CA2015584C - Process for the recovery of polysaccharides - Google Patents
Process for the recovery of polysaccharidesInfo
- Publication number
- CA2015584C CA2015584C CA002015584A CA2015584A CA2015584C CA 2015584 C CA2015584 C CA 2015584C CA 002015584 A CA002015584 A CA 002015584A CA 2015584 A CA2015584 A CA 2015584A CA 2015584 C CA2015584 C CA 2015584C
- Authority
- CA
- Canada
- Prior art keywords
- process according
- water
- polysaccharide fibers
- weight
- washing liquid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 229920001282 polysaccharide Polymers 0.000 title claims abstract description 37
- 239000005017 polysaccharide Substances 0.000 title claims abstract description 37
- 150000004676 glycans Chemical class 0.000 title claims abstract description 36
- 238000000034 method Methods 0.000 title claims abstract description 29
- 230000008569 process Effects 0.000 title claims abstract description 29
- 238000011084 recovery Methods 0.000 title 1
- 239000007788 liquid Substances 0.000 claims abstract description 34
- 238000005406 washing Methods 0.000 claims abstract description 34
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 30
- 238000000855 fermentation Methods 0.000 claims abstract description 10
- 230000004151 fermentation Effects 0.000 claims abstract description 10
- 230000001376 precipitating effect Effects 0.000 claims abstract description 9
- 241000589634 Xanthomonas Species 0.000 claims abstract description 6
- 241000186063 Arthrobacter Species 0.000 claims abstract description 5
- 241000894006 Bacteria Species 0.000 claims abstract description 4
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims description 50
- 239000000835 fiber Substances 0.000 claims description 29
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 7
- DKGAVHZHDRPRBM-UHFFFAOYSA-N Tert-Butanol Chemical compound CC(C)(C)O DKGAVHZHDRPRBM-UHFFFAOYSA-N 0.000 claims description 6
- 150000001298 alcohols Chemical class 0.000 claims description 3
- 238000005054 agglomeration Methods 0.000 claims description 2
- 230000002776 aggregation Effects 0.000 claims description 2
- 239000000203 mixture Substances 0.000 claims description 2
- 239000002245 particle Substances 0.000 abstract description 8
- 238000001556 precipitation Methods 0.000 description 12
- 239000000047 product Substances 0.000 description 10
- 238000001035 drying Methods 0.000 description 8
- 238000002156 mixing Methods 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 239000003795 chemical substances by application Substances 0.000 description 4
- 239000012467 final product Substances 0.000 description 3
- 238000000227 grinding Methods 0.000 description 3
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 description 2
- 241000589636 Xanthomonas campestris Species 0.000 description 2
- 238000010564 aerobic fermentation Methods 0.000 description 2
- 238000010981 drying operation Methods 0.000 description 2
- 239000008103 glucose Substances 0.000 description 2
- 239000008187 granular material Substances 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 239000003381 stabilizer Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 239000000839 emulsion Substances 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000008570 general process Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 235000015097 nutrients Nutrition 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 238000011020 pilot scale process Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 230000001172 regenerating effect Effects 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 239000012798 spherical particle Substances 0.000 description 1
- 238000009987 spinning Methods 0.000 description 1
- 239000006228 supernatant Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 239000002562 thickening agent Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/12—Powdering or granulating
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
- C08B37/00—Preparation of polysaccharides not provided for in groups C08B1/00 - C08B35/00; Derivatives thereof
- C08B37/0003—General processes for their isolation or fractionation, e.g. purification or extraction from biomass
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/12—Powdering or granulating
- C08J3/14—Powdering or granulating by precipitation from solutions
-
- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
- C12P19/00—Preparation of compounds containing saccharide radicals
- C12P19/04—Polysaccharides, i.e. compounds containing more than five saccharide radicals attached to each other by glycosidic bonds
- C12P19/06—Xanthan, i.e. Xanthomonas-type heteropolysaccharides
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2305/00—Characterised by the use of polysaccharides or of their derivatives not provided for in groups C08J2301/00 or C08J2303/00
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Polymers & Plastics (AREA)
- Medicinal Chemistry (AREA)
- Zoology (AREA)
- General Health & Medical Sciences (AREA)
- Wood Science & Technology (AREA)
- Biochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Biotechnology (AREA)
- Materials Engineering (AREA)
- Microbiology (AREA)
- Molecular Biology (AREA)
- Sustainable Development (AREA)
- Bioinformatics & Cheminformatics (AREA)
- General Engineering & Computer Science (AREA)
- Genetics & Genomics (AREA)
- Polysaccharides And Polysaccharide Derivatives (AREA)
- Preparation Of Compounds By Using Micro-Organisms (AREA)
Abstract
Proposed is a process of recovering polysaccharides in granular, free-flowing form produced by bacteria of the species Xanthomonas or Arthrobacter, wherein the polysaccharides are precipitated by the addition of the precipitating liquid to the fermentation medium, are then separated, washed with an organic liquid which is preferably also employed as the precipitating liquid, are then washed, separated and subsequently dried, the polysaccharide particles being coarsely separated from the washing liquid after washing, kept in motion with the addition of water and subsequently dried, preferably with continued motion.
