A method for extracting tyrosine from yeast extract

Abstract

The present invention relates to a method for extracting tyrosine from yeast extract, comprising the following steps: (1) adjusting the pH of a crude amino acid solution from yeast extract to 5.6-5.7, crystallizing and separating to obtain crude tyrosine; (2) preparing the crude tyrosine obtained in step (1) into a dispersion, adjusting the pH to 11.5-12.5 with an alkali for dissolution, decolorizing to obtain a decolorized solution, adjusting the pH of the decolorized solution to 5.6-5.7, crystallizing and separating to obtain a refined product, repeating the above operation once or twice to obtain tyrosine, wherein the alkali is potassium hydroxide and / or sodium hydroxide. The present invention uses a crude amino acid solution from yeast extract as a raw material, and the purity of the obtained tyrosine is above 90wt%, and the tyrosine yield is above 70%; the method of the present invention has a simple process and a short production process, and the purity of tyrosine can be controlled according to the downstream demand of tyrosine, and has good industrial value.

Description

Technical Field

[0001] The invention relates to the technical field of biochemical engineering, and in particular to a method for extracting tyrosine from yeast extract. Background Art

[0002] The chemical name of tyrosine (Tyr) is 2-amino-3-p-hydroxyphenylpropionic acid. It is an aromatic polar α-amino acid containing a phenolic hydroxyl group. Tyrosine is a conditionally essential amino acid and a ketogenic and glucogenic amino acid for the human body. Tyrosine can be used as a nutritional supplement in the food industry, and can also be used as a raw material in the fields of medicine and chemical industry.

[0003] At present, the industry usually uses protein hydrolysis, enzymatic method and biological fermentation method to produce tyrosine, but all of them have some disadvantages, such as limited raw material sources, poor stability, cumbersome processes, and complex product ingredients. The complexity of microorganisms in the microbial fermentation method and their sensitivity to the environment make the production of tyrosine technically difficult, and further purification is required, which is costly.

[0004] Chinese patent CN105969819B discloses a method for producing L-tyrosine by enzymatic method. The method uses fermentation to produce pyruvic acid, adds β-tyrosinase, phenol and NH4Cl in the late stage of pyruvic acid fermentation, converts the generated pyruvic acid into L-tyrosine, and obtains a fermentation broth containing L-tyrosine; takes the fermentation broth containing L-tyrosine, heats it to 70℃-90℃, and adds acid until the L-tyrosine crystals are completely dissolved; adds activated carbon for decolorization, and first uses a ceramic membrane to filter after decolorization to remove the bacteria, protein and activated carbon, and the resulting clear liquid is filtered for a second time through an acid-resistant liquid security filter; the clear liquid after the second filtration adjusts the pH to 5.0-7.0, cools down, crystallizes, and centrifuges to obtain L-tyrosine. The invention produces tyrosine by enzymatic method, and the process is complicated; the purification process uses acid to dissolve tyrosine crystals, requiring the equipment to be acid-resistant, and uses ceramic membrane filtration after decolorization, resulting in a high purification cost. Summary of the invention

[0005] Yeast extract is rich in a variety of amino acids and peptides. During the evaporation and concentration stage of the yeast extract production process, as the water content decreases, amino acids and other components are easily precipitated. At the same time, due to the acidic to neutral pH value, hydrophobic amino acids are also easily precipitated, especially tyrosine. The substances precipitated during the evaporation and concentration stage are separated from the yeast extract solution by filtration to obtain a crude amino acid solution. How to separate, collect and extract tyrosine from the above crude amino acid solution to achieve secondary utilization of tyrosine, turn waste into treasure, and improve the level of resource utilization has become a practical need for yeast extract production companies.

[0006] The technical problem to be solved by the present invention is as follows: The present invention provides a method for extracting tyrosine from yeast extract, which simplifies the production process and improves the purity and yield of tyrosine.

[0007] In view of the shortcomings of the prior art, one of the objectives of the present invention is to provide a method for extracting tyrosine from yeast extract.

