阅读说明：本技术 低含量苏氨酸制备方法及其专用防结块剂 (Preparation method of low-content threonine and special anti-caking agent thereof ) 是由 吴亮亮 郭小炜 付丽霞 赵春光 孟刚 白浩渊 王磊 于 2021-09-29 设计创作，主要内容包括：本发明公开了低含量苏氨酸制备方法及其专用防结块剂。本发明防结块剂由硫酸镁、氯化钙、硫酸钠、氯化钠、磷酸二氢钠、磷酸氢二钠、磷酸二氢钾、磷酸氢二钾、磷酸氢钙、碳酸钙、磷酸二氢钙、乳酸钙、氧化镁、氯化镁、硫酸亚铁、氯化亚铁、氯化铁、碳酸亚铁、碳酸锌、硫酸锌、氯化锌、乙酸锌、氯化锰、硫酸锰、碳酸锰、磷酸氢锰、氯化锰、碘化钾、碘化钠和碘酸钙中的任意两种或两种以上组分组成。本发明通过对苏氨酸陶清液直接进行浓缩,回收了损失的苏氨酸,再通过防结块剂的添加,与苏氨酸晶体互相结合,提高产品的分散性及流动性,达到降低产品结块的风险的目的。(The invention discloses a preparation method of low-content threonine and a special anti-caking agent thereof. The anti-caking agent consists of any two or more than two of magnesium sulfate, calcium chloride, sodium sulfate, sodium chloride, sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, calcium hydrophosphate, calcium carbonate, calcium dihydrogen phosphate, calcium lactate, magnesium oxide, magnesium chloride, ferrous sulfate, ferrous chloride, ferric chloride, ferrous carbonate, zinc sulfate, zinc chloride, zinc acetate, manganese chloride, manganese sulfate, manganese carbonate, manganese hydrogen phosphate, manganese chloride, potassium iodide, sodium iodide and calcium iodate. The invention directly concentrates the threonine pottery clear liquid, recovers the lost threonine, and then combines with threonine crystals by adding the anti-caking agent, improves the dispersibility and the fluidity of the product, and achieves the purpose of reducing the risk of caking of the product.)

1. An anti-caking agent comprises any two or more of magnesium sulfate, calcium chloride, sodium sulfate, sodium chloride, sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, calcium carbonate, calcium dihydrogen phosphate, calcium lactate, magnesium oxide, magnesium chloride, ferrous sulfate, ferrous chloride, ferric chloride, ferrous carbonate, zinc sulfate, zinc chloride, zinc acetate, manganese chloride, manganese sulfate, manganese carbonate, manganese hydrogen phosphate, manganese chloride, potassium iodide, sodium iodide and calcium iodate.

2. An anti-caking agent according to claim 1, characterized in that: the anti-caking agent at least comprises calcium carbonate.

3. An anti-caking agent according to claim 1, characterized in that: the anti-caking agent is any one of the following A1-A7:

a1, the mass ratio is 1: 1 calcium carbonate and magnesium sulfate;

a2, the mass ratio is 1: 1 calcium carbonate and calcium hydrogen phosphate;

a3, the mass ratio is 1: 1 magnesium sulfate and zinc carbonate;

a4, the mass ratio is 1: 1 calcium hydrogen phosphate and manganese carbonate;

a5, the mass ratio is 1: 1: 1 calcium carbonate, magnesium sulfate and calcium lactate;

a6, the mass ratio is 1: 1: 1 calcium hydrogen phosphate, manganese carbonate and calcium carbonate;

a7, the mass ratio is 1: 1: 1 magnesium sulfate, calcium lactate and calcium hydrogen phosphate.

4. Use of an anti-caking agent according to any one of claims 1 to 3 for the preparation of a low threonine or for the preparation of a feed containing a low threonine content.

5. A method for preparing low-content threonine comprises the following steps:

(1) filtering the threonine fermentation liquor by using a ceramic membrane to obtain a ceramic membrane clear solution; evaporating and concentrating the clear liquid of the ceramic membrane to obtain a concentrated solution;

(2) adding an anti-caking agent according to any one of claims 1 to 3 to the concentrate to obtain a mixed slurry;

(3) and drying the mixed slurry to obtain the low-content threonine.

