MÉTODO DE PREPARAÇÃO DE AMINOÁCIDOS COM FLUXO DE FILTRAÇÃO MELHORADO

Abstract

The present application relates to an amino acid production method, comprising the step of adding a coagulant and / or flocculant to a culture medium containing amino acids.

Description

1 / 24 METHOD FOR PREPARING AMINO ACIDS WITH IMPROVED FILTRATION FLOW [Technical Field]

[001] The present application relates to a method for preparing amino acids with an enhanced filtration flow, comprising the step of adding a coagulant and / or a flocculant to a culture broth containing amino acids. [Fundamentals of the Technique]

[002] Amino acids are the fundamental building blocks of proteins and are used as important components of pharmaceutical raw materials, food additives, animal feed, nutritional supplements, insecticides, and fungicides. In particular, branched-chain amino acids (BCAAs), which collectively refer to the essential amino acids valine, leucine, and isoleucine, are known to have antioxidant effects and to directly promote protein synthesis in muscle cells.

[003] Meanwhile, the production of BCAAs using microorganisms is mainly carried out using microorganisms of the genus Escherichia or the genus Corynebacterium, and is known to biosynthesize BCAAs from pyruvic acid through multiple steps using 2-ketoisocaproic acid as a precursor. In Petition 870250100612, dated 03 / 11 / 2025, page 33 / 56 2 / 24 However, the production of BCAAs using such microorganisms presents a problem, as large-scale industrial manufacturing cannot be easily achieved.

[004] Meanwhile, a general process for preparing amino acids is carried out including a series of steps, such as i) microorganism culture, ii) filtration of the culture broth containing amino acids, iii) decolorization, iv) filtration, v) concentration, and vi) crystallization, where unit processes may be added or omitted depending on the characteristics of the product. Among the above processes, the filtration process is a process of removing cells, proteins, colloidal substances, natural organic matter (NOM), and low molecular weight substances contained in the culture broth using a filtration membrane. When the culture broth is filtered through the membrane in the filtration process, impurities are deposited on the membrane over time, and a gel-like layer is formed on the membrane surface. Such membrane fouling reduces the membrane filtration flux.When the membrane filtration flow decreases, the daily product yield is reduced, the filtration membrane cleaning cycle becomes longer, and the membrane replacement interval becomes shorter, which increases maintenance costs and reduces unit production costs. Petition 870250100612, dated 03 / 11 / 2025, page 34 / 56 3 / 24 thus price competitiveness. Therefore, there is a need for a method capable of removing impurities in the culture broth or reducing membrane fouling caused by impurities in the filtration process, in order to suppress the formation of a layer of impurities on the membrane surface, which causes a decrease in the membrane filtration flux. [Description] [Technical Problem]

[005] An object of the present description is to provide a method for preparing an amino acid from a culture broth comprising an amino acid, comprising: (a) adding an organic coagulant, a cationic polymeric flocculant or both to the culture broth comprising an amino acid to precipitate impurities; and (b) subjecting the culture broth with precipitated impurities to membrane filtration.

[006] Another objective of the present description is to provide a feed composition comprising an amino acid prepared by the method of the present description. [Technical Solution]

[007] The present description will be described in detail below. Meanwhile, each description and modality described in this document can be applied to other descriptions and modalities, respectively. That is, all combinations of the various elements described. Petition 870250100612, dated 03 / 11 / 2025, p. 35 / 56 Items 4 / 24 in this document fall within the scope of this description. Furthermore, the scope of this description is not limited by the specific description below.

[008] Additionally, several articles and patent documents have been cited throughout this descriptive report. The content of the cited articles and patent documents is incorporated herein by reference in its entirety, in order to describe the level of the technical field to which this description belongs and the content of this description more clearly.

[009] To achieve the above objectives, one aspect of the present description provides a method for preparing an amino acid from a culture broth comprising an amino acid, comprising: (a) adding an organic coagulant, a cationic polymeric flocculant, or both to the culture broth comprising an amino acid to precipitate impurities; and (b) subjecting the culture broth with precipitated impurities to membrane filtration.

