Separation method of single-cell protein fermentation liquor

Abstract

The invention discloses a separation method of single-cell protein fermentation liquor. The separation method comprises the following steps: 1) adding a filter aid into fermentation liquor containing single-cell protein thalli to form mixed liquor; 2) filtering the mixed solution through a plate frame to form a filter cake; 3) introducing nitrogen to purge the filter cake to remove moisture in the filter cake; and 4) carrying out flash evaporation drying on the dewatered filter cake to obtain a single-cell protein product. According to the process, filter cakes are formed through plate and frame filtering and squeezing, and then single-cell protein thalli are obtained through a flash evaporation drying technology. The process not only improves the extraction efficiency of the single-cell protein, but also reduces the production cost, and is suitable for large-scale production.

Description

Technical Field

[0001] The invention relates to the field of biotechnology, in particular to a separation method for single-cell protein fermentation broth. Background Art

[0002] Single-cell protein (SCP), also known as microbial protein, is a microbial protein made by using industrial and agricultural waste and petroleum waste as culture medium to cultivate single-cell microorganisms such as algae, fungi or non-pathogenic bacteria, and then undergoing fermentation, purification, drying and other processes. Single-cell protein has a high protein content, rich and balanced amino acid content, similar to the amino acid composition of fish meal, and is also rich in vitamins and mineral elements.

[0003] However, how to efficiently separate and dry single cell protein from fermentation broth is still a challenge in the current technical field. The traditional single cell protein extraction process has problems such as low extraction efficiency, low purity, and high cost. In order to solve these problems, the present invention provides a new separation process. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a method for separating single-cell protein fermentation broth, which comprises adding a filter aid to the fermentation broth containing single-cell protein bacteria, and combining plate and frame filtration pressing technology with flash drying technology to achieve high-purity single-cell protein-rich bacteria in an efficient, energy-saving and environmentally friendly manner.

[0005] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for separating a single-cell protein fermentation broth, the steps comprising:

[0007] 1) adding a filter aid to a fermentation liquid containing single-cell protein bacteria to form a mixed liquid;

[0008] 2) filtering the mixed solution through a plate and frame to form a filter cake;

[0009] 3) Passing nitrogen to purge the filter cake to remove moisture;

[0010] 4) The filter cake after dehydration is flash dried to obtain a single cell protein product.

[0011] In one embodiment, the fermentation broth containing single-cell protein bacteria in step 1) has a single-cell protein bacteria dry weight content of 8-30wt%, which can be 8wt%, 10wt%, 12wt%, 14wt%, 16wt%, 18wt%, 20wt%, 22wt%, 24wt%, 26wt%, 28wt%, 30wt% or a range consisting of any two thereof;

[0012] The fermentation broth containing the single-cell protein bacteria described in the present invention can be obtained by conventional methods in the art, such as commercially available or homemade by conventional methods in the art, and there is no specific requirement for its source and type. In specific applications, it can be prepared by the methods disclosed in patents such as CN118995455A, CN118765329A, and CN118497087A. In specific applications, the relevant operations and process conditions actually used, and the devices used, can all be selected by the corresponding conventional methods in the art, and the present invention will not repeat them here.

[0013] In one embodiment, the filter aid in step 1) is selected from one or more of diatomaceous earth, perlite, cellulose, starch, asbestos, graphite powder, sawdust, magnesium oxide, gypsum, activated carbon, and acid clay, preferably one or more of diatomaceous earth, perlite powder, and starch;

[0014] Preferably, the mass concentration of the filter aid in the mixed liquid is 0.1-0.35%, which can be 0.1%, 0.12%, 0.14%, 0.16%, 0.18%, 0.2%, 0.22%, 0.24%, 0.26%, 0.28%, 0.30%, 0.32%, 0.34%, 0.35% or a range consisting of any two thereof.