6. The method of claim 5, wherein:

in the step (1), in the ceramic membrane filtering step, the aperture of the ceramic membrane is 50-100 nm, and the concentration multiple is 10-12 times;

in the evaporation concentration step, the concentration multiple is 5-6 times; the mass percentage content of the concentrated discharged dry matter is 55-60%, the concentrated discharged density is 1.18-1.22 g/mL, and the sedimentation solid-liquid ratio is 88-92%.

7. The production method according to claim 5 or 6, characterized in that:

in the step (2), the mass percentage of the anti-caking agent in the mixed slurry is 10-15%;

the mass percentage of water in the mixed slurry is 35-45%.

8. The production method according to any one of claims 5 to 7, characterized in that:

in step (3), the method further comprises, before the drying, the steps of: mixing the mixed slurry with the low threonine content; the mass percentage of water in the mixed materials is 10-15%.

9. A low threonine content produced by the production method according to any one of claims 5 to 8.

10. Use of the low threonine as defined in claim 9 as a feed additive or in the preparation of feed.

Technical Field

The invention belongs to the technical field of threonine preparation, and particularly relates to a preparation method of low-content threonine and a special anti-caking agent thereof.

Background

Threonine, the english name Threonine, has the chemical name α -amino- β -hydroxybutyric acid. Threonine has 4 isomers, and naturally occurring and physiologically acting threonine is L-threonine. Threonine is one of essential amino acids required for human and animals, and is widely used as a feed additive.

At present, the preparation method of threonine mainly comprises three methods, namely a biological synthesis method, a chemical synthesis method and a protein hydrolysis method. The biosynthesis method gradually becomes a main mode for industrial production of threonine due to the advantages of low production cost, resource conservation, small environmental pollution and the like. The fermentation method in the biosynthesis method has become the mainstream method for producing threonine, and is mainly prepared from casein, silk protein, sericin and the like. A fermentation method comprises threonine fermentation stage and threonine extraction stage. The production process of the threonine extraction stage mainly comprises fermentation liquor pretreatment, acidification, ceramic membrane filtration, reduced pressure concentration crystallization, airflow drying, primary mother liquor reflux concentration crystallization and the like, wherein the fermentation liquor is subjected to isoelectric point crystallization to obtain a threonine product, and the crystallized feed liquid is a threonine secondary mother liquor. The threonine extraction yield can only reach 88 percent (according to the liquid phase equilibrium yield is only 84 percent), and 16 percent of threonine is taken away by the secondary mother liquor. If this portion of threonine could be recovered, it would be advantageous to reduce the production cost. However, the threonine mother liquor contains a large amount of reducing sugar, organic acid, protein and inorganic salt, so that the secondary mother liquor is difficult to treat, even if lysine residue is produced, only 30% of the mother liquor can be dissolved, and the rest 70% of the mother liquor can be sold out or treated by other methods.

In the process of recovering the secondary mother liquor to prepare low-content threonine or threonine-containing feed, the secondary mother liquor is viscous and easy to absorb moisture, so that the quality of finished products is directly influenced.

Disclosure of Invention

In order to solve the technical problems, the invention aims to provide a preparation method of low-content threonine and a special anti-caking agent thereof, on one hand, the threonine pottery clear liquid is directly concentrated and recovered, so that the problems of low threonine yield, high cost and difficult secondary mother liquor treatment in the prior art are solved, and the market demand for low-content threonine is met; on the other hand, the caking risk of the product is reduced by adding the anti-caking agent in the preparation process.

The anti-caking agent provided by the invention is composed of any two or more than two of magnesium sulfate, calcium chloride, sodium sulfate, sodium chloride, sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, calcium carbonate, calcium dihydrogen phosphate, calcium lactate, magnesium oxide, magnesium chloride, ferrous sulfate, ferrous chloride, ferric chloride, ferrous carbonate, zinc sulfate, zinc chloride, zinc acetate, manganese chloride, manganese sulfate, manganese carbonate, manganese hydrogen phosphate, manganese chloride, potassium iodide, sodium iodide and calcium iodate.

