JPS5832959B2 - Glutamine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION It is already known to electrodialyze a glutamic acid-containing solution produced by a fermentation method using an ion exchange membrane.

In this case, the glutamic acid concentration is usually about 597 dl, and the current density is about IAzam''.

Although it is preferable to increase the current density in order to effectively utilize the device, there is a certain limit to the current density, and in order to increase this limit, it is necessary to increase the ion concentration of the liquid.

It is not clear why conventional treatments were carried out at such low concentrations and low current densities, but for example, when a sterilized and concentrated glutamic acid fermentation solution is electrodialyzed at room temperature at high concentrations and current densities, membrane clogging occurs. This seems to be because this method was not practical because deterioration occurred, causing the voltage to rise abnormally and the current effect to decline.

The present inventors set the temperature of the glutamic acid-containing liquid to 40-60°C.
°C, inflow velocity (membrane surface linear velocity) of 4 to 6C1rL/5ec
1. It was discovered that if electrodialysis is carried out at a current density of 2 to 4 A/'di with a glumemino acid concentration of 15 to 30 g/dl, stable operation can be continued with almost no voltage rise, and based on this knowledge, the present invention was developed. This is the completed version.

In the method of the present invention, the glutamic acid concentration of the glutamic acid-containing solution produced by the fermentation method is set to 15 to 309/dl, and the current density is set to 2 to 4 persons/d7r+2, and the cation exchange membrane and anion exchange membrane are This method uses electrodialysis.

The glutamic acid-containing liquid produced by the fermentation method includes, for example, a sterilized fermentation liquid, a crude crystal solution, and a crude crystal mother liquor.

The concentration of glutamic acid is 15-30 J! /dl range is appropriate.

Below 15 g/dl, the limiting current density is low at room temperature, and loss of glutamic acid due to putrefaction becomes a problem when heated.

On the other hand, at 30 g/di or more, the limiting current density is still low.

The higher the current density, the smaller the industrial equipment needs to be, but in the case of glutamic acid-containing liquids, it is 2 to 4 A/dm! is appropriate.

2-person/d-removal is particularly disadvantageous because the membrane is clogged with pigmented impurities, reducing current efficiency and lengthening the dialysis time, and glutamic acid is lost due to putrefaction.

On the other hand, if 4A/drn' is generated and the current is continued, glutamic acid will begin to adhere to the membrane, and as a result, the current will extremely stop flowing, making stable electrodialysis impossible.

If this continues, the ion exchange membrane will deteriorate significantly.

FIG. 1 is a schematic explanatory diagram showing one example of an apparatus used to carry out the present invention.

In the tank 1, there is an anion exchange membrane A1. A2. A3...
・Alo and cation exchange membranes C1, C2, C3...
..., C1o are arranged alternately, and then CI 1 * C1□ are arranged sequentially after C1o to form the compartment 22...
..., with an anode 3 and a cathode 4 facing each other at the end of the tank.
is provided.

Glu l'mic acid-containing liquid flows through conduit 5 and its branch conduits 6 and 7.
, 8...14 into the tank, passing through an anion exchange membrane and a cation exchange membrane (7J, ffl, branch pipe 6/,
7/, 8/...14' and is discharged via conduit 5'.

Further, an aqueous solution for collecting glutamic acid is introduced into the tank through the conduit 15 and branch pipes 16, 17, 18, 25, and branch pipes 16', 17', 18', .
- Take out via 25' and conduit 15'.

On the other hand, a solution of a suitable salt, e.g. sodium sulfate, as polar liquid is introduced via line 26 and its branches 27, 28, 29, 30 and discharged via branches 271, 28', 29', 30% and line 26'. be done.

During this time, direct current is passed between the two poles. The pH of the glutamic acid collection solution introduced into the tank may be other than the isoelectric point of glutamic acid, but it is usually adjusted to around pH 7 before use.

used for regulation.

The cations used for regulation are sodium, potassium,
Ammonium etc. may be used.

The temperature of this glutamic acid-containing liquid must be kept at 40 to 60°C to prevent abnormal voltage rise.

Increasing the temperature to around 80°C poses a problem in the heat resistance of the film.

The inflow velocity of the glutamic acid-containing liquid is the membrane surface linear velocity 1
m/sec or more, preferably 4 to 6c11L/sec
is used.

The anion exchange membrane and cation exchange membrane used in the present invention may be commercially available products, such as Selemion CMV (
Asahi Glass Company product, registered trademark), Selemion AMV (same as above)
etc. can be given.

There is no particular difficulty in obtaining glucinic acid from the dialysate, and it may be carried out in accordance with a conventional method for obtaining desired crystals.

For example, when obtaining monosodium glutamate in the form of crystals, if sodium ions are present at an enough level to crystallize sodium glutamate, adjust the pH as necessary;
What is necessary is to concentrate and crystallize after decolorizing using activated carbon.

When sodium ions are insufficient or the purity is poor, acid is added to separate the glutamic acid crystals, which are then converted into a sodium glutamate solution using sodium hydroxide, decolorized, and concentrated and crystallized.

