JPH0260597A - Purification of xanthane gum - Google Patents

Abstract

PURPOSE:To accomplish the purification of xanthane gum improved in the clearness of its aqueous solution without impairing its characteristics by holding a crude aqueous solution of xanthane gum at a specified temperature to flocculate the impurities contained followed by cooling the system to a specified temperature, filtration and the dehydration to make a recovery. CONSTITUTION:A crude aqueous solution of xanthane gum produced by e.g., a culture method is warmed for 0.5min-3hr to 80-90 deg.C and kept in this state to effect flocculation of the impurities protein contained in the solution without causing viscosity drip-off due to thermal deterioration. Thence, the temperature of this solution is lowered to 55-65 deg.C, and the system is subjected to filtration to remove the insolubles such as protein flocculated. KCl is added to the resultant filtrate followed by adding 2-3vol. times the filtrate volume of a hot water- soluble solvent such as isopropyl alcohol to the system to separate a xanthane gum precipitate out. This precipitate is then squeezed, dried and ground, thus obtaining a purified product. Thereby the objective purified xanthane gum can be obtained. This purified xanthane gum is such that its aqueous solution is favirable in clearness with the viscosity also favorably, retained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for purifying crude xanthan gum. Xanthan gum is a natural polysaccharide produced by xanthan gum-producing microorganisms of the genus Xanthomonas, such as Xanthomonas campestrinus. Its chemical structure is β-
The entire main chain of the cellulose skeleton has D-glucose bonded with β-t4, and 6 is attached to the 3rd position of the main chain glucose residue.
- Acetylmafnose, D-glucuronic acid, and pyruvic acid have side chains attached to D-mannose, which is coupled to the 4.6-position.

Generally, xanthan gum has better solubility in cold water than other natural gums, and its aqueous solution has high viscosity in the low concentration range. The viscosity properties show typical pseudoplanutic flow behavior, with high apparent viscosity at low shear rates and low apparent viscosity at high shear rates. This property makes it effective as an emulsion stabilizer, so it is used as an emulsion stabilizer in dressings. In addition, xanthan gum aqueous solution has high viscosity stability against acids, alkalis, various enzymes, heat, and salts, and due to these properties, it is used as a thickener and additive in many foods. ing. For example, xanthan gum's stability against acids makes it useful as an additive for acidic foods such as dressings, its stability against heat makes it useful as an additive for retort foods, and its stability against various enzymes and salts makes it useful as an additive for pickles. This is a useful property in some cases.

[Conventional technology]

Crude xanthan gum contains proteins and fibers that impair the transparency of the aqueous solution, and methods to improve the aqueous solution transparency of xanthan gum products have been studied. A method is used in which proteins are denatured by heat and then separated and removed. For example, Japanese Patent Publication No. 60-5478 describes a method for improving transparency by filtering a xanthan fermented liquid while heating it to a high temperature of 112°C to 160°C.

[Problem that the invention seeks to solve]

However, in the xanthan gum products developed by the xanthan gum purification method disclosed in Japanese Patent Publication No. 60-3478, the xanthan gum bath liquid is maintained at a temperature of 112 to 160°C, so the filtration of the aqueous solution is not completed. During this period, thermal deterioration of xanthan gum molecules progresses.

In addition, raising the temperature of the solution of crude xanthan gum to a high temperature of 112 to 160°C requires a lot of energy, which poses an economical problem, and tends to cause thermal deterioration. has safety issues.

For this reason, there has been a need for a method for purifying xanthan gum that can improve the transparency of the water bath solution without sacrificing the custom properties of xanthan gum.

Means for Solving Problem C] In view of the above situation, the present inventors have conducted extensive studies on a method for purifying crude xanthan gum that improves the transparency of an aqueous xanthan gum solution, and as a result, have arrived at the present invention.

That is, the present invention provides a crude xanthan gum aqueous solution t-80
After holding the xanthan gum at a temperature of ~90°C for a sufficient time to cause the impurities in the aqueous solution to coagulate without substantially detonating the thermal deterioration of the xanthan gum, the solution is cooled to 55~60°C, and then filtered and dehydrated. The main feature lies in the method for purifying xanthan gum.

The crude xanthan gum aqueous solution used in the present invention may be a xanthan gum culture solution obtained by a culture method, or a crude xanthan gum powder recovered by adding inglobil alcohol to the culture solution and dissolving it in water. good.

Alternatively, crude xanthan gum powder recovered after removing impurities (+- to some extent) may be dissolved in water.