The anti-caking agent can solve the problems of caking, moisture absorption and the like caused by residual protein and sugar in threonine fermentation liquor; and these supplements can also provide nutrition to the animal.

According to an embodiment of the invention, the anti-caking agent consists of any two or three of the above components.

According to an embodiment of the invention, the calcium carbonate is light calcium carbonate; the magnesium sulfate is light magnesium sulfate; the calcium hydrophosphate is light calcium hydrophosphate.

By way of example, the anti-caking agent is any one of the following A1-A7:

a1, the mass ratio is 1: 1 calcium carbonate and magnesium sulfate;

a2, the mass ratio is 1: 1 calcium carbonate and calcium hydrogen phosphate;

a3, the mass ratio is 1: 1 magnesium sulfate and zinc carbonate;

a4, the mass ratio is 1: 1 calcium hydrogen phosphate and manganese carbonate;

a5, the mass ratio is 1: 1: 1 calcium carbonate, magnesium sulfate and calcium lactate;

a6, the mass ratio is 1: 1: 1 calcium hydrogen phosphate, manganese carbonate and calcium carbonate;

a7, the mass ratio is 1: 1: 1 magnesium sulfate, calcium lactate and calcium hydrogen phosphate.

Preferably, the anti-caking agent comprises at least calcium carbonate.

The invention also provides the application of the anti-caking agent in preparing low-content threonine or preparing feed containing low-content threonine.

According to an embodiment of the invention, the low threonine content is prepared from a ceramic membrane supernatant obtained by filtering a threonine fermentation broth through a ceramic membrane.

The invention further provides a preparation method of the low-content threonine, which comprises the following steps:

(1) filtering the threonine fermentation liquor by using a ceramic membrane to obtain a ceramic membrane clear solution; evaporating and concentrating the clear liquid of the ceramic membrane to obtain a concentrated solution;

(2) adding the anti-caking agent to the concentrated solution to obtain mixed slurry;

(3) and drying the mixed slurry to obtain the low-content threonine.

In the above production method, step (1), the threonine fermentation broth is obtained by fermentation of an industrially commonly used L-threonine-producing strain and starting material.

In the ceramic membrane filtering step, the aperture of the ceramic membrane can be 50-100 nm, and specifically can be 50nm or 100 nm; the concentration ratio may be 10 to 12 times, specifically 12 times.

In the evaporation concentration step, the concentration multiple can be 5-6 times, specifically 5 times, 5.5 times, 6 times and 5.8 times; the mass percentage content of the concentrated discharged dry matter can be 55-60 percent, and can be 55 percent, 58 percent, 60 percent or 57 percent; the density of the concentrated discharge material can be 1.18-1.22 g/mL, and specifically can be 1.18g/mL, 1.20g/mL, 1.22g/mL or 1.21 g/mL; the settling solid-to-liquid ratio can be 88% -92%, specifically 88%, 91% or 92%.

By way of example, the conditions for concentration by evaporation under reduced pressure are as follows: the temperature is 60 ℃, and the vacuum degree is-0.085 MPa.

In the preparation method, in the step (2), the mass percentage of the anti-caking agent in the mixed slurry may be 10% to 15%, specifically 10%, 12%, 15%, 11% or 14%.

In the mixed slurry, the purity of the threonine can be 60-70%, and specifically can be 70.2%, 68%, 65.5%, 60.8%, 64.8%, 70.1% or 62.8%; the mass percentage of the water can be 35-45%, and specifically can be 45%, 40%, 38%, 35%, 44%, 40.5% or 42%.

In the above preparation method, step (3), the method may further comprise the following steps before the drying: mixing the mixed slurry with the low threonine content; the purity of threonine in the mixed material can be 60-70%, and specifically can be 70.2%, 68%, 65.5%, 60.8%, 64.8%, 70.1% or 62.8%; the mass percentage of the water can be 10-15%, and specifically can be 15%, 11%, 10%, 11%, 14%, 10.6% or 12%.