[0010] As used in this document, the term coagulant can refer to a substance that coagulates or agglutinates particles in a liquid for separation of the liquid. Specifically, it refers to a substance that promotes the aggregation of fine particles in a liquid into larger masses. For example, since particles in a liquid have surface charges that repel each other. Petition 870250100612, dated 03 / 11 / 2025, p. 36 / 56 5 / 24 mutually, they do not precipitate, remaining suspended in the water. A coagulant imparts opposite charges to these particles, destabilizing the charges and thus causing the particles to bind to each other. Coagulant is applied in various industrial fields, ranging from food, beverages, chemicals and pharmaceuticals to drinking water, municipal wastewater treatment and oil and gas drilling. It can be used to precipitate relatively small particles, typically several µm in size, for example, about 2 µm.

[0011] As used in this document, the term flocculant, “flocculating agent or flocculation agent” refers to a substance used to remove suspended solids from a liquid by inducing flocculation, whereby the solids aggregate to form flocs that settle to the bottom, also called a clarifying agent. The larger and / or heavier particles formed in this process are also called flocs. Unlike coagulants, which induce chemical flocculation by destabilizing charges, flocculants promote physical flocculation by flocculating colloids and other suspended particles in a liquid, thus forming flocs. Such flocculants can be used in filtration processes, such as water treatment processes, to precipitate small particles and improve filterability. Petition 870250100612, dated 03 / 11 / 2025, page 37 / 56 6 / 24 They can typically be used to precipitate relatively large particles, with a size of 10 μm or more.

[0012] For example, the coagulant or flocculant used in the method described herein may be an organic coagulant, a cationic polymeric flocculant, or a combination of both.

[0013] Specifically, the organic coagulant may include poly(dimethylamine-co-epichlorohydrin) (EPI-AMINE) or poly(diallyldimethylammonium chloride) (polyDADMAC), and the cationic polymeric flocculant may include long-chain polymeric components such as polyacrylamide (PAM), polyethyleneimine (PEI) or polyvinylamine (PVAM); however, the present description is not limited to this.

[0014] For example, the preparation method of the present description may further comprise adjusting the culture broth comprising an amino acid to an acidic pH of 3 to 5. For example, the culture broth comprising an amino acid may be adjusted to a pH of 3.0 to 4.5, pH of 3.5 to 4.0, pH of 3.7 to 4.3, or pH of 3.8 to 4.2, but is not limited to these. The specific embodiments of the present description confirm that the flocculation efficiency of a coagulant or flocculant is affected by the pH conditions of the solution and that, in particular, an enhanced flocculation efficiency is exhibited under acidic conditions. Petition 870250100612, dated 03 / 11 / 2025, p. 38 / 56 7 / 24 comparison with neutral conditions. In addition to pH conditions, the flocculation efficiency of a coagulant or flocculant is also affected by the concentration of the coagulant or flocculant, the type of amino acid to be prepared, the type, size and / or quantity of impurities in the culture broth, etc. Thus, the scope of this description is not limited to such pH conditions.

[0015] The method for preparing an amino acid of the present description is distinguished by the fact that the filtration flow rate of membrane filtration is improved compared to that without treatment with a coagulant and / or flocculant.

[0016] Furthermore, the method for preparing an amino acid of the present description can achieve the effect of improving the chromaticity of a filtrate, filtered by membrane, and reducing the impurity content in the filtrate.

[0017] For example, the culture broth comprising an amino acid may include, as impurities, one or more selected from the group consisting of cells, proteins, colloidal substances, natural organic matter (NOM), and low molecular weight substances. A culture broth for preparing amino acids may include various impurities, including colloidal substances derived from fermentation byproducts, such as fermentation medium and cell lysates, as well as materials in Petition 870250100612, dated 03 / 11 / 2025, page 39 / 56 8 / 24 suspension, such as cells. These particles can exert adverse effects on productivity by adhering to the membrane in the subsequent filtration process of the amino acid preparation process and thus forming a layer, which not only reduces filtration efficiency but also contaminates the membrane and shortens the membrane replacement interval. Meanwhile, the use of a coagulant and / or flocculant in the method of the present description aggregates / coagulates these impurities, leading to precipitation and thus significantly reducing fouling, such as layer formation, on the membrane. Thus, it can achieve the effects of improving membrane permeate flux and extending membrane life, which improves not only productivity but also production economics.

[0018] In the present description, the culture broth comprising an amino acid may be obtained by fermentation by a microorganism, but is not limited to this. In particular, fermentation by a microorganism may be carried out using methods known in the art, without limitation.

