CN107474102A - A kind of method that Sargassum protein is extracted using special extraction kettle material bag - Google Patents

Abstract

The invention discloses a method for extracting seaweed protein by using a special material bag of an extraction kettle, which comprises the following steps: (1) in subcritical water extraction equipment, put seaweed powder into a special material bag of an extraction kettle and hang it on In the extraction kettle, inject preheated deoxygenated deionized water into the extraction kettle, and under ultrasonic conditions, heat and pressurize to carry out the extraction reaction; (2) After the extraction is completed, collect the extract cooled to room temperature, then cool and precipitate, and centrifuge , take the supernatant, freeze, and dry to obtain thick seaweed protein. The present invention uses a special extraction kettle material bag to extract seaweed protein, which increases the contact area between the extract and the material, and significantly improves the yield of seaweed crude protein. When no ultrasound is used, the yield of seaweed protein is increased by 4 times; When supplemented with ultrasound, seaweed protein was enhanced by 1.6 times.

Description

A method for extracting seaweed protein using a special extraction kettle material bag

technical field

The invention relates to the technical field of subcritical water extraction, in particular to a method for extracting seaweed protein by using a special material bag of an extraction kettle.

Background technique

Subcritical water, also known as high-pressure hot water, super hot water or hot liquid water, refers to high-temperature water with a temperature above 100°C and a critical temperature below 374°C under a certain pressure (generally 5-20MPa), and it has been kept liquid state. Subcritical water extraction is to use subcritical water as the extraction agent, in a closed, oxygen-free, high-pressure container, according to the principle of similar solubility of organic matter, through the molecular diffusion process of the extraction material and the extraction agent during the soaking process, to achieve the solid material It is a new extraction and separation technology that transfers the fat-soluble components in the liquid to the liquid extractant, and then separates the extraction solvent from the target product through concentration and dehydration, and finally obtains the target product.

Most of the objects extracted by subcritical water extraction equipment are solid raw materials. Due to the properties of the solid matrix itself and the requirements and limitations of the special conditions of high temperature and high pressure of subcritical water, it is impossible to install a stirring device in the extraction kettle, and most of the materials are piled up together, resulting in The low mass transfer efficiency and the inhomogeneity of the extraction process, and with the increase of the charging amount and the increase of the accumulation height, this defect is extremely obvious. The extraction rate of subcritical water technology needs to be further improved, especially for the extraction of those heat-sensitive substances, it is necessary to add organic solvents or surfactants and other entraining agents to achieve a satisfactory extraction rate and recovery rate, which greatly limits its use. application and development.

Subcritical water extraction equipment is mainly composed of two parts, namely the control system and the operating system. The control system mainly includes temperature regulating controller, pressure regulating controller, over-temperature and over-pressure alarm and the circuit system of the whole equipment. For the convenience of operation, the controller of this part is designed as a control panel, and the whole machine is controlled through the switches, buttons and knobs on the panel. The operating system part is mainly composed of a reservoir, a pressure pump, a pre-heater, a constant temperature device, an extraction kettle, a regulating valve, a cooler and a collector.

Extraction mechanism: when the temperature is low, the distance between water molecules is close. In the subcritical state, as the temperature increases, the kinetic energy of the molecules increases, and the distance between molecules gradually increases. The hydrogen bonds of the fluid microstructure, ion hydration, Ion association, cluster structure, etc. have changed, so the physical and chemical characteristics of subcritical water are quite different from those of normal temperature and pressure water. The dielectric constant is a measure of the dissolving ability of a solvent. The polarity of water at normal temperature and pressure is strong. In the subcritical state, the dielectric constant ε of water decreases with the increase of temperature, and the hydrogen bond of water is opened or weakened, thereby greatly reducing the water Polarity, the polarity changes from strong to weak, which allows water molecules to get closer to low-polarity solute molecules to increase the attractive force. Its properties are similar to organic solvents, which promote the dissolution of solute molecules and can sequentially separate target substances of different polarities. Extract it. Therefore, by controlling the temperature and pressure of the subcritical water, the polarity of the water can be changed in a wide range, thereby realizing the continuous extraction of water-soluble to fat-soluble active substances in natural products. And only water is used as a solvent, which has the advantages of non-toxicity, strong safety, high efficiency and environmental protection, and easy operation, and has become a research hotspot in the field of extraction and separation.