[0008] Specifically, the present invention provides the following technical solutions:

[0009] In one aspect, the present invention provides a method for extracting tyrosine from a yeast extract, comprising the following steps:

[0010] (1) adjusting the pH of a crude amino acid solution from yeast extract to 5.6-5.7, and crystallizing and separating to obtain crude tyrosine;

[0011] (2) The crude tyrosine obtained in step (1) is prepared into a dispersion, and the pH value is adjusted to 11.5-12.5 with an alkali for dissolution, and decolorization is performed to obtain a decolorized solution, and the pH value of the decolorized solution is adjusted to 5.6-5.7, and crystallization and separation are performed to obtain a refined product, and the above operation is repeated once or twice to obtain tyrosine, wherein the alkali is potassium hydroxide and / or sodium hydroxide.

[0012] Preferably, in step (2), the pH of the dispersion is adjusted to 12.1-12.5 using alkali.

[0013] Preferably, the crystallization in step (1) is carried out at 4-10°C, preferably 6-10°C.

[0014] Preferably, the mass concentration of the dispersion in step (2) is 2-15%.

[0015] Preferably, the decolorization in step (2) uses activated carbon and / or activated clay, preferably activated carbon; preferably, the amount of activated carbon added is 1-2% based on the weight of the crude tyrosine.

[0016] Preferably, the decolorization temperature in step (2) is 20-50°C, preferably 45-50°C; preferably, the decolorization time is 30-60min, preferably 45-60min.

[0017] Preferably, the acid used for pH adjustment includes one or more of hydrochloric acid, phosphoric acid or citric acid.

[0018] Preferably, the separation is centrifugal separation or plate and frame filtration.

[0019] Preferably, the extraction method further comprises the step of drying the tyrosine.

[0020] Preferably, the drying is microwave drying or vacuum drying.

[0021] On the other hand, the present invention also provides tyrosine prepared by the above method, wherein the purity of the tyrosine is ≥90wt%, preferably ≥95wt%, and more preferably ≥98wt%.

[0022] Beneficial effects of the present invention:

[0023] (1) The method of the present invention firstly adopts isoelectric point crystallization to prepare crude tyrosine, and the concentration of the crude tyrosine is 60-90wt%; then, sodium hydroxide or potassium hydroxide is used to adjust the pH to 11.5-12.5 to dissolve the crude tyrosine, and then decolorize, crystallize and recrystallize to finally obtain tyrosine, and the tyrosine yield is ≥70% and the purity is ≥90wt%; further, a specific pH, a specific decolorization temperature and a decolorization time are adopted, and the purity of tyrosine can reach above 95wt% or even above 98wt% under the premise of ensuring the yield.

[0024] (2) The method of the present invention uses a crude amino acid solution from yeast extract as a raw material, and obtains tyrosine by separation means such as decolorization, crystallization and recrystallization. The process is simple, the production process is short, the yield of the extracted product is high, and the purity of tyrosine is high. The purity of tyrosine can be controlled according to the downstream demand of tyrosine, and has good industrial value. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and technical effect of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention is described clearly and completely. The embodiments described below are part of the embodiments of the present invention, not all of them. In combination with the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In order to separate and purify tyrosine from a crude amino acid solution derived from a yeast extract, the present invention provides a method for extracting tyrosine from a yeast extract.

[0027] In one embodiment of the present invention, the present invention provides a method for extracting tyrosine from yeast extract, comprising the following steps:

[0028] (1) adjusting the pH of the crude amino acid solution to 5.6-5.7, crystallizing and separating to obtain crude tyrosine;

[0029] (2) The crude tyrosine obtained is prepared into a dispersion, and the pH value is adjusted to 11.5-12.5 with an alkali for dissolution, and decolorization is performed to obtain a decolorized solution, and the pH value of the decolorized solution is adjusted to 5.6-5.7, and crystallization and separation are performed to obtain a refined product, and the above operation is repeated once or twice to obtain tyrosine, wherein the alkali is potassium hydroxide and / or sodium hydroxide.

