DE1900174A1 - Process for the production of non-gelatinized hydroxyalkyl starch ethers - Google Patents

Description

A.E. Staley Manufacturing Company, P.O.B. 3333 »Decatur, Illinois 62525, HSA

Process for the preparation of non-gelatinized hydroxyalkyl " ^: """ - '''starch ethers

The present invention relates to a process for the preparation of non-gelatinized starch derivatives of one for Appropriate quality food. The invention also relates to in detail a dry process for the production of non-gelatinized starch ethers and a process for purification this starch ether.

It is well known that various types of hydroxy- alkyl ethers of starch can be produced in that Alkylene oxides with starch-containing starting materials in the presence

different catalysts and under different reaction conditions can be implemented. For example, hy- Hydroxyalkyl starches are prepared in that starch with a concentrated aqueous solution of an alkali before or

is treated while adding an alkylene oxide. One of the disadvantages of this process is that the grainy Structure of starch destroyed by the action of alkali

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will. Another disadvantage is that special and expensive processing equipment is required if a dry powdered starch product is desired.

It has also been proposed to obtain the granular structure of the starch by using an aqueous starch slurry treated relatively dilute alkali solution and then this starch slurry is reacted with an alkylene oxide. That However, the extent to which the starch was substituted was so low that the application of heat was required to remove the starch To make starch soluble in water.

It is also known that a more substituted granular starch can be obtained by reacting a dry granular starch with alkylene oxide in the presence of a catalyst such as sodium hydroxide or a neutral salt such as sodium chloride. As a rule, this type of "dry reaction ¹¹ " is carried out in a closed system, namely under pressure and at elevated temperature. Although this also makes it possible to obtain a more highly substituted starch and consequently a starch that can be swelled in cold water, there are still several One of these disadvantages is that long reaction times are required in order to obtain a starch which is sufficiently derivatized to be able to swell in cold water

in that the starch material has bad taste properties especially when sodium chloride was used as a catalyst.

What has now become an improved process for the preparation of non-gelatinized hydroxyalkyl starches from a food corner found suitable quality, which is a more effective method of implementing a dry granular starch material with an alkylene oxide, the time required to produce cold water swellable starches being substantial abbreviated v / ird. The starches produced by this process show an improved color and better taste properties.

The present invention relates to a process for the production of non-gelatinized hydroxyalkyl starch ethers,

which is characterized according to the invention in that a dry, granular starch material with an alkylene oxide in The presence of catalytic amounts of a polybasic, water-soluble metal salt of phosphoric acid is implemented.

Polybasic water-soluble salts of phosphoric acid which are particularly suitable according to the present invention are, for example, the water-soluble secondary and tertiary metal ortho- and pyro-phosphates and in particular those, ih? ^for which the metal atom is an alkali or alkaline earth metal.

Examples of suitable metal phosphate catalysts of this type are disodium phosphate, trisodium phosphate, dipotassium phosphate, Tripotassium phosphate, trimagnesium phosphate, dilithium phosphate and Trilithium phosphate.

The phosphate catalyst can be added to the granular starch in any manner that is uniform or enables uniform distribution of the catalyst in the starch material. For example, the phosphate catalyst can be used for Starch can be added in the form of a concentrated solution, the catalyst being sprayed onto the dry starch.

If desired, the granular starch can be mixed with a dilute solution of the catalyst and then dried

will. If a granular starch slurry is available, catalytic amounts of the catalyst can be used as a solid added and dissolved in the starch slurry. After the catalyst has completely dissolved, will the excess water is removed and the granular starch is dried before contacting it with the alkylene oxide will. In addition to water, organic solvents or mixtures of water and organic solvents such as alcohol in water or acetone in water can also be used as carriers for the Catalyst can be used if desired.

The amount of catalyst used to make the hydroxyalkyl starch ethers is used is preferably in the range of

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0.5 to 1.5 # calculated on the dry weight of the starch. However, it can also be a relatively low amount such as up to 0.1 i "or a relatively large amount be used as fi up to 5.5. In most cases, the use of catalyst quantities below 0.1 $> or above 5.5 fo is unsatisfactory, since with low catalyst quantities the reaction proceeds too slowly, while with high catalyst concentrations a certain discoloration of the end product can occur. In addition, the use of large amounts of catalyst is undesirable for quality control purposes, particularly when low ash, low Gardner color products are desired.

