Granules comprising L-amino acid and method for preparing the same

Abstract

The present disclosure relates to granules comprising an L-amino acid and a method for preparing the same. The method may comprise: (a) preparing a fermentation liquid of L-amino acid; (b) removing moisture from the fermentation liquid of L-amino acid such that the solid content of the fermentation liquid of L-amino acid is in a range of 20% to 90%; (c) forming granulated particles with a moisture content of 0% to 40% by mixing the concentrated fermentation liquid of L-amino acid with a seed; (d) drying the granulated particles formed in Step (c); (e) sieving the granulated particles dried in Step (d); and (f) pulverizing or circulating the particles left in step (e) to be recycled as the seed in step (c).

Claims

1. A method for preparing L-amino acid granules, wherein the L-amino acid is one or more selected from the group consisting of L-threonine, L-tryptophan, L-methionine, L-valine, L-tyrosine, L-phenylalanine, L-isoleucine, and L-leucine, the method comprising: (a) preparing a fermentation liquid of L-amino acid; (b) removing moisture from the fermentation liquid of L-amino acid such that the solid content of the fermentation liquid of L-amino acid is in a range of 20% to 90%, to obtain a concentrated fermentation liquid; (c) forming granulated particles with a moisture content of 0% to 40% by mixing the concentrated fermentation liquid of L-amino acid with a seed; (d) drying the granulated particles formed in Step (c); (e) sieving the granulated particles dried in Step (d); and pulverizing or circulating the particles left in step (e) to be recycled as the seed in step (c).

2. The method according to claim 1, wherein the fermentation liquid of L-amino acids in Step (a) is obtained through the fermentation of a strain of the genus Corynebacterium.

3. The method according to claim 1, wherein in Step (b) is performed by a concentration method or slurry-drying method.

4. The method according to claim 1, wherein in the seed of Step (c), the particles with a particle size of 75 μm or less are present in a range of 9% or higher.

5. The method according to claim 1, wherein in the seed of Step (c), the particles with a particle size of 212 μm or less are present in a range of 97% or less.

6. The method according to claim 1, wherein the size of the particles obtained in Step (c) is adjusted by the particle size of the seed, the mixing ratio of the seed to the slurry, or the mixing ratio of the seed to the solid content of the slurry.

7. The method according to claim 6, wherein the mixing ratio of the seed to the slurry of Step (c) is in a range of 1 to 15.

8. The method according to claim 6, wherein the mixing ratio of the seed to the solid content of the slurry of Step (c) is in a range of 2.8 to 22.

9. The method according to claim 1, wherein the moisture content of the particles obtained in Step (c) is in a range of 1% to 30%.

10. The method according to claim 1, wherein with regard to the particle size of the granulated particles of Step (c), the particles with a particle size of 2,000 μm or higher are present in an amount of 1.0% or less and the particles with a particle size of 75 μm or less are present in a range of 5.0% or less.

11. The method according to claim 1, wherein with regard to the particle size of the granulated particles of Step (c), the particles with a particle size greater than 75 μm are present in a range of 50% or higher.

12. The method according to claim 1, wherein Step (d) is performed at a temperature of 60° C. to 90° C.

13. The method according to claim 1, wherein the fermentation liquid in Step (a) comprises the microorganism.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) Hereinafter, the present disclosure will be described in detail through exemplary embodiments. However, these exemplary embodiments are for illustrative purposes only and are not intended to limit the scope of the present disclosure.

EXAMPLE 1

Concentration and Granulation of Fermentation Liquid

EXAMPLE 1-1

Concentration of Fermentation Liquid

(2) In order to prepare granules containing L-threonine in this granulation process, a fermentation liquid having the following composition was obtained by culturing a microorganism producing L-threonine.

(3) The fermentation liquid contained a cultured medium and a microorganism, and moisture measurement and composition analysis were performed using the same. The composition analysis shown in Table 1 below was performed after removing the cells of the microorganism for LC analysis.

