DE102012216955A1 - A process comprising a continuous crystallization of isomaltulose - Google Patents

Abstract

The invention relates to processes comprising a continuous crystallization of isomaltulose.

Description

Field of the invention

The invention relates to a process comprising a continuous crystallization of isomaltulose.

State of the art

The known processes for the preparation of highly pure isomaltulose are based on isomerization of an aqueous sucrose solution which has been prepared from "white sugar" or "refined sugar", therefore from purified sucrose, and a separation of isomaltulose from the isomerization mixture via a batch evaporation of the solvent with a downstream one batchwise operated cooling crystallization. Appropriate procedures are in DE3241788 and EP0983374 described.

To increase the yield, the mother liquor is further evaporated and subjected to a second cooling crystallization. Alternatively, the mother liquor is mixed with fresh sucrose solution and fed to another isomerization stage. There are no high demands on the process control of the crystallizations described in these processes, since the isomerization mixture-based on the pure sucrose used as starting material-represents a less complex and well-defined composition, from which the isomaltulose can easily be separated off.

The previously known crystallization processes are unsuitable for separating isomaltulose from more contaminated solutions of satisfactory quality

The object of the invention was to provide a process which allows a simple separation of pure isomaltulose from complex compositions, in particular strongly colored compositions.

Description of the invention

It has been found that the produced isomaltulose can be continuously separated as described below in excellent quality from complex compositions such as isomerized thick juice.

In addition, it has been found that the continuous crystallization of isomaltulose has advantages in the practice of the process.

• A) Bereitstellen einer Feedlösung enthaltend Isomaltulose und Wasser,
• B) teilweises Entfernen des Wassers durch Verdampfen unter Erhalt einer Suspension von Isomaltulose-Kristallen,
• C) Auftrennen der Suspension in einen isomaltulosehaltigen Feststoff und eine Mutterlauge und gegebenenfalls
• D) Waschen des isomaltulosehaltigen Feststoffes.

The present invention therefore provides a process for the continuous crystallization of isomaltulose comprising the process steps

• A) providing a feed solution containing isomaltulose and water,
• B) partially removing the water by evaporation to obtain a suspension of isomaltulose crystals,
• C) separating the suspension into an isomaltulose-containing solid and a mother liquor and optionally
• D) washing the isomaltulose-containing solid.

An advantage of the method according to the invention is the constant product quality due to the stationary system state.

Yet another advantage of the method according to the invention is that an increased apparatus-specific space-time yield is achieved. Yet another advantage of the method of the invention is the reduced need for buffer containers.

Yet another advantage of the method according to the invention is that it is possible to dispense with expensive growth of saturated crystals for the necessary inoculation procedure, since in a continuous process seed crystals, e.g. be formed by pump abrasion, collision of two particles with each other and / or with the Kristallerwandung targeted.

A further advantage of the method according to the invention is the possible energy saving, since a sucrose crystallization can be dispensed with in the context of the provision of isomaltulose. This results in a further advantage of the process according to the invention in the form of the higher specific yield based on the sucrose used.

The term "for continuous crystallization" in connection with the process according to the invention is to be understood as meaning that the process according to the invention is carried out continuously. Thus, at least two process steps, for example B) and C), are carried out simultaneously. Therefore, the term "method step" X, Y, Z also does not mean a discrete, time-separated sequence of steps, in the sense of "finish X first, then start Y, if Y complete then Z first begin".

All percentages (%) are by mass unless otherwise specified.

In process step A), a feed solution containing isomaltulose and water is provided. As already mentioned above, the original preparation of isomaltulose for process step A) generally takes place via an, in particular enzymatic, isomerization of sucrose. Methods for such isomerization are for example Proc. Res. Soc. Jpn. Sugar Refineries Technol. 33, 55-63 (1984), Sugar Industry 116, 197 (1991) , of the JP03180172 , of the EP0028900 , of the EP0109009 and the EP0049742 known.

In order to reduce the production costs and to achieve better yields based on sucrose, it is advantageous and therefore preferred according to the invention if the feed solution containing isomaltulose and water provided in process step A) at least partially contains the direct isomerization product of a sucrose-containing vegetable juice. As a result, the preferably used feed solution of the process according to the invention contains many further, uncharacterized and to be separated secondary constituents, which can not be separated off by conventional methods.

The term "direct isomerization product of a sucrose-containing vegetable juice" in connection with the process according to the invention is to be understood that for the production of the isomerization product starting from a sucrose-containing vegetable juice no crystallization step was carried out and the plant juice was directly isomerized.

The sucrose-containing vegetable juice is preferably selected from thin juice and thick juice, the latter being particularly preferred.

The term "thin juice" is to be understood in the context of the present invention, the product which is present in sugar production from sugar beets or sugar cane after juice purification. Thin juice typically contains 10-20% by weight sucrose based on total juice.

