JPH04320691A - Method for purifying fermented organic acid - Google Patents

Abstract

PURPOSE:To purify a fermented organic acid to a high purity at a low cost according to simple operation by treating a fermentation liquor of the organic acid containing saccharides, etc., which are impurities with a weak basic ion exchange resin, separating the impurities and then separating the organic acid with an eluent containing an alkaline earth metallic salt. CONSTITUTION:A fermentation liquor of an organic acid containing saccharides (e.g. glucose) and lower fatty acids (e.g. acetic acid) as impurities is subjected to contact treatment with a weak basic ion exchange resin to make the organic acid adsorbed on the weak basic ion exchange resin. The saccharides are discharged, separated and removed and the organic acid adsorbed on the weak basic ion exchange resin is then eluted with an eluent containing an alkaline earth metallic salt (e.g. calcium chloride) at a high temperature. An eluate containing the eluted organic acid is subsequently cooled to deposit crystals of the alkaline earth metallic salt (e.g. calcium lactate) of the organic acid. Thereby, the lower fatty acids are separated and removed to separate and recover the alkaline earth metallic salt of the organic acid. As a result, the fermented organic acid is purified.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a method for purifying fermented organic acids, and more specifically, the present invention relates to a method for purifying fermented organic acids, and more specifically, purifying organic acids produced by microbial fermentation from a solution containing organic acids to high purity using a weakly basic ion exchange resin. The invention relates to a method for recovering organic acids.

0002

2. Description of the Related Art When organic acids are produced by microbial fermentation, the resulting organic acid-containing solution contains various by-products (impurities) in addition to the desired organic acid. These impurities include, for example, sugars such as glucose, molasses, and starch used as raw materials, and lower fatty acids such as acetic acid and butyric acid that are by-produced during the fermentation process. These impurities are
It is stipulated in the food standards that such substances will no longer be recognized qualitatively (edited by Morizo Ishidate and Akio Tanimura, 5th edition Food Additives Official Guidebook, Hirokawa Shoten, published in 1987). Therefore, it is necessary to remove these impurities and separate and purify the organic acid. As such purification methods, the following methods are known, for example. (1) An esterification method in which an organic acid is esterified, then purified by distillation, etc., then the ester is hydrolyzed, and the organic acid is recovered by crystallization, etc.; (2) an alkaline earth metal salt is added to the organic acid-containing solution; A crystallization method in which metal salts of organic acids are produced by adding organic acids, and this is separated into solid and liquid.

0003

[Problem to be solved by the invention] The above esterification method is
This is a very complicated method and requires a large amount of energy and large-scale processing equipment, so it has the drawback of increasing operating and construction costs. Further, the crystallization method has high purification efficiency and is an effective method for purifying fermented organic acids, but when the organic acid solution has a low concentration, concentration is required as a pre-step. Distillation methods and adsorption methods using adsorbents are used for concentration, but the distillation method requires a large amount of energy, and the adsorption method requires a large amount of utility costs for regenerating the adsorbent. It also has the disadvantage of high cost. In view of these circumstances, the present inventors conducted extensive research to find a low-cost and simple method for purifying fermented organic acids, and as a result, they completed the present invention.

0004

[Means for solving the problem] That is, the present invention has the following features:
A step of contacting an organic acid fermentation liquid containing sugars and lower fatty acids as impurities with a weakly basic ion exchange resin, adsorbing the organic acid to the ion exchange resin, and distilling the sugars;
(i) eluting the organic acid adsorbed on the ion exchange resin at high temperature with an eluent containing an alkaline earth metal salt;
and (1) cooling the eluent containing the eluted organic acid to precipitate crystals of the organic acid alkaline earth metal salt, thereby removing lower fatty acids and separating and recovering the organic acid alkaline earth metal salt. A method for purifying fermented organic acids is provided.

[0005] The organic acids that are the object of the present invention are organic acids produced by microbial fermentation, particularly food-grade organic acids, and the types thereof are not particularly limited, but include, for example, lactic acid, gluconic acid, tartaric acid, malic acid, and citric acid. Examples include hydroxycarboxylic acids such as acids. In the present invention, an organic acid-containing solution obtained by such microbial fermentation is brought into contact with a weakly basic ion exchange resin, and the organic acid is adsorbed onto the ion exchange resin.

[0006] The weakly basic ion exchange resin used here is
Any resin may be used as long as it has a primary to tertiary amino group in its molecule, and various commercially available resins can be used. Examples of such resin include Sumikaion KA-800.
, Sumikaion KA-830 , Sumikaion K
A-850, Sumikaion KA-890 [above,
manufactured by Sumitomo Chemical Co., Ltd.], Diaion WA-10,
Diamond ion WA-20, Diamond ion WA-30
, Diaion CR-20 [manufactured by Mitsubishi Kasei Corporation], Duolite A-367, Duolite A
-368, Duolite A-7 [manufactured by Diamond Shamrock], Amberlite IR-4B,
Amberlight IR-45 [above, ROHM &
manufactured by Haas Co., Ltd.).

