MXPA06005373A - Method for modifying starch or starch derivatives - Google Patents

Abstract

A method of modifying starch or starch derivatives comprising:introducing a continuos flow of starch substrate, gas and, optionally, one or more reagents, into a reactor, wherein the starch substrate has a moisture content between 0 and 45%by weight, a residence time in the reactor of between 1 and 60 minutes and is heated to between 50 and 220°C, characterized in that the starch substrate and the gas are introduced into the reactor in opposing directions and in that the reactor has a tubular body comprising a rotating shaft upon which is disposed one or a plurality of blades.

Description

M ALL TO MODIFY STARCH OR STARCH DERIVATIVES TECHNICAL FIELD The present invention relates to a method for modifying starch and starch derivatives in a continuous process. The invention also relates to the use of reactors in said methods.

BACKGROUND OF THE INVENTION Starch is the main carbohydrate component of higher plants and has many industrial applications. In the food industry, for example, starch is used, inter alia, as an extrusion agent, a gelling agent, a thickener and a stabilizer. In papermaking, starch is used as a sizing agent to improve the printability, surface resistance and solvent resistance. Starch is also used in the fermentation and textile industries, and in the manufacture of adhesives, detergents, cosmetics, pharmaceuticals, emulsifiers and dispersing agents, inks and dyes, plastics, coatings and many other products that are commonly used. However, to fulfill these roles, certain specific properties may be required (such as rheological properties, cut resistance, stability, viscosity at different temperatures, gelatinization, solubility, etc.). Often these properties are not associated with natural starch. Therefore, several methods have been developed for the modification of starch. Such methods include hydrothermal treatment, hydrolysis, degradation (dextrinization, acid thinning, oxidation), esterification, etherification, stabilization (for example by entanglement), etc. Traditionally the most successful methods for the modification of starch on an industrial scale are based on the processing of starch in aqueous solutions. However, said methods have various innate disadvantages. These include the production of huge quantities of aqueous effluents, the disposal of which results in a considerable burden on production and operating costs, and the fact that these methods have to be carried out in a discontinuous manner (in batches). which has an adverse effect on both the control and its overall costs. Various attempts have been made to develop alternative methods for starch modification that overcome these disadvantages.

For example, EP710670A1 describes a continuous process for chemical modification, according to which a starch powder and a reagent are simultaneously introduced into a reactor. A rotating screw inside the reactor quickly creates a thin layer of dynamic liquid, allowing the starch and reagent to interact. However, this method has several drawbacks. First, because of the speed at which the starch passes through the reactor, there is very little time to allow any reaction to occur (ie, an insufficient contact time between the starch and the reagent is achieved). Furthermore, under the centrifugal force created by the rotating screw, the starch has a tendency to accumulate in the walls of the reactor. If the rotational speed were reduced sufficiently to allow an acceptable contact time and to deal with the problem of operability, the starch and the reagent could no longer be mixed properly, and this would again have a negative effect on the levels of reaction and the quality of the final product. Another example is WO 97/13788 which describes a process for the chemical fluidification of starches, which is carried out under standard piston-type flow conditions, at temperatures greater than or equal to 77 ° C and in reaction times up to 6 hours. This method also has several disadvantages. First of all, due to the very nature of piston-type flow reactors, a very little mixture of materials occurs. As mentioned before, this will have a negative effect on the reaction levels. In addition, at temperatures not exceeding 77 ° C and due to the static movement of the starch particles through the reactor, they will not dry out properly, even if the residence times increase. Finally, because piston-type flow reactors do, in effect, mimic the conditions of the batch process, the disadvantages associated with the latter will arise.