The term "thick juice" is to be understood in the context of the present invention, the thickened "thin juice" containing more than 20 wt .-% sucrose based on the total juice.

A preferred method according to the invention is characterized in that process step B) in a temperature range of 50 ° C to 70 ° C, preferably from 55 ° C to 65 ° C, more preferably from 58 ° C to 62 ° C and in a pressure range of 70 mbar to 200 mbar, preferably from 100 mbar to 180, particularly preferably from 110 mbar to 140 mbar is performed. In particular, it is preferred in this context that, in the process according to the invention, process step B) is carried out in a temperature range from 58 ° C. to 62 ° C. and in a pressure range from 110 mbar to 140 mbar.

By varying the degree of evaporation different solids contents or yields can be approached, this can be controlled for example over the residence time in process step D). It is advantageous and thus preferred if in process step D) so much water is removed, so that based on the suspension, these 20 wt .-% to 70 wt .-%, preferably 30 wt .-% to 65 wt .-%, more preferably contains from 40 wt .-% to 60 wt .-% isomaltulose.

In process step E), all processes known to those skilled in the art for the separation of solids from liquids can be used, for example centrifugation, sedimentation, decantation, separation in the gravitational field and filtration. A process preferred according to the invention is characterized in that the separation in process step E) takes place by centrifugation.

It is inventively preferred that the washing in process step F) is carried out with water, in particular with water, which has a temperature of 20 ° C to 90 ° C, preferably from 30 ° C to 80 ° C, particularly preferably from 50 ° C to 70 ° C

In order to increase the yield of isomaltulose and to avoid product losses, it is preferred according to the invention that the liquid used for washing in process step D), in particular the water used for washing, is fed to the feed solution of process step A).

A preferred process according to the invention is thus characterized in that the feed solution of process step A) containing isomaltulose and water contains the liquid used for washing in process step D); The feed solution particularly preferably contains the liquid used for washing in process step D) and the direct isomerization product of a sucrose-containing vegetable juice.

• E) Abkühlen der Mutterlauge aus Verfahrensschritt C) unter Erhalt einer zweiten Suspension von Isomaltulose-Kristallen,
• F) Auftrennen der Suspension in einen zweiten isomaltulosehaltigen Feststoff und eine zweite Mutterlauge und gegebenenfalls
• G) Lösen des zweiten isomaltulosehaltigen Feststoffes in der Feedlösung des Verfahrensschrittes A).

In order to achieve the same technical effect, it is preferred that the method according to the invention is characterized in that it additionally comprises the method steps

• E) cooling the mother liquor from process step C) to obtain a second suspension of isomaltulose crystals,
• F) separating the suspension into a second isomaltulose-containing solid and a second mother liquor and optionally
• G) dissolving the second isomaltulose-containing solid in the feed solution of process step A).

In order to drive this preferred method as energetically favorable, it is preferred that in addition to step B) also step C) in a temperature range of 50 ° C to 70 ° C, preferably from 55 ° C to 65 ° C, particularly preferably from 58 ° C is carried out to 62 ° C and in a pressure range from 70 mbar to 200 mbar, preferably from 100 mbar to 180, particularly preferably from 110 mbar to 140 mbar.

In particular, it is preferred in this context that, in addition to process step B), process step C) is also carried out in a temperature range from 58 ° C. to 62 ° C. and in a pressure range from 110 mbar to 140 mbar.

A preferred process according to the invention is characterized in particular by the fact that in process step E) the mother liquor from process step C) is heated to 10 ° C. to 30 ° C., preferably to 15 ° C. to 25 ° C., more preferably to 18 ° C. to 22 ° C. is cooled. Process step E) is carried out in particular at atmospheric pressure, therefore at 0.90 to 1.10 bar absolute.

In process step F) of the preferred process according to the invention, the same processes for the separation of solids from liquids can be used as in process step C) of the process according to the invention to obtain a second isomaltulose-containing solid and a second mother liquor; Process step F) is preferably carried out at 10 ° C to 30 ° C, preferably at 15 ° C to 25 ° C, more preferably at 18 ° C to 22 ° C.

The second isomaltulose-containing solid can be further processed to end products or - as proposed - in the feed solution of process step A) are added in step G), it being preferred that the second isomaltulose-containing solid after addition to the feed solution of process step A) in this solved present.

In a method which is preferred according to the invention, method step G) is carried out. A method preferred according to the invention is thus characterized in that the feed solution of process step A) containing isomaltulose and water contains the second isomaltulose-containing solid from process step F); The feed solution particularly preferably contains the second isomaltulose-containing solid from process step F), the liquid used for washing in process step D) and the direct isomerization product of a sucrose-containing vegetable juice; more preferably, the feed solution consists of the three components and water.