The invention further provides the low-content threonine prepared by the preparation method.

The mass percentage of the threonine in the low-content threonine can be 60-70%, and specifically can be 70%, 68%, 65%, 60%, 64.8%, 70.1% or 62.8%.

The invention further provides the application of the low-content threonine as a feed additive or in preparing feed.

The invention has the following beneficial effects:

according to the invention, the threonine pottery clear liquid is directly concentrated, so that the lost threonine is recovered, the energy consumption is reduced, the cost is saved, and the anti-caking agent is added to be mutually combined with the threonine crystal, so that the dispersibility and the fluidity of the product are improved, and the purpose of reducing the risk of product caking is achieved.

Drawings

FIG. 1 is a flow chart of the process for preparing low levels of threonine in accordance with the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention without the need for inventive faculty, fall within the scope of protection of the invention.

Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs.

At least one embodiment of the present invention provides an anti-caking agent comprising any two or more components selected from the group consisting of magnesium sulfate, calcium chloride, sodium sulfate, sodium chloride, sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, calcium carbonate, calcium dihydrogen phosphate, calcium lactate, magnesium oxide, magnesium chloride, ferrous sulfate, ferrous chloride, ferric chloride, ferrous carbonate, zinc sulfate, zinc chloride, zinc acetate, manganese chloride, manganese sulfate, manganese carbonate, manganese hydrogen phosphate, manganese chloride, potassium iodide, sodium iodide, and calcium iodate.

At least one embodiment of the present invention provides a method for preparing low threonine, including the steps of: (1) filtering the threonine fermentation liquor by using a ceramic membrane to obtain a ceramic membrane clear solution; evaporating and concentrating the clear liquid of the ceramic membrane to obtain a concentrated solution; (2) adding an anti-caking agent into the concentrated solution to obtain mixed slurry; (3) and drying the mixed slurry to obtain the low-content threonine.

The preparation of the anti-caking agent and low threonine according to the invention is illustrated by the following specific examples. The experimental procedures used in the following examples are all conventional procedures unless otherwise specified. Materials, reagents and the like used in the following examples are commercially available unless otherwise specified.

The threonine ceramic membrane clear solution in the following example was prepared by the following steps:

1) receiving fermentation liquor: the acid production is more than or equal to 120g/L, the dry matter is less than or equal to 150g/L, the purity is more than or equal to 80 percent, the bacterial concentration is less than or equal to 80g/L, the reducing sugar is less than or equal to 0.3 percent, and the operation flux, the maximum concentration multiple and the yield of the ceramic membrane are ensured.

2) Acidifying: heating the fermentation liquor to 60 ℃, killing and inactivating bacteria, and adjusting the pH value to 4.5-5.0 by concentrated sulfuric acid.

3) Membrane filtration sterilization: the aperture of the ceramic membrane is 50-100 nm, the operating pressure of the ceramic membrane is 0.3mpa, the operating temperature is 55-60 ℃, the pre-concentration multiple is 7-8 times, the water starts to permeate, the dialyzed water accounts for 20-25% of the volume of the fermentation liquor, and the final concentration multiple is 10-12 times, so that the obtained mixed clear liquid is the clear liquid of the threonine ceramic membrane.

The mass percentage of the concentrated discharged dry matter is the mass of the solid matter after drying/the mass of the concentrated solution before drying;

the settled solid-to-liquid ratio is the volume of solid/total volume of slurry.

Example 1 preparation of Low threonine

The low-content threonine is prepared according to the process flow diagram shown in figure 1, and the specific steps are as follows:

filtering the acidified threonine fermentation liquor by using a ceramic membrane according to the steps to obtain a ceramic membrane clear solution; the filtration conditions were as follows: the aperture of the ceramic membrane is 50nm, and the final concentration multiple is 12 times.