Another example is described in US 4,021,927. This document describes a fluidization reactor in which the particles pass through a stirred zone, before entering a number of hot tubular reactors. Unfortunately, this reactor does not allow the fluldiation to be maintained through the reaction, which means that the substrate can react unevenly. In particular, since the agitated and reaction zones are separated, fluidization will not be maintained during heating. As a result, not all the particles of the substrate will come into contact with the hot wall of the tubular reactors, the heavier particles will pass through the hot zones faster than their lighter counterparts (the reactor relies on gravity to transport the substrate from the entrance to the exit) and the particles can stick on the walls of the reactor, thus affecting the operating capacity. In general, this leads to an inefficient non-homogeneous reaction. Therefore, there is a need in the art for an improved and more economical method for modifying starch. The present invention provides said method.

BRIEF DESCRIPTION OF THE INVENTION In a first aspect the present invention provides a method for modifying starch or starch derivatives, comprising: introducing a continuous stream of starch, gas substrate and, optionally, one or more reagents, into a reactor, wherein the starch substrate : - has a moisture content between 0 and 45% by weight, preferably between 1 and 30% by weight; - it has a residence time in the reactor of between 1 and 60 minutes, preferably between 2 and 45 minutes; and - it is heated between 50 and 220 ° C, preferably between 80 and 220 ° C, characterized in that: - the starch substrate and the gas are introduced into the reactor in opposite directions; and in that - the reactor has a tubular body comprising a rotary screw on which one or a plurality of blades is disposed. According to one embodiment, the blade or blades will have a circumferential speed of between 2 and 30 m / s. The starch substrate can be selected from one or more natural starches, starch derivatives, starch materials such as flour and mixtures of two or more thereof. Preferably, the starch substrate is introduced into the reactor in powder form. The reagent can be, for example, a chemical or enzymatic reagent selected from a hydrolyzing agent, an oxidizing agent, an acid, a dextrinization agent, an alkylating agent, an esterification agent, a heterification agent, an agent of interlacing and mixtures of two or more thereof. Preferably the reagent will be selected from a mineral acid such as HCI, H2SO4 or H2PO4, an organic acid such as citric acid, a peroxide such as hydrogen peroxide (with or without a catalyst such as copper), an oxidation agent such as persulfate and mixtures of two. or more of them. According to a preferred embodiment, the reagent is added to the starch substrate before it is introduced into the reactor. In a second embodiment of the present invention, there is provided a method for preparing highly soluble starch, comprising: introducing a continuous stream of starch, gas substrate and one or more reagents selected from a mineral acid, a peroxide and an oxidation agent , in the reactor, wherein the starch substrate has a moisture content of between 1 and 30% by weight, a residence time in the reactor of between 2 and 45 minutes and is maintained between 80 and 220 ° C, characterized in that the starch substrate and the gas are introduced into the reactor in opposite directions, and in that the reactor has a tubular body comprising a rotating shaft on which one or a plurality of blades are disposed. Preferably, the starch produced according to this method will be 70 to 100% soluble in cold water, preferably 75 to 100% soluble in cold water. In a third embodiment of the present invention, there is provided the use of a reactor for the modification of starch or starch derivatives, said reactor has a tubular body comprising: a rotating arrow on which one or a plurality of blades; and - at least two entries, one for the introduction of the starch substrate and, optionally, one or more reagents, and one for the introduction of a gas, characterized in that the inlets are located in such a way that the starch and the gas are they enter the reactor in opposite directions.

