JPH0734750B2 - Erythritol separation and recovery method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Purpose of the Invention (Field of Industrial Application) The present invention relates to mesoerythritol useful as an intermediate or the like for sweeteners, pharmaceuticals, industrial chemicals, etc. "Erythritol" is abbreviated as ".)" From a culture solution of an erythritol-producing bacterium.

(Prior art) In order to separate and recover high-purity erythritol from the culture solution of erythritol-producing bacteria, usually, the supernatant of the culture solution is pretreated and decolorized with activated carbon, and then ion-exchange resin is added. After desalting and decolorizing treatment using the product, it was concentrated and then cooled for crystallization. However, this method has a drawback that turbidity occurs during cooling and crystallization of the concentrated liquid, and the erythritol crystals become finer, which makes it difficult to separate erythritol crystals excessively in the crystallization step. Also,
The erythritol crystals obtained had the drawback of becoming turbid when dissolved in water, even if they were forcibly filtered and washed with water.

(Problems to be Solved by the Invention) The present invention has the above-mentioned drawbacks of the conventional method, that is, turbidity is generated 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 dissolved in water. It is intended to provide a method for separating and recovering erythritol which can solve the drawback that turbidity occurs when dissolved.

(B) Structure of the Invention The inventors of the present invention have made extensive studies on the causative substance of turbidity generated during the crystallization of erythritol and the dissolution of the produced erythritol crystals in water in the above-mentioned conventional method, and the causative substance is glucose. It was found to be a polysaccharide whose main constituent is.

Further, this polysaccharide has a molecular weight of several thousand to several tens of thousands, and although the production amount in the culture solution of the erythritol-producing bacterium is small, it is subjected to decolorization treatment with normal activated carbon, desalting with an ion exchange resin, Desalination is not removed even by decolorization treatment,
Even though it is completely dissolved in the decolorized solution, it not only causes turbidity due to precipitation in the erythritol crystallization step, but also causes the precipitated erythritol crystals to become fine and to prevent the excess. It was found that the erythritol crystals were remarkably difficult to be mixed with the crystals of erythritol to be precipitated, and when the product erythritol crystals were dissolved in water, white turbidity was generated, which was a cause of product quality deterioration.

Therefore, the present inventors have further studied the removal of polysaccharides as a causative substance that causes such turbidity. That is, when the removal of the polysaccharide was studied using various separation membranes ranging from a precision permeation membrane with a large pore size to a reverse osmosis membrane with a very small pore size, the following results were obtained.

First, when passed using a precision permeation membrane with a nominal diameter of 0.2μ, this membrane has a large liquid permeation flux, but all of the above-mentioned polysaccharides, which are the causative agents of turbidity, permeate through the membrane with the liquid. It could not be removed because it had clogged up, and showed no effect of removing the coloring component.

Further, when a test was performed on a so-called loose reverse osmosis membrane having a low desalination rate, the above-mentioned causative substance of turbidity could be removed at a high removal rate, and high results were obtained in both the decolorization rate and the desalination rate. However, some of the erythritol was removed by the membrane, and the result was that the permeation flux of the liquid was extremely low.

Furthermore, when a test was conducted on an ultrapermeable membrane, a membrane with a molecular weight cutoff of 100,000 or less could efficiently remove the turbidity components described above, and the smaller the molecular weight cutoff of the membrane, the higher the decolorization effect, and the use of activated carbon. It turned out that the amount can be reduced. However, when the molecular weight cutoff is too small, the permeation flux of the liquid is significantly reduced, and it was found that a membrane having a molecular weight cutoff 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 is a supernatant of a culture solution obtained by culturing an erythritol-producing bacterium under aerobic conditions in an aqueous medium, having a molecular weight cutoff of 1,
This is a method characterized by recovering erythritol from the obtained liquid after passing through an ultrapermeable membrane of 0000 to 100,000.

The ultrafiltration membrane used in the present invention has a molecular weight cutoff in the range of 1,000 to 100,000 as described above, but this is because if the molecular weight cutoff is too large, the removal efficiency of turbid components will decrease. Moreover, the decolorizing effect is also lost. Also, if the molecular weight cut off is too small, the permeation flux of the liquid will be small.

