A method for preparing epsilon-polylysine hydrochloride

Abstract

The application discloses a preparation method of epsilon-polylysine hydrochloride and belongs to the technical field of industrial fermentation. The application provides a preparation method of epsilon-polylysine hydrochloride, which comprises the following steps: sequentially subjecting epsilon-polylysine fermentation liquor to solid-liquid separation, ion exchange, nanofiltration membrane desalination, concentration, ethanol precipitation and drying to obtain epsilon-polylysine hydrochloride. The application can simplify the process, reduce the generation of waste water, reduce the consumption of acid and alkali and the generation of solid waste, improve the yield, make the yield be higher than 78%, make the purity be not lower than 95%, greatly reduce the production cost and have a great industrial application prospect.

Description

Technical Field

[0001] This invention relates to a method for preparing ε-polylysine hydrochloride, belonging to the field of industrial fermentation technology. Background Technology

[0002] ε-Polylysine (ε-PL) is a homopolymer of amino acids produced through microbial fermentation, composed of 25-35 L-lysine residues linked by heteropeptide bonds formed by ε-NH2 and α-COOH. Currently, most polylysine products on the market exist in the form of hydrochloride. ε-Polylysine hydrochloride is produced by adjusting the pH of ε-PL with hydrochloric acid to convert it into ε-polylysine hydrochloride. As a novel biological food antibacterial agent, it has advantages such as good antibacterial effect, broad antibacterial spectrum, and strong thermal stability. It has been approved as a legal food additive in the United States, Europe, Japan, China, and other countries and regions, and is widely used in the food, beverage, and daily chemical industries.

[0003] Currently, ε-PL is mainly produced through two methods: chemical synthesis and microbial fermentation. However, chemical synthesis can lead to toxicity due to configurational issues. In contrast, fermented ε-PL is safer, and therefore, the market primarily relies on fermentation for its production. After years of research, the fermentation level for ε-PL production has significantly improved, increasing from 20-30 g / L to over 70 g / L. However, the corresponding cell count has also increased dramatically, from 30 g / L to over 80 g / L. This significant increase in fermentation acid production and cell count means that traditional extraction processes cannot meet current industrial demands. The main problems are high extraction costs, low yields, and large amounts of wastewater, severely limiting its widespread application. Therefore, establishing efficient extraction methods is crucial.

[0004] In reported data, the extraction process of ε-polylysine hydrochloride mainly involves solid-liquid separation, ion exchange, activated carbon decolorization, concentration, and spray drying. The solid-liquid separation process primarily uses a combination of a disc centrifuge and an ultrafiltration membrane. Due to the high cell concentration, the fermentation broth needs to be diluted multiple times to ensure smooth operation and reduce losses, but this dilution generates a large amount of wastewater. The ion exchange process mainly employs a three-stage ion exchange method (anion, cation, and anion), resulting in significant wastewater generation during elution and regeneration. Furthermore, each stage of ion exchange leads to a significant loss of the target compound, resulting in a decreased yield. The decolorization unit primarily involves adding activated carbon for decolorization. Carbon adsorbs both pigments and target substances during the adsorption process. To achieve decolorization, the higher the amount of activated carbon added, the greater the loss, thus further reducing the yield. Nanofiltration membranes are mainly used for concentration. Since a high concentration is required for spray drying, excessively high concentrations of the target product during concentration can create excessively high osmotic pressure across the membrane, increasing the loss of the target substance. The product yield in the above extraction process is generally between 55-65%. As can be seen from the operation of each step, this extraction process ultimately leads to problems such as low extraction yield and large wastewater volume.

[0005] With continuous improvements in fermentation processes, many existing extraction techniques can no longer meet the requirements for separating and extracting ε-polylysine and its salts from fermentation broths with high cell concentrations. For example, patent CN1017011069B proposes a method for extracting ε-polylysine and its salts from fermentation broth. However, this invention has several shortcomings: It employs direct heating followed by plate and frame filtration, but the lack of filter aids leads to low filtration efficiency and significant water loss in the concentrate; furthermore, activated carbon decolorization not only increases losses but also generates solid waste such as activated carbon and adsorbents; since the target analyte has a molecular weight cutoff of 3500-5000, using a membrane with a molecular weight cutoff of 4000 Da for concentration, aiming for a concentration of 3-99%, results in substantial loss of the target analyte due to concentration polarization and the choice of membrane molecular weight cutoff. This leads to low recovery rates and significantly increased overall operating costs. Therefore, these factors will likely limit the widespread implementation of this invention.