DESCRIPTION OF THE FIGURES Figure 1 is a schematic representation of a reactor unit according to a possible embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for modifying starch or starch derivatives. The term "starch derivatives" refers to any molecule produced by a modification or a series of modifications, physical, chemical and / or genetic, of the natural starch. Accordingly, starch derivatives include (but are not limited to): in an enzyme or acid hydrolyzed derivatives (such as maltodextrins, glucose groups and hydrolyzates), degraded starches (e.g., heat degraded starches, oxidation, catalysis or acidification such as calcined dextrin and starch fluidized by acids), pregelatinized starches; starch esters (such as starch n-octenyl succinate); starch ethers; interlaced starches; retrograded starches; bleached starches; cationized or anionized starches; amphoteric starches; starch phosphates; hydroxyalkylated starches and starches treated with alkali. To make it simpler, any reference herein to starch will be understood to include both natural starch and starch derivatives. In contrast, the term "starch substrate" refers to the true product that is introduced into the reactor in a first step of the present method. The substrate may comprise one or more natural starches, or one or more starch derivatives or a mixture thereof. Preferably it will consist of starch and / or starch derivative (s). The starch itself can be of any desired origin (potato, wheat, corn, rice, tapioca, pea, barley, etc.) and can be waxy or not. The substrate may also include (or consist of) other suitable starch materials for use in a tubular reactor. For example one of said materials is flour (potato flour, soybean meal or a flour of a grain such as wheat flour). The substrate can be used in combination with one or more natural or synthetic polymers (such as cellulose or a hydrocolloid) and / or one or more organic or inorganic compounds. It can also be mixed with a pH regulator (such as NaOH).

The substrate can be in powder or cake form, and will have a moisture content of between 0 and 45% by weight, preferably between 1 and 30% by weight, more preferably between 3 and 25% by weight at its point of entrance to the reactor. If the substrate has a moisture level of more than 45%, it must be dried at least partially before it is introduced into the reactor. Humidity levels can be controlled inside the reactor if necessary (for example: with the addition of water or steam with the gas, controlling the reaction temperature and / or extracting the moisture, for example using an extractor fan). Preferably, moisture levels of 0 to 15% by weight will be obtained at the outlet of the reactor. The reactor, as defined herein, is a reactor having a tubular, preferably cylindrical body within which a rotating shaft is located. The rotary arrow is provided with one or a plurality of blades. With the phrase "one or a plurality of blades", it is not intended to limit the reactor in any particular construction. In fact, the blade or the blades may also be in the form of a number of separate blades or a single helical blade arranged around the arrow in the manner of a screw thread. The blade or knives will preferably have a circumferential speed of between 2 and 30 m / s, more preferably between 3 and 25 m / s, still more preferably between 4 and 20 m / s. In practice, the speed of rotation and the angle of the blades will be adjusted depending on the desired residence time of the substrate in the reactor.

In residence time it will be between 1 and 60 minutes, preferably between 2 and 45 minutes, more preferably between 10 and 30 minutes.

Of course, the exact residence time will be determined for each reaction, taking into account different variable factors (for example the nature of the substrate, the temperature of the reactor, the quality and nature of the reagent, the speed of rotation, etc.) and the type and extent of the modification that will be made. Thus, for example, while for certain reactions, the preferred residence time could be 4 minutes, for others it could be 30 minutes. In use, the blade or blades will transport the starch substrate from an inlet at one end of the reactor to an outlet at the other end in a continuous manner in a type of piston flow. As will be appreciated by those skilled in the art, the term "continuous" as used herein is intended to distinguish the present method from a lot-type process. As it is transported from its entrance through one end of the reactor to its exit through the other, the starch will be heated to a temperature between 50 and 220 ° C. In practice, this temperature is measured as the temperature of the product at the inlet of the reactor. Preferably it will be between 80 and 220 ° C, more preferably between 100 and 180 ° C, still more preferably between 100 and 160 ° C. Other reaction parameters, such as humidity, pH and pressure, can also be controlled. Those skilled in the art will know the appropriate means to control these parameters. However, for example, moisture can be controlled by regulating the amount of liquid produced in and / or extracted from the reactor. The extraction of moisture can be achieved by means of a simple moisture outlet or, for example, by using a humidity extractor fan. The pH can be controlled with the use of pH regulators. The pH regulators can be introduced into the reactor together with any one or more substrates of starch, reagent or gas. They can also be entered separately. According to one embodiment, the pH regulators will be used to ensure that the reaction is carried out under alkaline conditions. The pressure can be controlled, for example with the use of air locks at the reactor exits (for example at the outlet of the product and at the gas outlet and / or humidity) that prevent the gas from being released (the air , steam, etc.), until a certain pressure has been reached. As mentioned above, the reactor comprises an inlet for the starch substrate. It also comprises an inlet for gas which is located in such a way that the starch substrate and the gas are introduced into the reactor in opposite directions. For example, the entrances of the substrate and the gas do not necessarily have to be on geometrically opposite sides of the reactor, as long as they are sufficiently separated and angled so that, in use, the substrate flow and the gas flow run counter-current one with respect to the other.