[0019] For example, the preparation method of the present description may further comprise a pretreatment step for separating the cells from the culture broth comprising an amino acid. For example, cell separation may be carried out using a Petition 870250100612, dated 03 / 11 / 2025, pp. 40 / 56 9 / 24 mechanical separator (MS) or a membrane filter (MF), but is not limited to these. Cell separation using a mechanical separator typically employs centrifugation, but in these cases, colloidal substances may not be separated and may pass into the filtrate. Therefore, when combined with the preparation method of the present description, it can exhibit a particularly noticeable improvement effect.

[0020] As used in this document, the term “culture broth” refers to a culture product obtained by culturing a microorganism. The culture broth may comprise the microorganism being cultured. Furthermore, the culture broth may be used interchangeably with fermentation broth.

[0021] As used in this document, the term “culture broth comprising an amino acid” may be used interchangeably with “amino acid-containing culture broth” or “amino acid culture broth”.

[0022] In the present description, the culture broth comprising an amino acid may be a fermentation product comprising cells obtained by a known microorganism fermentation method, a liquid obtained by removing cells from the fermentation product, or a concentrate obtained by concentrating the same (US 8465962 B2, US 9885093 B2, US 10351859 B2, US 7863435 B2, US 10787692 B2, US 9029105 B2, US 2021-0094903 A1), but is not limited to Petition 870250100612, dated 03 / 11 / 2025, pp. 41 / 56 10 / 24 that's it.

[0023] Specifically, the culture broth comprising an amino acid of the present description can be obtained by culturing or fermenting a microorganism that produces the corresponding amino acid, and the microorganism and a method of culturing or fermenting it can be selected and used by a person skilled in the art from known types and methods. For example, the microorganism includes both wild-type microorganisms and microorganisms that have undergone natural or artificial genetic modification. It may be a microorganism (US 9587261 B2, US 7863435 B2, etc.) that has undergone genetic modification or has enhanced activity for the preparation of a target L-amino acid, in which a specific mechanism is weakened or enhanced due to factors such as the insertion of exogenous genes or the enhancement or inactivation of the activity of endogenous genes.Specifically, although the microorganism is not particularly limited in its type, as long as it can prepare the desired amino acid, it can be a microorganism from the genera Enterobacter, Escherichia, Erwinia, Serratia, Providencia, Corynebacterium, and Brevibacterium. More specifically, it can be a microorganism from the genus Corynebacterium or Escherichia. The microorganism from the genus Corynebacterium can be Corynebacterium glutamicum, Corynebacterium ammoniagenes, etc. Petition 870250100612, dated 03 / 11 / 2025, pages 42 / 56 11 / 24 Corynebacterium thermoaminogenes, Corynebacterium efficiens, Corynebacterium stationis, Corynebacterium phocae, Corynebacterium flavescens, Corynebacterium humireducens, Corynebacterium halotolerans, Corynebacterium pollutisoli, Corynebacterium marinum, Corynebacterium freiburgense, Corynebacterium cystitidis, Corynebacterium durum, Corynebacterium pilosum or Corynebacterium testudinoris, but is not limited to them. The microorganism of the genus Escherichia may be Escherichia coli, but is not limited to it.

[0024] In addition, the method of the present description may further comprise, after the membrane filtration step, optionally one or more steps selected from the group consisting of a decolorization step, a filtrate concentration step, a crystallization step, a crystal separation step, a drying step, a separation step and a product marketing step. Each step may be carried out using methods known in the art, without limitation (e.g., US 2021-0094903 A1). The specific conditions may be suitably altered to optimize the process, but are not limited to this.

[0025] For example, the amino acid that can be prepared by the method of the present description may be isoleucine, valine or leucine, but is not limited to these. Petition 870250100612, dated 03 / 11 / 2025, pp. 43 / 56 12 / 24 Depending on the type of amino acid to be prepared, the type and / or size of impurities in the culture broth may vary. Therefore, with regard to the amino acid being prepared, a suitable coagulant or flocculant to improve membrane permeate flux can be selected and used taking into account the factors above, or both can be used in combination.

[0026] Another aspect of the present description provides a feed composition comprising an amino acid prepared by the method of the present description.