[0006] The extraction processes described in patents ZL200920069827.5, ZL200910152931.2, and ZL201110053004.2 can achieve a yield of 70-80% and a purity of 95-97% for fermentation broths with ε-PL fermentation levels below 40 g / L. However, for fermentation broths fermented by the inventors' team using Streptomyces simonii CGMCC No.10480 as the fermenting microorganism, which contain ε-PL ≥60 g / L and have a cell dry weight ≥70 g / L, effective product separation cannot be achieved, ultimately resulting in a yield below 55% and a purity of only about 60%. This shows that for the same product, the extraction process varies depending on the properties of the material. Furthermore, the extraction process cannot be copied from one product to another. For example, patent CN106544372A is relatively easy to separate bacteria with a cell count of only 2-8 g / L, so it can achieve an extraction yield of γ-aminobutyric acid of ≥70% and a purity of ≥95%. However, the extraction process reported therein is not applicable to the material characteristics (cell count above 70 g / L) in the inventor's patent application. Summary of the Invention

[0007] This invention addresses the problems of existing fermentation processes that cannot meet the requirements of ε-polylysine yields of 60 g / L or more and cell dry weights of 70 g / L or more, resulting in long extraction routes, low efficiency, low yields, and large amounts of wastewater. This invention provides a new method for extracting ε-polylysine hydrochloride from the fermentation broth under this new fermentation process.

[0008] The technical solution adopted in this invention is: This invention provides a method for preparing ε-polylysine hydrochloride, the method comprising: sequentially subjecting ε-polylysine fermentation broth to solid-liquid separation, ion exchange, nanofiltration membrane desalination, concentration, ethanol precipitation and drying to obtain ε-polylysine hydrochloride.

[0009] In one implementation, the method includes the following steps: (1) The ε-polylysine fermentation broth was subjected to solid-liquid separation to remove suspended solids such as bacterial cells and obtain a clear liquid; (2) The clear liquid obtained in step (1) is then adsorbed and desorbed by ion exchange resin to obtain the desorbed liquid; (3) The eluent obtained in step (2) is desalted by passing it through a nanofiltration membrane to obtain a desalted solution; (4) The desalination solution obtained in step (3) is concentrated by evaporation to obtain a concentrated solution; (5) Add ethanol to the concentrate obtained in step (4) to precipitate, filter to obtain precipitate and filtrate respectively, and dry the precipitate to obtain ε-polylysine hydrochloride product. The ethanol recovered from the filtrate by distillation can be recycled to the next batch of process step (5).

[0010] In one embodiment, the solid-liquid separation employs any one or a combination of two of plate and frame filtration and ultrafiltration membrane filtration.

[0011] In one embodiment, when using plate and frame filtration, the temperature is controlled at 25~40℃, preferably the original temperature of the fermentation broth, and the pH does not need to be specially adjusted, preferably maintaining the original pH of the fermentation broth at 3.8~4.5; before filtration, diatomaceous earth is pre-coated, with the amount of diatomaceous earth pre-coated per square meter of filtration area being 0.35~0.8 kg, and the amount of diatomaceous earth added during filtration is 1-3% (m / v) of the fermentation broth.

[0012] In one embodiment, when using ultrafiltration membrane filtration, the ultrafiltration membrane is a tubular ultrafiltration membrane or a ceramic ultrafiltration membrane, with a molecular weight cutoff of 30~100 kDa, an operating temperature of 25~45°C, an operating pressure of 0.2~0.6 MPa, a membrane surface flow rate of 2~4 m / s, and a pH maintained at 3.8~4.5.

[0013] In one embodiment, the ion exchange is a single-stage cation exchange resin, which includes a strong acid type or a weak acid type; the strong acid type cation exchange resin is a sodium-type cation exchange resin, and the weak acid type cation exchange resin is an ammonia-type cation exchange resin.

[0014] In one embodiment, the cation exchange resin is loaded at a pH of 6.0-8.2, with a loading rate of 1-4 BV / h, and sodium hydroxide is used as the eluent with an elution concentration of 0.6-1.2N.