The gas inlet can be of any type, allowing, for example, that the gas be pumped into the reactor or that it be sucked inward. In fact, according to one embodiment, the reaction can be carried out under vacuum. According to this embodiment, the reactor will comprise a gas and / or humidity outlet, located substantially opposite to the gas inlet and preferably comprising one or more means for increasing gas extraction and / or humidity, as an extractor fan. Also according to this embodiment, the gas inlet will have no more than, for example, an opening or a one-way valve. Thus, as the gas is extracted at one end of the reactor, it will be sucked at the other end, thereby creating a countercurrent flow of gas and starch substrate through the reactor. The countercurrent flow produces a better mixing of the starch substrate with any possible reagent and allows better control of the residence times (because the substrate is prevented from passing too fast through the reactor). As well, thanks to the resulting turbulence, each particle of the substrate will come into contact with the hot wall of the reactor more frequently, resulting in a more homogeneous reaction. In addition, the particle temperature will increase more rapidly thereby accelerating the reaction ratio, and thus decreasing the reaction time. Countercurrent flows also provide an efficient method for transporting reagents through the reactor, while maintaining the substrate particles in a fluidized state (and therefore preventing them from accumulating and / or sticking to the wall of the reactor). reactor). This results in an increased reaction efficiency and, consequently, reduced costs. In addition, the usual drawbacks associated with the use of the reactors in batches, and with the continuous reactors of the prior art (e.g., operating capacity) are avoided. The gas used to create the countercurrent can be any gas, but preferably it can be air, steam, nitrogen, carbon dioxide, an inert gas, controlled oxygen or a mixture of two or more thereof. This may include reagents, such as oxidants (e.g. ozone), amines, neutralizing agents or additives that are capable of modifying or controlling the reaction conditions. It can include a pH regulator such as NH3 or SO2. The gas can also be heated before entering the reactor. Preferably the gas will have a flow velocity through the reactor of 0.2-10 m / s, more preferably 0.2-2 m / s, still more preferably 0.2-1 m / s. The reactor may comprise one or more additional inputs for the introduction, if desired, or one or more reagents (enzyme, catalyst, etc.). The use of a reagent is not always necessary since the modification may simply consist of a physical modification (for example by heating). However, if a reagent is used, it may be selected, for example, from any one or more of: a hydrolyzing agent (such as α-amylase, β-amylase, glucoamylase or pullulanase), an oxidation agent (as a sodium hypochlorite or persulfate), an acid as an acid-eluting agent (eg H SO4 or H3PO4) or a dextrinization agent (such as HCI), an alkylating agent, an esterification agent (such as acetic anhydride, vinyl or n-octenyl succinate anhydride) an etherification agent (such as propylene oxide), an entanglement agent (such as phosphorous oxychloride, sodium trimetaphosphate or mixed anhydride of acetic and adipic acid) or other reactive compounds such as urea, proteins or phosphate compounds such as polyphosphates. Of course, this is not an exhaustive list, since the selection of a reagent will depend on the type of modification that you want to achieve. A person skilled in the art will be able to choose which reagent or reagents should be used in view of the type of reaction desired. For example, if it is desired to increase the solubility of the starch, the reagent can be a mineral acid (such as H2SO4 or H3PO4), an organic acid (such as citric acid), a peroxide (such as hydrogen peroxide) and / or an oxidation agent. (as hypochlorite or sodium persulfate). It has indeed been found that by using the method of the present invention, highly soluble starches can be produced in an economical manner on an industrial scale. In particular, the method of the present invention can