In the present invention, the step of bringing the organic acid-containing solution into contact with the weakly basic ion exchange resin (hereinafter referred to as the adsorption step) is generally carried out at a temperature of 90° C. or lower. If the temperature exceeds 90°C, deterioration of the functional groups in the weakly basic ion exchange resin may occur, which is not preferable. The method of contacting the ion exchange resin and the organic acid-containing solution is not particularly limited, and it is sufficient to bring the ion exchange resin into contact with the solution so that the organic acid in the solution is substantially absorbed by the ion exchange resin. For example, a method of immersing an ion exchange resin in a solution containing an organic acid,
A method such as passing an organic acid-containing solution through a column filled with an ion exchange resin is used. Since the treatment operation is easy, a method of passing the organic acid-containing solution through a column filled with an ion exchange resin is preferably used.

The amount of ion exchange resin to be used varies depending on the concentration of the organic acid in the solution to be treated, the type of ion exchange resin used, etc., and can be appropriately determined through preliminary experiments according to each condition.

[0009] As described above, by bringing an organic acid-containing solution into contact with a weakly basic ion exchange resin, the saccharides contained as impurities in the solution are distilled out and removed while remaining in the solution, and the organic acid is removed. Adsorbed by ion exchange resin. At this time, lower fatty acids contained in the solution are also usually adsorbed by the ion exchange resin.

The weakly basic ion exchange resin that has thus adsorbed the organic acid is washed with water if necessary, and then subjected to a step of eluting the organic acid with an eluent containing an alkaline earth metal salt (
(hereinafter referred to as the elution step). The alkaline earth metal salt contained in the eluent is preferably an inorganic alkaline earth metal salt, and more preferably a halide, such as calcium chloride, magnesium chloride, strontium chloride, barium chloride, and the like. The solution used as an eluent preferably has an alkaline earth metal ion concentration of about 5 g/L or more, more preferably 10 to 100 g/L.
It is an aqueous solution. When the concentration of alkaline earth metal ions is less than about 5 g/L, the elubility of organic acids deteriorates,
Since it is necessary to use a large amount of eluent, it is often difficult to separate the organic acid from the eluent in the next step.

The pH of the eluent may be within a range in which the alkaline earth metal salt does not precipitate in the elution step and does not pose a problem in separating the alkaline earth metal salt of the organic acid in the next separation step, and there are no particular restrictions. Although not intended to be used, it is usually p
About H3 to 8 is preferable. Further, the eluent may contain an organic solvent. The amount of eluent used is not particularly limited and varies depending on the type and concentration of alkaline earth metal salt, the type of weakly basic ion exchange resin, the type and amount of adsorbed organic acid, etc., so preliminary experiments should be carried out as appropriate. It can be set by doing the following.

[0012] The contact temperature between the weakly basic ion exchange resin adsorbing the organic acid and the eluent is usually preferably about 40 to 90°C. If the temperature is less than 40°C, there is a risk that the organic acid once eluted may precipitate into the ion exchange resin as a metal salt during the elution operation. Also, when the temperature exceeds 90℃,
This is not preferable because it may cause deterioration of the functional groups in the weakly basic ion exchange resin. The optimal temperature within this range varies depending on the type of organic acid, the amount of organic acid adsorbed to the weakly basic ion exchange resin, the type and concentration of the eluent, and can be determined by conducting preliminary experiments as appropriate. can.

[0013] The method of contacting the ion exchange resin adsorbing the organic acid with the eluent is not particularly limited, and the contact between the two may be such that the organic acid adsorbed on the ion exchange resin is substantially eluted. Bye. For example, a method of immersing an ion exchange resin that has adsorbed an organic acid in an eluent, a method of passing the eluent into a tower filled with an ion exchange resin that has adsorbed an organic acid, etc. can be adopted. Since the treatment operation is easy, a method in which the eluent is passed through a column filled with an ion exchange resin adsorbing an organic acid is preferably used. In addition, in combination with the previous adsorption step, a weakly basic ion exchange resin is packed into the column, and an organic acid-containing solution is passed through it to adsorb the organic acid.After washing with water as necessary, an eluent is added to the column. A method in which the organic acid is eluted through a solvent is preferably used.

[0014] The resin after eluting the organic acid in this way is
After washing with water if necessary, it can be reused as is, or alternatively, it can be washed with acid or alkali and finally treated with an alkaline solution before being reused.