When using subcritical water extraction equipment to extract natural products, the yield of active substances is usually improved by controlling pressure, time, temperature, ultrasonic frequency, and power. There are few reports on increasing the yield of active substances by increasing the surface area of the material. . The material particles extracted by this equipment are generally larger than 60 mesh. Without the action of external force, the smaller the particle size of the material is, the easier it is to agglomerate under the action of water, which seriously affects the contact between the material and subcritical water. In the subcritical water that cannot be stirred In the extraction kettle of the equipment, increasing the contact area between the material and subcritical water can better extract the target active product. The active material yield obtained by the operation according to the patent 200710032663.1 is low, and the subcritical water material basket is improved to increase the material and There is no report on subcritical water contact to improve the yield of active substances.

Contents of the invention

The purpose of the present invention is to provide a method for extracting seaweed protein by using a special extraction kettle material bag to address the deficiencies in the prior art. The method uses a special extraction kettle material bag to extract seaweed protein, which increases the contact area between the material and the extract, and solves the problem of material wrapping and agglomeration that are easily caused by direct use of subcritical water extraction equipment in the prior art. , leading to the problem of low extraction rate, so as to obtain the active substance of seaweed protein with high extraction yield.

The purpose of the present invention is achieved through the following technical solutions.

A method for extracting seaweed protein using a special extraction kettle material bag, comprising the steps of:

(1) In the subcritical water extraction equipment, put the seaweed powder into the special material bag of the extraction kettle and hang it in the extraction kettle, inject the preheated deoxygenated deionized water into the extraction kettle, and heat it under ultrasonic conditions Pressurize for extraction reaction;

(2) After the extraction is completed, the extract cooled to room temperature is collected, cooled and precipitated, centrifuged, the supernatant is taken, frozen, and dried to obtain crude seaweed protein.

Further, the special extraction kettle material bag includes a support hoop, a gauze layer, a gauze bag and a beam;

The bracket hoop is composed of a plurality of coaxial stainless steel hoops arranged in the vertical direction; the stainless steel hoop is not closed and has an opening; two adjacent stainless steel hoops are connected by steel wires, and the two ends of the steel wires are respectively connected At the open ends of two adjacent stainless steel hoops, and from bottom to top, the two ends of the steel wire connecting the first stainless steel hoop and the second stainless steel hoop are connected to the open ends of the same side of the two stainless steel hoops, while the other two The connection between adjacent stainless steel hoops is an open end dislocation connection;

The gauze layer is fixed on each stainless steel hoop of the bracket hoop by gauze for holding materials;

Described gauze bag is the bag that gauze is made, is used for wrapping the bracket hoop that has gauze layer;

The mouth rope is threaded through the opening of the gauze bag, and is used for closing the gauze bag and the suspension of the whole material bag.

Furthermore, the stainless steel hoop and steel wire of the stent hoop are made of stainless steel wire with a diameter of 2mm.

Furthermore, the steel wire is connected to the stainless steel hoop by welding, or directly by folding the steel wire into a steel hoop.

The specifications of the steel wire are determined according to the size of the actual extraction kettle cavity. When the extraction kettle cavity is large, use a stainless steel wire with a larger diameter to achieve a better supporting effect; at the same time, the diameter of the stainless steel hoop is designed according to the size of the extraction kettle cavity , and ensure that the size of the entire material bag does not exceed the size of the extraction kettle and can be placed in the extraction kettle.

Furthermore, the gauze bag includes two forms: a gauze bag with a stainless steel tow rope and a stainless steel hoop combined with gauze; the gauze bag of the stainless steel tow rope is in the form of a stainless steel wire passing through the open end of the gauze bag It is also used to suspend the entire material bag at the mouth of the beam; the gauze bag used in conjunction with the stainless steel hoop and gauze is in the form of a stainless steel hoop and the gauze bag being placed separately in the material basket, and the opening of the gauze bag and the stainless steel hoop are fixed on the ultrasonic probe for suspension.

Furthermore, the material of the beam rope is 0.2-1 mm stainless steel wire, preferably 0.5 mm stainless steel wire, which is easy to fold and bend, and convenient to use.