be used to produce starches or starch derivatives that are 70-100%, preferably 75-100% soluble in cold water (ie soluble in water having a temperature of no more than 50 ° C). The reagents, if used, may be added in the form of a solution, powder or gas, and in amounts of 0.001-20% by weight (based on the total dry weight of the starch). Preferably, they are added in amounts of 0.001-10% by weight and, more preferably, in amounts of 0.01-3% by weight. Again, those skilled in the art will be able to determine the appropriate concentration of reagent that is needed depending, for example, the quality of the substrate that will be modified, the desired level of modification, the nature and concentration of the reagent to be used, etc. As mentioned above, any reagents or optional reagents can be introduced into the reactor by means of one or more centripetals separated from that used for the starch substrate. For example, if the reagent is in the form of gas, it would be preferable to introduce it to the reactor by means of a gas inlet. Alternatively, the reagent and the starch could be introduced via the same inlet. Thus, the reactant and the starch can be mixed inside the reactor, or in a preferred embodiment, they can be mixed before they are introduced into the reactor. Accordingly, the method of the present invention may contain an initial step comprising forming a premix by combining the reagent and the starch substrate. The premix can then be introduced (as the starch substrate) into the reactor by means of a single inlet. If the reagent is to be added to the starch substrate before it is introduced into the reactor, the mixing step can be carried out in a mixing chamber attached to the reactor. In this way the reactor that has already been described can be part of a larger unit ("reactor unit") comprising both upstream components and downstream components. The upstream components could include, for example, the aforementioned mixing chamber or a premodification chamber (for example if the starch substrate needs to undergo an initial modification before being introduced into the reactor, for example, by cooking or by a hydrothermal treatment) while the downstream components could include, for example, a drying chamber, an insulated holding tank (where the temperature of the product could be maintained to extend the reaction time effectively), a recycle element or one or more additional reactors. According to one embodiment, the common unit may all include more than one reactor in accordance with the present invention (eg, if several different modifications are necessary or if a longer residence time is desired). In this way, the product leaving a reactor can pass (directly or indirectly) to one or more additional reactors. When there is more than one reactor according to the present invention, it would be preferable to arrange them in series. A possible reactor unit, according to the present invention, is illustrated in Figure 1, in which (1) represents a countercurrent reactor, (2) represents a finishing reactor, (3) represents a rotation motor of arrow, (4) represents a dust separator, (5) represents a condenser and (6) represents a heat exchanger. The starch substrate is introduced into the rector through an inlet (a). The gas (with or without reagent and / or water added in (f)) is introduced through the inlet (c) and exits the reactor through the outlet (d). Then it can leave the reactor unit through the exhaust (k) or it can be recycled to the heat exchanger through the inlet (j). The modified starch product leaves the reactor through the outlet (b). After an optional additional procedure, the product leaves the reactor (2) through the outlet (e). The condensate is released from the condenser through the outlet (g). Alternatively, the powder that is joined in (4) can be recycled to the reactor of the inlets (h) and / or (i). The present invention also provides the use of a reactor or a reactor unit as described above for the modification (hydrolysis, degradation, esterification, etherification, heat treatment with heat, etc.) of starch or starch derivatives. The invention will now be illustrated by the following non-limiting examples.