In the examples given below, the present invention is described by way of example, without the invention, the scope of application of which is apparent from the entire description and the claims, to be limited to the embodiments mentioned in the examples.

The following figures are part of the examples:

: Exemplary technical process management

Examples:

Continuous crystallization of isomaltulose from isomerized thick juice

Crystallization of the isomaltulose was performed using a Mixed Suspension Mixed Product Removal (MSMPR) apparatus. The effective usable volume is 3 liters.

For the solid-liquid separation and crystal washing, a filter basket centrifuge from Cepa with a basket diameter of 200 mm was available. The filter cake could be washed with ultrapure water via a plug-in tube.

step 1

The starting material used was a thick juice feed stream isomerized with Protaminobacter rubrum. The isomerized thick juice has a dry matter content of about 41% by weight. The composition with respect to the sugars and isomerization product contained is shown in Table 1. water [Wt%] 59.0% fructose [Wt%] 1.4% glucose [Wt%] 0.8% sucrose [Wt%] 3.4% isomaltulose [Wt%] 30.6% trehalulose [Wt%] 2.8% melezitose [Wt%] 0.0% rest [Wt%] 2.0% Table 1 Composition of isomerized thick juice

The isomerized thick juice was tempered in the receiver to a temperature of about 60 ° C. A volume flow of 2 kg / h was set via the piston metering pump. The isomerized thick juice was fed at a temperature of 60 ° C via a submerged feed tube into the recirculated crystal suspension. In the crystallizer was at a temperature of about 60 ° C and a pressure of 110-140 mbar abs. set a distillate stream of 1 kg / h. As a result of the evaporation of water, the solution was continuously supersaturated to a constant value. The supersaturation in the crystallizer was degraded with the help of the already existing crystals and crystal nuclei, so that an efficient crystal growth took place. From the crystallizer, a suspension flow of about 1 kg / h was withdrawn batchwise every hour.

The crystal suspension was introduced into the centrifuge at a speed of 500 rpm. The solid-liquid separation was then carried out for 2 min at a speed of 1000 rpm. The mother liquor obtained in the solid-liquid separation was weighed. From the difference between filled mass and mother liquor a theoretical amount of solids was determined. Based on the theoretical amount of solids, the solid was washed with 10% ultrapure water at a speed of 500 rpm. For dehumidification, the speed of the centrifuge was increased to 4000 rpm for about 2 minutes. Subsequently, the solid could be removed from the centrifuge. On average, 0.40 kg / h of solid is obtained from 1 kg / h suspension. At a suspension density of 1.3 kg / L and a mean hold-up of 3.5 L, this corresponds to a residence time of 4.5 hours.

The separated solid had the following composition: fructose [Wt%] 0.05% glucose [Wt%] 0.05% sucrose [Wt%] 0.0% isomaltulose [Wt%] 99.5% trehalulose [Wt%] 0.4% melizitose [Wt%] 0.0% rest [Wt%] 0.0% Table 2 Composition of the washed solid

For stage 1, an isomaltulose yield of 62% can be calculated.

The separated mother liquor of stage 1 has the following composition: water [Wt%] 30.0% fructose [Wt%] 4.6% glucose [Wt%] 2.6% sucrose [Wt%] 11.3% isomaltulose [Wt%] 35.7% trehalulose [Wt%] 9.2% melizitose [Wt%] 0.0% rest [Wt%] 6.6% Table 3 Composition of the mother liquor stage 1

Level 2

To increase the yield, the mother liquor could then be treated in a further step. This was done via a so-called. Cooling crystallization of 60 ° C to about 20 ° C. In the experiment, the mother liquor was tempered for this purpose in the feed template at 60 ° C and retracted via the Kolbendosierpumpe in the crystallizer at atmospheric pressure. The feed stream was 0.6 kg / h. The crystallizer was run in continuous operation at 20 ° C. By lowering the temperature, the saturation limit of the solution was exceeded. The generated supersaturation was degraded in the crystallizer by crystal growth on the primary particles formed. From the crystallizer, a suspension having a solids content of about 27% was taken. The crystal suspension was introduced into the centrifuge at a speed of 500 rpm. The solid-liquid separation was then carried out for 2 minutes at a speed of 4000 rpm. Crystal washing of the solid was omitted. The yield of the second crystallization stage is about 20.1% for a separated solid of 0.137 kg / h. For the overall process, this results in an overall yield of 85.1%. The compositions of the mother liquor and the solid from the second crystallization stage are listed below. water [Wt%] 37.1% fructose [Wt%] 5.7% glucose [Wt%] 3.2% sucrose [Wt%] 14.0% isomaltulose [Wt%] 20.4% trehalulose [Wt%] 11.4% melizitose [Wt%] 0.0% rest [Wt%] 8.3% Table 4 Composition of the mother liquor stage 2 water [Wt%] 4.7% fructose [Wt%] 1.3% glucose [Wt%] 0.8% sucrose [Wt%] 3.3% isomaltulose [Wt%] 90.0% trehalulose [Wt%] 1.4% melizitose [Wt%] 0.0% rest [Wt%] 1.0% Table 5 Composition of solids Stage 2

