JPH01215293A - Separation and recovery of erythritol - Google Patents

Abstract

PURPOSE:To industrially advantageously provide the title compound useful for sweeteners, etc., by filtering the supernatant of a culture solution prepared by culturing an erythritol-producing bacterium in an aqueous medium under an aerobic condition with an ultrafiltration membrane having a specific fractional mol.wt. and subsequently recovering the product from the filtrate. CONSTITUTION:A culture solution prepared by culturing an erythritol-producing bacterium (e.g., Aureobasidium Sp.SN-G42) in an aqueous medium under an aerobic condition is thermally sterilized and centrifuged to produce a supernatant. The supernatant is filtered with an ultrafiltration membrane having a fractional mol.wt. of 1,000-100,000 and the filtrate is heated to 50 deg.C and treated with charcoal to decolor the filtrate. The decolored filtrate is treated with an ion exchange resin and concentrated to crystallize erythritol contained therein. The resultant erythritol crystals are separated and recovered to provide the objective erythritol.

Description

Detailed Description of the Invention (a) Object of the Invention (Field of Industrial Application) The present invention is directed to the production of menerythritol (herein simply referred to as K
It is abbreviated as "erythritol". ) from the culture solution of erythritol-producing bacteria.

(Prior technology) Highly purified Eris'J is produced from the culture solution of erythritol-producing bacteria.
) - In order to separate and recover the cultured loincloth, the supernatant liquid of the cultured loincloth is usually decolorized using activated carbon as a pretreatment, then desalted and decolorized using an ion exchange resin, and then concentrated. Then cool it and let it crystallize. However, this method has the drawback that turbidity occurs during cooling and crystallization of the concentrated solution, and the erythritol crystals become fine, making it difficult to separate the erythritol crystals by filtration or the like in the first step of crystallization.

Furthermore, even if forced K filtration and water washing are performed, the resulting erythritol crystals have the disadvantage of becoming cloudy when dissolved in water.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned drawbacks of the conventional method, namely, turbidity occurs in the crystallization step in the conventional method, it is difficult to pass through the crystals of the produced erythritol, and the produced erythritol is hydrated. The purpose of the present invention is to provide a method for separating and recovering erythritol that can solve the problem of turbidity that sometimes occurs when dissolved in erythritol.

The present inventors have repeatedly investigated the causative agent of turbidity that occurs during the crystallization of erythritol in the conventional method described above and when the produced erythritol crystals are dissolved in water, and have found that the causative agent is glucose. It was found that the main constituent is polysaccharide.

In addition, this polysaccharide has a molecular weight of several thousand to tens of thousands, and is produced in a small amount in the culture solution of Eris IJ)-lease producing bacteria. Despite being completely dissolved in the desalting and decolorizing solution, it precipitates during the crystallization process of erythritol and causes FIa. Not only does it make the precipitated erythritol crystals thinner, making it extremely difficult to pass them through, but it also mixes into the precipitated erythritol crystals, causing cloudiness when the product erythritol crystals are dissolved in water. , which was found to cause a decline in product quality.

Therefore, the present inventors conducted further research on the removal of polysaccharides, which are the causative agent of such turbidity. In other words, we have conducted research on the removal of polysaccharides using various separation membranes ranging from precision F:iM membranes with large pores to reverse osmosis membranes with very small pores. Although the bundle is large, all of the polysaccharides that cause cloudy spots pass through the membrane along with the liquid and cannot be removed.
Moreover, it did not show any effect of removing colored components.

My friend, when we tested a so-called loose reverse osmosis membrane with a low salt removal rate, we found that it was able to remove the above-mentioned turbidity-causing substances with a high removal rate, and both the color removal rate and salt removal rate were high. However, some of the erythritol was removed by the membrane, and the permeation flux of the liquid in that case was extremely low.

Furthermore, when testing ultrafiltration membranes, it was found that membranes with a molecular weight cutoff of 100,000 or less can efficiently remove the above-mentioned turbidity components, and the smaller the molecular weight cutoff of the membrane, the higher the decolorizing effect. It has been found that the amount of activated carbon used can be reduced. However, if the molecular weight cut-off becomes too small, the permeation flux of the liquid decreases significantly, so it has been found that a membrane having a molecular weight cut-off of 1.000 or more is preferable, and the present invention has been achieved.