EXAMPLE 1 Method for producing a starch of low solubility and low viscosity 150 kg of corn starch (CIGel 03402 from Cerestar) were mixed at 11.5% moisture, 479.7 ml HCI (from Sigma-Aldrich) to 11.7 N and 15.5 L water in a Lodige mixer for approximately 10 minutes at room temperature. The mixture was then introduced, in a continuous flow of 150 kg / h, into a pilot plant turbo reactor having multiple blades with a circumferential speed of 9.3 m / s (and 2 cm from the reactor wall). A counter current of hot air at 150 ° C was introduced simultaneously at 0.5 m / s. The substrate was transported through the reactor in a piston flow type movement and had a residence time in the reactor of approximately four minutes. The jacket temperature of the reactor was maintained at about 185 ° C such that the starch product reached a temperature of 117 ° C (measured at the outlet of the reactor). The Brookfield viscosity and the solubility of the product obtained at the outlet of the reactor were measured, using the methods that will be described below. The following results were obtained: As can be seen from these results, the starch product obtained had a significantly lower paste viscosity (despite a relatively high dry substance) than an untreated starch and a low solubility.

Dry substance The percen of dry substances was determined by drying a 5g sample for 4 hours at 120 ° C under vacuum. Dry substance,% = 100 - [(loss in weight, g x 100) / (weight of the sample, g)].

Soluble A 2000 g sample was weighed and transferred to a dry 200 ml Kohlrausch flask. The flask was partially filled with water at 25 ° C and stirred vigorously until the sample was completely in suspension. Then the suspension was diluted for volume. The flask was capped and gently shaken while immersing in a water bath at 25 ° C for a total time of one hour. After agitation, the suspension was filtered through a Whatman paper no. 2V. 50.0 ml of filtrate were measured and transferred to a heavy evaporation dish. The filtrate was then evaporated to dryness in a steam bath and dried in a vacuum oven for 1 hour at 100 degrees centigrade. The residue was dried in a desiccator and weighed to the nearest gram. The percen of solubles was determined according to the following formula: soluble,% d.b. = (weight of the residue, g x 100) / [(50 ml / 200 ml) x (weight of the sample, g) x (d.s.,% / 100)].

Brookfield Viscosity 180 g of the sample was weighed at 30% d.s. in a one liter beaker, made of stainless steel. Water was added to the beaker until the total weight of the sample reached 600 g. The water and the sample were then mixed with a plastic rod until a homogeneous suspension was obtained. A paddle was then placed in the beaker, the beaker was covered and the paddle was connected to a stirrer on a boiling water bath. Immediately stirring started at 250 rpm. After exactly 30 min., The beaker was removed from the boiling water bath and the contents were transferred very rapidly to a 600 ml glass beaker. The glass beaker was placed in a cooling water bath (in which the water was maintained at 15-20 ° C). The suspension was stirred using a plastic stirring rod together with a thermometer until a temperature of 40 ° C was reached. The viscosity was then measured (in mPas) in a Brookfield RVT series viscometer equipped with a No. 2 bar. The measurement was carried out at 40 ° C and at 100 rpm.

EXAMPLE 2 Method for producing a starch of high solubility and low viscosity 150 kg of corn starch (CIGel 03402 from Cerestar) at 11.5% humidity, 312.4 ml HCI (from Sigma-Aldrich) to 11.7 N and 15.6 L water were mixed in a Lódige mixer for approximately 10 minutes at room temperature. After the mixture was introduced, in a continuous flow of 150 kg / h, inside a turbo-reactor of pilot plant that had multiple blades with a circumferential speed of 5.0 m / s (and was located 2 cm from the reactor wall). An opposing air stream of hot air at 150 ° C was introduced simultaneously at 0.5 m / s. The substrate was transported through the reactor in a piston flow type movement and had a residence time in the reactor of about 30 minutes. The jacket temperature of the reactor was maintained at about 185 ° C, so that the starch product reached a temperature of 125 ° C (measured at the outlet of the reactor). The Brookfield viscosity and the solubility of the product obtained at the outlet of the reactor were measured, using the same methods as described above (except that a sample of 270 g to 45% d.s. was used for the viscosity measurement). The following results were obtained: As can be seen from the results, the starch product obtained had a significantly lower paste viscosity (despite a high dry substance) than the untreated starch. The product also had a much higher solubility.