[0015] In one embodiment, in step 2), the plate and frame filtration is performed to separate the bacterial cells and the fermentation liquid through the plate and frame, and the mixed liquid is squeezed under a certain pressure to form a filter cake, and the pressure is controlled at 0.3-0.6Mpa, which can be 0.3Mpa, 0.32Mpa, 0.35Mpa, 0.38Mpa, 0.4Mpa, 0.42Mpa, 0.45Mpa, 0.48Mpa, 0.5Mpa, 0.52Mpa, 0.55Mpa, 0.58Mpa, 0.6Mpa or a range consisting of any two thereof;

[0016] Preferably, the pore size of the filter cloth used in the plate and frame filtration is controlled to be 800-1500 mesh, which can be 800 mesh, 850 mesh, 900 mesh, 950 mesh, 1000 mesh, 1050 mesh, 1100 mesh, 1150 mesh, 1200 mesh, 1250 mesh, 1300 mesh, 1350 mesh, 1400 mesh, 1450 mesh, 1500 mesh or a range between any two thereof;

[0017] The filter cloth material may be one or more of polypropylene, polyester, nylon, vinylon, aramid, PTFE, PVDF, asbestos fiber, and glass fiber, preferably one or more of polypropylene and polyester;

[0018] Preferably, the filtration area of ​​the filter frame is 800-1200 m2, which can be 800 m2, 850 m2, 900 m2, 950 m2, 1000 m2, 1050 m2, 1100 m2, 1150 m2, 1200 m2 or a range between any two thereof;

[0019] In specific applications, when the filter press enters the pressure maintaining state, feeding begins, the feed valve is opened, and the feed pump is started to feed, the filtration pressure is controlled at 0.3-0.6Mpa, and the filtration time is 2-5h. The specific feeding time depends on the valve discharge liquid flow after filtration. For example, when 1 / 3 of the valve discharge liquid flow is not in line, the pump is stopped in time. Specifically, the filtration time can be 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h or a range composed of any two of them.

[0020] In one embodiment, in step 3), the nitrogen purge has a nitrogen flow rate of 30-50 L / min and a purge time of 1-2 h. Specifically, the nitrogen flow rate may be 30 L / min, 32 L / min, 34 L / min, 36 L / min, 38 L / min, 40 L / min, 42 L / min, 44 L / min, 46 L / min, 48 L / min, 50 L / min or a range consisting of any two thereof, and the purge time may be 1 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h, 2 h or a range consisting of any two thereof;

[0021] Preferably, nitrogen purging is used to reduce the moisture content in the filter cake to below 5 wt %.

[0022] In one embodiment, in step 4), the gas inlet pressure of the flash drying is 0.5-0.6Mpa, the inlet temperature is 350-400°C, the drying residence time is 15-40s, and the filter cake is sent to the flash dryer. The principle of rotary flash drying is used to rapidly evaporate the water in the filter cake through high-temperature hot air and swirl. Specifically, the gas inlet pressure can be 0.5Mpa, 0.51Mpa, 0.52Mpa, 0.53Mpa, 0.54Mpa, 0.55Mpa, 0.56Mpa, 0.57Mpa, 0.58Mpa, 0.59Mpa, 0.6Mpa or a range consisting of any two thereof, the inlet temperature may be 350°C, 355°C, 360°C, 365°C, 370°C, 375°C, 380°C, 385°C, 390°C, 395°C, 400°C or a range consisting of any two thereof, the drying residence time may be 15s, 18s, 20s, 22s, 25s, 28s, 30s, 32s, 35s, 38s, 40s or a range consisting of any two thereof;

[0023] In practical applications, the flash drying described in step 4) is specifically operated as follows: starting the induced draft fan, then starting the blower, opening the scale of the butterfly valve to ensure gas flow, starting the flash dryer air compressor, opening the bag pulse backflush system controller, and adjusting the frequency to ensure that the gas inlet pressure works at 0.5-0.6Mpa; opening the flash dryer gas valve to enter the gas ignition temperature and the air dryer inlet, starting the motor, adjusting and controlling to ensure that the stable inlet temperature reaches 350-400°C; separating the dried single-cell protein bacteria from the hot air through a cyclone separator, collecting them at the outlet, and obtaining a high-purity single-cell protein product.

[0024] The single cell protein product obtained by the separation method described above in the present invention is a bacterial body rich in single cell protein. The whole process yield of the bacterial body is calculated to be above 95%, and can reach above 98% under preferred conditions.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] Suspended matter such as bacterial cells and coagulated proteins in the fermentation broth is often small and easily deformed, and direct filtration easily causes the filter holes of filter media such as filter cloth to be blocked, resulting in filtration difficulties. The present invention adds a filter aid to the fermentation broth to improve the filtration of the fermentation broth and increase the filtration speed of the fermentation broth.