That is, the method for separating and recovering erythritol of the present invention involves culturing erythritol-producing bacteria in an aqueous medium under aerobic conditions, and then culturing the supernatant of the erythritol culture with a molecular weight cut-off of 1. This method is characterized by filtration through an ultrafiltration membrane of .000 to 100,000 and recovering erythritol from the obtained tL7t filtrate.

The ultrafiltration membrane used in the present invention has a molecular weight cut-off in the range of 1.000 to 100,000, as described above, but if the molecular weight cut-off is too large, the removal of turbidity components may be difficult. The efficiency will be reduced and the decolorizing effect will be lost. This is because if the molecular weight cut-off becomes too small, the permeation flux of the liquid will become small.

There are various materials for the ultra-diaphragm, such as Irisulfone, polyacrylonitrile, polyamide,
Examples include ν vinylidene fluoride, chlorinated preethylene, polyvinyl alcohol, polymethyl methacrylate, -limide, cellulose acetate, cellulose, and various other polymers or copolymers, or mixtures of these (co)polymers. In addition, the shape of the ultrafiltration membrane is hollow fiber,
Various shapes such as flat membranous, cylindrical, and tubular shapes are used.

To explain the separation and recovery method of the present invention in more detail, first, erythritol-producing bacteria are cultured in an aqueous medium under aerobic conditions, and the resulting culture solution is cultured using a method such as centrifugation or passing. Solid matter such as bacterial cells is separated and removed to obtain a supernatant liquid. Since the cultivation of erythritol-producing bacteria itself is already known, its explanation will be omitted.

Next, when the supernatant is treated with the above-mentioned ultrafiltration membrane, the polysaccharide contained in the supernatant, which is the causative substance of the above-mentioned /1iil#), is removed. , the filtrate no longer contains the polysaccharide.

The liquid obtained by P treatment with an ultraparticle membrane is preferably treated with activated carbon to decolorize it, but during filtration with the ultrafiltration membrane, some of the colored components are removed at the same time as polysaccharides are removed. (Coloring component 2
(approximately 0 to 40%) is also removed, so the amount of activated carbon used during activated carbon treatment can be smaller than in normal cases.

The supernatant liquid after the activated carbon treatment is preferably further desalted and decolorized using an ion exchange resin similar to a normal ion exchange resin treatment, and then desalted and decolorized to a desired concentration (for example, an erythritol concentration of 40 to 80 %) and then precipitate erythritol crystals while cooling. High purity erythritol crystals can be obtained by centrifuging or filtering the slurry to separate it from the mother liquor. In this case, since the polysaccharides in the supernatant are removed by filtration using an ultrafiltration membrane, the precipitated erythritol crystals do not become finer, making separation by centrifugation or filtration extremely easy. becomes.

Moreover, the product Eris IJ)-le crystal obtained is of good quality and does not become cloudy even when dissolved in water.

In addition, in the above method I/c, the filtrate from the ultrafiltration membrane was treated with activated carbon and further treated with an ion exchange resin, and then concentrated and crystallized, but the erythritol to be obtained was Depending on the desired purity of the crystals, part or all of the activated carbon treatment and ion exchange resin treatment may be omitted and the crystals may be concentrated and crystallized.

Margin below (Examples, etc.) Next, the present invention will be further explained in detail by giving Examples and Comparative Examples.

Example 1 5N-G 42 strain of Aureopathizoum Sp was added to a medium containing 3001/l of anhydrous crystalline glucose and 6.71/l of yeast extract, and cultured with shaking at 30°C for 72 hours. A seed medium was obtained. This seed medium 1.51
In addition to medium 251 (initial value: 4.2) containing anhydrous crystalline glucose 34011/Il, corn, stave, liquor 55971, aeration rate 25j/min, stirring speed 600.
rpm, temperature 35°C, and pressure 0.5 kg 7 cm”
When cultured for 93 hours under the conditions of G, glucose completely disappeared. Immediately stop the culture, heat sterilize it, and then centrifuge it. The il1 body was isolated. The obtained supernatant contained 1879/l of erythritol and 2/l of glycerin.
Contains 51/l.

Each of the obtained supernatants (IOl) (absorbance at 420 mμ measured in one cell as an indicator of the degree of coloration, that is, A42
0 was 5.8. ), various hollow fiber ultrapolar membranes (membrane 1) having the performance shown in Table 1.

Using a membrane module containing membranes 2 and 3) under the following filtration operating conditions, the results shown in Table 2 were obtained.