Furthermore, the specifications of the gauze in the gauze layer are selected according to the particle size of the material, and the gauze with a pore size larger than the particle size of the material is selected.

The area of the gauze layer is larger than the area surrounded by the stainless steel hoop; at the same time, the number of layers of the gauze layer is the same as that of the stainless steel hoop, and the degree of dispersion of the material can be adjusted by adjusting the number of layers of the stainless steel hoop and the gauze layer. The number of layers can further spread the material and further increase the contact area between the material and the extract.

Furthermore, the gauze specification of the gauze layer and the gauze bag is 40-60 mesh, preferably 40 mesh.

Without changing the structure of the extraction kettle of the subcritical water extraction equipment and the equipment is not equipped with a stirring device, the special material bag can well increase the direct contact area between the material and the subcritical water, and improve the extraction yield of natural products. At the same time, the two forms of special gauze bags are designed to be suitable for subcritical water extraction equipment equipped with ultrasonic probes and without ultrasonic probes, and stainless steel wire and gauze are used as materials, which have minimal impact on the extraction effect. Source Simple and easy to obtain, low manufacturing cost, simple device structure and convenient operation make the special material bag more practical.

Further, in step (1), the preheating is to preheat to 60-100°C.

Further, in step (1), the rate at which the deoxidized and deionized water is injected into the extraction tank is 100 mL/min.

In the process of extracting with deoxygenated and deionized water to form subcritical water as the extractant, the problem of the oxidation of the extract is avoided, so that the final extract will have excellent activity.

Further, in step (1), the power of the ultrasound is 50-500W.

Further, in step (1), the heating is to make the temperature reach 100-150°C.

Further, in step (1), the pressurization is to make the pressure reach 1-20 MPa.

Further, in step (1), the extraction reaction time is 0.5-2.5 hours.

Further, in step (2), the cooling precipitation is cooling to 4° C. for precipitation.

Further, in step (2), the centrifugation is performed at 4° C. and 8000 r/min for 30 minutes.

Further, in step (2), the freezing is freezing into ice cubes at a temperature ≤ -20°C; the drying is vacuum freeze-drying.

Further, in the method described above, ultrasonic assistance is not used in step (1), and the gauze bag in the material bag of the special extraction kettle adopts a gauze bag with a stainless steel tow mouth rope.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

(1) The present invention uses a special extraction kettle material bag to extract seaweed protein, which increases the contact area between the extract and the material, significantly improves the yield of seaweed crude protein, and uses stainless steel wire to change the configuration of the material when it is placed Strong operability, no pollution, no impact on the extracted materials;

(2) the making of the special extraction kettle material bag that the inventive method adopts is simple and convenient, operability is strong, is easy to realize industrial application;

(3) The present invention uses a special extraction kettle material bag to extract seaweed protein. When not supplemented with ultrasound, the yield of seaweed protein is increased by 4 times; when supplemented with ultrasound, the seaweed protein is increased by 1.6 times.

Description of drawings

Fig. 1 is the structural representation of the subcritical water extraction equipment that adopts in the specific embodiment of the present invention;

Fig. 2 is the front view of the material bracket hoop in the special extraction kettle material bag in the specific embodiment of the present invention;

Fig. 3 is the front view of the material bracket hoop in the special extraction kettle material bag in the specific embodiment of the present invention;

Fig. 4 is the sectional schematic diagram in the subcritical water extraction tank that does not add ultrasonic probe in the specific embodiment of the present invention;

Fig. 5 is the schematic sectional view of carrying the special extraction kettle material bag of stainless steel tow mouth rope in the subcritical water extraction kettle without ultrasonic probe in the specific embodiment of the present invention;

Fig. 6 is the sectional schematic diagram in the subcritical water extraction tank that adds ultrasonic probe in the specific embodiment of the present invention;

Fig. 7 is a schematic cross-sectional view of a special extraction kettle material bag in which stainless steel hoops and gauze are used together in a subcritical water extraction kettle with an ultrasonic probe added in a specific embodiment of the present invention.

detailed description

The technical solutions of the present invention will be further described in detail below in conjunction with specific embodiments and drawings, but the present invention is not limited thereto.