The eluate containing the alkaline earth metal salt of the organic acid obtained from the elution step is then cooled to precipitate the desired organic acid as crystals of the alkaline earth metal salt (hereinafter referred to as the crystallization step). ). Here, since the alkaline earth metal salt of the lower fatty acid contained as an impurity hardly precipitates out even after cooling and remains in the eluent, a highly pure organic acid alkaline earth metal salt can be precipitated. Cooling at this time can be performed by a known technique. The optimal cooling temperature, cooling time, etc. vary depending on the type and concentration of the organic acid in the eluent, and are determined by conducting preliminary experiments as appropriate. Normally, the alkaline earth metal salt of the organic acid is precipitated by cooling the eluent to a temperature 10°C or more lower than the temperature of the eluent obtained in the elution step, but preferably at this time, the eluent is cooled to about 0 to 30°C. be done.

[0016] The organic acid alkaline earth metal salt crystals precipitated in the crystallization step are separated and recovered from the eluent by a separation method such as filtration. The separated and recovered alkaline earth metal salt of an organic acid can be easily converted into a high-purity organic acid by a known method such as acid decomposition, either as it is or, if necessary, after undergoing known purification treatments such as recrystallization. can do.

[0017]

[Examples] The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples.

Example 1 [Adsorption step] Aqueous solution 1 containing 100 g of lactic acid, 5 g of acetic acid, 1 g of butyric acid and 20 g of glucose
liter was brought into contact with 1 liter of a commercially available weakly basic ion exchange resin Sumikaion KA-890 (manufactured by Sumitomo Chemical Co., Ltd.) at 50° C. for 30 minutes. After removing the treatment liquid, the ion exchange resin was washed with 1 liter of deionized water. As a result, lactic acid 97g, acetic acid 3g, butyric acid 0.8g
was adsorbed to the resin, and no glucose was adsorbed at all.

[Elution Step] The ion exchange resin that had adsorbed the organic acid in the above adsorption step was then contacted with 500 ml of a 2M calcium chloride aqueous solution at 50° C. for 30 minutes. Thereafter, the resin was filtered to obtain an eluent. The organic acid content in the eluent was 95 g of lactic acid as free acid.
, 2.5 g of acetic acid and 0.7 g of butyric acid.

[Crystallization Step] The eluate obtained in the above elution step was gradually cooled to room temperature to precipitate crystals, yielding 85 g of calcium lactate. The purity of the obtained calcium lactate was approximately 100%, and the presence of acetic acid and butyric acid was not observed.

Examples 2 to 4 The weakly basic ion exchange resins were Sumikaion KA-850 (manufactured by Sumitomo Chemical Co., Ltd.) in Example 2, and Sumikaion KA-850 (manufactured by Sumitomo Chemical Co., Ltd.) in Example 3.
In Example 4, Duolite A-367 [manufactured by Diamond Shamrock] was used, and in Example 4, Diamond Ion WA-
The same operation as in Example 1 was performed except that the material was changed to No. 30 (manufactured by Mitsubishi Kasei Corporation). The results are shown in Table-1.

[0022]

Examples 5 to 6 The same procedure as in Example 1 was carried out, except that the aqueous solutions containing organic acids were changed as follows. Example 5: Gluconic acid 50g, acetic acid 2g, butyric acid 0.6
Organic acid aqueous solution Example 6 containing g and glucose 11 g
: The results of an organic acid aqueous solution containing 60 g of tartaric acid, 1.5 g of acetic acid, 0.3 g of butyric acid, and 16 g of starch are shown in Table 2.

[0024]

In Examples 1 to 6 above, an aqueous solution containing an organic acid is passed into a column filled with an ion exchange resin to adsorb the organic acid, and after washing with water, an aqueous calcium chloride solution is passed into the column to elute the organic acid. Organic acids can be similarly purified by cooling the eluent.

[0026]

[Effects of the Invention] Compared to conventional techniques, the method for purifying organic acids does not require complicated operations, has simple processing operations, and has low utility costs, making it an economically superior method. , its industrial value is extremely high.

Claims (4)

[Claims] Claims 1: ■ A step of contact-treating an organic acid fermentation liquid containing sugars and lower fatty acids as impurities with a weakly basic ion exchange resin, adsorbing the organic acid onto the ion exchange resin, and distilling off the sugars; A step of eluting the organic acid adsorbed on the ion exchange resin with an eluent containing an alkaline earth metal salt at high temperature; 1. A method for purifying fermented organic acids, comprising the steps of removing lower fatty acids and separating and recovering organic acid alkaline earth metal salts by precipitating salt crystals. 2. The method according to claim 1, wherein the fermented organic acid is lactic acid, gluconic acid, tartaric acid, malic acid or citric acid. 3. The method according to claim 1 or 2, wherein the impurity saccharide is glucose, molasses or starch. 4. The method according to claim 1, wherein the impurity lower fatty acid is acetic acid or butyric acid.