Claims (19)

NOVELTY OF THE INVENTION CLAIMS

1. - A method for modifying starch or starch derivatives, comprising: introducing into a reactor a continuous flow of a substrate of starch, gas and, optionally, one or more reagents, wherein the starch substrate has a moisture content of between 0 and 45% by weight, a residence time in the reactor of between 1 and 60 minutes and heated between 50 and 220 ° C, characterized in that the starch substrate and the gas are introduced into the reactor in opposite directions, and because the reactor has a tubular body comprising a rotary arrow on which one or a plurality of blades is disposed.

2. The method according to claim 1, further characterized in that the knives have a circumferential speed of between 2 and 30 m / s, preferably between 3 and 25 m / s.

3. The method according to claim 1 or 2, further characterized in that the starch substrate has a moisture content between 1 and 3% by weight.

4. The method according to any of the preceding claims, further characterized in that the starch substrate is selected from natural starch, derived from starch, material with starch and mixtures of two or more thereof.

5. - The method according to any of the preceding claims, further characterized in that the starch substrate is introduced into the reactor in powder form.

6. The method according to any of the preceding claims, further characterized in that the reagent is selected from a hydrolyzing agent, an oxidation agent, an acid, a dextrinization agent, an alkylating agent, an esterification agent, an etherification agent, an entanglement agent and mixtures of two or more thereof.

7. The method according to any of the preceding claims, further characterized in that the reagent is selected from a mineral acid, a peroxide, an oxidation agent and mixtures of two or more thereof.

8. The method according to any of the preceding claims, further characterized in that the one or more reagents are added in an amount between 0.001 and 20% by weight.

9. The method according to any of the preceding claims, further characterized in that the one or more reagents are introduced into the reactor in the form of liquid, powder or gas.

10. The method according to any of the preceding claims, further characterized in that at least one of the one or more reactants is added to the starch substrate before introducing it into the reactor.

11. - The method according to any of the preceding claims, further characterized in that the residence time of the starch in the reactor is between 2 and 45 minutes.

12. The method according to any of the preceding claims, further characterized in that the reaction is maintained at a temperature between 80 and 220 ° C.

13. The method according to any of the preceding claims, further characterized in that the gas that is introduced into the reactor is selected from: air, steam, nitrogen, carbon dioxide and a mixture of two or more thereof.

14. A method for preparing a highly soluble starch, comprising: introducing a continuous flow of a substrate of starch, gas and one or more reagents selected from a mineral acid, a peroxide and an oxidizing agent, in a reactor, in wherein the starch substrate has a moisture content of between 1 and 30% by weight, a residence time in the reactor of between 2 and 45 minutes and is heated to between 80 and 220 ° C, characterized in that the substrate of starch and the gas is introduced into the reactor in opposite directions, and in that the reactor has a tubular body comprising a rotary arrow on which one or a plurality of blades is disposed.

15. The method according to claim 14, further characterized in that the reaction is carried out under alkaline conditions.

16. The method according to claim 14 or 15, further characterized in that the highly soluble starch is 70% to 100% soluble in water having a temperature of not more than 50 ° C.

17. The use of a reactor for the modification of starch or starch derivatives, said reactor has a tubular body comprising: a rotary arrow on which one or a plurality of blades is disposed; and at least two entries, one for the introduction of a starch substrate and, optionally, one or more reagents, and one for the introduction of a gas, characterized in that the inlets are located in such a way that the starch and the gas are they enter the reactor in opposite directions.

18. The use as claimed in claim 17, wherein the blade or knives have a circumferential speed of between 2 and 30 m / s, preferably between 3 and 25 m / s.

19. The use as claimed in claim 17 or 18, for the hydrolysis, degradation, oxidation, degradation with acid, dextrinization, bleaching, etherification, esterification, entanglement, alkylation or acetylation of starch and / or starch derivatives.