In a specific embodiment of the present invention, a schematic structural diagram of a subcritical water extraction device for extracting algae protein is shown in Figure 1, including a control system part and an operating system part, and the control system part and the operating system part are connected by means of electrical signals;

The operating system part includes: nitrogen cylinder 1-1, water storage device 1-2, pressure pump 1-3, preheating kettle 1-4, material basket 1-5, extraction kettle 1-6, constant temperature device 1-7, cooling Kettle 1-8, collector 1-9, pressure gauge 1-10, temperature gauge 1-11, cooling water inlet 1-12, cooling water outlet 1-13, back pressure valve 1-14 and shut-off valve 1-15;

The nitrogen cylinder 1-1 is connected to the inlet of the water storage device 1-2 through a pipeline and a regulating valve; one end of the pressure pump 1-3 is connected to the outlet of the water storage device 1-2 through a regulating valve, and is passed through a shut-off valve 1-15 They are respectively connected to the outlet of the cooling kettle 1-8, and the other end is connected to the preheating kettle 1-4 through a regulating valve; the preheating kettle 1-4 is connected to the inlet port of the extraction kettle 1-6 through a regulating valve; the extraction kettle 1-6 There is a material basket 1-5 inside, a constant temperature device 1-7 is arranged outside the extraction kettle 1-6, and a pressure gauge 1-10 and a temperature gauge 1-11 are arranged on the top of the extraction kettle 1-6 for monitoring the kettle. The pressure and temperature inside; the outlet port of the extraction kettle 1-6 is connected to the inlet port of the cooling kettle 1-8 through a regulating valve; the upper end of the cooling kettle 1-8 is provided with a cooling water outlet 1-13, and the lower end is provided with a cooling water inlet 1-12; one end of the cooling kettle 1-8 connected to the pressure pump 1-3 is also connected to the collector 1-9 through the back pressure valve 1-14;

The control system part is designed as a control panel 1-16, and the control panel 1-16 is designed with a temperature adjustment controller 1-17, a pressure adjustment controller 1-18, an over-temperature and over-pressure alarm 1-19 and a power switch for the entire device 1-20;

During the extraction process, open the regulating valve connecting the nitrogen cylinder 1-1 and the water storage device 1-2, feed nitrogen to remove the oxygen in the water storage device 1-2, and form deoxidized deionized water; the materials to be extracted are placed in In the material blue 1-5 of the extraction kettle 1-6, the extraction solvent water passes through the pressure pump 1-3 and the preheating kettle 1-4 to form deoxidized and deionized subcritical water, enters the extraction kettle 1-6, and passes through the constant temperature device 1 -7 Keep the temperature in the extraction kettle 1-6, monitor the pressure and temperature in the kettle through the pressure gauge 1-10 and the temperature gauge 1-11; after the extraction, the subcritical water dissolved with the extract enters the cooling kettle 1 through the regulating valve -8 for cooling, and the cooled water enters the collector 1-9 through the back pressure valve 1-14 for collection.

In a specific embodiment of the present invention, the special extraction kettle material bag includes a support hoop, a gauze layer, a gauze bag and a beam;

The front view and side view of the bracket hoop are shown in Figure 2 and Figure 3 respectively. The bracket hoop is composed of multiple coaxial stainless steel hoops arranged in the vertical direction; the stainless steel hoop is not closed and has an opening; two adjacent stainless steel hoops The hoops are connected by steel wires, and the two ends of the steel wires are respectively connected to the open ends of two adjacent stainless steel hoops, and from bottom to top, the two ends of the steel wires connecting the first stainless steel hoop and the second stainless steel hoop are connected to the The open end of the same side of the two stainless steel hoops, and the connection between the other two adjacent stainless steel hoops is an open end dislocation connection; and the stainless steel hoop and steel wire of the bracket hoop are made of stainless steel wire with a diameter of 2mm, and the diameter of the stainless steel hoop is The height of the bracket hoop is 55mm, the height of the bracket hoop is 100mm, and there are 6 stainless steel hoops in total. The connection method between the steel wire and the stainless steel hoop is welding, or it is directly folded by the steel wire that is held into a steel hoop;