[0027] The present invention adds a filter aid to a fermentation liquid containing single-cell protein bacterial bodies, forms a filter cake through plate and frame filtration, then introduces nitrogen to back-blow the water in the filter cake, and then flash evaporation and drying are performed to obtain bacterial bodies rich in single-cell protein. The whole-process yield of the bacterial bodies can reach more than 95%, and the obtained single-cell protein bacterial body product has stable quality and meets market demand. DETAILED DESCRIPTION

[0028] The following examples of the present invention only illustrate specific implementation schemes for implementing the present invention. These schemes should not be understood as limiting the present invention. Any changes made without departing from the principle and essence of the present invention fall within the protection scope of the present invention.

[0029] The experimental techniques and methods used in this example are all conventional technical methods unless otherwise specified. The materials, reagents, etc. used in this example can be obtained through regular commercial channels unless otherwise specified.

[0030] Fermentation broth containing single-cell protein bacteria: Yarrowia lipolytica was used as the fermentation bacteria (purchased from China Industrial Microbiological Culture Collection Center, collection number: CICC 31067), and was prepared according to the method disclosed in patent CN118995455A (a process for producing single-cell protein and its application).

[0031] Calculation method of dry weight of bacteria: unit is wt%

[0032] Weigh 1.00 kg of fermentation liquid, centrifuge at 8000 rpm for 10 min, add 1 L of water to obtain the bacterial cells, resuspend them evenly, centrifuge again at 8000 rpm for 10 min to obtain wet bacterial cells, dry them and weigh them to obtain a mass of m1 kg (accurate to 4 decimal places);

[0033] Dry weight of bacteria = m1 / 1×100%.

[0034] Embodiment 1:

[0035] 1) Take 100 L of fermentation liquid containing single-cell protein bacteria (10 wt% of dry weight of bacteria) and add diatomaceous earth as a filter aid to form a mixed liquid. The added mass concentration is 0.1% (100 g).

[0036] 2) Pass the mixed liquid through a plate and frame filter, control the filtration pressure at 0.45Mpa, the filtration area of ​​the filter frame is 1200㎡, the pore size of the polypropylene filter cloth is 1000 mesh, and stop the pump when 1 / 3 of the valve discharge liquid flow is not in line. The filtration time is 5 hours to obtain a filter cake.

[0037] 3) The filter cake was purged with nitrogen at a flow rate of 30 L / min for 1 h, and the purging was terminated when the water content in the filter cake was lower than 5 wt %.

[0038] 4) Send the filter cake into a flash dryer, ensure that the gas inlet pressure of the flash dryer operates at 0.5 MPa, the gas inlet temperature is 350° C., and the filter cake residence time is 15 s to obtain a single cell protein product.

[0039] The mass of the single-cell protein product is 9900 g, and the yield of the bacteria is calculated to be (9.9-0.1) / (100*10%)=98%.

[0040] Embodiment 2:

[0041] 1) Take 100L of fermentation liquid containing single-cell protein bacteria (15wt% of dry weight of bacteria) and add perlite powder as a filter aid to form a mixed liquid with a mass concentration of 0.2% (200g).

[0042] 2) Pass the mixed liquid through a plate and frame filter, control the filtration pressure at 0.3Mpa, the filtration area of ​​the filter frame is 800㎡, the pore size of the polypropylene filter cloth is 800 mesh, and stop the pump when 1 / 3 of the valve discharge liquid flow is not in line. The filtration time is 3h to obtain a filter cake.

[0043] 3) The filter cake was purged with nitrogen at a flow rate of 40 L / min for 1.5 h, and the purging was terminated when the water content in the filter cake was lower than 5 wt %.

[0044] 4) Send the filter cake into a flash dryer, ensure that the gas inlet pressure of the flash dryer operates at 0.54Mpa, the gas inlet temperature is 360°C, and the filter cake residence time is 25s to obtain a single cell protein product.

[0045] The mass of the single-cell protein product is 14450 g, and the yield of the bacteria is calculated to be (14.45-0.2) / (100*15%)=95%.

[0046] Embodiment 3:

[0047] 1) Take 100 L of fermentation liquid containing single-cell protein bacteria (20 wt% of dry weight of bacteria) and add filter aid starch to form a mixed liquid with a mass concentration of 0.35% (350 g).

[0048] 2) Pass the mixed liquid through a plate and frame filter, control the filtration pressure at 0.6Mpa, the filtration area of ​​the filter frame is 1000㎡, the pore size of the polypropylene filter cloth is 1200 mesh, and stop the pump when 1 / 3 of the valve discharge liquid flow is not in line. The filtration time is 2h to obtain a filter cake.