Description
~ 2 ~ ~ 5 ~ ~ 4 The invention relates to a process of recovering polysaccharides in granular, free-flowing form produced by bacteria of the species Xanthomonas or Arthrobacter, wherein the polysaccharides are precipitated by adding a precipitating liquid to the fermentation medium, are then separated, washed with an organic washing liquid which is preferably also used as the precipitating liquid, separated and subsequently dried.
Processes of this type are known and described, e.g.
in Austrian Patent No. 330,121 issued on June 10, 1976.
Polysaccharides fermentatively formed by Xanthomonas and Arthrobacter are exo-polysaccharides; the Xanthomonas products are designated as xanthane and are an industrial product which is used as a regulator of the flowing properties of aqueous systems due to its rheological behavior and as a stabilizer for emulsions and suspensions. Its high thermostability, pronounced pH
resistance and unusually good compatibility with salts have opened a broad industrial application spectrum for xanthane. Xanthane formed by Xanthomonas campestris, for instance, is admitted as a thickener and stabilizer for foodstuffs.
Xanthane is produced industrially by aerobic fermentation of a glucose-containing fermentation broth.
After depletion of the carbon source, the xanthane-containing mash is pasteurized and the xanthane is precipitated by adding an organic liquid, usually a low alcohol like isopropanol. When using isopropanol, the precipitation concentration ranges between 45 and 60~ by weight of alcohol. The precipitation concentration is influenced by the electrolyte content of the mash and can be reduced by the addition of salts prior to precipitation. The precipitated and separated xanthane is subsequently taken up, but not dissolved, in a suitable organic liquid for further purification. The washing liquid is usually identical with the liquid used for 2 ~
precipitation, thus mostly isopropanol. After separating the washed and thus purer xanthane, this is dried and ground.
In its usual commercial form, xanthane is a powdered, free-flowing product. As the free-flowing property of the powder is determined by the structure of the individual particles, particles of granular appearance are sought, while fibrous, fluffy particles cause difficulties during grinding, packing and finally during metering.
AT-PS 330 121 discusses the problem of obtaining xanthane with granular and not fibrous particles and proposes as a solution of this problem to use a washing liquid whose organic portion does not exceed a certain range to be determined by experiments, as this would result in a fibrous structure, and does not fall short of this range, as this would yield a tacky product. When using isopropanol/water as a washing liquid, the reference states that the isopropanol content should be by 8 to 25% by weight higher than the isopropanol content just barely sufficient for dissolving the xanthane; a range of 9 to 28% by weight is indicated for tert-butanol/water. The usual azeotropic distillates, i.e.
87.8% isopropanol and 96.5% tert-butanol, are explicitly mentioned in AT-PS 330 121 as washing liquids unsuitable for obtaining a granular structure: these alcohols must always be diluted with water.
This results, among others, in the fact that the washing liquid can subsequently not be used as the precipitation liquid because its alcohol concentration is too low; precipitation liquid and washing liquid must be upgraded.
