Method for extracting theanine by continuous ion exchange technology

Abstract

The invention belongs to the technical field of production and extraction of L-theanine, and discloses a method for efficiently extracting theanine by a continuous ion exchange technology, which mainly comprises the following steps: 1) pretreatment of fermentation liquor; 2) decolorizing with activated carbon; 3) cation exchange resin adsorption; the invention discloses a method for extracting L-theanine from fermentation broth, which comprises the following steps: 1) preparing L-theanine, 2) preparing L-theanine, 3) preparing L-theanine, 4) concentrating and deaminizing, 5) eluting with anion exchange resin, 6) concentrating and crystallizing, and 7) centrifugally drying to obtain the finished L-theanine. L-theanine is extracted from the fermentation broth by the method, mycoprotein and other impurities and pigments with strong binding force can be effectively removed, the product purity and the extraction yield are high, the production cost is reduced, and the method is suitable for large-scale industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of L-theanine production, and specifically relates to a method for extracting theanine using a continuous ion exchange technology. Background Art

[0002] Theanine (L-Theanine), also known as glutamic acid γ-ethylamide, is a unique free amino acid in tea, accounting for more than 50% of the total free amino acids in tea. As the main component of the sweet taste of tea, theanine determines the quality of tea to a certain extent. Theanine has many beneficial effects on human health, including promoting the learning and memory function of the brain, preventing cardiovascular diseases, inhibiting fat accumulation, and acting as a tranquilizer. In the food industry, it can be used as a quality improver for tea beverages, an additive to improve food flavor, and an additive for functional foods. It can inhibit bitterness and spiciness in food and reduce astringency. Therefore, it has been widely used in the pharmaceutical and food industries and has become a highly anticipated compound in the research of tea health ingredients.

[0003] At present, theanine is mainly extracted from tea leaves or tea waste, which generally has problems such as cumbersome extraction steps, high use of organic solvents, low extraction yield and product purity, and cannot meet the needs of large-scale production. The microbial fermentation method uses cheap carbon and nitrogen sources as substrates, and synthesizes theanine directly through glucose fermentation through microbial metabolism and its own ability to produce theanine. The fermentation method has relatively low raw material source costs, mild fermentation reaction conditions, relatively stable production process, high controllability, and is easy to scale up production, making it the main method for producing theanine at present.

[0004] However, the current fermentation technology for theanine production in my country is not mature, and the industrial production of L-theanine is often restricted by production costs, and the cost of downstream projects such as separation and extraction accounts for a considerable proportion of the production cost. Therefore, new technological breakthroughs and production processes are urgently needed to improve the conversion rate of theanine while reducing production costs. Summary of the invention

[0005] In order to solve the above problems and overcome the shortcomings of the prior art, the present invention provides a method for efficiently extracting theanine using continuous ion exchange technology. The process is easy to operate, can realize waste utilization, and rationally configures strains, greatly improving fermentation efficiency.

[0006] The purpose of the present invention is achieved through the following technical solutions.

[0007] A method for efficiently extracting theanine using continuous ion exchange technology comprises the following steps: Step 1) pretreatment of the fermentation broth: filtering the L-theanine fermentation broth through a ceramic membrane to remove macromolecular proteins, collecting the filtrate, adding hydrochloric acid to adjust the pH to 4-5, and collecting the ceramic membrane clear liquid; Step 2) activated carbon decolorization: add 0.5-2% (w / v) activated carbon to the ceramic membrane clear liquid collected in step 1), stir and decolorize at 50-55°C for 2-2.5h, filter on a plate and frame; add 0.5-2% (w / v) activated carbon to the filtrate for secondary decolorization, stir and decolorize at 50-55°C for 2-2.5h, filter on a plate and frame, and collect the filtrate; Step 3) cation exchange resin adsorption: The filtrate obtained in step 2) is adjusted to a pH value of 3-4 with hydrochloric acid, passed through a continuous ion exchange column, maintaining a column flow rate of 1.0 BV / h, a column liquid theanine concentration of 1.5 mg / ml, adsorbed using a strong acid cation exchange resin, and eluted with a certain concentration of ammonia water to obtain an L-theanine eluate; Step 4) Concentration and deamination: The L-theanine eluate obtained in step 3) is concentrated in vacuo to a concentration of 1.05±0.05 g / ml at a concentration temperature of 60-65°C, deaminated, and the L-theanine concentrate is collected; Step 5) elution with anion exchange resin: the L-theanine concentrate obtained in step 4) is passed through a weakly basic anion exchange resin, decolorized, and washed with water to obtain an L-theanine solution; Step 6) Concentration and crystallization: The L-theanine solution obtained in step 4) is concentrated to a concentration of 1.05±0.05 g / ml, and crystallized to obtain L-theanine wet product; Step 7) Centrifugal drying: The wet L-theanine product obtained in step 6) is centrifuged and vacuum dried to obtain the finished L-theanine product.

[0008] Preferably, In the step 1), the pore size of the ceramic membrane is 100-200 nm, the membrane temperature is 60-65° C., and the membrane operating pressure is 0.25-0.35 MPa.