[0015] In one embodiment, the nanofiltration membrane has a molecular weight cutoff of 600-1000 Da; during nanofiltration membrane desalination, the pH of the retentate is controlled at 3.8-4.2 (the pH of the eluent is maintained at 3.8-4.2 by adjusting the eluent with concentrated hydrochloric acid), and after controlling the conductivity of the retentate to be lower than 800 μs / cm, the nanofiltration is stopped when the concentration of ε-polylysine reaches 50 g / L or higher.

[0016] In one embodiment, the evaporation and concentration is carried out using a single-effect evaporator or a multi-effect evaporator with reduced pressure.

[0017] In one embodiment, the evaporation and concentration are carried out using double-effect vacuum evaporation, and the concentration is stopped when the concentration of ε-polylysine hydrochloride reaches 300~500g / L.

[0018] In one embodiment, the ethanol precipitation is achieved by adding ethanol to the evaporation concentrate while stirring during the addition process, ultimately controlling the ethanol concentration in the mixture to be 80-95% (v / v); after the addition is complete, stirring is performed for 10-30 minutes, then stirring is stopped, and the mixture is allowed to stand for at least 2 hours before filtration; the filtration method is not limited.

[0019] In one embodiment, the solid obtained after ethanol precipitation and filtration is dried to obtain ε-polylysine hydrochloride, preferably by vacuum low-temperature drying.

[0020] In one embodiment, the method also recovers and collects ethanol from the filtrate after ethanol precipitation.

[0021] In one embodiment, the ethanol recovery is achieved by vacuum distillation of the filtrate after ethanol precipitation and filtration. The specific distillation method is not limited, but the concentration of recovered ethanol must reach 95% (v / v) or higher.

[0022] In one embodiment, the recovered ethanol is recycled back into the ethanol precipitation process.

[0023] In one embodiment, the fermentation broth refers to a fermentation broth that produces ε-polylysine through microbial fermentation, wherein the ε-polylysine concentration is above 60 g / L and the cell concentration is above 70 g / L.

[0024] In one embodiment, fermentation broth with concentrations lower than those described above can also be separated and extracted using the method of the present invention.

[0025] The present invention also claims protection for the use of the method in the production of products containing ε-polylysine hydrochloride.

[0026] Beneficial effects: 1. This invention simplifies and optimizes each operation unit of the extraction process, resulting in a simple preparation method for ε-polylysine hydrochloride with a yield of over 78% and a purity of not less than 95%, which greatly reduces production costs. 2. This invention improves the traditional solid-liquid separation process, reduces the dilution of the fermentation broth, and thus reduces the amount of wastewater generated; 3. This invention uses a single-stage ion exchange process to replace the two-stage or even three-stage ion exchange process of traditional processes, and the acid and alkali consumption is less than 70% of that of traditional processes. 4. This invention eliminates the traditional activated carbon decolorization, reducing product loss and solid waste; it can reduce wastewater generation to less than 40% of the traditional process, and generates no activated carbon solid waste. 5. This invention uses alcohol precipitation to replace traditional activated carbon decolorization and spray drying operations, thereby increasing the yield. 6. The method of the present invention can also recover ethanol and reuse it in the extraction process, thus realizing the recycling of resources. Attached Figure Description

[0027] Figure 1The chromatogram is for ε-polylysine hydrochloride standard.

[0028] Figure 2 The chromatogram is of the ε-polylysine hydrochloride product prepared in Example 1 of this invention. Detailed Implementation

[0029] The present invention will be further described below by way of embodiments: The fermentation broth used in the examples was obtained by fermenting *Streptomyces leucosus* with preservation number CGMCC No. 10480, with ε-PL ≥ 60 g / L and cell dry weight ≥ 70 g / L.

[0030] The yield is calculated as follows: ε-PL yield = {(C1×V1)÷(C0×V0)}×100%, where C0 is the initial ε-PL concentration of the sample solution (g / L), V0 is the initial sample solution volume (L); C1 is the ε-PL concentration of the treated sample solution (g / L), and V1 is the treated sample solution volume (L).

[0031] The purity calculation method is as follows: ε-PL purity = {(C×V)÷m}×100%, where C is the ε-PL concentration of the sample redissolved in deionized water (g / L), V is the volume of the sample after redissolution (L), and m is the mass of the redissolved sample (g).