[0027] The amino acid described herein may be suitable for use as a feed additive in the preparation of animal feed. For example, as a feed additive, the amino acid may be mixed with feed materials on its own, as part of an animal feed premix, or as an animal feed precursor. The feed composition comprising the amino acid may be administered to an animal alone or in combination with other feed additives in edible vehicles. In addition, the feed composition may be readily administered to an animal as a coating by mixing it directly into the animal feed or in a separate oral formulation. [Beneficial Effects]

[0028] The method described herein may not only improve productivity through precipitation of Petition 870250100612, dated 03 / 11 / 2025, pp. 44 / 56 13 / 24 impurities in the culture broth are removed by adding a coagulant and / or flocculant to the culture broth, thus reducing membrane fouling in the subsequent filtration process and improving membrane permeate flow, but also achieving an improvement in the quality of the prepared product by reducing the protein and coloring substance content in the filtrate. [Method of Implementing the Invention]

[0029] The present description is explained in more detail by the following examples. However, these examples are presented to illustrate the present description, and the scope of the present description is not limited to them. Example 1: Effect of Adding Coagulant / Flocculant in a Flocculation Experiment

[0030] An amino acid culture broth prepared using a microorganism was used as the process liquid. Isoleucine culture broth, valine culture broth, and leucine culture broth were provided as amino acid culture broths. To test the efficiency of membrane filtration, numerous cells with large particles were first removed by centrifugation using a mechanical separator (Alfa Laval), and the supernatant was used as feed for the membrane filtration test. The pH of the feed Petition 870250100612, dated 03 / 11 / 2025, pages 45 / 56 14 / 24 was 6, and the pH was adjusted using 98% H2SO4 and 50% NaOH.

[0031] Specifically, in the membrane filtration test, 200 mL of the separation solution from the previously mentioned amino acid culture broth, from which the cells had been primarily removed, were prepared, and the pH was adjusted using 98% H2SO4 and 50% NaOH. To each of the pH-adjusted solutions, 200 ppm of each of the seven coagulants / flocculants listed in Table 1 were added, followed by rapid mixing for 10 seconds, slow mixing for 30 seconds, and standing for 30 minutes. The decanted liquid was filtered through a filter cloth with a diameter of 3.6 cm and a membrane area of ​​0.001 m2, fixed in a vacuum filtration apparatus under reduced pressure. The process liquid was separated into precipitated agglomerated solids (layers) and a liquid filtrate using the filter cloth.The average membrane flux was measured based on the time required for 200 mL of filtrate to be discharged and was calculated as the flow rate (L) per unit area of ​​membrane (m2) per unit time (h):. Mean membrane flux (LMH) _______________ Filtrate volume (0.2 L)________________ Membrane area (0.001 m2) x Measured discharge time (h) Petition 870250100612, dated 03 / 11 / 2025, pages 46 / 56 15 / 24 [Table 1] Product Name Component Chemical Name: CAS No. Active Ingredient Content (%) Average Molecular Weight MW BASF Magnafloc LT-7991 EPI-AMINE poly(dimethylamine-coepichlorohydrin) 42751-79-1 50 (adjusting water) 150,000 - 300,000 BASF Magnafloc LT-7994 polyDADMAC poly(diallyldimethylammonium chloride) 26062-79-3 40 (adjusting water) 200,000 - 350,000 BASF Zetag8185 PAM polyacrylamide 9003-05-08 88.751 10,000,000 BASF Zetag IP 2M PEI polyethyleneimine 114133-44-7 24 (adjusting water) 2,000,000 BASF Hercobond™ 6960 PVAM polyvinylamine (formamide, ethenyl-, homopolymer, conjugated dimap-quat, hydrochloride) 1353435-58-1 10 (adjusting water) 34,000 -1,500,000 BIOSYNTH FP31706 PAC polyaluminum chloride 1327-41-9 min 9 9 100-1000 SigmaAldrich 434957 APAM poly(acrylamide-acrylic acid) 9003-06-09 87 15,000,000 Example 2: Effect of pH in a Flocculation Experiment

[0032] To confirm the effect of pH on the flocculation experiment above, the experiment was carried out in the same way as in Example 1, except that the pH was adjusted to 4 (acidic), 6 (neutral), and 8 (basic), and flocculation at each pH was examined. The results are presented in Tables 2 to 7 below. In summary, no precipitation was observed at pH 6 and pH 8, regardless of the type of coagulant / flocculant, whereas at acidic pH 4, precipitation or absence of precipitation was observed depending on the presence and / or type of coagulant / flocculant. These results indicate that Petition 870250100612, dated 03 / 11 / 2025, pp. 47 / 56 16 / 24 The combination of adding an appropriate coagulant / flocculant and using an acidic pH promotes precipitation and further improves filtration flow and filtrate quality. Example 3: Effect of Coagulant / Flocculant Addition and pH on Isoleucine Preparation