After the catalyst has been added to the granular starch, the starch-catalyst combination is dried, suitably to a moisture content of less than $ 15, calculated on the weight of the starch and more preferably to a moisture content of about 8 to 13 # , calculated on the total weight of the starch. In general, it is convenient to the moisture content of the starch to a height γοη more to keep than $ 5 because at a moisture content of less than 5 #, the reaction tends as to · to run it * considerably slower. With a moisture content of significantly more than 15 1 ° , the moisture in the starch tends to touch the walls of the reaction vessel.

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condense, forming globules of solubilized starch material which cause clumping of the final starch product. For the purposes of the present invention, therefore, the term "a dry granular starch" means a starch that contains less than 15% moisture based on the weight of the starch, although starch materials often look dry and contain more than 15% moisture based on the weight

feel dry. After the desired moisture content has been obtained, the alkylene oxide goes straight to dryness

granular starch given. The alkylene oxide can either be added all at once or gradually added slowly over a period of time varying from a few minutes to a few hours or more.

The amount of alkylene oxide added can vary within wide limits, depending on the desired degree of substitution. Extremely small amounts such as up to 1 i * and also very large amounts of up to 300 #, calculated on the weight of the starch material dry matter, can be added. In the case of most of the strengths and in particular in the case of shock produced by maize variety ( "dent corn variety") v / ith the alkylene oxide is generally in an amount of 20 to 25 ^carbon / °

admitted. With these amounts is the hydroxy-alkylated starch Cold water swellable and easier to disperse in water. Unmodified potato starch is required for example in the

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Usually about 30 to 35 # of an alkylene oxide such as propylene oxide, to obtain a cold water swellable starch material and to make the starch more easily dispersible in water.

The alkylene oxides made according to the present invention with a starch material in the presence of a phosphate catalyst can be implemented include all compounds that have an epoxy structure. Examples of such compounds

are ethylene oxide, propylene oxide, butylene oxide, styrene oxide, butadiene monoxide and epichlorohydrin. It should be noted, however, that the products obtained with the above reagents

can have different properties. For example, a starch reacted with ethylene oxide or propylene oxide can be converted into be swellable in cold water, while a starch that has been reacted with epichlorohydrin yields branched products

which are inhibited from swelling in cold water. The reaction between styrene oxide and starch is called The main product is probably 2-hydroxy-2-phenylethyl ether received from strength.

The dry reaction of the starch with an alkylene oxide in Presence of a water-soluble phosphate catalyst required Reaction conditions are not particularly critical. They can be varied within a relatively wide range will. However, when maximum efficiency can be achieved

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^ ₈ - 190Q174

should, certain reaction conditions must be maintained within certain preferred ranges.

The reaction temperatures should, for example, be kept in a range between about 60 and 88 ° C. Temperatures below about 60 ^c have considerably longer reaction times result, while temperatures above about 88 ° C to a .'beanstandungswerten color of the hydroxyalkylated starch product

being able to lead. The hydroxyalkylation reaction is usually carried out at pressures of at least about 1.4 atmospheres. However, if there is very little degradation of the product, much higher pressures of up to about 14 atmospheres or even higher can be used. For most reactions to react starch with either ethylene oxide or propylene oxide, pressures between about 2.45 to 5.25 atmospheres are satisfactory, especially when the reaction temperature is maintained in the range of about 77 to 88 ° ^C.

As starch materials, according to the method and using Any of the catalysts that can be hydroxyalkylated according to the present invention can be modified

or unmodified root or grain starches are used if they still contain reactive hydroxyl groups. For example, strengths can be used that made from maize, wheat, tapioca, sago, rice, sorghum, wax maize, a lot

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Amylose-containing corn, etc. were recovered. The starch fractions amylose and amylopectin as well as modified ones can also be used

Starches, "for example acid-diluted, oxidized, dextrinized, Acid-diluted hydroxyethylated starches and cationic starches, cross-linked starches, for example by means of Epichlorohydrin crosslinked starches can be used.