(4) TABLE-US-00001 TABLE 1 Composition Value Threonine 174.7 g/L Amino Acids Other Than Threonine 5.8 g/L Carboxylic Acid 0.3 g/L (8 carbon atoms or less) Inorganic Materials 6.3 g/L Moisture Content 77.8%

(5) The moisture in the fermentation liquid of a microorganism was removed by concentrating the fermentation liquid under reduced pressure. Specifically, as shown in Table 2, the concentration of the solids was performed variously to be in a range of 40.3% to 79.4%, and thereby slurries of the fermentation liquid were prepared.

(6) Additionally, based on the determination that a solid content of 40% or less is not efficient in terms of productivity and the amount of steam consumption, and that a solid content of 80% or higher will cause a difficulty in slurry transportation, etc., the solid content was adjusted to be in a range of 40.3% to 79.4%.

(7) Meanwhile, the seeds were prepared such that the fermentation liquid was pre-dried in advance and then pulverized so that the particles with a particle size of 75 μm or less were present in a range of 9% or more.

EXAMPLE 1-2

Confirmation of Changes in Particle Size of Granules According to Solid Content of Fermentation Liquid

(8) The slurries of the fermentation liquid and the seeds, which were prepared in Example 1-1, were injected into a granulator to perform granulation. The mixed-type granulator used in this granulation process was a CM5 model (Lodige), and the obtained wet granules were dried with a fluidized bed dryer (GR Engineering).

(9) Meanwhile, before performing the granulation, the seed injection rate and the slurry injection rate were measured in advance so as to set the moisture level of the wet granules being discharged from the granulator at a level around 7%. The subsequent experimental conditions and results are shown in Table 2 below.

(10) It was confirmed that the overall particle size distribution of granules and the L-threonine content had no significant effect on the solid content of the fermentation liquid. That is, it was confirmed that a fermentation liquid with a low solubility could also increase productivity by performing the granulation in a state with a high solid content. Since the particles of 2,000 μm or more were present in a range of 1.0% or less and the particles of 75 μm or less were all present in a range of 5.0% or less, it was confirmed that granulated particles with appropriate quality for commercialization can be obtained using the granulation method of the present disclosure.

(11) TABLE-US-00002 TABLE 2 Granulation Conditions Solid Content % — 40.3 51.2 60.3 66.7 79.4 of Slurry Amount of kg/ — 7.7 9.9 12.1 15.9 29.8 Slurry Injection hr Seed Injection kg/ — 65.8 65.8 65.8 65.8 65.8 Rate hr Moisture % — 0.8 0.8 0.8 0.8 0.8 Content of Seed Seed Injection — — 21.2 13.0 9.0 6.2 2.8 Ratio (Seed to Solid Content of Slurry) Seed Injection — — 8.5 6.6 5.2 4.1 2.2 Ratio (Seed to Slurry) Moisture % — 7.0 7.2 7.0 7.1 7.1 Content of Wet Granules Analysis Results of Granulated Particles According Type Seed to Conditions L-threonine % 78.2 77.9 77.8 77.5 78.1 78.2 Content Apparent kg/ 652 775 753 762 795 765 Density m.sup.3 Moisture % 0.8 1.5 1.3 1.0 0.8 0.9 Content Protein Content % 12.5 12.3 12.4 12.2 12.6 12.7 Range of Particle Size (μm) Particle Size Distribution ≥2,000 % 0.0 0.3 0.2 0.5 0.3 0.1 1,000 ≤ X ≤ 2,000 0.0 1.7 1.8 1.6 1.6 1.4 750 ≤ X ≤ 1,000 0.8 5.9 6.2 5.7 6.3 5.5 500 ≤ X ≤ 750 18.6 33.6 30.0 34.2 32.1 31.2 350 ≤ X ≤ 500 26.3 45.1 43.2 40.0 43.3 45.2 212 ≤ X ≤ 350 33.0 10.3 15.1 14.5 12.3 13.3 75 ≤ X ≤ 212 12.1 2.6 2.0 2.5 2.7 2.1 0 ≤ X ≤ 75 9.1 0.5 1.5 1.0 1.4 1.2 Total 100.0 100.0 100.0 100.0 100.0 100.0