The gauze layer is gauze fixed on each stainless steel hoop of the support hoop, which is used to hold the material; the specifications of the gauze layer are selected according to the particle size of the material, and the gauze with a hole diameter larger than the particle size of the material is selected, and 40 mesh gauze is selected. ;

The gauze bag is a bag made of gauze, which is used to wrap the support hoop with a gauze layer. The gauze specification of the gauze bag is 40 mesh; the gauze bag includes a gauze bag with a stainless steel tow rope and a combination of stainless steel hoop and gauze. The form of the gauze bag of the stainless steel wire tow rope is that the stainless steel wire passes through the opening end of the gauze bag and is used to suspend the entire material bag at the mouth of the gauze; basket, and fix the opening of the gauze bag and the stainless steel hoop on the ultrasonic probe for suspension;

The gauze rope is threaded through the opening of the gauze bag to close the gauze bag and hang the entire material bag; the material of the gauze rope is 0.5mm stainless steel wire.

The extraction kettle of traditional subcritical water extraction equipment is easy to agglomerate and form agglomerates when extracting materials. It is difficult for the materials to fully react with subcritical water, resulting in low extraction efficiency; Contact with the material basket made of stainless steel will cause the gauze bag and the material to be scorched to varying degrees under high temperature conditions, which will affect the experimental effect;

In the process of using the subcritical water extraction equipment to extract seaweed protein, the extraction kettle does not add an ultrasonic probe to extract directly, or add an ultrasonic probe to supplement it with ultrasound for extraction; the extraction kettle without adding an ultrasonic probe adopts the form of a stainless steel tow rope The gauze bag, the extraction kettle with ultrasonic probe adopts the gauze bag in the form of stainless steel hoop and gauze;

Wherein, the schematic cross-sectional view of the subcritical water extraction kettle without an ultrasonic probe is shown in Figure 4, and the structure shown in the figure includes an extraction kettle cover 4-1, a gauze bag 4-2, a water inlet 4-3, and the bottom of the kettle cover 4-4, material hanging basket 4-5, screen 4-6, material 4-7 and extraction kettle wall 4-8, material 4-7 is directly packed in gauze bag 4-2 and then suspended at the bottom of the kettle cover 4- 4.

The sectional view of the extraction kettle behind the material bag of the gauze bag of the stainless steel tow mouth rope in the subcritical water extraction kettle without an ultrasonic probe is shown in Figure 5. The structure in the figure includes an extraction kettle cover 5-1, a gauze bag 5 -2, water inlet 5-3, kettle cover bottom 5-4, material hanging basket 5-5, screen 5-6, material 5-7, extraction kettle wall 5-8, gauze layer 5-9, material 5- 7 spread and be placed in the gauze bag of packing into stainless steel tow mouth rope after being placed on the gauze layer 5-9, hang on the kettle lid bottom 5-4 by the tie rope again. The gauze bag is suspended on the top of the material basket through the stainless steel wire tow rope so that the material is suspended in the air without touching the wall of the material basket, which effectively prevents the material and the gauze bag from being scorched.

The schematic cross-sectional view of the subcritical water extraction kettle with ultrasonic probe added is shown in Figure 6. The structure in the figure includes an extraction kettle cover 6-1, a gauze bag 6-2, a water inlet 6-3, an ultrasonic probe 6-4, and a material hanger. Basket 6-5, screen 6-6, material 6-7 and extraction kettle wall 6-8; ultrasonic probe 6-4 is placed on the inner top of the extraction kettle, and material 6-7 wrapped in gauze bag 6-2 is placed directly In material basket 6-5.

In the subcritical water extraction kettle with ultrasonic probe added, the sectional view of the extraction kettle after the material bag of the gauze bag with stainless steel hoop and gauze is used is shown in Figure 7. The structure in the figure includes the extraction kettle cover 7-1 and the gauze bag 7 -2. Water inlet 7-3, ultrasonic probe 7-4, material hanging basket 7-5, screen 7-6, material 7-7, extraction kettle wall 7-8, gauze layer 7-9 and stainless steel hoop 7- 10. Lay materials 7-7 on the gauze layer layer by layer.