To obtain a crude xanthan gum aqueous solution, an aqueous solution obtained by a known xanthan gum culture method may be used as is, or a crude xanthan gum form may be used, and the crude xanthan gum form may be placed in water at 5 to 50°C to prevent the formation of lumps. After adding and stirring to disperse the
An example is a method of heating to 0 to 90°C and holding at that temperature to obtain a water bath liquid.

When carrying out the method of the present invention, the crude xanthan gum aqueous solution is heated and maintained, and if the temperature of the solution M for coagulating impurities is less than 80°C, the proteins contained in the crude xanthan gum aqueous solution will sufficiently agglomerate due to heat. However, filtration is difficult, and even if the solution is cake-filtered using an ordinary filter aid, the unbathed/I# protein contained in the solution is not sufficiently filtered out, and furthermore, such undissolved matter is removed by filtration. In order to remove xanthan gum from an aqueous solution by filtration, it is necessary to use a very small filter aid with an average particle size of 1 to 5 μm, and when such a filter aid is used, the furnace material often gets clogged during filtration. It is not preferable to set the processing temperature to less than 80° C., since there is a problem that productivity is greatly reduced.

Further, when the temperature of the aqueous solution exceeds 90° C., although thermal aggregation of proteins is sufficient, the viscosity of the aqueous solution of purified xanthan gum decreases due to thermal deterioration of xanthan gum molecules, which is not preferable.

The gum concentration in the xanthan gum aqueous solution used in carrying out the present invention is preferably α5 to t2% (w/w).

If the gum concentration is less than α5% (w/w), the recovery efficiency will decrease, which is not preferable. Also, the gum concentration is t2% (w
/w) 't: If it exceeds, the viscosity of the aqueous solution is too high;
This is not preferable because filtration in the post-process becomes difficult. In addition, the heating time of the crude xanthan gum aqueous solution at 80 to 90°C is [
The heating time is preferably between 15 minutes and 6 hours; if the heating time is too short, the effect of aggregating impurities cannot be obtained, and if the heating time is too long, the xanthan gum will thermally decompose, which is not preferable.

Next, the solution temperature of the crude xanthan gum aqueous solution prepared as described above is lowered to 55 to 65°C, and then subjected to filtration to remove insoluble matter such as aggregated proteins and fibers.

Examples of methods for lowering the temperature of the crude xanthan gum aqueous solution in the heat treatment layer include a method of adding cold water to the solution and a method of passing cold water through the rotation of the dissolution tank.

In the present invention, in order to improve the transparency of the aqueous solution, it is necessary to discharge Fd'kj=IN after a cake layer is sufficiently formed by a filter press and the F solution becomes clear, but the solution temperature at the time of filtration is 55°C. If it is less than that, filtration takes a long time and productivity decreases, which is not preferable. Also 65℃
If it exceeds 10%, the viscosity of the aqueous solution of ff1U xanthan gum will decrease due to thermal deterioration of the xanthan gum molecules until the entire amount of p-liquid is taken out, which is not preferable.

1,0 for r1 filtration stock solution as cooling axe of filter aid j
~2.0% (w/v) is preferable, and the average particle size of the filter aid is preferably 5 to 10 μm.

If the average particle size of the filter aid is less than 5 μm, the filtration property will be poor and the filtration characteristics will be deteriorated, which is undesirable. If the particle size is larger than 10 μm, insoluble matter cannot be removed sufficiently, which is not preferable.

The P solution obtained as described above is then subjected to a dehydration/recovery step, where v'i, KCl (i-1%
(w/v), and then add xanthan gum precipitate by adding hot water-soluble bath agents, such as alcohols, ketones, dioxane, especially 2 to 3 times the volume of Inglobil alcohol tP liquid volume, and press it. This is done by drying and pulverizing, and by doing so, xanthan gum made from dichotomous can be obtained.

〔Effect of the invention〕

According to the present invention, it is possible to provide purified xanthancum that can maintain a good water bath solution viscosity and have good aqueous solution transparency.

Hereinafter, the present invention will be explained in detail according to the embodiments. still,
The water @ liquid viscosity of purified xanthan gum and the transparency of the aqueous solution in the practical column and ratio 'Is column are 0.6? (absolutely dry equivalent) was stirred and dispersed in ion-exchanged water 4002, stirred and dissolved in a 85°C water bath for 1 hour, and then the water content was corrected to 2[-400r], which was then cooled to 25°C. The sample is shown as the measured value (cps) using a BL type viscometer NQ, 2 spindles, 6 Orpm, and the transmittance (T%) at 660 Ωm using a spectrophotometer.