EXAMPLE 2

Confirmation of Changes in Particle Size of Granules According to Amount of Slurry Injection

(12) In order to confirm that the particle size of granules can be adjusted according to the mixing ratio of a seed and a slurry of a fermentation liquid, an experiment was performed as follows. A fermentation liquid of threonine was concentrated under reduced pressure. Then, granulation was performed by varying the injected amount of the threonine slurry, which was concentrated to have a solid content of 63.2%, while fixing the particle size and injection rate of the seed, and the resulting moisture content and particle size of the granules before drying are shown in Table 3 below. In order to more clearly confirm the changes in the particle size of granules according to an increase in the injected amount of the slurry (the amount of the slurry or the solid content of the slurry), a seed with an extremely large amount of fine particles was used. A seed in which particles with a particle size of 212 μm or less were present in 97.9% was used. As shown in Table 3, it was confirmed that the particle size was increased as a whole while the seed injection ratio was decreased according to the injected amount. In addition, the moisture content of the granules before drying varied within a range of 5% to 12.8% according to the changes in the injected amount. In contrast, it was confirmed that under the condition of a moisture content of 15%, the particles were in a state of a paste rather than granules, and thus the drying in a fluid bed dryer was impossible.

(13) Taken together, it was confirmed that under certain specific seed conditions, the seed injection ratio decreased as the amount of the slurry of the fermentation liquid injected increased, and the moisture content of wet granules before drying increased, and additionally, the particle size of the granulated products showed a tendency of growth.

(14) From the above results, it was confirmed that the particle size of granulated particles and the moisture content of granules can be controlled according to the amount of the slurry of the fermentation liquid injected. In addition, it may be interpreted that it is possible to control the moisture content of granules and the particle size of granulated particles according to the ratio of seed injection to a slurry.

(15) TABLE-US-00003 TABLE 3 Granulation Conditions Solid Content of % — 63.2 63.2 63.2 63.2 63.2 Slurry Amount of Slurry kg/hr — 7.7 12.4 17.5 23.6 30.8 Injection Seed Injection Rate kg/hr — 62.2 62.2 62.2 62.2 62.2 Moisture Content of % — 1.1 1.1 1.1 1.1 1.1 Seed Seed Injection Ratio (Seed to Solid — — 12.8 7.9 5.6 4.2 3.2 Content of Slurry) Seed Injection Ratio — — 8.1 5.0 3.6 2.6 2.0 (Seed to Slurry) Analysis of Granulated Particles After Granulation (Before Drying) Moisture Content of % — 5.0 6.9 8.9 11.1 12.8 Wet Granules Type Seed Analysis of Granulated Particles After Drying Range of Particle Size (μm) Particle Size Distribution ≥2,000 % 0.0 0.0 0.0 0.7 3.7 10.3 1,000 ≤ X ≤ 2,000 0.0 0.0 0.0 5.5 8.8 26.5 750 ≤ X ≤ 1,000 0.0 0.0 1.1 11.3 17.8 25.8 500 ≤ X ≤ 750 0.0 0.0 5.9 26.3 31.8 17.2 350 ≤ X ≤ 500 0.0 0.1 18.8 26.0 19.3 11.3 212 ≤ X ≤ 350 2.1 10.1 33.2 16.2 10.2 5.2 75 ≤ X ≤ 212 30.2 44.3 25.5 9.2 5.5 2.2 0 ≤ X ≤ 75 67.7 45.5 15.5 4.8 2.9 1.5 Total 100.0 100.0 100.0 100.0 100.0 100.0