[0030] According to the present invention, under alkaline conditions, tyrosine and other protein substances are dissolved.

[0031] In the above method, the crystallization in step (1) is carried out at 4-10° C., preferably 6-10° C. The purity of crude tyrosine can be improved by using the freezing isoelectric point crystallization method, and the purity of tyrosine is 60-90%.

[0032] In the above method, the mass concentration of the dispersion in step (2) is 2-15%.

[0033] In the above method, in step (2), the pH of the dispersion is adjusted to 12.1-12.5 using alkali.

[0034] In the above method, the decolorization in step (2) is carried out by adsorption decolorization using activated carbon and / or activated clay, preferably activated carbon; preferably, the amount of activated carbon added is 1-2% based on the weight of the crude tyrosine.

[0035] In the above method, the decolorization temperature in step (2) is 20-50°C, preferably 45-50°C; preferably, the decolorization time is 30-60min, preferably 45-60min. Too high a decolorization temperature or too long a decolorization time has little effect on the purity of tyrosine, but will lead to a decrease in the total yield.

[0036] In the above method, the acid used for pH adjustment includes one or more of hydrochloric acid, phosphoric acid, or citric acid.

[0037] In a preferred embodiment of the present invention, the method for extracting tyrosine from yeast extract comprises the following steps:

[0038] (1) The crude amino acid solution is placed at 4-10°C, the pH is adjusted to 5.6-5.7, and allowed to stand for 2-4 hours to allow tyrosine and other hydrophobic amino acids to crystallize and precipitate, and then separated and filtered through a separator or a plate and frame filter press. The separated heavy phase or the plate and frame retentate is the aqueous crude tyrosine.

[0039] (2) adding water to adjust the concentration of crude tyrosine to 2%-15%, adjusting the pH to 11.5-12.5 with sodium hydroxide or potassium hydroxide solution, adding 1-2% activated carbon based on the weight of crude tyrosine at 20-50° C., and decolorizing for 30-60 minutes; after decolorization, performing plate and frame filtration to remove the activated carbon and collecting the decolorized liquid.

[0040] (3) Acid is added to the decolorizing solution to adjust the pH to 5.6-5.7, and the solution is allowed to stand for 1-2 hours to allow tyrosine to crystallize. After the tyrosine crystallizes, it is subjected to plate and frame filter pressing or separation filtration by a separator, and the separated heavy phase or plate and frame retentate is collected.

[0041] (4) Repeat steps (2) and (3) once or twice, and subject the obtained hydrous tyrosine crystals to microwave drying or vacuum drying to obtain tyrosine.

[0042] The present invention also provides tyrosine prepared by the above method, wherein the purity of the tyrosine is ≥90wt%, preferably ≥95wt%, and more preferably ≥98wt%.

[0043] The beneficial effects of the method for extracting tyrosine from a crude amino acid solution from yeast extract of the present invention will be further described below by means of specific examples. However, the technical scope of the present invention is not limited to these examples. It should be noted that, unless otherwise specified, all percentages, parts, and ratios used in the present invention are based on mass.

[0044] The crude amino acid product in the embodiment of the present invention is a substance precipitated during the evaporation and concentration stage when yeast extract is produced using brewer's yeast as a raw material, and is obtained by filtration and separation. When used, the crude amino acid product is prepared into a dispersion of different concentrations using water.

[0045] The purity of crude tyrosine and refined tyrosine can be obtained by measuring the tyrosine content. The test method for the tyrosine content is determined by the method in "GB 5009.124-2016 National Food Safety Standard Determination of Amino Acids in Food".

[0046] Example 1

[0047] A method for extracting tyrosine from yeast extract is carried out according to the following steps:

[0048] 1) Preparation of crude tyrosine: 100 kg of crude amino acid solution (tyrosine concentration of 0.8%) was taken, placed at 5° C., adjusted to pH 5.62 with hydrochloric acid, and allowed to stand for 2 hours to allow tyrosine and some hydrophobic amino acids to crystallize and precipitate. The solution was then centrifuged at 5000 r / min for 10 minutes, and the heavy phase was collected to obtain 935 g of crude tyrosine. The purity of the crude tyrosine is shown in Table 1.