[0009] Preferably, In the step 3), the cation exchange resin model is: 001X8 resin, the adsorption capacity is 4 mg / ml resin, the column flow rate is 1.0 BV / h, and the concentration of theanine in the column liquid is 1.5 mg / ml.

[0010] Preferably, In the step 4), the eluent is 1.5 mol / L ammonia water, and the elution flow rate is 1 / 3 BV / h.

[0011] Preferably, In the step 6), the mixed solution is concentrated 2.5 times, the concentrated steam pressure is 0.1-0.15 MPa, the concentrated temperature is ≤65°C, and the concentrated time is 4 hours; the crystallization temperature is controlled to be ≤10°C, and the crystallization time is 36 hours.

[0012] Preferably, In the step 7), the drying temperature is 60-70°C, the vacuum degree is ≥-0.075MPa, the material is turned over every 4 hours, and the moisture content is controlled to be ≤1.3%.

[0013] The beneficial effects achieved by the present invention mainly include but are not limited to the following aspects: 1. The present invention introduces anion and cation exchange resin technology, which can effectively remove acidic and neutral amino acid impurities in L-theanine, has stronger selectivity for L-theanine, is easy to elute, has less impurities in the eluent, and has high light transmittance, thus ensuring the stability of product quality.

[0014] 2. The equipment of the present invention can be equipped with an automation system to realize automatic control of feed quantity, heating temperature, discharge concentration, and cleaning. It can also be equipped with protection measures for sensitive materials in case of sudden power outages and failures. At the same time, it can reduce the discharge of sewage, reduce pollution to the environment, and increase social benefits. DETAILED DESCRIPTION

[0015] Those skilled in the art can refer to the content of this article and appropriately improve the process parameters. It is particularly important to point out that all similar replacements and modifications are obvious to those skilled in the art, and they are all considered to be included in the present invention. The products and methods of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the products and methods described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention. In order to further understand the present invention, the present invention is described in detail below in conjunction with embodiments. Example

[0016] A method for extracting theanine using continuous ion exchange technology comprises the following steps: Step 1) pretreatment of fermentation broth: the L-theanine fermentation broth was filtered through a ceramic membrane with a pore size of 100 nm, the membrane temperature was 60° C., the membrane operating pressure was 0.25 MPa, the macromolecular protein was removed, the filtrate was collected, hydrochloric acid was added to adjust the pH to 4.5, and the ceramic membrane clear liquid was collected; Step 2) activated carbon decolorization: add 0.5% (w / v) activated carbon to the ceramic membrane clear liquid collected in step 1), stir and decolorize at 50°C for 2h, filter on a plate and frame; add 0.5% (w / v) activated carbon to the filtrate for secondary decolorization, stir and decolorize at 50°C for 2h, filter on a plate and frame, and collect the filtrate; Step 3) cation exchange resin adsorption: The filtrate obtained in step 2) is adjusted to pH 3.5 with hydrochloric acid, passed through a continuous ion exchange column, maintaining a column flow rate of 1.0 BV / h, a column liquid theanine concentration of 1.5 mg / ml, adsorbed using a 001X8 type strong acid cation exchange resin, and eluted with a certain concentration of ammonia water to obtain an L-theanine eluate; Step 4) Concentration and deamination: The L-theanine eluate obtained in step 3) is vacuum concentrated to a concentration of 1.05±0.05 g / ml, the concentration temperature is 60°C, 1.5 mol / L ammonia water is used for deamination, the elution flow rate is 1 / 3 BV / h, and the L-theanine concentrate is collected; Step 5) elution with anion exchange resin: the L-theanine concentrate obtained in step 4) is passed through a weakly basic anion exchange resin, decolorized, and washed with water to obtain an L-theanine solution; Step 6) Concentration and crystallization: The L-theanine solution obtained in step 4) is concentrated by 2.5 times, the concentration steam pressure is 0.1 MPa, the concentration temperature is ≤ 65°C, the concentration is carried out for 4 hours, and the concentration is concentrated to a concentration of 1.05±0.05 g / ml, and the L-theanine wet product is obtained by crystallization; Step 7) Centrifugal drying: centrifuge the wet L-theanine product obtained in step 6) and vacuum dry it to obtain the finished L-theanine product at a drying temperature of 60° C. and a vacuum degree of ≥-0.075 MPa.