It was now surprisingly found that it is also possible in the recommendable use of high-percentage organic washing liquids to obtain a granular, free-flowing final product in spite of the primarily fibrousstructure of the xanthane formed.
According to the present invention, there is provided a process of recovering polysaccharides in granular, free-flowing form produced in a fermentation medium by bacteria of the species Xanthomonas or Arthrobacter, wherein the polysaccharides are precipitated in the form of fibers by the addition of a precipitating liquid to the fermentation medium, and the polysaccharide fibers are separated and washed with an organic washing liquid.
The process of the invention is characterized in that the polysaccharide fibers are coarsely separated from the washing liquid after washing, are kept in motion with the addition of water to cause agglomeration of the polysaccharide fibers, and the agglomerated polysaccharide fibers are dried to obtain the desired polysaccharides in granular, free-flowing form.
Preferably, up to about 40% by weight, in particular 8 to 30% by weight, more particularly 10 to 15% by weight, of water based on their dry weight are added to the polysaccharide fibers, based on the dry weight of the polysaccharide fibers. The agglomerated polysaccharide fibers are preferably dried with continued motion.
In other words, the xanthane fibers are moistened prior to drying, the most uniform, possible distribution of the amount of water added being aimed at, to be achieved by intimate mixing.
Not all the water should be added at once in order to prevent the formation of lumps; the water is preferably added within a period of up to one hour, in particular of 10 to 30 minutes, preferably continuously.
It is assumed that in the process according to the invention, the xanthane fibers are first surface-solubilized and subsequently agglomerated; this results in a granular, free-flowing and easily manipulable final product.
,, ~ ~ ~ $ ~ $ ~
Keeping the material in motion prevents the formation of larger aggregates.
Since the washing agent still present evaporates in the course of subsequent drying, i.e. the H20 concentration increases locally, the material is conveniently also kept in motion during drying.
The moistening of the washed material is most conveniently effected in the drier itself, in particular in a drum drier at rotating drum.
A preferred manner of carrying out the washing and drying treatment according to the invention is described as follows:
The precipitated xanthane is taken up in isopropanol recovered by industrial distillation (about 87%) and washed with stirring at room temperature. The dwell time amounts to 10 to 30 minutes. The amount of isopropanol is up to 100 times, preferably 45 to 55 times, the amount of xanthane. After this washing operation, the xanthane is of fibrous structure - 4a -CA 020l~84 l999-02-lO
and is introduced into a vacuum drum drier after separating the washing solution. This drier is equipped with a spinning device for the intensive mixing of the product. Prior to drying, water is sprayed onto the 5 fibrous xanthane with intimate mixing. In order to prevent the possible formation of lumps, the water must be finely distributed. This is achieved by gradual addition via jets during mixing. The addition period ranges from 10 to 30 minutes. The amount of water 10 metered in amounts to 8 to 30 percent, preferably 10 to 15 percent, of the dry substance present in the drier.
If the volume of water metered in is too low, the product remains fibrous. Too much water causes the formation of grains difficult to comminute. The 15 subsequent drying operation with continued intimate mixing is effected in the usual gentle manner in vacuo and is to assure an adequately low residual isopropanol content in the final product (500 ppm). Prior to the addition of water, so much washing liquid is separated, 20 e.g. squeezed, from the polysaccharide particle/washing agent phase that a solids content of at least about 40 percent by weight, preferably 50 to 55 percent by weight, is obtained. The drying operation itself is effected within a temperature range of 50 to 120~C, 25 preferably of 60 to 80~C, and preferably with application of negative pressure. In particular, a residual vacuum of about 100 mbar is adjusted.
By the intensive motion of the material with the addition of water by means of the spinner, the fibers 30 are transformed to spherical particles. Since the volatile isopropanol first evaporates during drying, the higher water content of the drying material facilitates the surface-solubilizing of the xanthane fibers. This causes the formation of xanthane particles of denser 35 granular structure.