The hydroxyalkylated crosslinked starches referred to above are especially valuable for use in food or where one swells in cold water Starch or a starch with a certain stability in terms of viscosity is desired. In addition, the hydroxyalkylated crosslinked starches have excellent properties with regard to freezing-thawing, the Clarity and rheological properties. According to the

Starches produced according to the present invention can also be used as * Thickeners used for agricultural sprays, when the water used to reconstitute the spray constituents is taken from streams and rivers that contain ice cold water. The derivatized starches according to the invention can also be used as sizing and coating aids used in the paper and textile industry. The ease with which the strengths in cold or in warm Water can be regenerated is of value in applications where a viscosity range similar to that of

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those of freshly cooked starch is desired.

For the purposes of the present invention, a non-gelatinized Starch product and / or referred to a starch product which is capable of swelling and in cold water to disperse. For the purposes of the present invention, one non-gelatinized starch material and one ground in cold water swellable starch defined as follows. Under a polarizing microscope show the granules of ungelatinized Strengthen a dark cross pattern on a Späro crystal. In general, this property is referred to as birefringence. However, if water is added to, for example, a non-gelatinized cold water swellable medium, the in

The starch granules observed crosses gradually less determined and eventually disappear completely. This phenomenon also occurs when one does not swell in cold water Starch in suspension to the gel elatinization temperature is heated. The swollen starch is easily dispersed in water, and the optical transmittance of the dispersion becomes elevated. Very often a starch swollen and dispersed in water is said to be in solution.

In addition to the invention, that the hydroxyalkylation of starch using a polybasic water-soluble salt can be catalyzed by phosphoric acid, it has been found

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that a more uniformly substituted hydroxyalkylated starch product can be obtained by carrying out the reaction according to the present invention in the presence of a flow agent such as tricalcium phosphate. A complete theoretical explanation for the G _r and this improvement cannot be given at the moment. It is believed, however, that more uniformly substituted products will be obtained which have more uniform cold water swellability properties.

The advantage that a more uniformly substituted reaction product is obtained is when using a flow agent ("flow agent *) a product obtained which has improved flowability and whirling properties. Bas

Caking of the starch product on the reactor walls and on the blades of the stirrer during the reaction can be reduced to a minimum in this way. Although tricalcium phosphate is the preferred flow agent, other substances such as magnesium oxide and magnesium carbonate can also be used. The amount of superplasticizer required to achieve such good results can vary within fairly wide limits. In any event, however, most preferred is an amount which is capable of maintaining the starch in a substantially swirling state during the reaction. Excellent results have been obtained when the flow agent is used in amounts of 0.05 to 3 x 5 $> or above, and preferably in amounts of

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0.1 to 1.5 i> is used. The flow agent is generally added to the starch material prior to the addition of the alkylene oxide. The flow agent can, however, also be added to the finished reaction product if only the property of good flowability and fluidity is desired.

After making a hydroxyalkylated starch product According to the invention, it can be purified and thus made more suitable for food by treating it with a water-alcohol mixture is brought into contact, which has a water / alcohol weight ratio of about 0.1: 1 to 0.7: 1.

For example, if the hydroxyalkyl starch material is a granular hydroxypropyl starch that is at least 98 # cold water soluble, the water-alcohol mixture should be preferred have a water-alcohol weight ratio between about 0.2: 1 and 0.5: 1. When the amount of water in the water-alcohol mixture is significantly above the 0.5: 1 ratio, there is a risk that the granular hydroxypropyl starch will be significant swells, which results in the loss of the granular structure. However, if that is present in the water-alcohol mixture If the amount of water is significantly below the ratio 0.2: 1, only small amounts of undesirable smells and flavors will be produced removed from the starch material.

Any monohydric alcohols such as methanol,

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Ethanol, propanol, isopropanol, butanol, isobutanol, the Pentanols and hexanols can be used for the purification process according to the invention. However, ethanol is the preferred one monohydric alcohol, especially when the purified starch product is used in the food industry shall be.