a. Preparation of threonine clear liquid concentrate

Carrying out reduced pressure evaporation concentration on the threonine ceramic membrane clear liquid by 5 times, wherein the concentration discharge dry matter is 55 percent, the concentration discharge density is 1.18g/ml, and the sedimentation solid-liquid ratio is 88 percent; the conditions for evaporation and concentration under reduced pressure were as follows: the temperature is 60 ℃, and the vacuum degree is-0.085 MPa; obtaining a concentrated solution;

b. premixing clear liquid concentrated solution and dispersing agent

Taking light calcium carbonate and magnesium sulfate according to a mass ratio of 1: 1 as an anti-caking agent to be added into the concentrated solution to obtain mixed slurry; the mass percentage of the anti-caking agent in the mixed slurry is 10%, the purity of the threonine in the mixed slurry is 70.2%, and the water content in the mixed slurry is 45%.

c. Mixing the slurry with the low-threonine content product at high speed

And c, mixing the slurry mixed in the step b with a low-content threonine finished product at a high speed, wherein the water content of the mixed material is 15%, and the purity of the threonine is 70.2%.

d. Drying

And c, drying the material in the step c, sieving the dried material, wherein the moisture content of the dried material is less than 0.5, and verifying the moisture absorption, accelerated agglomeration and fluidity test of the sieved material.

The mass percentage of the L-threonine in the low-threonine finished product prepared by the embodiment is 70%; theoretical acid consumption of threonine (theoretical acid consumption/finished product quality): 0.742.

example 2 preparation of Low threonine

Filtering the acidified threonine fermentation liquor by using a ceramic membrane according to the steps to obtain a ceramic membrane clear solution; the filtration conditions were as follows: the aperture of the ceramic membrane is 50nm, and the final concentration multiple is 12 times.

The low-content threonine is prepared according to the process flow diagram shown in figure 1, and the specific steps are as follows:

a. preparation of threonine concentrate

Carrying out reduced pressure evaporation concentration on the threonine ceramic membrane clear liquid by 5.5 times, wherein the concentration discharge dry matter is 58 percent, the concentration discharge density is 1.20g/ml, and the sedimentation solid-liquid ratio is 91 percent; the conditions for evaporation and concentration under reduced pressure were as follows: the temperature is 60 ℃, and the vacuum degree is-0.085 MPa; obtaining a concentrated solution;

b. premixing the concentrated solution and a dispersant

Taking light calcium carbonate and calcium hydrophosphate according to a mass ratio of 1: 1 as an anti-caking agent, and adding the mixture into the concentrated solution to obtain mixed slurry; the mass percentage of the anti-caking agent in the mixed slurry is 12%, the purity of the threonine in the mixed slurry is 68%, and the water content in the mixed slurry is 40%.

c. Mixing the slurry with the low-threonine content product at high speed

And c, mixing the slurry mixed in the step b with a low-content threonine finished product at a high speed, wherein the water content of the mixed material is 11%, and the purity of the threonine is 68%.

d. Drying

And c, drying the material in the step c, sieving the dried material, wherein the moisture content of the dried material is less than 0.5, and verifying the moisture absorption, accelerated agglomeration and fluidity test of the sieved material.

The mass percentage of the L-threonine in the low-threonine finished product prepared by the embodiment is 68%; theoretical acid consumption of threonine (theoretical acid consumption/finished product quality): 0.702.

example 3 preparation of Low threonine

The low-content threonine is prepared according to the process flow diagram shown in figure 1, and the specific steps are as follows:

filtering the acidified threonine fermentation liquor by using a ceramic membrane according to the steps to obtain a ceramic membrane clear solution; the filtration conditions were as follows: the aperture of the ceramic membrane is 50nm, and the final concentration multiple is 12 times.

a. Preparation of threonine concentrate

Carrying out reduced pressure evaporation concentration on the threonine ceramic membrane clear liquid by 6 times, wherein the concentration discharge dry matter is 60 percent, the concentration discharge density is 1.22g/ml, and the sedimentation solid-liquid ratio is 92 percent; the conditions for evaporation and concentration under reduced pressure were as follows: the temperature is 60 ℃, and the vacuum degree is-0.085 MPa; obtaining a concentrated solution;

b. premixing the concentrated solution and a dispersant

Taking light magnesium sulfate and zinc carbonate according to the weight ratio of 1: 1 as an anti-caking agent to be added into the concentrated solution to obtain mixed slurry; the mass percentage of the anti-caking agent in the mixed slurry is 15%, the purity of the threonine in the mixed slurry is 65.5%, and the water content in the mixed slurry is 40%.