CA 0201~84 1999-02-10 As the isopropanol does not have to be diluted for washing, the advantage of this manner of proceeding, among others, resides in the fact that the spent washing solution does not have to be regenerated, but can 5 economically directly be used for the precipitation of the xanthane from the mash. This saves operating and installation costs for washing liquid regeneration. Only a single isopropanol purification and recovering facility is required. The economical use of the washing solution for the precipitation of the xanthane from the mash is made possible by the high isopropanol concentration of the washing solution. At a given amount of mash and a given precipitation concentration, the amount of alcohol to be regenerated depends on the 15 isopropanol concentration in the precipitating agent.
Since the increase of the isopropanol concentration in the precipitating agent causes a decrease of the amount of isopropanol to be regenerated, the regenerating cost is reduced.
The general process is described on the basis of the following practical example.
Example:
A fermentation broth was obtained by aerobic fermentation of a glucose-containing nutrient solution 25 (40 g/l) inoculated with Xanthomonas campestris. The fermentation was interrupted at a residual sugar content of 0.1 percent. The fermentation broth was pasteurized and the xanthane was subsequently continuously precipitated by the addition of isopropanol of about 86 30 percent by weight. The precipitation was carried out in a vessel of a volume of 100 1 equipped with turbine agitator by parallel pumping in of mash and of isopropanol of about 86 percent by weight. At the same time, the precipitated xanthane with the suspending 35 alcohol-water mixture was pumped off. The ratio of amount of mash to amount of alcohol is determined by the CA 020l~84 l999-02-lO
precipitation concentration which ranges at about 50 percent by weight of isopropanol. In order to assure an intimate contact between mash and isopropanol, the turbine agitator is operated at 1,000 rpm. The xanthane 5 fibers are subsequently separated from the supernatant, suspended in 50 times the amount of isopropanol (86 percent by weight) and washed for 10 minutes with intensive stirring (turbine agitator at 1,000 rpm).
Precipitation and washing are carried out at about 20~C.
10 The washed fibrous xanthane is separated via a fine mesh screen and manually pressed out.
a) Further treatment not according to the invention:
30 kg of moist product (this amount corresponds to 15 about 15 kg of dry xanthane substance) are introduced into a pilot scale vacuum drum drier. The drum drier is equipped with a spinner for mixing the dry matter. After applying the vacuum, the temperature is increased with the spinner running at 300 rpm until a final temperature 20 of 80~C and a residual vacuum of 100 mbar is obtained.
The dried xanthane has a dry matter content of about 93 percent and is of fibrous or fluffy structure. The portion to be ground (particle size 95 percent 180 ~m) has an apparent density of 0.41. The ground product has 25 the appearance (at 50-fold enlargement) shown in Fig. 1.
b) Further treatment according to the invention:
The drum drier is charged as indicated under a).
Then the spinner is turned on and operated at 300 rpm and about 2 liters of water are sprayed onto the moving 30 xanthane via a nozzle within about 10 minutes. The drying process is as described in a). The xanthane is obtained in the form of round grains and small granules.
The residual moisture content amounts to about 7 percent, the residual isopropanol content amounts to CA 0201~84 1999-02-10 less than 500 ppm. After grinding, the power consists of granules, has a higher apparent density than the product dried without the addition of water and flows more freely. The apparent density after grinding (grain size 5 95 percent 180 ~m) amounts to about 0.7 (mean value).
The ground product has the appearance (at 50-fold enlargement) shown in Fig. 2.
- 7a -
Processes of this type are known and described, e.g.
in Austrian Patent No. 330,121 issued on June 10, 1976.
Polysaccharides fermentatively formed by Xanthomonas and Arthrobacter are exo-polysaccharides; the Xanthomonas products are designated as xanthane and are an industrial product which is used as a regulator of the flowing properties of aqueous systems due to its rheological behavior and as a stabilizer for emulsions and suspensions. Its high thermostability, pronounced pH
resistance and unusually good compatibility with salts have opened a broad industrial application spectrum for xanthane. Xanthane formed by Xanthomonas campestris, for instance, is admitted as a thickener and stabilizer for foodstuffs.
Xanthane is produced industrially by aerobic fermentation of a glucose-containing fermentation broth.