[0049] 2) Refining of tyrosine: 935 g of the crude tyrosine obtained in step 1) was prepared into a 2% mass concentration dispersion, the pH was adjusted to 11.7 with sodium hydroxide solution, and the solution was stirred and dissolved until clear, and then 1% activated carbon (based on the weight of the crude tyrosine) was added, and decolorization was performed at 30° C. for 30 minutes. After the decolorization was completed, the activated carbon was removed by plate and frame filtration, and the decolorized solution was collected; hydrochloric acid was added to the decolorized solution to adjust the pH to 5.61, and the solution was allowed to stand for 1 hour to allow tyrosine to crystallize, and filtered using a plate and frame filter to obtain a primary refined product;

[0050] (3) The primary refined product was subjected to secondary purification according to the purification method of step (2) to obtain 654 g of refined tyrosine. The purity and total yield of the refined tyrosine are shown in Table 1.

[0051] Example 2

[0052] A method for extracting tyrosine from yeast extract is carried out according to the following steps:

[0053] 1) Preparation of crude tyrosine: 100 kg of crude amino acid dispersion (tyrosine concentration of 0.9%) was taken, placed at 6° C., adjusted to pH 5.65 with hydrochloric acid, and allowed to stand for 2 hours to allow tyrosine and some hydrophobic amino acids to crystallize and precipitate, then centrifuged at 5000 r / min for 10 minutes, and the heavy phase was collected to obtain 1096 g of crude tyrosine. The purity of the crude tyrosine is shown in Table 1;

[0054] 2) Refining of tyrosine: 1096 g of the crude tyrosine obtained in step 1) is prepared into a 5% mass concentration dispersion, the pH is adjusted to 12.1 with sodium hydroxide solution, stirred and dissolved until clear, and then 1% activated carbon (based on the weight of the crude tyrosine) is added, decolorized at 35° C. for 30 minutes, and after the decolorization is completed, the activated carbon is removed by plate and frame filtration, and the decolorized liquid is collected; hydrochloric acid is added to the decolorized liquid to adjust the pH to 5.64, and the tyrosine is allowed to stand for 1 hour to crystallize, and filtered using a plate and frame filter to obtain a primary refined product;

[0055] 3) The first refined product was purified for a second time according to the purification method of step (2) to obtain 721 g of refined tyrosine. The purity and total yield of the refined tyrosine are shown in Table 1.

[0056] Example 3

[0057] A method for extracting tyrosine from yeast extract is carried out according to the following steps:

[0058] 1) Preparation of crude tyrosine: 100 kg of yeast extract concentrated by-product dispersion (tyrosine concentration of 0.85%) was taken, placed at 7° C., adjusted to pH 5.67 with hydrochloric acid, and allowed to stand for 3 hours to allow tyrosine and some hydrophobic amino acids to crystallize and precipitate, then centrifuged at 5000 r / min for 10 minutes, and the heavy phase was collected to obtain 936 g of crude tyrosine. The purity of the crude tyrosine is shown in Table 1;

[0059] 2) Refining of tyrosine: 936 g of the crude tyrosine obtained in step 1) is prepared into a dispersion liquid with a mass concentration of 8%, the pH is adjusted to 11.8 with a sodium hydroxide solution, and the solution is stirred and dissolved until it is clear, and then 1.5% activated carbon (based on the weight of the crude tyrosine) is added, and the solution is decolorized at 40° C. for 30 minutes. After the decolorization is completed, the activated carbon is removed by plate and frame filtration, and the decolorized solution is collected; hydrochloric acid is added to the decolorized solution to adjust the pH to 5.65, and the solution is allowed to stand for 1.5 hours to allow tyrosine to crystallize, and filtered using a plate and frame filter to obtain a primary refined product;

[0060] (3) The first refined product was purified for a second time according to the purification method of step (2) to obtain 698 g of refined tyrosine. The purity and total yield of the refined tyrosine are shown in Table 1.