Filtration operation conditions Membrane inlet pressure 1.5mm/32G Membrane outlet pressure 1.0 to 97cm G liquid temperature
25℃ filtrate amount 107 In addition, the solution (approx.
．． After decolorizing the mixture by stirring for 5 hours, the activated carbon was removed by filtration.

Approximately 8.81 of the filtrate (A420 was 0.3) was transferred to a cation exchange resin tower (filled with Diaion 5KIB, a product of Mitsubishi Chemical Industries, Ltd.) and an anion exchange resin tower (a product of Mitsubishi Chemical Industries, Ltd.). Famous Diamond Aeon WA 30 filling)
, and a mixed bed tower (filled with Diaion 5KIB (trade name, manufactured by Mitsubishi Chemical Industries, Ltd.) and PA408) to carry out desalination treatment. The ion exchange treatment liquid 121 including the ion exchange tower extrusion and washing water after desalination treatment is 1
The mixture was evaporated and concentrated by heating to 80° C. under a reduced pressure of 0.00 mmHH. The obtained concentrate having an erythritol concentration of 62% by weight was gradually cooled to 15° C. to precipitate erythritol crystals. Dissolve the obtained crystals in water for 10
Although it was made into an aqueous solution with a weight of 5, no K removal was observed at all.

Comparative Example 1 Using the precision filtration membrane shown in Table 1, the supernatant of the culture solution was otherwise filtered in the same manner as in Example 1. The results are shown in Table 2, and no polysaccharides could be removed.

Comparative Example 2 Using a flat membrane filtration device using a so-called loose reverse osmosis membrane with low desalting performance shown in Table 1, the supernatant liquid of the same culture solution as in Example 1 was treated as follows. When filtration was carried out under the following filtration operating conditions, the results shown in Table 2 were obtained.

Filtration operating conditions Operating pressure: 10 kll/cm" G Stirring: 500 rpm Liquid temperature: 25°C Filtrate volume: 250 d In the case of Comparative Example 2, polysaccharides were removed, but erythritol was also removed at the same time, and the permeate volume was extremely small. , it could not be put to practical use.

Comparative Example 3 After heat sterilizing the same culture solution as in Example 1, the bacterial cells were separated by centrifugation. The obtained supernatant contained 18,711/l of erythritol and 251/l of glycerin. The resulting supernatant liquid (approximately 10%) was heated to 50°C and treated with activated carbon.

After adding I and decolorizing the mixture by treating it for 0.5 hours, the activated carbon was removed by filtration. In this case, compared to Example 1, 82
A4□ of the decolorizing solution requires % excess amount of activated carbon. was 0.3.

Next, the decolorizing solution was subjected to the same ion exchange resin treatment as in Example 1. The treatment liquid level 121 is 100 m
Evaporate by heating to 80°C under reduced pressure of mHg.

The concentrated liquid having an erythritol concentration of 62% by weight was gradually cooled to 15° C. to precipitate erythritol crystals. I tried to separate the precipitated liquid of the crystals by F and separate the crystals of Eri and Thritol from the mother liquor.
Although turbidity occurred and filtration was difficult, erythrol crystals were obtained by forcibly washing and filtering with water. When the crystals were dissolved in water to form a 10% by weight aqueous solution, turbidity was observed.

(EJ Effects of the Invention According to the erythritol separation and recovery method of the present invention, polysaccharides that cause turbidity are easily and completely removed during filtration using an ultrafiltration membrane, so turbidity does not occur in the erythritol crystallization process) Erythritol crystals are easily separated, and high-quality erythritol crystals that do not form turbidity when dissolved in water are obtained.In addition, when filtered through the ultrafiltration membrane, 20% of the coloring components are removed. Since about 40% is removed, the amount of activated carbon used for decolorization can be significantly reduced.

Patent applicant: Mitsubishi Chemical Industries, Ltd. Nikken Chemical Co., Ltd.

Claims (1)

[Scope of Claims] 1) The supernatant of the culture obtained by culturing erythritol-producing bacteria in an aqueous medium under aerobic conditions has a molecular weight cut-off of 1.
,000 to 100,000 ultrafiltration membrane,
A method for separating and recovering erythritol, which comprises recovering erythritol from the obtained filtrate. 2) The method according to claim 1, wherein erythritol is recovered after treating the filtrate through the ultrafiltration membrane with activated carbon. 3) The method according to claim 1, wherein the filtrate from the ultrafiltration membrane is treated with activated carbon, then treated with an ion exchange resin, and then concentrated and crystallized to obtain erythritol crystals.