After depletion of the carbon source, the xanthane-containing mash is pasteurized and the xanthane is precipitated by adding an organic liquid, usually a low alcohol like isopropanol. When using isopropanol, the precipitation concentration ranges between 45 and 60~ by weight of alcohol. The precipitation concentration is influenced by the electrolyte content of the mash and can be reduced by the addition of salts prior to precipitation. The precipitated and separated xanthane is subsequently taken up, but not dissolved, in a suitable organic liquid for further purification. The washing liquid is usually identical with the liquid used for 2 ~
precipitation, thus mostly isopropanol. After separating the washed and thus purer xanthane, this is dried and ground.
In its usual commercial form, xanthane is a powdered, free-flowing product. As the free-flowing property of the powder is determined by the structure of the individual particles, particles of granular appearance are sought, while fibrous, fluffy particles cause difficulties during grinding, packing and finally during metering.
AT-PS 330 121 discusses the problem of obtaining xanthane with granular and not fibrous particles and proposes as a solution of this problem to use a washing liquid whose organic portion does not exceed a certain range to be determined by experiments, as this would result in a fibrous structure, and does not fall short of this range, as this would yield a tacky product. When using isopropanol/water as a washing liquid, the reference states that the isopropanol content should be by 8 to 25% by weight higher than the isopropanol content just barely sufficient for dissolving the xanthane; a range of 9 to 28% by weight is indicated for tert-butanol/water. The usual azeotropic distillates, i.e.
87.8% isopropanol and 96.5% tert-butanol, are explicitly mentioned in AT-PS 330 121 as washing liquids unsuitable for obtaining a granular structure: these alcohols must always be diluted with water.
This results, among others, in the fact that the washing liquid can subsequently not be used as the precipitation liquid because its alcohol concentration is too low; precipitation liquid and washing liquid must be upgraded.
It was now surprisingly found that it is also possible in the recommendable use of high-percentage organic washing liquids to obtain a granular, free-flowing final product in spite of the primarily fibrousstructure of the xanthane formed.
According to the present invention, there is provided a process of recovering polysaccharides in granular, free-flowing form produced in a fermentation medium by bacteria of the species Xanthomonas or Arthrobacter, wherein the polysaccharides are precipitated in the form of fibers by the addition of a precipitating liquid to the fermentation medium, and the polysaccharide fibers are separated and washed with an organic washing liquid.
The process of the invention is characterized in that the polysaccharide fibers are coarsely separated from the washing liquid after washing, are kept in motion with the addition of water to cause agglomeration of the polysaccharide fibers, and the agglomerated polysaccharide fibers are dried to obtain the desired polysaccharides in granular, free-flowing form.
Preferably, up to about 40% by weight, in particular 8 to 30% by weight, more particularly 10 to 15% by weight, of water based on their dry weight are added to the polysaccharide fibers, based on the dry weight of the polysaccharide fibers. The agglomerated polysaccharide fibers are preferably dried with continued motion.
In other words, the xanthane fibers are moistened prior to drying, the most uniform, possible distribution of the amount of water added being aimed at, to be achieved by intimate mixing.
Not all the water should be added at once in order to prevent the formation of lumps; the water is preferably added within a period of up to one hour, in particular of 10 to 30 minutes, preferably continuously.
It is assumed that in the process according to the invention, the xanthane fibers are first surface-solubilized and subsequently agglomerated; this results in a granular, free-flowing and easily manipulable final product.
,, ~ ~ ~ $ ~ $ ~
Keeping the material in motion prevents the formation of larger aggregates.
Since the washing agent still present evaporates in the course of subsequent drying, i.e. the H20 concentration increases locally, the material is conveniently also kept in motion during drying.
The moistening of the washed material is most conveniently effected in the drier itself, in particular in a drum drier at rotating drum.
A preferred manner of carrying out the washing and drying treatment according to the invention is described as follows:
The precipitated xanthane is taken up in isopropanol recovered by industrial distillation (about 87%) and washed with stirring at room temperature. The dwell time amounts to 10 to 30 minutes. The amount of isopropanol is up to 100 times, preferably 45 to 55 times, the amount of xanthane. After this washing operation, the xanthane is of fibrous structure - 4a -CA 020l~84 l999-02-lO
and is introduced into a vacuum drum drier after separating the washing solution. This drier is equipped with a spinning device for the intensive mixing of the product. Prior to drying, water is sprayed onto the 5 fibrous xanthane with intimate mixing. In order to prevent the possible formation of lumps, the water must be finely distributed. This is achieved by gradual addition via jets during mixing. The addition period ranges from 10 to 30 minutes. The amount of water 10 metered in amounts to 8 to 30 percent, preferably 10 to 15 percent, of the dry substance present in the drier.