There are various materials for the ultrafiltration membrane, such as polysulfone, polyacrylonitrile, polyamide, polyvinylidene fluoride, chlorinated polyethylene, polyvinyl alcohol, polymethylmethacrylate, polyimide, cellulose acetate, cellulose, and various other heavy metals. Examples thereof include a polymer or a copolymer, or a mixture of these (co) polymers. Also, the shape of the ultrapermeable membrane is hollow fiber,
Various shapes such as a flat film shape, a spiral shape, and a tubular shape are used.

The separation / recovery method of the present invention will be described in more detail. First, a culture solution obtained by culturing an erythritol-producing bacterium under aerobic conditions in an aqueous medium is used to centrifuge cells by a method such as centrifugation or excess. Solid substances such as are separated and removed to obtain a supernatant. The culture itself of the erythritol-producing bacterium is already known, and therefore its explanation is omitted.

Then, when the supernatant liquid is passed through the ultrafiltration membrane, the polysaccharide that is the causative agent of the turbidity contained in the supernatant liquid is removed, so that the liquid is no longer contained in the liquid. Contains no polysaccharides. The liquid obtained by passing through the ultrafiltration membrane is preferably decolorized by treatment with activated carbon, but when passing through the ultrafiltration membrane, a part of the coloring component (20% of the coloring component) is removed simultaneously with the removal of the polysaccharide. (About ~ 40%) is also removed, so the amount of activated carbon used during activated carbon treatment is smaller than usual.

The supernatant after the activated carbon treatment is preferably desalted and decolorized by using the same ion exchange resin as the ordinary ion exchange resin treatment, and then the desired concentration (for example, 40 to 80% by weight in erythritol concentration). ), And then precipitate erythritol crystals while cooling. Highly pure erythritol crystals can be obtained by centrifuging or passing the slurry in which crystals have been precipitated to separate it from the mother liquor. In this case, since the above-mentioned polysaccharide in the supernatant liquid has been removed by filtration with the ultrafiltration membrane, the precipitated erythritol crystals do not cause micronization, so that the separation by centrifugation or filtration is significantly facilitated. Become. Further, the obtained product erythritol crystals are of good quality with no turbidity even when dissolved in water.

In the above method, the liquid with the ultrafiltration membrane was treated with activated carbon, further treated with an ion exchange resin, and then concentrated for crystallization, but the desired erythritol crystal to be obtained was obtained. Depending on the purity, part or all of the treatment with activated carbon or the treatment with ion-exchange resin may be omitted to carry out concentration for crystallization.

(Examples, etc.) Next, examples and comparative examples will be described in more detail.

Example 1 SN-G42 strain of Aureobasidium sp. Was added to a medium containing 300 g / anhydrous crystalline extract and 6.7 g / yeast extract and shake-cultured at 30 ° C for 72 hours to obtain a seed medium. . This seed medium 1.5 was mixed with anhydrous crystalline glucose 340 g / corn. Medium 25 containing 55 g of staple liquor (with an initial pH of 4.
2), aeration rate 25 / min, stirring speed 600 rpm, temperature 35
After culturing for 93 hours under conditions of ℃ and pressure of 0.5 kg / cm ² G, glucose was completely lost. Immediately after stopping the culture and sterilizing by heating, the cells were separated by centrifugation. The obtained supernatant contained 187 g / erythritol and 25 g / glycerin.

Each of the resulting supernatants (10) (absorbance at ₄₂₀ mμ measured with a 1 cm cell as an index of coloring degree, that is, A ₄₂₀ was 5.8) was used as various hollow fiber-like materials having the performance shown in Table 1. Using the membrane module devices containing the respective ultra-supermembranes (membrane 1, membrane 2 and membrane 3) under the following over-operation conditions, the results shown in Table 2 were obtained.

Over-operation conditions Membrane inlet pressure 1.5 kg / cm ² G Membrane outlet pressure 1.0 kg / cm ² G Liquid temperature 25 ° C Superfluid volume 10 In addition, the liquid obtained by repeating the above membrane 1 (about 9) The temperature was raised to 50 ° C., 248 g of activated carbon was added, the mixture was stirred for 0.5 hour to decolorize, and then the activated carbon was removed by filtration.