c. Mixing the slurry with the low-threonine content product at high speed

And c, mixing the slurry mixed in the step b with a low-content threonine finished product at a high speed, wherein the water content of the mixed material is 10%, and the purity of the threonine is 65.5%.

d. Drying

And c, drying the material in the step c, sieving the dried material, wherein the moisture content of the dried material is less than 0.5, and verifying the moisture absorption, accelerated agglomeration and fluidity test of the sieved material.

The mass percentage of the L-threonine in the low-threonine finished product prepared by the embodiment is 65%; theoretical acid consumption of threonine (theoretical acid consumption/finished product quality): 0.683.

example 4 preparation of Low threonine

The low-content threonine is prepared according to the process flow diagram shown in figure 1, and the specific steps are as follows:

filtering the acidified threonine fermentation liquor by using a ceramic membrane according to the steps to obtain a ceramic membrane clear solution; the filtration conditions were as follows: the aperture of the ceramic membrane is 50nm, and the final concentration multiple is 12 times.

a. Preparation of threonine concentrate

Carrying out reduced pressure evaporation concentration on the threonine ceramic membrane clear liquid by 5.8 times, wherein the concentration discharge dry matter is 57 percent, the concentration discharge density is 1.21g/ml, and the sedimentation solid-liquid ratio is 91 percent; the conditions for evaporation and concentration under reduced pressure were as follows: the temperature is 60 ℃, and the vacuum degree is-0.085 MPa; to obtain a concentrated solution.

b. Premixing the concentrated solution and a dispersant

Taking light calcium hydrophosphate and manganese carbonate according to the weight ratio of 1: 1 as an anti-caking agent to be added into the concentrated solution to obtain mixed slurry; the mass percentage content of the anti-caking agent in the mixed slurry is 12 percent, the purity of threonine in the mixed slurry is 60.8 percent, and the water content in the mixed slurry is 38 percent.

c. Mixing the slurry with the low-threonine content product at high speed

And c, mixing the slurry mixed in the step b with a low-content threonine finished product at a high speed, wherein the water content of the mixed material is 11%, and the purity of the threonine is 60.8%.

d. Drying

And c, drying the material in the step c, sieving the dried material, wherein the moisture content of the dried material is less than 0.5, and verifying the moisture absorption, accelerated agglomeration and fluidity test of the sieved material.

The mass percentage of the L-threonine in the low-threonine finished product prepared by the embodiment is 60%; theoretical acid consumption of threonine (theoretical acid consumption/finished product quality): 0.634.

example 5 preparation of Low threonine

The low-content threonine is prepared according to the process flow diagram shown in figure 1, and the specific steps are as follows:

filtering the acidified threonine fermentation liquor by using a ceramic membrane according to the steps to obtain a ceramic membrane clear solution; the filtration conditions were as follows: the aperture of the ceramic membrane is 50nm, and the final concentration multiple is 12 times.

a. Preparation of threonine concentrate

Carrying out reduced pressure evaporation concentration on the threonine ceramic membrane clear liquid by 5 times, wherein the concentration discharge dry matter is 55 percent, the concentration discharge density is 1.18g/ml, and the sedimentation solid-liquid ratio is 88 percent; the conditions for evaporation and concentration under reduced pressure were as follows: the temperature is 60 ℃, and the vacuum degree is-0.085 MPa; obtaining a concentrated solution;

b. premixing the concentrated solution and a dispersant

Taking light calcium carbonate, magnesium sulfate and calcium lactate according to the weight ratio of 1: 1: 1 as an anti-caking agent to be added into the concentrated solution to obtain mixed slurry; the mass percentage of the anti-caking agent in the mixed slurry is 15%, the purity of threonine in the mixed slurry is 64.8%, and the water content in the mixed slurry is 44%.

c. Mixing the slurry with the low-threonine content product at high speed

And c, mixing the slurry mixed in the step b with a low-content threonine finished product at a high speed, wherein the water content of the mixed material is 14%, and the purity of the threonine is 64.8%.

d. Drying

And c, drying the material in the step c, sieving the dried material, wherein the moisture content of the dried material is less than 0.5, and verifying the moisture absorption, accelerated agglomeration and fluidity test of the sieved material.