If the volume of water metered in is too low, the product remains fibrous. Too much water causes the formation of grains difficult to comminute. The 15 subsequent drying operation with continued intimate mixing is effected in the usual gentle manner in vacuo and is to assure an adequately low residual isopropanol content in the final product (500 ppm). Prior to the addition of water, so much washing liquid is separated, 20 e.g. squeezed, from the polysaccharide particle/washing agent phase that a solids content of at least about 40 percent by weight, preferably 50 to 55 percent by weight, is obtained. The drying operation itself is effected within a temperature range of 50 to 120~C, 25 preferably of 60 to 80~C, and preferably with application of negative pressure. In particular, a residual vacuum of about 100 mbar is adjusted.
By the intensive motion of the material with the addition of water by means of the spinner, the fibers 30 are transformed to spherical particles. Since the volatile isopropanol first evaporates during drying, the higher water content of the drying material facilitates the surface-solubilizing of the xanthane fibers. This causes the formation of xanthane particles of denser 35 granular structure.
CA 0201~84 1999-02-10 As the isopropanol does not have to be diluted for washing, the advantage of this manner of proceeding, among others, resides in the fact that the spent washing solution does not have to be regenerated, but can 5 economically directly be used for the precipitation of the xanthane from the mash. This saves operating and installation costs for washing liquid regeneration. Only a single isopropanol purification and recovering facility is required. The economical use of the washing solution for the precipitation of the xanthane from the mash is made possible by the high isopropanol concentration of the washing solution. At a given amount of mash and a given precipitation concentration, the amount of alcohol to be regenerated depends on the 15 isopropanol concentration in the precipitating agent.
Since the increase of the isopropanol concentration in the precipitating agent causes a decrease of the amount of isopropanol to be regenerated, the regenerating cost is reduced.
The general process is described on the basis of the following practical example.
Example:
A fermentation broth was obtained by aerobic fermentation of a glucose-containing nutrient solution 25 (40 g/l) inoculated with Xanthomonas campestris. The fermentation was interrupted at a residual sugar content of 0.1 percent. The fermentation broth was pasteurized and the xanthane was subsequently continuously precipitated by the addition of isopropanol of about 86 30 percent by weight. The precipitation was carried out in a vessel of a volume of 100 1 equipped with turbine agitator by parallel pumping in of mash and of isopropanol of about 86 percent by weight. At the same time, the precipitated xanthane with the suspending 35 alcohol-water mixture was pumped off. The ratio of amount of mash to amount of alcohol is determined by the CA 020l~84 l999-02-lO
precipitation concentration which ranges at about 50 percent by weight of isopropanol. In order to assure an intimate contact between mash and isopropanol, the turbine agitator is operated at 1,000 rpm. The xanthane 5 fibers are subsequently separated from the supernatant, suspended in 50 times the amount of isopropanol (86 percent by weight) and washed for 10 minutes with intensive stirring (turbine agitator at 1,000 rpm).
Precipitation and washing are carried out at about 20~C.
10 The washed fibrous xanthane is separated via a fine mesh screen and manually pressed out.
a) Further treatment not according to the invention:
30 kg of moist product (this amount corresponds to 15 about 15 kg of dry xanthane substance) are introduced into a pilot scale vacuum drum drier. The drum drier is equipped with a spinner for mixing the dry matter. After applying the vacuum, the temperature is increased with the spinner running at 300 rpm until a final temperature 20 of 80~C and a residual vacuum of 100 mbar is obtained.
The dried xanthane has a dry matter content of about 93 percent and is of fibrous or fluffy structure. The portion to be ground (particle size 95 percent 180 ~m) has an apparent density of 0.41. The ground product has 25 the appearance (at 50-fold enlargement) shown in Fig. 1.
b) Further treatment according to the invention:
The drum drier is charged as indicated under a).