About 8.8 of the liquid (A ₄₂₀ was 0.3.) Was used as a cation exchange resin tower (trade name DIAION
SK1B packed), anion exchange resin tower (Mitsubishi Kasei Kogyo Co., Ltd., trade name Diaion WA30 packed), and mixed bed tower (Mitsubishi Kasei Kogyo Co., Ltd., trade name Diaion SK1B and PA408 packed) are sequentially passed through and dewatered. Salt treatment was performed. About 12 of the ion-exchange treated liquid including the ion-exchange tower extruded after the desalting treatment and washing water was heated to 80 ° C. under reduced pressure of 100 mmHg to be evaporated and concentrated. Crystals of erythritol were precipitated while gradually cooling the obtained concentrated solution having an erythritol concentration of 62% by weight to 15 ° C. The crystals obtained are dissolved in water to give 10
The solution was a wt% aqueous solution, but no turbidity was observed.

Comparative Example 1 The precision permeation membrane shown in Table 1 was used, and otherwise the same culture supernatant as in Example 1 was passed. The results are shown in Table 2, and the polysaccharide could not be removed at all.

Comparative Example 2 Using the flat membrane filtration device using a so-called loose reverse osmosis membrane having low desalting performance shown in Table 1, the same supernatant of the culture solution as in Example 1 was used as follows. When passed under the over-operation condition, the results shown in Table 2 were obtained.

Overoperation conditions Operating pressure 10kg / cm ² G Stirring 500rpm Liquid temperature 25 ℃ Liquid excess 250ml In the case of Comparative Example 2, polysaccharide could be removed, but at the same time erythritol was also removed and the amount of permeate was remarkably small. Therefore, it could not be put to practical use.

Comparative Example 3 The same culture solution as in Example 1 was heat-sterilized, and then the cells were separated by centrifugation. The obtained supernatant contained 187 g / erythritol and 25 g / glycerin. The resulting supernatant (about 10) was heated to 50 ° C and activated carbon 500g
Was added and treated for 0.5 hour for decolorization, and then the activated carbon was removed by filtration. In this case, 82% excess amount of activated carbon was required as compared with Example 1, and the A _{420 of the} decolorization treatment solution was 0.3.

Then, the decolorization treatment liquid was subjected to the same ion exchange resin treatment as in Example 1. Erythritol crystals were precipitated while gradually cooling the concentrated solution of erythritol concentration of 62 wt% obtained by evaporating and concentrating the treated solution of about 12 at 80 ° C under reduced pressure of 100 mmHg to 15 ° C. . An attempt was made to separate the erythritol crystals from the mother liquor by separately separating the crystal precipitation liquid, but it was difficult to pass due to turbidity, but erythritol crystals were forcibly washed with water to obtain erythritol crystals. When the crystals were dissolved in water to prepare a 10 wt% aqueous solution, turbidity was observed.

(E) Effect of the Invention According to the method for separating and recovering erythritol of the present invention, the polysaccharide as the turbidity-causing substance is easily and completely removed at the time of passing through the ultrafiltration membrane. Erythritol crystals which do not occur, facilitate the separation of erythritol crystals, and do not cause turbidity when dissolved in water, and which are excellent in quality are obtained. Further, since about 20 to 40% of the coloring component is removed by the ultrafiltration membrane, the amount of the activated carbon for decolorization used can be greatly reduced.

Claims (3)

[Claims] 1. A supernatant of a culture solution obtained by culturing an erythritol-producing bacterium in an aqueous medium under aerobic conditions, which is obtained by passing it through an ultrafiltration membrane having a molecular weight cutoff of 1,000 to 100,000. A method for separating and recovering erythritol, which comprises recovering erythritol from the obtained liquid. 2. The method according to claim 1, wherein erythritol is recovered after treating the liquid with the ultrafiltration membrane with activated carbon. 3. The method according to claim 1, wherein the erythritol crystal is obtained by subjecting the liquid obtained by the ultrafiltration membrane to activated carbon treatment, then ion exchange resin treatment, and then concentration to cause crystallization.