[0033] A membrane filtration experiment was performed using, as feed, the separation solution from the amino acid culture broth from which the cells had been primarily removed, as per Example 1, except that the amino acid culture broth used was a culture broth containing isoleucine, the pH was adjusted to 4, 6, or 8, and the coagulants / flocculants from Table 1 were included or excluded. Precipitate formation in each sample was observed as per Example 1, and the permeate flux was calculated. The results are presented in Tables 2 and 3. In addition, for each filtrate obtained, absorbances at 280 nm and 420 nm were measured, which are used as indices of protein content and chromaticity. The results are presented together in Tables 2 and 3. [Table 2] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 Comparative Example 9 pH of the process liquid 4 6 8 4 6 8 4 6 8 Petition 870250100612, dated 03 / 11 / 2025, p. 48 / 56 17 / 24 Tipo de aditivo Not added PAC APAM Resultados Formação de precipit ado XXXOXXXXX Fluxo de permeado (IMH) 236 199 186 418 395 169 257 181 179 UV (280nm) 7,0 7,4 7,4 6,9 7,3 7,5 7,4 6,7 6,9 UV (420nm) 0.7 0.9 1.1 0.3 0.8 1.0 0.7 0.9 1.0 [Table 3] Example 1 Example Comparative 10 Example Comparative 11 Example 2 Example Comparative 12 Example Comparative 13 Example 3 Example Comparative 14 Example Comparative 15 Example 4 Example Comparative 16 Example Comparative 17 Example 5 Example Comparative 18 Example Comparative 19 pH of the process liquid 4 6 8 4 6 8 4 6 8 4 6 8 4 6 8 Additive type EPI-AMINE poliDlMAC PAM PEI PVAM Results Formation of prec ipitated OXXOXXOXXOXXOXX Permeate flux (IMH ) 108 6 474 190 127 6 398 171 135 3 502 180 999 483 193 103 2 431 188 UV (280 nm) 5.4 7.0 7.3 5.2 7.1 7.3 5.7 7.2 7.7 5.8 7.1 6.9 5.2 6.9 7.3 UV (420 nm) 0.1 0.8 0.9 0.1 0.8 0.9 0.1 0.8 0.9 0.1 0.8 1.2 0.1 0.8 1.2

[0034] As shown in Tables 2 and 3, in the samples without coagulant / flocculant tested in the isoleucine preparation process, no precipitation was observed regardless of pH, and the permeate flux was low. Among the groups treated with Petition 870250100612, dated 03 / 11 / 2025, pp. 49 / 56 18 / 24 coagulants / flocculants, the group treated with APAM similarly showed no precipitation regardless of pH, and no improvement in permeate flux was observed compared to the control without coagulant / flocculant. The group treated with the inorganic coagulant PAC showed precipitation at pH 4, but only a slight improvement in permeate flux was observed, and no precipitation was observed at the other pH values. Meanwhile, in the groups treated with EPI-AMINA, polyDADMAC, PAM, PEI, or PVAM, no precipitation and no improvement in permeate flux were observed in the test groups adjusted to pH 6 and 8, while precipitation and a significant increase in permeate flux were observed in the test groups adjusted to pH 4. In particular, it was confirmed that the group treated with PAM showed an improvement of approximately 5.7 times in filtration flux.Furthermore, these test groups exhibited a significant reduction in absorbance at 420 nm, which is an index of chromaticity. These results indicate that the quality of the filtrate can be improved through the process described above. Example 4: Effect of Coagulant / Flocculant Addition and pH on Valine Preparation