[0032] ε-PL determination method: ε-PL concentration was determined by HPLC (RSC Advances, 2020.10:29587-29593).

[0033] Example 1 (1) First, add a certain amount of diatomaceous earth to the clean water. The amount of diatomaceous earth added should be controlled at 0.8 kg / m³. 2 For filtration, the pump is started to deliver all the water and diatomaceous earth into the plate frame for pre-coating. Diatomaceous earth is then added to the fermentation broth at 3% (m / v). The fermentation broth temperature is 30℃, and the pH is 4.0. After stirring evenly, the mixture is pumped into the plate frame for filtration. After filtration, the plate frame is washed with an appropriate amount of water and then purged with compressed air. The resulting filtrate is collected. The filtrate is then passed through a ceramic membrane with a molecular weight cutoff of 30 kDa. The filtration pressure is controlled at 0.4 MPa, and the membrane velocity is 3 m / s. The filtrate and retentate are collected separately. The collected retentate continues to be filtered through the ceramic membrane. When the filtration rate decreases, water is added to the retentate, and filtration continues until the concentration of ε-polylysine in the retentate is below 1 g / L. Filtration is then stopped.

[0034] (2) Adjust the pH of the membrane filtrate obtained in step (1) to 7.5 with 6N sodium hydroxide, and load the sample onto the strongly acidic cation (sodium type) resin at a rate of 1.5 BV / h. Stop loading the sample when the effluent shows color after passing through the Dradorf detector. Wash with water and then elute with 0.6N sodium hydroxide. The elution is completed and the eluent is obtained.

[0035] (3) Adjust the pH of the eluent obtained in step (2) with 6N hydrochloric acid and control it to 4.0. Then perform nanofiltration through a nanofiltration membrane with a molecular weight cutoff of 600 Da. The operating pressure is controlled at 1.2 MPa. During the desalting process, deionized water is added to maintain the volume of the eluent. The retentate is collected and circulated into the nanofiltration membrane until the conductivity of the retentate is 780 μs / cm. Then stop adding deionized water and continue nanofiltration to concentrate until the concentration of ε-polylysine in the retentate is higher than 50 g / L.

[0036] (4) The nanofiltration retentate from step (3) is introduced into a two-effect vacuum concentration system. The first effect evaporation pressure is controlled at an absolute pressure of 50 kPa, and the second effect evaporation pressure is controlled at 10 kPa. Evaporation and concentration are completed when the concentration of ε-polylysine is ≥500 g / L.

[0037] (5) Add ethanol to the concentrate obtained in step (4) while stirring until the ethanol concentration reaches 90% (v / v) of the mixture. Then stir for 30 min, let stand for 5 hours, filter to obtain precipitate, and then dry the precipitate at a low temperature under an absolute pressure of 15 kPa to constant weight. The yield reaches 84.8% and the purity reaches 95.8%.

[0038] (6) The filtrate collected in step (5) is subjected to double-tower vacuum distillation to obtain ethanol with a purity of 98%. The distilled ethanol is returned to the next batch of ethanol precipitation for use.

[0039] Example 2 (1) First, add a certain amount of diatomaceous earth to the clean water. The amount of diatomaceous earth added should be controlled at 0.35 kg / m³. 2 To pre-coat the filter area, start the pump to deliver all the clean water and diatomaceous earth into the plate frame. Then add diatomaceous earth to the fermentation broth at 2% (m / v). The fermentation broth temperature is 25℃ and the pH of the fermentation broth is 4.1. After stirring evenly, pump the mixture into the plate frame for filtration. After the filtration operation is completed, wash the plate frame with an appropriate amount of clean water, then purge it with compressed air, and collect the obtained filtrate.

[0040] (2) After adjusting the pH of the filtered liquid obtained in step (1) to 6.5 with 0.6N sodium hydroxide, the sample is loaded onto a strong acidic cation exchange resin (sodium form) at a rate of 2.0 BV / h for adsorption. When the effluent shows color after passing through the Dradorf detector, the loading is stopped. The sample is then washed with water and then eluted with 0.8N sodium hydroxide. The elution is completed and the eluent is obtained.