The amount of water-alcohol-G-emiseh necessary to be effective

Purification of the hydroxyalkyl starches is not required particularly critical and can fluctuate over a relatively large range. Excellent results have been achieved if 1.0 to 2.0 parts of solvent per part of starch material were used. However, in most cases it will too Good results are obtained when only using a relatively low amount such as 0.25 parts of solvent per part of starch and relatively large amounts such as 10.0 parts solvent per part starch are used. Because of economical reasons the lower concentration range is generally preferred.

The order in which the granular hydroxypropyl starch is combined with the water-alcohol mixture is also not particularly important. In most cases, however, it will Starch material added to the water-alcohol mixture. The kind

however, the addition can, if desired, also be reversed.

909831/1336 - _U.

follow. Kachdem the starch material and the cleaning solvent have been combined, the mixture is preferably stirred or agitated to form a continuous suspension of the

To get starch granules in the water-alcohol-mix. this allows maximum surface contact between the Starch material and the cleaning solvent and allows this reaction to become acidic.

The effectiveness of the Rwinigungsreaktion can continue thereby improves v / earth that the starch material is mixed with the water-alcohol mixture u is brought into contact at a slightly elevated temperature. However, care must be taken to ensure that that temperatures are avoided. Which are an essential Loss of solvent or the undel''tinated Form of the starch inatc; rii: ls would destroy. Iu in general, temperatures are between about 1 and about 6 !? C.

satisfactory for most cases. Temperatures in the area however, generally from about 27 to about 50 ° C opreferred. The preferred temperatures are particularly then

useful when using a cold water soluble hydroxypropyl starch is washed with a water-ethanol-mixture.

Effective purification of the hydroxyalkyl starches is then achieved when the water-alcohol mixture has a pH-fourth of

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SAD ORiGIMAL

7 or below and maintained at that pH is · For hydroxypropyl starches which are soluble in cold water, the water-alcohol mixture is preferably adjusted to a pH of

held about 3 · 5 to 7 · Ο. When the water-alcohol mixture comes up is maintained at a pH greater than 7, there is a slight possibility that the granular properties of the starch material be destroyed. If the pH of the water-alcohol mixture is significantly below 3 · 5, hydrolysis of the Enter starch material.

The hydroxyalkyl starches that can be purified according to the method of the present invention can generally be as hydroxyalkylated starch materials are defined which have a Have a degree of substitution sufficient to provide a starch material that is at least 50 $ cold water soluble.

In other words, at least 50 $ of the starch material are soluble then in water at normal temperature and at least 50 ^c ß> of the starch material lose their granular ( "granular") property. A starch material is considered to be granular if the starch granules show a dark cross pattern under a polarizing microscope. However, if the starch is soluble

is made, the crosses observed are less determined and eventually disappear completely. In most cases a hydroxyalkylated starch material is then cold-

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water soluble if it is between about 5 and about 15 percent by weight Contains hydroxyalkyl groups.

Although the hydroxyalkyl starches that can be purified according to the method described above were preferably prepared by a method in which a polybasic water-soluble salt of phosphoric acid was used as a catalyst (fewer impurities are obtained in this way), hydroxyalkyl starches can also be used for this purpose produced by other processes. For example, a method described in U.S. Patent 2,516,634 can also be used. According to this patent, a granular starch is reacted with an alkylene oxide in the presence of an alkaline catalyst at temperatures between about 24 ° C and about 80 ° C and preferably at temperatures between about 38 and 55 ° C. Although this patent is primarily concerned with the implementation of only small amounts (1 to 5 #) alkylene oxide with a starch material, substantially the same procedure for the conversion of up to 25 fi Propjplenoxid with the starch material may be used.

The following examples further illustrate the invention.

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-17-

example 1

A solid disodium phosphate catalyst was added to a starch slurry of 21 ^° Be in such an amount that a catalyst concentration of 1 to 1.5%, calculated on the dry weight of the starch, was obtained. The catalyst starch slurry was then filtered and the starch cake dried to a moisture content of 8 to 11 pounds. The starch treated with the catalyst was then converted into a

I liter bottle was given, and propylene oxide was in an amount of 25 #, calculated on the weight of the starch dry substance, added. The bottle was capped and placed in a hot water bath set on a temperature for 8 to 9 hours.