[0035] A membrane filtration experiment was performed using, as feedstock, the solution of Petition 870250100612, dated 03 / 11 / 2025, pages 50 / 56 19 / 24 separation of the amino acid culture broth from which the cells had been primarily removed as per Example 1, except that the amino acid culture broth used was a culture broth containing valine, the pH was adjusted to 4 or 6, and the coagulants / flocculants from Table 1 were included or excluded. Precipitate formation in each sample was observed as per Example 1, and the permeate flux was calculated. The results are presented in Tables 4 and 5. In addition, for each filtrate obtained, absorbances at 280 nm and 420 nm were measured, which are used as indices of protein content and chromaticity. The results are presented together in Tables 4 and 5. [Table 4] Comparative Example 20 Comparative Example 21 Comparative Example 22 Comparative Example 23 Comparative Example 24 Comparative Example 25 pH of the process liquid 4 6 4 6 4 6 Additive type Not added PAC APAM Results Precipitate formation XXOXXX Permeate flux (LMH) 1415 1074 1888 1172 1181 1036 UV (280nm) 19 21 19 22 19 19 UV (420nm) 2.4 2.8 1.8 3.0 3.2 2.6 [Table 5] Example 6 Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 Comparative Example Petition 870250100612, dated 03 / 11 / 2025, pages 51 / 56 20 / 24 26 27 28 29 30 pH of the process liquid 4 6 4 6 4 6 4 6 4 6 Additive type EPI-AMINE polyDADMAC PAM PEI PVAM Results Precipitate formation OXOXOXOXOX Permeate flux (LMH) 3931 1987 5661 1718 3022 1838 3825 1686 3629 1441 UV (280nm) 19 21 19 19 18 19 19 19 19 19 UV (420nm) 1.8 2.9 1.9 2.6 1.9 2.3 1.8 2.6 1.8 2.6

[0036] As shown in Tables 4 and 5, in the samples without coagulant / flocculant tested in the valine preparation process, no precipitation was observed regardless of pH, and the permeate flux was low. Among the groups treated with coagulants / flocculants, the group treated with APAM similarly showed no precipitation regardless of pH, and no improvement in permeate flux was observed compared to the control without coagulant / flocculant. The group treated with the inorganic coagulant PAC showed precipitation at pH 4, but only a slight improvement in permeate flux was observed, and no precipitation was observed at the other pH values.Meanwhile, in the groups treated with EPIAMINA, polyDADMAC, PAM, PEI, or PVAM, no precipitation and no improvement in permeate flux were observed in the test groups adjusted to pH 6, whereas precipitation and a significant increase in permeate flux were observed in the adjusted test groups. Petition 870250100612, dated 03 / 11 / 2025, pages 52 / 56 21 / 24 for pH 4. In particular, it was confirmed that the group treated with polyDADMAC showed an approximately 4.0-fold improvement in filtration flow. Furthermore, these test groups exhibited a significant reduction in absorbance at 420 nm, which is a chromaticity index. These results indicate that the quality of the filtrate can be improved through the above process. Example 5: Effect of Coagulant / Flocculant Addition and pH on Leucine Preparation

[0037] A membrane filtration experiment was performed using, as feed, the separation solution from the amino acid culture broth from which the cells had been primarily removed as per Example 1, except that the amino acid culture broth used was a culture broth containing leucine, the pH was adjusted to 4 or 6, and the coagulants / flocculants from Table 1 were included or excluded. Precipitate formation in each sample was observed as per Example 1, and the permeate flux was calculated. The results are presented in Tables 6 and 7. In addition, for each filtrate obtained, absorbances at 280 nm and 420 nm were measured, which are used as indices of protein content and chromaticity. The results are presented together in Tables 6 and 7. [Table 6] Petition 870250100612, dated 03 / 11 / 2025, pages 53 / 56 22 / 24 Comparative Example 31 Comparative Example 32 Comparative Example 33 Comparative Example 34 Comparative Example 35 Comparative Example 36 pH of the process liquid 4 6 4 6 4 6 Additive type Not added PAC APAM Results Precipitate formation XXOXXX Permeate flux (LMH) 693 561 847 636 707 578 UV (280nm) 19 20 10 24 17 19 UV (420nm) 3.2 4.3 2.0 4.7 3.0 3.6 [Table 7] Example 11 Comparative Example 37 Example 12 Comparative Example 38 Example 13 Comparative Example 39 Example 14 Comparative Example 40 Example 15 Comparative Example 41 pH of the process liquid 4 6 4 6 4 6 4 6 4 6 Additive type EPI-AMINE polyDADMAC PAM PEI PVAM Results Precipitate formation OXOXOXOXOX Permeate flux (LMH) 1938 804 1862 796 2775 651 1989 427 1769 826 UV (280nm) 16 24 16 21 14 20 14 20 13 23 UV (420nm) 1.1 4.6 0.7 4.0 0.8 1.0 1.8 3.9 2.0 4.4