[0017] After testing, the yield of L-theanine was 88.9% and the purity was 99.7%. Example

[0018] A method for extracting theanine using continuous ion exchange technology comprises the following steps: Step 1) pretreatment of fermentation broth: the L-theanine fermentation broth was filtered through a ceramic membrane with a pore size of 200 nm, the membrane temperature was 65° C., the membrane operating pressure was 0.35 MPa, the macromolecular protein was removed, the filtrate was collected, hydrochloric acid was added to adjust the pH to 4.5, and the ceramic membrane clear liquid was collected; Step 2) activated carbon decolorization: add 2% (w / v) activated carbon to the ceramic membrane clear liquid collected in step 1), stir and decolorize at 50-55°C for 2.5 hours, filter on a plate and frame; add 2% (w / v) activated carbon to the filtrate for secondary decolorization, stir and decolorize at 55°C for 2.5 hours, filter on a plate and frame, and collect the filtrate; Step 3) cation exchange resin adsorption: The filtrate obtained in step 2) is adjusted to pH 3.5 with hydrochloric acid, passed through a continuous ion exchange column, maintaining a column flow rate of 1.0 BV / h, a column liquid theanine concentration of 1.5 mg / ml, adsorbed using a 001X8 type strong acid cation exchange resin, and eluted with a certain concentration of ammonia water to obtain an L-theanine eluate; Step 4) Concentration and deamination: The L-theanine eluate obtained in step 3) is vacuum concentrated to a concentration of 1.05±0.05 g / ml, the concentration temperature is 65°C, 1.5 mol / L ammonia water is used for deamination, the elution flow rate is 1 / 3 BV / h, and the L-theanine concentrate is collected; Step 5) elution with anion exchange resin: the L-theanine concentrate obtained in step 4) is passed through a weakly basic anion exchange resin, decolorized, and washed with water to obtain an L-theanine solution; Step 6) Concentration and crystallization: The L-theanine solution obtained in step 4) is concentrated 3 times, the concentration vapor pressure is -0.15 MPa, the concentration temperature is ≤ 65°C, the concentration is carried out for 4 hours, and the concentration is concentrated to a concentration of 1.05±0.05 g / ml, and the L-theanine wet product is obtained by crystallization; Step 7) Centrifugal drying: centrifuge the wet L-theanine product obtained in step 6) and vacuum dry it to obtain the finished L-theanine product at a drying temperature of 70° C. and a vacuum degree of ≥-0.075 MPa.

[0019] After testing, the yield of L-theanine was 87.1% and the purity was 99.8%.

[0020] Although the above describes the specific implementation of the present invention in combination with the embodiments, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that it should be clear to those skilled in the art that these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection of the present invention.

Claims

1. A method for efficiently extracting theanine using continuous ion exchange technology, characterized in that: The process comprises the following steps: Step 1) pretreatment of the fermentation broth: filtering the L-theanine fermentation broth through a ceramic membrane, collecting the filtrate, adding hydrochloric acid to adjust the pH to 4-5, and collecting the ceramic membrane clear liquid; Step 2) activated carbon decolorization: add activated carbon to the ceramic membrane clear liquid collected in step 1) and stir at 50-55°C for 2-3 hours for decolorization, and then filter on a plate and frame; add activated carbon to the filtrate for secondary decolorization, stir at 50-55°C for 2-3 hours for decolorization, and filter on a plate and frame to collect the filtrate; Step 3) cation exchange resin adsorption: the filtrate obtained in step 2) is adjusted to a pH value of 3-4 with hydrochloric acid, passed through a continuous ion exchange column, adsorbed with a strong acid cation exchange resin, and eluted with a certain concentration of ammonia water as an eluent to obtain an L-theanine eluent; Step 4) Concentration and deamination: The L-theanine eluate obtained in step 3) is concentrated in vacuo to a concentration of 1.05±0.05 g / ml at a concentration temperature of 60-65°C, deaminated, and the L-theanine concentrate is collected; Step 5) elution with anion exchange resin: the L-theanine concentrate obtained in step 4) is passed through a weakly basic anion exchange resin, decolorized, and washed with water to obtain an L-theanine solution; Step 6) Concentration and crystallization: The L-theanine solution obtained in step 4) is concentrated to a concentration of 1.05±0.05 g / ml, and crystallized to obtain L-theanine wet product; Step 7) Centrifugal drying: The wet L-theanine product obtained in step 6) is centrifuged and vacuum dried to obtain the finished L-theanine product.

2. The process according to claim 1, characterized in that The pore size of the ceramic membrane is 100-200nm, the membrane temperature is 60-65℃, and the membrane operating pressure is 0.25-0.35Mpa.

3. The process according to claim 1, characterized in that The model of the strong acid cation exchange resin is 001X8 resin, the adsorption capacity is 4 mg / ml resin, the column flow rate is 1.0 BV / h, and the concentration of theanine in the column liquid is 1.5 mg / ml.

4. The process according to claim 1, characterized in that The eluent is 1.5 mol / L ammonia water, and the elution flow rate is 1 / 3 BV / h.

5. The process according to claim 1, characterized in that In the step 6), the concentrated steam pressure is 0.1-0.15 MPa, the concentrated temperature is ≤ 65° C., and the concentrated time is 2-4 hours.

6. The process according to claim 1, characterized in that The crystallization temperature is controlled to be ≤10°C, and the crystallization time is 36 hours.

7. The process according to claim 1, characterized in that The drying temperature is 60-70°C, the vacuum degree is ≥-0.075MPa, the material is turned over every 4 hours, and the moisture content is controlled to be ≤1.3%.