O
temperature was kept between 73 and 82 C. The product was then analyzed. It was found that it was too

I1 to 15 $> is hydroxypropylated and is essentially completely (100? S) swellable with cold water.

The above example has been repeated with the modification that the

Disodium phosphate has been replaced by sodium sulfate. It was found that to achieve a product with a cold water swellability comparable to that using obtained from disodium phosphate as a catalyst, it was necessary to keep the reaction below essentially the to carry out the same reaction conditions for a period of 16 to 18 hours. This means that the reaction

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time is about twice as long as that using disodium phosphate as a catalyst.

If the above example is repeated under conditions common to other alkylene oxides such as ethylene oxide or Bpichlorohydrin are optimal, comparable results are achieved.

Examples 2 to 1 0

Example 1 was repeated with the modification that an acrolein-crosslinked starch with an alkali liquidity of 49 ml (0.25 NaOH) was used to demonstrate the catalytic effect that various polybasic water-soluble Metal salts of phosphoric acid on the manufacture of hydroxy

exercise propyl ethers of crosslinked starches. The reaction was carried out at a temperature of 82 ° C for periods of 4 to 24 hours Hours performed. The Brookfield viscosity was for each

Product determined and is given in Table 1. The Brookfield Viscosity reflects the extent of the hydroxypropyl starch substitution.

-19-

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- 19 Table 1

19UUI

Analytical data of dry route produced hydroxypropyl starch catalyst comparison

Example catalyst Reak Kozen Brook odor and

Tration field taste of the star viscose stems (Stuntsity

den) schläm- cps mung

2 NaCl 3 Na ₂ HPO ₄ 4th Na ₂ SO ₄ 5 NaCl 6th Na ₂ HPO ₄ 7th Na ₂ SO ₄ 8th NaCl 9 Na ₂ HPO ₄ 10 Na ₂ SO ₄

135

2.760

9f800 unsatisfactory

10.100 satisfactory 3.700 moderate

8,280 unsatisfactory

8,280 satisfactory

8,260 unsatisfactory

The above table clearly shows the catalytic advantage of using disodium phosphate over sodium chloride and disodium sulfate. This catalytic advantage

is most obvious with a reaction time of 4 hours. The catalytic advantage is with reaction times of 8 hours

still conspicuous to disodium sulfate. He is then about the same as that for sodium chloride. The product obtained using sodium chloride as a catalyst however, was usually for food use

-20-

not satisfactory. After 15 hours, the extent of substitution of the starch material was for all three catalysts essentially the same. The taste and color of the products obtained without the use of a phosphate catalyst however, were generally unsatisfactory. In such cases a series of further cleaning washes was in the pipeline Usually required before the product is for sale as food was suitable. If a product is rated as "satisfactory"

Taste and color obtained is the number of still required Cleaning washes considerably less.

Brookfield viscosities were measured on starch slurries at concentrations of 5 and 10 fo using a Brookfield viscometer model RVT. The mixture was stirred and the viscosity was measured after a period of 5 minutes at 20 revolutions per minute. A # 3 spindle was used for viscosities less than 5,000cps. A # 4 spindle was used for viscosities below 10,000 cps and a # 5 spindle was used for viscosities above 10,000 cps.

Examples 11-17

There were hydroxypropyl starch ether according to the procedure described in Example 1 prepared using, however, various phosphate salts, which are listed in the table below 2 are given. With the exception of Example 17, in which

3.0 g of catalyst per 100 g of starch were used, in each example 1 to 1.5 g of the catalyst per 100 g of starch are used

been used.

Phosphate salt Table 2 Cold water swellability example NaH ₂ PO ₄ reaction time less than 10 ^c ß> 11 Na ₂ HPO ₄ 8 hours $ 90 to $ 99> 12th Na ₅ PO ₄ ti 90 to 99 ° h 13th K ₂ HPO ₄ ti $ 90 to $ 99> H Ii ₂ HPO ₄ It 90 to 99% 15th Oa ₅ PO ₄ n less than $ 10 16 (NH ₄ ) ₂ HP0 ₄ 24 hours less than 10 ° / o 17th Il

These examples show that the preferred catalyst for making cold water swellable hydroxyalkyl starches is a polybasic water-soluble metal salt of phosphoric acid.

