rotation speed of 5000rpm for 30min by using a disc centrifuge, and collecting the precipitate.

9. Washing the precipitate with 30% ethanol solution, centrifuging again at 5000rpm for 30min, and collecting the precipitate.

10. Freeze drying the precipitate to obtain phycocyanin freeze-dried powder.

11. Through detection, the purity of phycocyanin is 99.2%, the protein capture rate is 87%, and the protein activity is 98%.

Comparative example 1

Phycocyanin in Chlorella marinum is extracted by referring to the extraction method of example four in patent publication No. CN109160947A (a preparation method and application of phycocyanin of Spirulina). The method comprises the following specific steps:

the cultured marine chlorella (algae density: 800 ten thousand cells/mL) is added with sodium azide at a dosage of 0.2 mg/L. And then, carrying out centrifugal separation on the microalgae liquid by using a disc type centrifuge, and extracting algae somatic cells to form concentrated algae liquid. The rotation speed of the centrifuge is 8000rpm, and the water content of the separated algae liquid is 55%.

Adding the separated concentrated algae solution into phosphate buffer solution (with the concentration of 0.1mol/L and containing 0.004mol/L sodium azide) according to the volume ratio of 1:20g/ml of the feed liquid, and uniformly mixing; swelling the mixture for 6 hours in an environment of 4 ℃, shearing the mixture for 15min by using an ultra-fine shearing machine, centrifuging the sheared feed liquid, and taking supernatant; slowly adding ammonium sulfate into the supernatant until the saturation degree is 30%, removing other protein impurities, centrifuging, and taking the supernatant; continuously and slowly adding an ammonium sulfate solution into the supernatant until the saturation degree is 70%, and centrifuging to obtain a blue precipitate; freeze-drying the precipitate for 18 hours to obtain phycocyanin, wherein the capture rate of the phycocyanin is 65%, and the purity is 73%.

Comparative example 2

This comparative example refers to example 1, but is protected all the way without the addition of sodium azide.

1. And (3) centrifuging the cultured marine chlorella (the density of the chlorella is 800 ten thousand cells/mL) by a disc centrifuge to extract algal cells to form concentrated chlorella solution. The rotation speed of the centrifuge is 8000rpm, and the water content of the separated algae liquid is 58 percent.

2. Adding glycerol (100% purity, 10g/kg concentrated algae), stirring, and freezing at-18 deg.C for 12 hr.

3. Thawing the frozen concentrated algae solution at normal temperature for 6 h.

4. Repeat the second step and the third step 2 times.

5. Adding tween 80 (the addition amount is 5 mL/L) and Dow DF104 polyether defoaming agent (1mL/L) into the thawed concentrated algae solution, mixing uniformly, and placing into a homogenate crusher for cell crushing.

6. And (3) centrifuging the crushed algae liquid at a low rotation speed of 2000rpm for 40min by using a disc centrifuge, collecting supernatant, and removing precipitates.

7. To the collected supernatant, ammonium sulfate solid (added amount: 10g/L) and polypropylene glycol (added amount: 20mL/L) were added, and the mixture was stirred for 1 hour.

8. And (4) centrifuging the stirred feed liquid at a high rotation speed of 5000rpm for 30min by using a disc centrifuge, and collecting the precipitate.

9. Washing the precipitate with 30% ethanol solution, centrifuging again at 5000rpm for 30min, and collecting the precipitate.

10. And (4) freeze-drying the precipitate to obtain the phycocyanin freeze-dried powder.

11. Through detection, the phycocyanin purity is 65%, the protein capture rate is 80%, and the protein activity is 40%.

Comparative example 3

This comparative example refers to example 1, but repeated freeze-thawing was not performed, only one freeze-thawing was performed.

1. The cultured marine chlorella (algae density: 800 ten thousand cells/mL) is added with sodium azide at a dosage of 0.2 mg/L. And then, carrying out centrifugal separation on the microalgae liquid by using a disc type centrifuge, and extracting algae somatic cells to form concentrated algae liquid. The rotation speed of the centrifuge is 8000rpm, and the water content of the separated algae liquid is 58 percent.

2. Adding glycerol (100% purity, 10g/kg concentrated algae), stirring, and freezing at-18 deg.C for 12 hr.

3. Thawing the frozen concentrated algae solution at normal temperature for 6 h.

4. Adding sodium azide (the addition amount is 2mg/L), tween 80 (the addition amount is 5 mL/L) and the Dow DF104 polyether defoaming agent (1mL/L) into the thawed concentrated algae solution, uniformly mixing, and placing into a homogenate crusher for cell crushing.

5. And (3) centrifuging the crushed algae liquid at a low rotation speed of 2000rpm for 40min by using a disc centrifuge, collecting supernatant, and removing precipitates.

6. To the collected supernatant, ammonium sulfate solid (added amount: 10g/L) and polypropylene glycol (added amount: 20mL/L) were added, and the mixture was stirred for 1 hour.

7. And (4) centrifuging the stirred feed liquid at a high rotation speed of 5000rpm for 30min by using a disc centrifuge, and collecting the precipitate.

8. Washing the precipitate with 30% ethanol solution, centrifuging again at 5000rpm for 30min, and collecting the precipitate.

9. And (4) freeze-drying the precipitate to obtain the phycocyanin freeze-dried powder.

10. The detection proves that the phycocyanin has the purity of 85 percent, the protein capture rate of 35 percent and the protein activity of 89 percent.

Comparative example 4

This comparative example, referring to example 1, the ammonium sulfate and polypropylene glycol in step 7 were replaced with polyaluminum chloride flocculant (PAC)

1. The cultured marine chlorella (algae density: 800 ten thousand cells/mL) is added with sodium azide at a dosage of 0.2 mg/L. And then, carrying out centrifugal separation on the microalgae liquid by using a disc type centrifuge, and extracting algae somatic cells to form concentrated algae liquid. The rotation speed of the centrifuge is 8000rpm, and the water content of the separated algae liquid is 58 percent.

2. Adding glycerol (100% purity, 10g/kg concentrated algae), stirring, and freezing at-18 deg.C for 12 hr.

3. Thawing the frozen concentrated algae solution at normal temperature for 6 h.

4. Repeat the second step and the third step 2 times.

5. Adding sodium azide (the addition amount is 2mg/L), tween 80 (the addition amount is 5 mL/L) and the Dow DF104 polyether defoaming agent (1mL/L) into the thawed concentrated algae solution, uniformly mixing, and placing into a homogenate crusher for cell crushing.

6. And (3) centrifuging the crushed algae liquid at a low rotation speed of 2000rpm for 40min by using a disc centrifuge, collecting supernatant, and removing precipitates.

7. To the collected supernatant, a polyaluminum chloride flocculant (PAC) (added in an amount of 2g/L) was added and stirred for 1 hour.

8. And (4) centrifuging the stirred feed liquid at a high rotation speed of 5000rpm for 30min by using a disc centrifuge, and collecting the precipitate.

9. Washing the precipitate with 30% ethanol solution, centrifuging again at 5000rpm for 30min, and collecting the precipitate.

10. And (4) freeze-drying the precipitate to obtain the phycocyanin freeze-dried powder.

11. Through detection, the phycocyanin purity is 25%, the protein capture rate is 35%, and the protein activity is 40%.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.