EXAMPLE 3

Confirmation of Productivity According to Changes in Particle Size of Seed

(16) The productivity of the granule preparation method of the present disclosure increases as the amount of the slurry of the fermentation liquid increases relative to the amount of a unit seed. However, when the ratio of slurry injection increases, the particles being discharged from a granulator undergo conversion to a state of a paste as the amount of slurry injection reaches a certain level or higher, and when the amount of slurry injection increases further, the particles are converted further to a slurry state. When the granules are in a slurry state or a paste-like state, it is difficult to dry the granules in a fluidized bed dryer, and an agglomerated mass of granules is generated, which becomes the most serious cause of trouble for the dryer.

(17) In this Example, with respect to the method of increasing productivity, the maximum amount of slurry injection compared to the seed amount according to the changes in particle size of the seed was confirmed.

(18) In order to allow variations in the particle size of the seed, granulated particles were used by recirculating them as the seed, and the circulation was performed 3 times in total. The solid content of the slurry of a fermentation liquid used was 59.6%. With respect to the particle size distribution of the initial seed, a seed with an extremely large amount of particles was used as the primary seed as shown in Table 4, and the obtained granules were used as a seed in the next circulation, thereby allowing the particle size of the seed of a subsequent circulation to increase. As mentioned, when the amount of slurry injection increases, the moisture being discharged from a granulator increases, thus making it difficult to dry the particles in a fluidized bed dryer. Therefore, this Example was performed by confirming the maximum injected amount of the slurry under which the particles discharged from a granulator can be dried in a fluidized bed dryer, and the values are shown in Table 4.

(19) It was confirmed that as the circulation continued, the particle size of the granulated products and the seeds used in the granules of the subsequent circulations increased, and as a result, the amount of slurry injection per seed amount decreased, thus resulting in a decrease of the moisture content of wet granules.

(20) That is, it was found that as the particle size of the seeds increased, the amount of slurry injection decreased, and when the particle size of the seeds became too large, the amount of slurry injection became too low and the seed injection ratio became relatively high, thereby resulting in decreased productivity.

(21) From these results, it was confirmed that the particle size of granules can be adjusted by the particle size of a seed or the mixing ratio of a seed to a slurry.

(22) TABLE-US-00004 TABLE 4 Granulation Conditions Solid Content of % — 59.6 59.6 59.6 59.6 Slurry Amount of Slurry kg/hr — 35.4 19.7 8.8 5.7 Injection Seed Injection Rate kg/hr — 52.3 53.5 54.2 53.7 Moisture Content % — 1.8 1.5 1.3 1.0 of Seed Seed Injection — — 2.5 4.6 10.3 15.8 Ratio (Seed to Solid Content of Slurry) Seed Injection 1.5 2.7 6.2 9.4 Ratio (Seed to Slurry) After Granulation (Before Drying) Moisture Content % — 17.4 11.8 6.8 4.7 of Wet Granules Particle Size Distribution Primary Secondary Tertiary Granules Granules Granules Range of Particle Primary (Secondary (Tertiary (Quaternary Quaternary Size (μm) Seed Seed) Seed) Seed) Granules ≥2,000 % 0.0 0.0 0.0 0.6 1.3 1,000 ≤ X ≤ 2,000 0.0 0.0 0.4 2.0 3.7 750 ≤ X ≤ 1000 0.0 0.2 3.4 11.9 17.7 500 ≤ X ≤ 750 0.0 0.1 10.1 27.1 32.2 350 ≤ X ≤ 500 0.0 4.2 32.7 40.1 35.2 212 ≤ X ≤ 350 0.0 19.9 39.8 17.0 7.9 75 ≤ X ≤ 212 5.3 38.2 13.2 1.2 0.7 0 ≤ X ≤ 75 94.7 37.4 0.5 0.3 1.2 Total 100.0 100.0 100.0 100.0 100.0