The mass percentage of the L-threonine in the low-threonine finished product prepared by the embodiment is 64.8%; theoretical acid consumption of threonine (theoretical acid consumption/finished product quality): 0.673.

example 6 preparation of Low threonine

The low-content threonine is prepared according to the process flow diagram shown in figure 1, and the specific steps are as follows:

filtering the acidified threonine fermentation liquor by using a ceramic membrane according to the steps to obtain a ceramic membrane clear solution; the filtration conditions were as follows: the aperture of the ceramic membrane is 50nm, and the final concentration multiple is 12 times.

a. Preparation of threonine concentrate

Carrying out reduced pressure evaporation concentration on the threonine ceramic membrane clear liquid by 6 times, wherein the concentration discharge dry matter is 60 percent, the concentration discharge density is 1.22g/ml, and the sedimentation solid-liquid ratio is 92 percent; the conditions for evaporation and concentration under reduced pressure were as follows: the temperature is 60 ℃, and the vacuum degree is-0.085 MPa; obtaining a concentrated solution;

b. premixing the concentrated solution and a dispersant

Calcium hydrogen phosphate, manganese carbonate and light calcium carbonate are taken according to the proportion of 1: 1: 1 as an anti-caking agent to be added into the concentrated solution to obtain mixed slurry; the mass percentage of the anti-caking agent in the mixed slurry is 11%, the purity of threonine in the mixed slurry is 70.1%, and the water content in the mixed slurry is 40.5%.

c. Mixing the slurry with the low-threonine content product at high speed

And c, mixing the slurry mixed in the step b with a low-content threonine finished product at a high speed, wherein the water content of the mixed material is 10.6%, and the purity of the threonine is 70.1%.

d. Drying

And c, drying the material in the step c, sieving the dried material, wherein the moisture content of the dried material is less than 0.5, and verifying the moisture absorption, accelerated agglomeration and fluidity test of the sieved material.

The mass percentage of the L-threonine in the low-threonine finished product prepared by the embodiment is 70.1%; theoretical acid consumption of threonine (theoretical acid consumption/finished product quality): 0.741.

example 7 preparation of Low threonine

The low-content threonine is prepared according to the process flow diagram shown in figure 1, and the specific steps are as follows:

filtering the acidified threonine fermentation liquor by using a ceramic membrane according to the steps to obtain a ceramic membrane clear solution; the filtration conditions were as follows: the aperture of the ceramic membrane is 50nm, and the final concentration multiple is 12 times.

a. Preparation of threonine concentrate

Carrying out reduced pressure evaporation concentration on the threonine ceramic membrane clear liquid by 5.5 times, wherein the concentration discharge dry matter is 58 percent, the concentration discharge density is 1.20g/ml, and the sedimentation solid-liquid ratio is 90 percent; the conditions for evaporation and concentration under reduced pressure were as follows: the temperature is 60 ℃, and the vacuum degree is-0.085 MPa; to obtain a concentrated solution.

b. Premixing the concentrated solution and a dispersant

Taking magnesium sulfate, calcium lactate and calcium hydrophosphate according to a proportion of 1: 1: 1 as an anti-caking agent to be added into the concentrated solution to obtain mixed slurry; the mass percentage of the anti-caking agent in the mixed slurry was 14%, the purity of threonine in the mixed slurry was 62.8%, and the moisture in the mixed slurry was 42%.

c. Mixing the slurry with the low-threonine content product at high speed

And c, mixing the slurry mixed in the step b with the low threonine-containing finished product at a high speed, wherein the water content in the mixed material is 12%, and the purity of threonine is 62.8%.

d. Drying

And c, drying the material in the step c, sieving the dried material, wherein the moisture content of the dried material is less than 0.5, and verifying the moisture absorption, accelerated agglomeration and fluidity test of the sieved material.