Example 18

Example 1 was repeated with the modification that the disodium phosphate catalyst was replaced by tricalcium phosphate. The reaction was carried out at a temperature above 82 ° C for carried out over a period of 16 hours. The product was examined. It was found that the cold water

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Swellability is less than 10 ^c / o . This partially cold water swellable hydroxypropyl starch was returned to the reaction vessel and subjected to the reaction for a further 24 hours. The reaction product was examined. It was found that it is still only partially swellable with cold water. However, when this experiment was repeated with a catalytic generator containing both disodium phosphate and tricalcium phosphate, the product was found to be 100 ° F. cold water swellable and free from lump formation. Furthermore, it was evident that in the presence of small amounts of a flow agent such as tricalcium phosphate in addition to the catalyst, a more uniformly substituted product was obtained.

Example 19

In a 5,000 ml, three-necked round bottom flask, 500 g of raw, cold-water-soluble, granular hydroxypropyl starch was placed which was mixed through Implementation of granular starch with propylene oxide according to the in

Example 1 was obtained. This product was suspended in 750 ml of a water-alcohol mixture, the weight ratio of water: alcohol being 0.3: 1. The round bottom flask was equipped with a mechanical stirrer

Glass shaft and Teflon agitation blades fitted. (The stirring blades were in the form of a sheet were 10.2 cm long and 20.64 mm wide on average.) The water-alcohol starch suspension was gO9fi31 / 1336 '-23-

adjusted to pH 5.5 to 6.5 and to a temperature of 37.8 ° G heated. After stirring the suspension for about 30 minutes, the granular starch became from the water-alcohol wipe separated by filtration and examined. The washed product was found to have a good taste owned and exhibited relatively low (5 to 7) Gardner colors (based on a Gardner white plate secondary standard).

An analysis of the piltrate also showed that the cleaning method according to the invention removes essentially all (98 to 100 fo) of the substances which are responsible for the bad

Taste of the starch material were responsible, from the granular cold water-swellable hydroxylpropyl starch made possible. When the procedure of this example was repeated with hydroxypropyl starches obtained by other procedures, e.g. procedures described in U.S. Patent 2,516,634 gave essentially the same results achieved. If the levels of contaminants present in the starch are greater than normal, several must be Washing should be done until most of the bad taste and discoloration has been removed.

Examples 20 to 25

These examples show that the relationship between water and

Alcohol is of great importance when essentially the 9Q9B3 1/1336 " ² ^"

900174

all interfering substances are to be removed while, at the same time the granular! form of the hydroxypropyl starch materials should be preserved.

The procedure described in Example 19 was carried out , whereby only the water-alcohol ratio changes * was changed. The results obtained are shown in Table 3.

Table 3

Examples of weight alcohol "

Cleaning starch shape taste of the

strength

20th
21

22nd
23
24

25th

1: 1 0.7: 1

0.5: 1 0.3: 1 0.1: 1

0.05: 1

swollen

bad

87.0

93.0
99.0
83.0

10.0

Beginning of satisfied-. Putting source

grainy
grainy
grainy

grainy

good Good

satisfactory

bad

♦ The taste of starch was experienced by a jury of five Appraisers determined to use standard test procedures.

Examples 26-30

These examples illustrate the influence of temperature on the cleaning process according to the invention. Apart from the in the temperature differences given in Table 4 was the in

9Q9831 / 1336 " ²⁵ ~

Example 19 was carried out.

Table 4

Example temperature # cleaning Gardner flavor

Aiv Ϊ «? ? Effectiveness color * Alcohol

misohes ⁰ C

26 10.0 91.0 7.2 satisfactory

27 23.9 95.0 6.7 good

28 37.8 99.0 6.0 good

29 51.7 97.0 6.5 good

30 65.6 93.0 7.5 satisfactory

* The stated color values were measured with an automatic Gardner photometer using a "White Plate Secondary Standard ¹ *, which had been made available by Gardner Instruments, Inc."