[0041] (3) Adjust the pH of the eluent obtained in step (2) to 4.0 with 6N hydrochloric acid, and then perform nanofiltration through a nanofiltration membrane with a molecular weight cutoff of 1000 Da. The operating pressure is controlled at 1.0 MPa. During the desalting process, deionized water is added to maintain the volume of the eluent. The retentate is collected and circulated into the nanofiltration membrane until the conductivity of the retentate is 800 μs / cm. Then the addition of deionized water is stopped. Then nanofiltration is continued to concentrate until the concentration of ε-polylysine in the retentate is higher than 55 g / L.

[0042] (4) The nanofiltration retentate collected in step (3) is introduced into a two-effect vacuum concentration system. The first effect evaporation pressure is controlled at an absolute pressure of 70 kPa, and the second effect evaporation pressure is controlled at 20 kPa. Evaporation and concentration are completed when the concentration of ε-polylysine is higher than 300 g / L.

[0043] (5) Add ethanol to the concentrate obtained in step (4) while stirring until the ethanol concentration reaches 80% (v / v) of the mixture. Then stir for 15 min, let stand for 2 hours, filter to obtain precipitate, and then dry the precipitate at a low temperature under an absolute pressure of 15 kPa to constant weight. The yield reaches 79.6% and the purity reaches 96.1%.

[0044] (6) The ethanol precipitate is filtered to obtain filtrate. The filtrate is then subjected to double-tower vacuum distillation to obtain ethanol with a purity of 97%. The distilled ethanol is returned to the next batch of ethanol precipitate for use.

[0045] Example 3 (1) First, add a certain amount of diatomaceous earth to the clean water. The amount of diatomaceous earth added should be controlled at 0.5 kg / m³. 2For filtration, the pump is started to deliver all the clean water and diatomaceous earth into the plate frame for pre-coating. Then, 1% (m / v) diatomaceous earth is added to the fermentation broth. The fermentation broth temperature is 37℃, and the pH is 4.2. After stirring evenly, it is pumped into the plate frame for filtration. After filtration, the plate frame is washed with an appropriate amount of clean water, then purged with compressed air, and the obtained filtrate is collected. The filtrate then passes through a ceramic membrane with a molecular weight cutoff of 100 kDa. The filtration pressure is controlled at 0.3 MPa, and the membrane surface velocity is 4 m / s. The membrane filtrate and retentate are collected separately. The collected retentate continues to be filtered through the ceramic membrane. When the filtration speed decreases, clean water is added to the retentate, and filtration continues until the ε-polylysine concentration in the retentate is below 1 g / L, at which point filtration can be stopped. (2) Adjust the pH of the filtrate collected in step (1) to 7.0 with 6N hydrochloric acid, and load it onto a strong acid cation exchange resin (sodium type) at a rate of 1.0 BV / h for adsorption. Stop loading the sample when the effluent shows color after passing through the Dradorf test. Then wash with water and then elute with 1N sodium hydroxide. The elution is completed and the eluent is obtained.

[0046] (3) Adjust the pH of the eluent obtained in step (2) to 3.8 with 6N hydrochloric acid, and then perform nanofiltration through a nanofiltration membrane with a molecular weight cutoff of 1000 Da. The operating pressure is controlled at 0.8 MPa. During the desalting process, deionized water is added to maintain the volume of the eluent. The retentate is collected and circulated into the nanofiltration membrane until the conductivity of the retentate is 750 μs / cm. Then the addition of deionized water is stopped. Then nanofiltration is continued to concentrate until the concentration of ε-polylysine in the retentate is 52 g / L.

[0047] (4) The nanofiltration retentate from step (3) is introduced into a single-effect vacuum concentration system, and its evaporation pressure is controlled at absolute pressure of 20 kPa until the concentration of ε-polylysine is higher than 400 g / L and the evaporation concentration ends.

[0048] (5) Add ethanol to the concentrate obtained in step (4) while stirring until the ethanol concentration reaches 80% (v / v) of the mixture. Then stir for 20 min, let stand for 2 hours, filter to obtain precipitate, and then dry the precipitate at a low temperature under an absolute pressure of 15 kPa to constant weight. The yield reaches 76.2% and the purity reaches 97.3%.

[0049] (6) The ethanol precipitate collected in step (5) is filtered to obtain filtrate. The filtrate is then subjected to double-tower vacuum distillation to obtain ethanol with a purity of 98%. The distilled ethanol is returned to the next batch of ethanol precipitate for use.