Then the spinner is turned on and operated at 300 rpm and about 2 liters of water are sprayed onto the moving 30 xanthane via a nozzle within about 10 minutes. The drying process is as described in a). The xanthane is obtained in the form of round grains and small granules.
The residual moisture content amounts to about 7 percent, the residual isopropanol content amounts to CA 0201~84 1999-02-10 less than 500 ppm. After grinding, the power consists of granules, has a higher apparent density than the product dried without the addition of water and flows more freely. The apparent density after grinding (grain size 5 95 percent 180 ~m) amounts to about 0.7 (mean value).
The ground product has the appearance (at 50-fold enlargement) shown in Fig. 2.
- 7a -
Claims (22)
1. A process of recovering polysaccharides in granular, free-flowing form produced in a fermentation medium by bacteria of the species Xanthomonas or Arthrobacter, wherein the polysaccharides are precipitated in the form of fibers by the addition of a precipitating liquid to the fermentation medium, and the polysaccharide fibers are separated and washed with an organic washing liquid, characterized in that the polysaccharide fibers are coarsely separated from the washing liquid after washing, are kept in motion with the addition of water to cause agglomeration of the polysaccharide fibers, and the agglomerated polysaccharide fibers are dried to obtain the desired polysaccharides in granular, free-flowing form.
2. A process according to claim 1, wherein the water is added in an amount up to about 40% by weight based on the dry weight of the polysaccharide fibers.
3. A process according to claim 2, wherein the water is added in an amount of 8 to 30% by weight, based on the dry weight of the polysaccharide fibers.
4. A process according to claim 3, wherein the water is added in an amount of 10 to 15% by weight, based on the dry weight of the polysaccharide fibers.
5. A process according to any of claims 1 to 4, wherein the water is added little by little over a period of up to one hour.
6. A process according to claim 5, wherein the water is added little by little over a period of 10 to 30 minutes.
7. A process to any one of claims 1 to 4, wherein the water is added continuously over a period of up to one hour.
8. A process according to claim 7, wherein the water is added continuously over a period of 10 to 30 minutes.
9. A process according to any one of claims 1 to 8, wherein the addition of water is effected in a drum drier while rotating the drum drier.
10. A process according to any one of claims 1 to 9, wherein the washing liquid is used as the precipitating liquid.
11. A process according to any one of claims 1 to 10, wherein the washing liquid is selected from the group consisting of azeotropic technical distillates of alcohols with low molecular weight.
12. A process according to claim 11, wherein the alcohols are selected from the group consisting of ethanol, isopropanol, tert-butanol and mixtures thereof.
13. A process according to claim 11, wherein the washing liquid is 87.8 vol.% isopropanol.
14. A process according to any one of claims 1 to 13, wherein the amount of washing liquid is ten to one hundred times that of the polysaccharide fibers.
15. A process according to claim 14, wherein the amount of washing liquid is 45 to 55 times that of the polysaccharide fibers.
16. A process according to any one of claims 1 to 15, wherein the washing liquid is separated to such an extent that a dry matter content of at least about 40% by weight is present in the polysaccharide fibers prior to the addition of water.
17. A process according to claim 16, wherein the dry matter content is between 50 and 55% by weight.
18. A process according to any one of claims 1 to 17, wherein the agglomerated polysaccharide fibers are dried at a temperature of 50 to 120°C.
19. A process according to claim 18, wherein the agglomerated polysaccharide fibers are dried at a temperature of 50 to 80 C.
20. A process according to any one of claims 1 to 19, wherein the agglomerated polysaccharide fibers are dried under vacuum.
21. A process according to claim 20, wherein the agglomerated polysaccharide fibers are dried under vacuum, with adjustment of a residual vacuum of about 100 mbar.