The gauze bag combined with the stainless steel hoop and gauze is used to fix the gauze bag to the ultrasonic probe to ensure that the material bag is suspended in the air and avoid direct contact with the metal to cause scorching.

Use a special material bag to extract seaweed protein, spread the material layer by layer to fully increase the contact area between the material and subcritical water, and place the material rack in the gauze bag, and hang it in the material basket with stainless steel to prevent the material bag Directly contact the wall and bottom of the material basket, so that the subcritical water can fully react with the material to achieve the extraction effect, and at the same time avoid the scorching phenomenon of the gauze bag caused by the material bag directly contacting the wall of the high-temperature hanging basket, so as to improve the extraction rate of the equipment.

Example 1

Using the above-mentioned special extraction kettle material bag, using subcritical water extraction equipment to prepare high-pressure water to extract protein from spirulina, the specific steps are as follows:

(1) First check whether the subcritical water extraction equipment can start normally, then add the water in the water storage device to the predetermined position of 15L, and start to prepare for the experiment. Amount 50g;

Spread the dry powder of spirulina evenly in the gauze layer of the 6-layer bracket hoop, put the bracket hoop into the gauze bag, close the gauze bag with a tie rope and hang it in the extraction kettle, cover the kettle, and insert the temperature sensor It is convenient to detect the temperature of the top and bottom of the extraction kettle and the temperature inside the kettle;

(2) After turning on the main switch of the equipment, turn on the switch of the water pump, control the flow rate of 100mL/min to inject deionized water into the preheating furnace to preheat to 90°C, and then inject it into the extraction kettle through the preheating furnace;

(3) Set the extraction parameters and extraction conditions: under the conditions of extraction temperature 150°C, extraction pressure 10MPa, ultrasonic power 300W or without ultrasound, extract the active ingredients of the raw materials, and the extraction time is 1h; extract the active ingredients of the raw materials When the extraction of the equipment reaches the set conditions, the timing is started, and the experiment is performed in parallel three times;

(4) After the extraction is finished, the extract is cooled to room temperature, and the extract is collected;

(5) Place the collected extract in a refrigerator to cool and precipitate for 2 hours to 4°C;

(6) Centrifuge the cooled and precipitated algae solution at 4°C and 8000r/min for 30 minutes, and the supernatant is the spirulina protein solution;

(7) Divide the protein solution into plastic petri dishes and place in a -20°C refrigerator to freeze;

(8) Freezing and vacuum-drying the treated algae liquid ice cubes to obtain thick spirulina protein;

Note that the whole process should be protected from light when performing the above operations.

Test method without improvement: In step (1), the material is directly placed in a gauze bag and placed at the bottom of the extraction kettle, and the rest of the steps are the same.

Scan the obtained active substance on the spectrophotometer in full band, and compare it with the spirulina protein extracted from water. The main absorption peaks are all between 210-220nm, indicating that the extracted substance is spirulina protein.

At the same time, the crude protein yield of the improved subcritical water extraction was calculated and compared with that of the unmodified subcritical water extraction.

The protein content in the Spirulina extract was determined by Bio-Rad Protein Assay, and the mass concentration of standard bovine serum albumin was taken as the abscissa, and the absorbance value of the solution measured at 595 nm was plotted as the ordinate for quantitative analysis. Comparing the protein content extracted by the four extraction methods, the calculation method:

The results are shown in Table 1.

Table 1 Protein content extracted by four extraction methods

According to the data analysis in Table 1, improving the material basket structure of the subcritical water extraction kettle significantly increased the protein yield of the material. Using subcritical water extraction equipment to extract seaweed protein, the extraction rate is only 10.3% without improved equipment and ultrasound. When the contact area between the material and subcritical water is increased, the protein yield reaches 40.2% without ultrasound. %, nearly 4 times that before the device was not improved; similarly, for the improvement of equipment, the protein yield was 41.% when the equipment was added with ultrasound, but under the situation of improved equipment and ultrasound, the protein yield was 67.1%, Almost a 1.6-fold increase. It shows that increasing the contact area between materials and subcritical water can make the reaction between materials and subcritical water more fully and significantly increase the protein yield.