When there is a large amount of ammonium ions, it is also possible to remove ammonium by adding enough sodium hydroxide to replace the ammonium ions, followed by decolorization and concentration crystallization.

If it is obtained in the form of glutamic acid crystals, it may be neutralized and crystallized after decolorization.

In all of the above methods, recrystallization is repeated depending on the purity of the obtained crystal.

By using the method of the present invention, it is possible to stably perform electrodialysis over a long period of time without causing abnormal voltage increases or loss of glutamic acid due to putrefaction.

FIG. 2 shows the results of measuring the relationship between the limiting current density and the glutamic acid concentration at each temperature using the sterilized fermentation liquid.

The experiment was carried out using the apparatus shown in Figure 1 equipped with Selemion CMV and Selemion AMV (effective membrane area 2 d m', membrane spacing 2 m).
m) was used.

Glutamic acid concentration 10 g/dl, 15 g/dl, 20
9/dl.

25 g/di! , 309/dl, 35 g/
A fermentation solution adjusted to pH=6.5 with dl and aqueous ammonia was prepared, and 1M thereof was simultaneously introduced into conduits 5 and 15 of the dialysis tank, discharged from conduits 5 and 15 simultaneously, and circulated.

The introduction volume of each conduit was 450 l/h.

The temperature was maintained at 30°C, 40°C, 50°C, and 60'C, respectively.

Electricity was applied to the dialysis tank to increase the current density in stages, and the current density at the point when the sliding voltage suddenly increased was measured and recorded as the critical current density.

At the same time, a 5 g/dl Na2SO4 aqueous solution 21 was circulated to the dialysis tank as a polar liquid.

Examples are shown below.

Example 1 2 obtained by sterilizing a glutamic acid fermentation liquid using acetic acid as a raw material, adjusting the pH to 6.3 with aqueous ammonia, and concentrating it.
A glutamic acid-containing solution with a concentration of 7.09/di was prepared.

This liquid 151 was kept at 55°C and poured into the dialysis tank shown in Fig. 1 at a membrane surface linear velocity of around 5 cm/sec.
It circulated at a speed of /h.

Na C at a concentration of 3 g/di as a glutamic acid collection liquid
1 aqueous solution 21 was circulated to the dialysis tank.

Further, an aqueous Na2SO4 solution 21 having a concentration of 5 g/dl was circulated to the dialysis tank as an polar liquid.

A direct current of 3 A/di' was applied to the dialysis tank.

After 18 hours, the glutamic acid collection liquid became 1M, and the glutamic acid content was measured to be 24.8 g/dl.

This indicates that 98% of the glutamic acid in the glutamic acid-containing solution was dialyzed.

During the current application time, the sliding voltage always showed 12.9 to 14.0 volts, and dialysis was performed stably without any voltage increase.

Next, in the above method, the temperature of the glutamic acid-containing liquid was lowered to 2
Electrodialysis was performed without changing the conditions except for maintaining the temperature at 5°C.

The sliding voltage was 18 volts at the beginning of dialysis, but rose to 32 volts after 1 hour, and then rapidly increased further.

When the voltage is returned to 18 volts and the current is measured, it is 0.2A.
/dm or less, indicating that glutamic acid dialysis was not performed in most cases.

Example 2 Crude glutamic acid crystals separated from a glutamic acid fermentation liquid using sugar as a raw material were suspended in water and purified with concentrated NaOH water.
A glutamic acid-containing solution with a concentration of 25 g/dl was prepared by adjusting the concentration to H7.0.

The glutamic acid-containing liquid 151 was maintained at 52°C and introduced into a dialysis tank in exactly the same manner as in Example 1 to carry out an experiment.

After 16 hours, the amount of glutamic acid collection liquid was 161, and the glutamic acid content was 23.09/dl, which means that 98 pieces of glutamic acid in the glutamic acid-containing liquid had been dialyzed.

The sliding voltage during the dialysis time was 13.5-14.4 volts;
Electrodialysis was performed stably with no voltage increase observed.

Next, in the above method, the temperature of the glutamic acid-containing liquid was adjusted to 3
Electrodialysis was performed in exactly the same manner except that the temperature was maintained at 0°C.

The sliding voltage at the start of dialysis was 17 volts, but after 15 hours it reached 42 volts, and continued to rise rapidly over time.

When I returned the sliding voltage to 17 volts and measured the current, it was 0.
Dialysis of glutamic acid was no longer possible below 2 A/d-.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram showing one example of an apparatus used to carry out the method of the present invention. In the figure, 1 is the tank body, A1. ... is an anion exchange membrane, 3 is an anode, and 4 is a cathode. FIG. 2 shows the results of measuring the relationship between limiting current density and glutamic acid concentration using a sterilized fermentation solution.

Claims (1)

[Claims] 1. A method for purifying glutamic acid from a solution containing glutamic acid produced by a fermentation method using a cation exchange membrane and an anion exchange membrane, in which the concentration of glutamic acid in the solution is 15 to 30 g/ dls inflow velocity (membrane surface linear velocity) 4~
6crfL/5ec1 A gourmet m purification method characterized by performing electrodialysis at a temperature of 40 to 60°C and a current density of 2 to 4 A/drrl.