Example of a technical process management

A possible, technical process control of a erfindungemäß preferred method is in shown:
The feed solution containing isomaltulose ( 1 ) is used at the beginning of the process to remove the non-washed solid ( 14 ) from the crystallization stage S2 (D) and the wash water ( 10 ) from the crystal wash (B). The total current ( 3 ) is then retracted into the evaporation crystallization S1 (A). Here, by evaporation at 60 ° C and a pressure of 110-140 mbar of a corresponding proportion of water ( 5 ) exceeded the solubility of isomaltulose, so that isomaltulose crystallized out and as a suspension ( 4 ) from the evaporation crystallization (A) into the solid-liquid separation / crystal washing (B) can be driven. In the solid-liquid separation / crystal washing (B), the isomaltulose crystals are separated from the mother liquor ( 11 ) separated. The mother liquor-containing solid is mixed with ultrapure water ( 7 ) washed. The washed crystals ( 6 ) are used for product preparation (C). The product preparation can be used as drying or as a solution station with ultrapure water ( 9 ). To increase the yield, the mother liquor ( 11 ) is fed to a cooling crystallization (D). Here, the solution is cooled in a continuous process from 60 ° C to a temperature of 20 ° C. The solubility limit of isomaltulose is exceeded so that isomaltulose crystallizes out and a suspension ( 12 ) is formed. The suspension ( 12 ) is supplied from the cooling crystallization (D) of the solid-liquid separation (E). Herein are the crystals produced ( 14 ) from the mother liquor ( 13 ) separated. The crystals are not washed. The mother liquor ( 13 ) leaves the procedure. The solid ( 14 ) is recrystallized in the isomaltulose feed stream ( 1 ) dissolved again. 1 Feed solution 8th product 2 Feed solution + solid S2 9 Ultrapure water (if required) 3 Feed solution + solid S2 + wash water S1 10 wash water 4 Suspension S1 11 Mother liquor S1 5 Distillate S1 12 Suspension S2 6 Solids S1 13 Mother liquor S2 7 ultrapure water 14 Solid S2 Table 6 Material flow table

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 3241788 [0002]
• EP 0983374 [0002]
• JP 03180172 [0015]
• EP 0028900 [0015]
• EP 0109009 [0015]
• EP 0049742 [0015]

Cited non-patent literature

• Proc. Res. Soc. Jpn. Sugar Refineries Technol. 33, 55-63 (1984), Sugar Industry 116, 197 (1991) [0015]

Claims (9)

Process for the continuous crystallization of isomaltulose comprising the process steps A) providing a feed solution containing isomaltulose and water, B) partially removing the water by evaporation to obtain a suspension of isomaltulose crystals, C) separating the suspension into an isomaltulose-containing solid and a mother liquor and optionally D) washing the isomaltulose-containing solid. A method according to claim 2, characterized in that the feed solution of process step A) at least partially contains the direct isomerization of a sucrose-containing vegetable juice, in particular thin juice or thick juice. Method according to at least one of the preceding claims, characterized in that process step B) in a temperature range from 50 ° C to 70 ° C, preferably from 55 ° C to 65 ° C, more preferably from 58 ° C to 62 ° C and in a Pressure range from 70 mbar to 200 mbar, preferably from 100 mbar to 180, particularly preferably from 110 mbar to 140 mbar is performed. Process according to at least one of the preceding claims, characterized in that the separation in process step C) takes place by centrifugation. Process according to at least one of the preceding claims, characterized in that the washing in step D) is carried out with water. Process according to at least one of the preceding claims, characterized in that the liquid used for washing in process step D) is fed to the feed solution of process step A). Process according to at least one of the preceding claims, characterized in that it additionally comprises the process steps E) cooling the mother liquor from process step C) to obtain a second suspension of isomaltulose crystals, F) separating the suspension into a second isomaltulose-containing solid and a second mother liquor and optionally G) adding the second isomaltulose-containing solid to the feed solution of process step A). A method according to claim 7, characterized in that in process step E), the mother liquor from process step C) to 10 ° C to 30 ° C, preferably to 15 ° C to 25 ° C, particularly preferably to 18 ° C to 22 ° C is cooled , Process according to claim 7 or 8, characterized in that the feed solution of process step A) comprises the second isomaltulose-containing solid from process step F), the liquid used for washing in process step D) and the direct isomerization product of a sucrose-containing vegetable juice.

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