[0038] As shown in Tables 2 to 7, in the samples without coagulant / flocculant tested in the leucine preparation process, no precipitation was observed regardless of pH, and the permeate flux was low. Among the groups treated with coagulants / flocculants, the group treated with APAM similarly showed no precipitation regardless of pH, and no improvement in permeate flux was observed compared to the control without coagulant / flocculant. The treated group Petition 870250100612, dated 03 / 11 / 2025, pp. 54 / 56 23 / 24 treated with the inorganic coagulant PAC showed precipitation at pH 4, but only a slight improvement in permeate flux was observed, and no precipitation was observed at the other pH values. Meanwhile, in the groups treated with EPIAMINA, polyDADMAC, PAM, PEI, or PVAM, no precipitation and no improvement in permeate flux were observed in the test groups adjusted to pH 6, while precipitation and a significant increase in permeate flux were observed in the test groups adjusted to pH 4. In particular, the group treated with PAM showed an approximately 4.0-fold improvement in filtration flux. Furthermore, these test groups exhibited a significant reduction in absorbance at 420 nm, which is a chromaticity index. These results indicate that the filtrate quality can be improved through the above process.

[0039] In general, the method described herein, which additionally includes the addition of a coagulant / flocculant before membrane filtration, can significantly improve the average membrane permeate flux while maintaining the concentration ratio at a level equivalent to that of the case without coagulant / flocculant, thus markedly increasing the daily preparation of amino acids. Therefore, it is suggested that an improved process offering superior cost competitiveness could be... Petition 870250100612, dated 03 / 11 / 2025, pages 55 / 56 24 / 24 proportioned. Furthermore, it was specifically confirmed that the method of the present description significantly reduces absorbance at 420 nm, which is a product specification requirement in the food-grade amino acid industry, by efficiently removing impurities including coloring substances as well as proteins, and may therefore be useful for improving the quality of amino acid products.

[0040] As set forth above, a person skilled in the art will be able to understand that the present description can be embodied in other specific forms without departing from the technical spirit or essential characteristics thereof. In this sense, the embodiments described herein are for illustrative purposes only and should not be construed as limiting the scope of the present description. The scope of the present description should be construed as including the meaning and scope of the appended claims, rather than the detailed description, and all alterations or variations derived from equivalent concepts are within the scope of the present description. Petition 870250100612, dated 03 / 11 / 2025, page 56 / 56

Claims

1 / 2 CLAIMS 1. Method for preparing an amino acid from a culture broth comprising an amino acid, characterized in that it comprises: (a) adding an organic coagulant, a cationic polymeric flocculant or both to the culture broth comprising an amino acid to precipitate impurities; and (b) subjecting the culture broth with precipitated impurities to membrane filtration.

2. Method according to claim 1, characterized in that the organic coagulant is poly(dimethylamine-co-epichlorohydrin) (EPI-AMINE) or poly(diallyldimethylammonium chloride) (polyDADMAC) and the cationic polymeric flocculant is polyacrylamide (PAM), polyethyleneimine (PEI) or polyvinylamine (PVAM).

3. Method according to claim 1, characterized in that it further comprises adjusting the culture broth comprising an amino acid to an acidic pH of 3 to 5.

4. Method according to claim 1, characterized in that the filtration flow of membrane filtration is improved.

5. Method, according to claim 1, characterized in that the chromaticity of the membrane-filtered filtrate is improved and the impurity content in the filtrate is reduced.

6. Method according to claim 1, characterized in that the impurities are one or more selected from the group consisting of cells, proteins, colloidal substances, natural organic matter (NOM) and low molecular weight substances.

7. Method according to claim 1, characterized in that the culture broth comprising an amino acid is obtained through fermentation by a microorganism.

8. Method according to claim 1, characterized in that it further comprises a pretreatment step for separating cells from the culture broth comprising an amino acid.

9. Method according to claim 1, characterized in that it further comprises, after the membrane filtration step, optionally one or more steps selected from the group consisting of a decolorization step, a filtrate concentration step, a crystallization step, a crystal separation step, a drying step, a separation step and a product marketing step. Petition 870250082324, dated 12 / 09 / 2025, p. 21 / 25