22. A process according to any one of claims 1 to 21, wherein the agglomerated polysaccharide fibers are dried with continued motion.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ATA1142/89 | 1989-05-12 | ||
| AT0114289A AT392083B (en) | 1989-05-12 | 1989-05-12 | METHOD FOR OBTAINING BY BACTERIA OF THE GENUS XANTHOMONAS OR. ARTHROBACTER-MADE POLYSACCHARID |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2015584A1 CA2015584A1 (en) | 1990-11-12 |
| CA2015584C true CA2015584C (en) | 1999-06-15 |
Family
ID=3507512
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002015584A Expired - Lifetime CA2015584C (en) | 1989-05-12 | 1990-04-27 | Process for the recovery of polysaccharides |
Country Status (7)
| Country | Link |
|---|---|
| AT (1) | AT392083B (en) |
| CA (1) | CA2015584C (en) |
| DE (1) | DE4008944C2 (en) |
| ES (1) | ES2019820A6 (en) |
| FR (1) | FR2646857B1 (en) |
| GB (1) | GB2232993B (en) |
| IT (1) | IT1246384B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4110549C1 (en) * | 1991-03-30 | 1992-12-03 | Gesellschaft Fuer Biotechnologische Forschung Mbh (Gbf), 3300 Braunschweig, De | |
| JPH08842B2 (en) * | 1991-05-22 | 1996-01-10 | 信越化学工業株式会社 | Purification method of polysaccharides |
| US6881838B2 (en) * | 2002-05-21 | 2005-04-19 | A.E. Staley Manufacturing Company | Polysaccharide gum and process for its manufacture |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1419299A1 (en) * | 1958-04-28 | 1968-12-19 | Motomco Inc | Process and apparatus for the production of easily dispersible and / or non-dusting materials |
| FR2228106B1 (en) * | 1973-05-04 | 1976-05-28 | Rhone Poulenc Ind | |
| US4053699A (en) * | 1976-03-31 | 1977-10-11 | General Mills Chemicals, Inc. | Flash drying of xanthan gum and product produced thereby |
| US4135979A (en) * | 1976-08-24 | 1979-01-23 | Merck & Co., Inc. | Treatment of xanthan gum to improve clarity |
| US4260741A (en) * | 1979-06-22 | 1981-04-07 | Merck & Co., Inc. | Low-density xanthan gums |
| DE3812682A1 (en) * | 1988-04-16 | 1989-11-02 | Wolff Walsrode Ag | METHOD FOR PRODUCING HETEROPOLYSACCHARIDES WITH IMPROVED PROPERTIES, IN PARTICULAR XANTHANE |
| JPH0768284B2 (en) * | 1988-06-16 | 1995-07-26 | 三菱レイヨン株式会社 | Method for removing residual water-friendly organic solvent in solid polysaccharides |
-
1989
- 1989-05-12 AT AT0114289A patent/AT392083B/en not_active IP Right Cessation
-
1990
- 1990-03-20 DE DE4008944A patent/DE4008944C2/en not_active Expired - Lifetime
- 1990-04-09 ES ES9001023A patent/ES2019820A6/en not_active Expired - Lifetime
- 1990-04-17 IT IT02005890A patent/IT1246384B/en active IP Right Grant
- 1990-04-27 CA CA002015584A patent/CA2015584C/en not_active Expired - Lifetime
- 1990-05-10 FR FR9005816A patent/FR2646857B1/en not_active Expired - Lifetime
- 1990-05-11 GB GB9010593A patent/GB2232993B/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| IT1246384B (en) | 1994-11-18 |
| DE4008944A1 (en) | 1990-12-20 |
| CA2015584A1 (en) | 1990-11-12 |
| ES2019820A6 (en) | 1991-07-01 |
| GB9010593D0 (en) | 1990-07-04 |
| GB2232993B (en) | 1993-03-10 |
| GB2232993A (en) | 1991-01-02 |
| AT392083B (en) | 1991-01-25 |
| DE4008944C2 (en) | 1998-04-16 |
| ATA114289A (en) | 1990-07-15 |
| IT9020058A1 (en) | 1991-10-17 |
| IT9020058A0 (en) | 1990-04-17 |
| FR2646857A1 (en) | 1990-11-16 |
| FR2646857B1 (en) | 1995-02-10 |
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| EEER | Examination request | ||
| MKEX | Expiry |