In the embodiment of the present invention, the bracket hoop of the special extraction kettle material bag has 6 stainless steel hoops, which can increase the number of hoops, further increase the area where the material is spread, and facilitate the full contact between the material and the subcritical water to obtain a higher yield. active substance.

Claims (10)

1. a method for extracting seaweed protein using a special extraction kettle material bag, is characterized in that, comprises the steps: (1) In the subcritical water extraction equipment, put the seaweed powder into the special material bag of the extraction kettle and hang it in the extraction kettle, inject the preheated deoxygenated deionized water into the extraction kettle, and heat it under ultrasonic conditions Pressurize for extraction reaction; (2) After the extraction, collect the extract cooled to room temperature, then carry out cooling precipitation, centrifuge, take the supernatant, freeze and dry to obtain crude seaweed protein. 2. a kind of method that adopts special extracting kettle material bag to extract seaweed protein according to claim 1, is characterized in that, described special extraction kettle material bag comprises bracket hoop, gauze layer, gauze bag and bundle mouth rope; The bracket hoop is composed of a plurality of coaxial stainless steel hoops arranged in the vertical direction; the stainless steel hoop is not closed and has an opening; two adjacent stainless steel hoops are connected by steel wires, and the two ends of the steel wires are respectively connected At the open ends of two adjacent stainless steel hoops, and from bottom to top, the two ends of the steel wire connecting the first stainless steel hoop and the second stainless steel hoop are connected to the open ends of the same side of the two stainless steel hoops, while the other two The connection between adjacent stainless steel hoops is an open end dislocation connection; The gauze layer is fixed on each stainless steel hoop of the bracket hoop by gauze for holding materials; Described gauze bag is the bag that gauze is made, is used for wrapping the bracket hoop that has gauze layer; The mouth rope is threaded through the opening of the gauze bag, and is used for closing the gauze bag and the suspension of the whole material bag. 3. a kind of method that adopts special extraction kettle material bag to extract seaweed protein according to claim 2, is characterized in that, the material of the stainless steel hoop of described bracket hoop and steel wire all adopts the stainless steel wire of diameter 2mm; Said steel wire The connection method with the stainless steel hoop is welding, or it is directly folded by the steel wire that is held into a steel hoop; the gauze bag includes a gauze bag with a stainless steel wire tow rope and a combination of stainless steel hoop and gauze; the stainless steel The form of the gauze bag of the tow mouth rope is that the stainless steel wire passes through the opening end of the gauze bag and is used to suspend the whole material bag at the mouth of the gauze; basket, and the opening of the gauze bag and the stainless steel hoop are fixed on the ultrasonic probe for suspension; the material of the beam rope is 0.2~1mm stainless steel wire; the gauze specification of the gauze layer and the gauze bag is 40~60 mesh . 4. A method for extracting seaweed protein using a special extraction kettle material bag according to claim 1, characterized in that, in step (1), the preheating is to preheat to 60-100°C; the deoxygenation The rate of injecting deionized water into the extraction kettle was 100mL/min. 5. A method for extracting algae protein using a special extraction kettle material bag according to claim 1, characterized in that, in step (1), the power of the ultrasound is 50-500W. 6. A method for extracting seaweed protein using a special extraction kettle material bag according to claim 1, characterized in that in step (1), the heating is to make the temperature reach 100-150°C; the pressurization The method is to make the pressure reach 1-20MPa; the extraction reaction time is 0.5-2.5h. 7. A method for extracting seaweed protein using a special extraction kettle material bag according to claim 1, characterized in that, in step (2), the cooling precipitation is cooling to 4°C for precipitation; the centrifugation is Centrifuge at 4°C and 8000r/min for 30min. 8. A method for extracting seaweed protein using a special extraction kettle material bag according to claim 1, characterized in that in step (2), the freezing is freezing into ice cubes at a temperature ≤ -20°C; The drying is vacuum freeze drying. 9. A kind of method that adopts special extraction kettle material bag to extract seaweed protein according to claim 1, is characterized in that, the whole process of extraction is carried out under the dark condition. 10. A method for extracting seaweed protein using a special extraction kettle material bag according to claim 3, characterized in that, in step (1), no ultrasonic assistance is used, and the gauze bag in the special extraction kettle material bag is made of stainless steel The gauze bag form of the drawstring.