[0061] Example 4

[0062] A method for extracting tyrosine from yeast extract is carried out according to the following steps:

[0063] 1) Preparation of crude tyrosine: 100 kg of yeast extract concentrated byproduct dispersion (tyrosine concentration of 1.1%) was taken, placed at 8° C., adjusted to pH 5.69 with hydrochloric acid, and allowed to stand for 3 hours to allow tyrosine and some hydrophobic amino acids to crystallize and precipitate, then centrifuged at 5000 r / min for 10 minutes, and the heavy phase was collected to obtain 1215 g of crude tyrosine. The purity of the crude tyrosine is shown in Table 1;

[0064] 2) Refining of tyrosine: 1215 g of the crude tyrosine obtained in step 1) is prepared into a 10% mass concentration dispersion, the pH is adjusted to 12.2 with sodium hydroxide solution, stirred and dissolved until clear, and then 1.5% activated carbon (based on the weight of the crude tyrosine) is added, decolorized at 40° C. for 60 minutes, and after the decolorization is completed, the activated carbon is removed by plate and frame filtration, and the decolorized liquid is collected; hydrochloric acid is added to the decolorized liquid to adjust the pH to 5.67, and the tyrosine is allowed to stand for 1.5 hours to crystallize, and filtered using a plate and frame filter to obtain a primary refined product;

[0065] (3) The first refined product was purified for a second time according to the purification method of step (2) to obtain 879 g of purified tyrosine. The purity and total yield of the purified tyrosine are shown in Table 1.

[0066] Example 5

[0067] A method for extracting tyrosine from yeast extract is carried out according to the following steps:

[0068] 1) Preparation of crude tyrosine: 100 kg of yeast extract concentrated by-product dispersion (tyrosine concentration of 0.98%) was taken, placed at 9° C., adjusted to pH 5.66 with hydrochloric acid, and allowed to stand for 4 hours to allow tyrosine and some hydrophobic amino acids to crystallize and precipitate, then centrifuged at 5000 r / min for 10 minutes, and the heavy phase was collected to obtain 1098 g of crude tyrosine. The purity of the crude tyrosine is shown in Table 1;

[0069] 2) Refining of tyrosine: 1098 g of the crude tyrosine obtained in step 1) is prepared into a 12% mass concentration dispersion, the pH is adjusted to 12.3 with potassium hydroxide solution, stirred and dissolved until clear, and then 2% activated carbon (based on the weight of the crude tyrosine) is added, decolorized at 45° C. for 60 minutes, and after the decolorization is completed, the activated carbon is removed by plate and frame filtration, and the decolorized liquid is collected; hydrochloric acid is added to the decolorized liquid to adjust the pH to 5.69, and the tyrosine is allowed to stand for 2 hours to crystallize, and filtered using a plate and frame filter to obtain a primary refined product;

[0070] (3) The first refined product was purified for a second time according to the purification method of step (2) to obtain 802 g of purified tyrosine. The purity and total yield of the purified tyrosine are shown in Table 1.

[0071] Example 6

[0072] A method for extracting tyrosine from yeast extract is carried out according to the following steps:

[0073] 1) Preparation of crude tyrosine: 100 kg of yeast extract concentrated by-product dispersion (tyrosine concentration of 1.06%) was taken, placed at 10° C., adjusted to pH 5.7 with hydrochloric acid, and allowed to stand for 4 hours to allow tyrosine and some hydrophobic amino acids to crystallize and precipitate, then centrifuged at 5000 r / min for 10 minutes, and the heavy phase was collected to obtain 1048 g of crude tyrosine. The purity of the crude tyrosine is shown in Table 1;