Example row 1: Crude xanthan gum 4.0 @Ji 267 t of water at 20°C
Disperse with stirring, raise the temperature to 80℃, and maintain the temperature at 85℃ for 1 hour.
The mixture was kept stirring for an hour. Next, add 133 tt of water at 20℃ to the solution.
The solution temperature was adjusted to 60°C by adding and stirring. Next &0
Yuno perlite was added and mixed, and filtered under pressure at 60°C using a filter press to obtain 350 L of liquid P. KCL next
Add and mix 5-5 Yu to the P solution, then add 87 to the F solution at 60℃.
．． 0% (W/W) inpropyl alcohol 700t
f was added to precipitate a gummy substance, which was then compressed, dehydrated, dried, and crushed to obtain purified xanthan gum of 2.8%. The viscosity of this aqueous solution of purified xanthan gum was 90 cps, and the transparency was 99.0%.

Comparative Example 1 Crude xanthan gum 4. The mixture was stirred and dispersed in 400 tons of water at 20°C, heated to 80°C, and kept stirring for 1 hour while maintaining the temperature at 85°C. Next, perlite from Tokyo was added and mixed, and filtered under pressure at 80°C using a filter press to obtain 550 tons of liquid F.

Next, KC4551K9f: After addition and mixing, the filtrate was cooled and adjusted to 60°C, then 700t of 87% (w/w) Ingrobil alcohol was added to precipitate a gummy substance, which was then compressed, dehydrated, dried, and crushed. .8 units of nI xanthan gum was obtained.

The viscosity of this purified xanthan gum water bath solution is 50 cps.
The transparency was 99.1%, and the viscosity was inferior to the examples.

Comparative Example 2 40 ml of crude xanthan gum was stirred and dispersed in 365 tons of water at 20°C, heated to 80°C, and kept stirring for 1 hour while maintaining the temperature at 80°C. Next, 671 g of 20°C water was added to the solution and stirred to adjust the solution temperature to 70°C. Next, &0 yu of perlite was added and mixed, and filtered under pressure at 70°C using a filter press to obtain 350 t of liquid F.

Next, in the same manner as in Comparison Row 1, 2.8 nI xanthan gum was obtained.

The viscosity of this aqueous solution of xanthan gum made by N is 70 cps
The transparency was 990% and the viscosity was inferior to that of the actual sample.

Comparison row 3 Crude xanthan gum 10Kl? The mixture was stirred and dispersed in 450 tons of water at 20°C, heated to 60°C, and kept stirring for 1 hour while maintaining the temperature at 60°C. Next, the mixture was filtered and dehydrated and recovered in the same manner as in the example to obtain xanthan gum manufactured by nI at 2.8 hours.

The viscosity of this aqueous solution of purified kisa/tan gum is 95 cps.
``C reed, the transparency was 85.0, which was significantly inferior to the actual row.

Comparative Example 4 Crude xanthan gum 4. 213 tons of water at 20℃
Disperse with stirring, raise the temperature to 95°C, and while maintaining 95°C.
The mixture was kept stirring for an hour. Next, 187 tons of water at 20° C. was added to the solution, stirred, and the solution temperature was adjusted to 60° C., followed by filtration and dehydration recovery in the same manner as in the example to obtain 2.8 units of purified xanthan gum.

The viscosity of the aqueous solution of xanthan gum made from this (“;
ape), the transparency was 99.2%, and the viscosity was inferior to that of the actual sample.

Claims (5)

[Claims] (1) After holding the crude xanthan gum aqueous solution at a temperature of 80 to 90°C for a time that does not cause substantial thermal deterioration to the xanthan gum and sufficiently coagulates impurities in the aqueous solution, the aqueous solution is adjusted to 55 to 65°C. A method for purifying xanthan gum characterized by filtration and dehydration recovery. (2) The method for purifying xanthan gum according to claim 1, characterized in that the heat treatment time of the crude xanthan gum aqueous solution at 80 to 90°C is 0.5 minutes to 3 hours. (3) The method for purifying xanthan gum according to claim 1, wherein the method for cooling the crude xanthan gum solution after heat treatment is performed by adding water to the xanthan gum solution. (4) The method for recovering purified xanthan gum from the filtrate of the crude xanthan gum aqueous solution after heat treatment is carried out by adding potassium chloride and 1.5 to 4 times the amount of a hydrophilic organic solvent to the filtrate. The method for purifying xanthan gum described in Section 1. (5) The method for purifying xanthan gum according to claim 4, characterized in that isopropyl alcohol is used as the hydrophilic organic solvent.