[0049] 3) The filter cake was purged with nitrogen at a flow rate of 50 L / min for 2 h, and the purging was terminated when the water content in the filter cake was lower than 5 wt %.

[0050] 4) Send the filter cake into a flash dryer, ensure that the gas inlet pressure of the flash dryer operates at 0.6 MPa, the gas inlet temperature is 400° C., and the filter cake residence time is 40 seconds to obtain a single cell protein product.

[0051] The mass of the single-cell protein product is 19550 g, and the yield of the bacteria is calculated to be (19.55-0.35) / (100*20%)=96%.

[0052] Embodiment 4:

[0053] The same steps as those in Example 1 were followed, except that the filtration pressure of the filter press was controlled at 0.45 MPa, the filtration area of ​​the filter frame was 900 m2, and the pore size of the polyester filter cloth was 800 mesh.

[0054] The mass of the single-cell protein product is 9600 g, and the yield of the bacteria is calculated to be (9.6-0.1) / (100*10%)=95%.

[0055] Comparative Example 1:

[0056] The same steps as in Example 1 were followed, except that diatomaceous earth was not added as a filter aid in step 1), the filtration time was 14 h, and other operations and conditions remained unchanged.

[0057] The mass of the single-cell protein product is 4500 g, and the bacterial yield is calculated to be (4.5) / (100*10%)=45%.

[0058] Comparative Example 2

[0059] The same steps as in Example 1 are followed, except that step 3) is omitted, i.e. nitrogen purging is not used to remove moisture from the filter cake, and other operations and conditions remain unchanged.

[0060] The mass of the single-cell protein product is 5100 g, and the bacterial yield is calculated to be (5.1-0.1) / (100*10%)=50%.

[0061] Comparative Example 3

[0062] The same steps as in Example 1 are followed, except that step 4) flash drying is replaced by double cone drying, and other operations and conditions remain unchanged.

[0063] The mass of the single-cell protein product is 5600 g, and the yield of the bacteria is calculated to be (5.6-0.1) / (100*10%)=55%.

Claims

1. A method for separating a single-cell protein fermentation broth, characterized in that the steps include: 1) adding a filter aid to a fermentation liquid containing single-cell protein bacteria to form a mixed liquid; 2) filtering the mixed solution through a plate and frame to form a filter cake; 3) Passing nitrogen to purge the filter cake to remove moisture; 4) The filter cake after dehydration is flash dried to obtain a single cell protein product.

2. The separation method according to claim 1, characterized in that In step 1), the fermentation liquid containing single-cell protein bacteria has a dry weight content of 8-30 wt%.

3. The separation method according to claim 1, characterized in that Step 1) The filter aid is selected from one or more of diatomaceous earth, perlite, cellulose, starch, asbestos, graphite powder, sawdust, magnesium oxide, gypsum, activated carbon, and acid clay, preferably one or more of diatomaceous earth, perlite powder, and starch.

4. The separation method according to claim 1 or 3, characterized in that The mass concentration of the filter aid in step 1) in the mixed solution is 0.1-0.35%.

5. The separation method according to claim 1, characterized in that In step 2), the plate and frame filtration has a pressure of 0.3-0.6 MPa; preferably, the filtration time is 2-5 h.

6. The separation method according to claim 1 or 5, characterized in that Step 2) the plate and frame filtration uses a filter cloth with an aperture of 800-1500 mesh; Preferably, the filter cake cloth is made of one or more of polypropylene, polyester, nylon, vinylon, aramid, PTFE, PVDF, asbestos fiber, and glass fiber, preferably one or more of polypropylene and polyester; Preferably, the filter area of ​​the filter frame is 800-1200 m2.

7. The separation method according to claim 1, characterized in that Step 3) The nitrogen purge has a nitrogen flow rate of 30-50 L / min; preferably, the purge time is 1-2 h.

8. The separation method according to claim 1 or 7, characterized in that: Step 3) The nitrogen purge reduces the moisture content in the filter cake to below 5 wt %.

9. The separation method according to claim 1, characterized in that In step 4), the flash drying has a gas inlet pressure of 0.5-0.6 MPa and an inlet temperature of 350-400° C.; preferably, the drying residence time is 15-40 s.