[0074] 2) Refining of tyrosine: 1048 g of the crude tyrosine obtained in step 1) is prepared into a 15% mass concentration dispersion, the pH is adjusted to 12.4 with sodium hydroxide solution, stirred and dissolved until clear, and then 2% activated carbon (based on the weight of the crude tyrosine) is added, decolorized at 50° C. for 60 minutes, and after the decolorization is completed, the activated carbon is removed by plate and frame filtration, and the decolorized liquid is collected; hydrochloric acid is added to the decolorized liquid to adjust the pH to 5.69, and the tyrosine is allowed to stand for 2 hours to crystallize, and filtered using a plate and frame filter to obtain a primary refined product;

[0075] (3) The first refined product was purified for a second time according to the purification method of step (2) to obtain 863 g of purified tyrosine. The purity and total yield of the purified tyrosine are shown in Table 1.

[0076] Table 1 Test results of Examples 1-6

[0077] serial number Total yield of tyrosine, % Purity of crude tyrosine, wt% Tyrosine purity, wt% Example 1 76.4 73.6 93.5 Example 2 76.6 69.8 95.6 Example 3 80.3 78.3 97.8 Example 4 74.9 77.8 93.7 Example 5 80.9 79.8 98.8 Example 6 77.8 85.6 95.6

[0078] As can be seen from Table 1, firstly, the isoelectric point crystallization method is used to obtain a crude tyrosine product with a purity of 69.8-85.6wt% from the crude amino acid solution, and then the pH is adjusted to 11.5-12.5 to dissolve the crude tyrosine product. After decolorization, crystallization and recrystallization, a tyrosine product with a purity of 93.5-98.8wt% can be obtained, and the total yield of tyrosine is 74.9-80.9%.

[0079] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A method for extracting tyrosine from crude amino acids from yeast extract, characterized in that: The steps include: (1) The pH of the crude amino acid solution from yeast extract is adjusted to 5.6-5.7, and crude tyrosine is obtained by crystallization and separation; (2) preparing the crude tyrosine obtained in step (1) into a dispersion, adjusting the pH to 11.5-12.5 with alkali for dissolution, decolorizing to obtain a decolorized solution, adjusting the pH of the decolorized solution to 5.6-5.7, crystallizing, and separating to obtain a refined product; (3) Repeat step (2) once or twice to obtain tyrosine, wherein the base is potassium hydroxide and / or sodium hydroxide; Wherein, the mass concentration of the dispersion in step (2) is 2-15%; The decolorization in step (2) uses activated carbon, and the amount of activated carbon added is 1-2% based on the weight of the crude tyrosine; The crude amino acid product is obtained by filtering and separating substances precipitated during the evaporation and concentration stage when yeast extract is produced using brewer's yeast as a raw material.

2. The method according to claim 1, characterized in that In step (2), the pH of the dispersion is adjusted to 12.1-12.5 using alkali.

3. The method according to claim 1, characterized in that The crystallization in step (1) is carried out at 4-10°C.

4. The method according to claim 3, characterized in that: The crystallization in step (1) is carried out at 6-10°C.

5. The method according to claim 1, characterized in that The decolorization temperature in step (2) is 20-50°C.

6. The method according to claim 5, characterized in that The decolorization temperature is 45-50°C.

7. The method according to claim 5, characterized in that The decolorization time is 30-60min.

8. The method according to claim 7, characterized in that The decolorization time is 45-60min.

9. The method according to any one of claims 1 to 8, characterized in that: The acid used for pH adjustment is selected from one or more of hydrochloric acid, phosphoric acid or citric acid.

10. The method according to any one of claims 1 to 8, characterized in that: The separation is centrifugal separation or plate and frame filtration.

11. The method according to claim 9, characterized in that The separation is centrifugal separation or plate and frame filtration.

12. The method according to any one of claims 1 to 8, characterized in that: The extraction method further comprises the step of drying the tyrosine.

13. The method according to claim 12, characterized in that The drying is microwave drying or vacuum drying.

14. The method according to claim 9, characterized in that The extraction method further comprises the step of drying the tyrosine.

15. The method according to claim 10, characterized in that The extraction method further comprises the step of drying the tyrosine.