[0050] Comparative Example 1: The specific implementation method is the same as in Example 1, except that step (5) is omitted and activated carbon is used for decolorization. The results show that the yield is 67.2% and the purity is 94.1%. Not only will some products be adsorbed by activated carbon, resulting in yield loss, but also excess activated carbon solid waste will be generated.

[0051] Comparative Example 2: The specific implementation method is the same as in Example 1, except that plate and frame filtration is not used, but ultrafiltration membrane filtration is used directly. Since ultrafiltration membrane filtration requires dilution of the fermentation broth, it can only achieve a yield of 80.5% and a purity of 95.5% after dilution by 8 times, which is equivalent to the effect of plate and frame filtration. The amount of wastewater generated is 8 times that of Example 1, the amount of acid and alkali consumed is 1.6 times that of Example 1, and the amount of steam consumed is 1.2 times that of Example 1.

[0052] Comparative Example 3: The specific implementation method is the same as in Example 1, except that step 1 and step 2 are swapped (i.e. step 2 is performed first and then step 1 is performed). The result shows that the operation cannot be continued, that is, it is almost impossible to obtain the product.

[0053] If steps 3 and 4 are swapped, the yield is only 63.9%, the purity is 56.3%, the amount of ethanol consumed is 1.4 times that of Example 1, and the amount of steam heat consumed is also 1.4 times that of Example 1.

[0054] Comparative Example 4: The specific implementation method is the same as in Example 1, except that the amount of diatomaceous earth pre-coated per square meter is adjusted to 0.2 kg. The results show that the yield is 73.7% and the purity is 95.2%.

[0055] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for preparing ε-polylysine hydrochloride, characterized in that, The method involves sequentially passing the ε-polylysine fermentation broth through solid-liquid separation, ion exchange, nanofiltration membrane desalting, concentration, ethanol precipitation, and drying to obtain ε-polylysine hydrochloride. The fermentation broth is a fermentation broth for the production of ε-polylysine by microbial fermentation, wherein the concentration of ε-polylysine in the fermentation broth is ≥60g / L and the cell concentration is ≥70g / L; The solid-liquid separation is carried out by plate and frame filtration, with the temperature controlled at 25~40℃ and the pH at 3.8~4.

5. Before filtration, diatomaceous earth is pre-coated, with 0.35~0.8 kg of diatomaceous earth pre-coated per square meter of filtration area. During filtration, the amount of diatomaceous earth added is 1-3% (m / v) of the fermentation liquid mass-volume ratio. The ethanol precipitation is achieved by adding ethanol to the evaporated concentrate to make the ethanol concentration in the mixture 80-95%; after the addition is complete, the mixture is stirred for 10-30 minutes, then allowed to stand for a period of time before filtration. The solid collected after ethanol precipitation is dried; the drying method is vacuum low-temperature drying.

2. The method according to claim 1, characterized in that, The solid-liquid separation described above can also be achieved using ultrafiltration membrane filtration after plate and frame filtration. When using ultrafiltration membrane filtration, the molecular weight cutoff of the ultrafiltration membrane is 30~100 kDa, the operating temperature is 25~45℃, the operating pressure is 0.2~0.6 MPa, the membrane surface flow rate is 2~4 m / s, and the pH is maintained at 3.8~4.

5.

3. The method according to claim 1, characterized in that, The ion exchange is a single-stage cation exchange resin, which includes strong acid type or weak acid type; the strong acid type cation exchange resin is sodium type cation exchange resin, and the weak acid type cation exchange resin is ammonia type cation exchange resin.

4. The method according to claim 1, characterized in that, The nanofiltration membrane has a molecular weight cutoff of 600~1000 Da. During nanofiltration desalination, the conductivity of the retentate is controlled to be below 800 μs / cm, and then the nanofiltration is stopped when the concentration of ε-polylysine reaches ≥50g / L.

5. The method according to claim 1, characterized in that, The concentration method is evaporation concentration, and the concentration is stopped when the concentration of ε-polylysine hydrochloride reaches 300~500g / L.

6. The method according to claim 1, characterized in that, The method also recovers and collects ethanol from the filtrate after ethanol precipitation; the recovered ethanol can be recycled back into the ethanol precipitation process.

7. The use of the method according to any one of claims 1 to 6 in the production of products containing ε-polylysine hydrochloride.

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