From this table it can be seen that despite the proportionate low influence of the temperature of the water-alcohol mixture on the effectiveness of the cleaning at higher Temperatures obviously have some influence on the Gardner color.

Examples 31 to 33

These examples illustrate that the hydroxypropyl starches with

various monohydric alcohols can be purified.

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The cleaning conditions are the same except for those in Table 5 the same information as in Example 19-

Table 5

example alcohol Weight
behaves
nis water:
alcohol temperature
⁰ C 7th Gardner
colour Cleaning
effectiveness ψ 31 methyl 0.3: 1 51. 7th 6.7 99.0 32 ethyl 0.3: 1 51. 7th 6.5 99.0 33 Iso-
propyl 0.3: 1 . 51. 7.0 97.0

Essentially the same good results are obtained when the cleaning process is carried out with poorer types of hydroxyalkyl starches how hydroxyethyl starch is carried out.

Patent claims:

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Claims (1)

Patent claims: 1. Process for the production of non-gelatinized hydroxyalkyl starch ethers, characterized in that a dry, granular starch material with a Alkylene oxide in the presence of catalytic amounts of a polybasic water-soluble metal salt of phosphoric acid is implemented. 2. The method according to claim 1, characterized in that the polybasic, water-soluble salt a dibasic or tribasic Is the metal salt of phosphoric acid. 3 · Process according to claims 1 to 2 "characterized in that the water-soluble metal salt contains an alkali or alkaline earth metal as metallic α. 4. Process according to Claims 1 to 3, characterized in that the water-soluble metal salt is disodium phosphate. 5. Process according to Claims 1 to 4, characterized in that that the amount of catalyst is at least 0.1%, calculated on is the dry weight of the starch. 6. The method according to claims 1 to 5 »characterized in that the amount of catalyst 0.5 to 1.5 #i calculated on the SC Λ ft Λ 1 /**>. ·,, —28 · " 1300174 Starch dry weight 7. Process according to Claims 1 to 6, characterized that the implementation in the present of a fluidity causing quantities of a flow insoluble in water «» is carried out « 8. The method according to claims 1 to 7, characterized in that that the superplasticizer is tricalcium phosphate. 9. Process according to claims 1 to 7, characterized in that the amount of plasticizer is 0.05 to 3.5 fi, calculated on the dry weight of the starch. 10. The method according to claims 1 to 9 »characterized in that the granular starch material treated with a catalytic amount of a polybasic water-soluble metal salt of phosphoric acid containing solution, the starch then to a moisture content of less than 15 fit based on the weight of the starch, dried and the dried starch with a sufficient amount of one Alkylene oxides is reacted to obtain a completely cold water soluble starch derivative. -29- 9Q9831 / 1336 _29- 190017Λ 11. Method for cleaning a cold water soluble hydroxy alkylated starch material, characterized in that the starch material is washed in a water-alcohol mixture until essentially all undesirable contaminants are removed from the starch material, wherein the water and the alcohol are present in the mixture in a weight ratio between 0.1x1 and 0.7: 1, and from the mixture a purified, non-gelatinized, hydroxyalkylated starch material is then separated off. 12. The method according to claim 11, characterized in that the temperature of the water-alcohol Geraisches below 66 C. lies. 13. The method according to claims 11 to 12, characterized in that that the water-alcohol ratio is between 0.2: 1 and 0.5: 1. H. The method according to claims 11 to 13, characterized in that that the hydroxyalkyl starch is a hydroxypropyl starch. 15. The method according to claims 11 to H, characterized in that that the water-alcohol mixture on a pH below 7.0 is held. 909831/1336 ~ ³⁰ "" 16. The method according to claims 11 to 15j, characterized in that the water-alcohol mixture at a temperature between 1 ⁰ C and 66 ° C and the pH between 3.0 and 7.0 are held. 17. The method according to claims 11 to 16, characterized in-P net that ethyl alcohol is used as alcohol. Dr. T / H 909831/1336