The mass percentage of the L-threonine in the low-threonine finished product prepared by the embodiment is 62.8%; theoretical acid consumption of threonine (theoretical acid consumption/finished product quality): 0.653%.

Comparative example 1 preparation of Low threonine content

The low-content threonine is prepared according to the process flow diagram shown in figure 1, and the specific steps are as follows:

filtering the acidified threonine fermentation liquor by using a ceramic membrane according to the steps to obtain a ceramic membrane clear solution; the filtration conditions were as follows: the aperture of the ceramic membrane is 50nm, and the final concentration multiple is 12 times.

a. Preparation of threonine concentrate

Carrying out reduced pressure evaporation concentration on the threonine ceramic membrane clear liquid by 6 times, wherein the concentration discharge dry matter is 60 percent, the concentration discharge density is 1.22g/ml, and the sedimentation solid-liquid ratio is 92 percent; the conditions for evaporation and concentration under reduced pressure were as follows: the temperature is 60 ℃, and the vacuum degree is-0.085 MPa; obtaining a concentrated solution;

b. premixing the concentrated solution and a dispersant

Adding light calcium carbonate into the concentrated solution to obtain mixed slurry; the mass percentage content of calcium carbonate in the mixed slurry was 10%, the purity of threonine in the mixed slurry was 70.2%, and the moisture in the mixed slurry was 41%.

c. Mixing the slurry with the low-threonine content product at high speed

And c, mixing the slurry mixed in the step b with a low-content threonine finished product at a high speed, wherein the water content of the mixed material is 10.7%, and the purity of the threonine is 70.2%.

d. Drying

And c, drying the material in the step c, sieving the dried material, wherein the moisture content of the dried material is less than 0.5, and verifying the moisture absorption, accelerated agglomeration and fluidity test of the sieved material.

The mass percentage of the L-threonine in the low-threonine finished product prepared by the embodiment is 70.2%; theoretical acid consumption of threonine (theoretical acid consumption/finished product quality): 0.735%.

Comparative example 2

The low threonine content was prepared as follows:

filtering the acidified threonine fermentation liquor by using a ceramic membrane according to the steps to obtain a ceramic membrane clear solution; the filtration conditions were as follows: the aperture of the ceramic membrane is 50nm, and the final concentration multiple is 12 times.

a. Preparation of threonine concentrate

And (3) carrying out reduced pressure evaporation concentration on the threonine ceramic membrane clear liquid by 6 times, wherein the concentration discharge dry matter is 60%, the concentration discharge density is 1.22g/ml, and the sedimentation solid-to-liquid ratio is 92%. The conditions for evaporation and concentration under reduced pressure were as follows: the temperature is 60 ℃, and the vacuum degree is-0.085 MPa.

b. Premixing the concentrated solution and a dispersant

And (c) directly entering the step (c) without adding any dispersing agent into the concentrated solution.

c. Mixing the slurry with the low-threonine content product at high speed

And c, mixing the mixed slurry in the step b with a low-threonine-content finished product at a high speed, wherein the water content of the mixed material is 10%, and the purity of threonine is 79.7%.

d. Drying

And c, drying the material in the step c, sieving the dried material, wherein the moisture content of the dried material is less than 0.5, and verifying the moisture absorption, accelerated agglomeration and fluidity test of the sieved material.

The test results are shown in the following table:

TABLE 1 results of low threonine related assays

From the test results of the above examples, it can be seen that the combination of the different dispersants (anti-caking agents) of examples 1, 2, 5 and 6 can significantly improve the moisture absorption rate of the product, so that the moisture absorption rate is controlled within 4%, the caking rate is controlled within 7%, the angle of repose is controlled within 40 °, and the combination of the above components all contain calcium carbonate. Compared with a product without a dispersant (anti-caking agent), the moisture absorption rate after the addition is reduced by more than 40%, the caking rate is reduced by more than 80%, and the fluidity is improved by more than 25%. Therefore, the anti-caking agent and the method provided by the invention can obviously prevent caking, can reduce the production cost and are suitable for industrial use.