EXAMPLE 4

Confirmation of Productivity According to Re-Concentration of Concentrated Fermentation Liquid

(23) This Example is an example related to a method for increasing productivity by separating the solids produced after concentrating a fermentation liquid, followed by further concentrating its mother liquor (supernatant). That is, after concentrating a fermentation liquid, the solids were separated and sent to a granulator using the SDC (PTM006™, Tomoe Engineering Co., Ltd.), and the filtrate, from which the solids were separated, was further concentrated and sent to a granulator to reduce the total amount of moisture being transferred to the granulator, thereby increasing the productivity of the granulator.

(24) The fermentation liquid was concentrated to have a solid content of 60.1%, and then solids and the mother liquor were separated using the SDC. In particular, according to the measurement, the recovered solids were measured to have a moisture content of 18.1%, and the separated mother liquor had a solid content of 28.1%. The mother liquor was further concentrated under reduced pressure to have a solid content of 35%, 45%, and 55%, respectively, so as to prepare slurries of the mother liquor. Based on the amount of 1 kg of the separated solids, a slurry of the mother liquor was injected into a granulator according to the amount produced. The amount of seed injection to be injected into the granulator was adjusted so that the moisture content of wet granules could be at a level of 10.5%.

(25) As a result of the granulation test, it was possible to obtain granules at a uniform level in all aspects relating to content, particle size distribution, and apparent density, regardless of the solid content of the mother liquor slurry. Specifically, regardless of the concentration degree of the mother liquor slurry, all of the particles having a particle size of 75 μm or less were present in less than 1.0%, and all of the particles having a particle size of 1,000 μm to 2,000 μm were present in less than 1.0%, so that more uniform and high-quality granulated products could be produced.

(26) From these results, it was confirmed that L-amino acid granules can be produced with a higher productivity when the granulation process is performed in such a manner that the solids produced after concentrating a fermentation liquid are separated, the mother liquor is re-concentrated, and then the resulting mother liquor and the separated solids are mixed for granulation.

(27) TABLE-US-00005 TABLE 5 Granulation Conditions Mother Solid Content % — 34.8 45.5 54.4 Liquor Amount Injected kg — 0.37 0.29 0.23 Slurry Separated Moisture Content % — 18.1 18.1 18.1 Solid Amount Injected kg — 1.0 1.0 1.0 Content Seed Moisture Content % — 0.9 0.9 0.9 Amount Injected kg — 2.9 2.1 1.6 Moisture Content Before % — 10.4 10.6 10.4 Drying Type Seed Granules After Drying Content % 76.3 76.5 76.3 76.4 Apparent Density kg/m.sup.3 632 769 761 765 Range of Particle Size (um) Particle Size Distribution ≥2,000 % 0.0 0.0 0.0 0.1 1,000 ≤ X ≤ 2,000 0.0 0.2 0.5 0.4 750 ≤ X ≤ 1000 0.2 2.2 3.3 3.1 500 ≤ X ≤ 750 0.1 9.7 11.3 10.3 350 ≤ X ≤ 500 4.2 33.4 32.1 34.2 212 ≤ X ≤ 350 19.9 39.8 38.7 36.7 75 ≤ X ≤ 212 24.9 14.3 13.7 14.5 0 ≤ X ≤ 75 50.7 0.5 0.4 0.7 Total 100.0 100.0 100.0 100.0

(28) From the foregoing, a person skilled in the art to which the present disclosure pertains will be able to understand that the present disclosure may be embodied in other specific forms without modifying the technical concepts or essential characteristics of the present disclosure. In this regard, the exemplary embodiments disclosed herein are only for illustrative purposes and should not be construed as limiting the scope of the present disclosure. On the contrary, the present disclosure is intended to cover not only the exemplary embodiments but also various alternatives, modifications, equivalents, and other embodiments that may be included within the spirit and scope of the present disclosure as defined by the appended claims.