Process for preparation of pregelatinized starch and / or pregelatinized flour

Abstract

To provide a process for preparing pregelatinized starch.SOLUTION: There is provided a process for preparing pregelatinized starch, comprising the steps of: providing an aqueous medium having a pH of -1.0 to 7.5; mixing thermally-inhibited starch with the aqueous medium in the mixing step to form a starch composition having a pH of 4.0 to 6.5, pregelatinizing the starch composition, wherein the composition is heated using a drum dryer, while rotating the drum, to form the pregelatinized starch, wherein during the heating the starch composition is dried using the drum dryer; allowing the pregelatinized starch to cool to a temperature of at most 80°C; and storing the obtained pregelatinized starch at a temperature of at most 60°C; wherein the process comprises a thermal inhibition process prior to the mixing step, and the thermal inhibition comprises a heat treatment at temperatures between 100 and 200°C and is carried out at pH greater than 8.0, thereby reducing the water content of the starch to less than 1 wt.%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The field of the invention relates to methods for preparing pregelatinized starch and / or pregelatinized flour. [Background technology]

[0002] Starch and / or flour are widely used in the food manufacturing industry for processing and as food thickeners or stabilizers. Methods for pregelatinizing starch and / or flour are generally known. Native starch granules are insoluble in cold water. When the native granules are dispersed in water and cooked, they hydrate and swell. Pregelatinized starch and / or flour are dried before packaging and shipping. Pregelatinized starch and / or flour can be easily dissolved in cold water.

[0003] Pregelatinized starch and / or flour can be derived from native starch and / or flour, chemically crosslinked starch and / or flour, and physically modified starch and / or flour. The term physically modified starch and / or flour includes starch and / or flour that has been subjected to heat / moisture treatment, annealing, heat inhibition, etc. As meant herein, the term physical modification does not include pregelatinization.

[0004] Chemically and physically modified starches and / or flours are known to offer increased process resistance and are suitable as food thickeners or stabilizers under more extreme processing conditions.

[0005] However, it has been found that known pregelatinized starches and / or flours can lose some or all of their beneficial high viscosity properties when gels prepared from said pregelatinized starches or flours are subjected to high levels of shear, such as may occur during food preparation. Summary of the Invention

[0006] Thus, there remains a need for improved methods of preparing pregelatinized starch and / or pregelatinized flour.

[0007] There is also a need for improved pregelatinized starches and / or pregelatinized flours.

[0008] According to a first aspect of the present invention there is provided a method for preparing pregelatinized starch and / or flour, comprising the steps of: - providing an aqueous medium having a pH in the range of from 1.0 to 7.5, preferably from 1.0 to 5.0; - mixing starch and / or flour with an aqueous medium in a mixing step to form a starch composition having a pH in the range of 2.0 to 7.9, preferably 4.0 to 7.5, more preferably 4.0 to 6.5, the starch composition having the aqueous medium as a continuous phase and containing 20 to 60% by weight, preferably 30 to 50% by weight, of starch and / or flour particles, expressed as a percentage of dry matter relative to the total weight of the starch composition; and - pregelatinizing a starch composition in a pregelatinization step, wherein the composition is heated using a drum dryer while rotating a drum to form pregelatinized starch and / or pregelatinized flour, and during the pregelatinization step, the starch composition is dried using a drum dryer; cooling the pregelatinized starch and / or pregelatinized flour to a temperature of at most 80°C; and storing the resulting pregelatinized starch and / or pregelatinized flour at a temperature of up to 60°C. A method is provided that includes:

[0009] As a result of the method of the present invention, pregelatinized starch and / or flour is available which may be native, physically modified or chemically modified, the starch or flour being preferably rice starch and / or rice flour.

[0010] As a result of the method of the present invention, pregelatinized rice starch and / or pregelatinized rice flour is obtainable, which is physically modified and characterized by a loss factor value of at most 0.99, said loss factor value being measured on a gel of pH 3.6 obtained from said starch and / or flour, which has been subjected to successive mixing steps at room temperature of 1200 rpm for 8 minutes, 900 rpm for 5 minutes and 300 rpm for 5 minutes, and a shear rate application step of 3000 to 9000, preferably 5000 rpm for 1 minute, said loss factor being measured using an amplitude sweep at a frequency of 1 Hz with a deformation of 0.01% to 1000%.

[0011] In certain instances, the pregelatinized rice starch and / or pregelatinized rice flour are physically modified and characterized by a loss factor value of at most 0.35 for pregelatinized rice starch and at most 0.55 for pregelatinized rice flour.

[0012] In the research leading to the present invention, the inventors have found that when starch and / or flour are mixed with an aqueous medium to form a starch composition, the pH of the resulting starch composition is important for obtaining a pregelatinized starch and / or flour with improved properties, such as high shear stability. The pH of the starch composition is controlled in the range of 2.0 to 7.9. It has surprisingly been found that when the pH of the aqueous starch composition is controlled in the range of 2.0 to 7.9 before the starch composition is pregelatinized, the resulting gels and other compositions containing pregelatinized starch and / or flour can have improved properties, such as enhanced high shear stability and a more elastic structure / texture. This allows the amount of pregelatinized starch and / or flour to be reduced to achieve a given viscosity.

[0013] The drum-dried pregelatinized starch and / or pregelatinized flour is cooled to a temperature of at most 80° C. and the resulting pregelatinized starch and / or pregelatinized flour is cooled to a temperature of at most 60° C., preferably to a temperature in the range of 10° C. to +50° C., and even more preferably to a temperature in the range of −10° C. to +40° C. Thus, the improved properties of the resulting pregelatinized starch and / or pregelatinized flour are maintained in an appropriate manner during storage and prior to processing of the pregelatinized starch and / or pregelatinized flour as a food or feed ingredient. DETAILED DESCRIPTION OF THE INVENTION

[0014] In a preferred embodiment, the pH of the starch composition of the slurry during the pre-gelatinization step is selected to be lower than the pH of the starch and / or flour itself. Such pH depends on the type of starch. For thermally inhibited starches, such a pH may be alkaline, e.g., greater than 8.0. For native starches, the pH of the starch and / or flour typically ranges from 5 to 7. For chemically modified starches, the pH depends on the chemical modification. The pH may further depend on the type of starch and the processing conditions of the inhibition or modification.

[0015] In the mixing step of the present invention, starch and / or flour are mixed with an aqueous medium to form a starch composition, which is an aqueous starch composition. As meant herein, the term starch composition means a composition comprising at least one starch and / or flour.

[0016] As used herein, the term starch composition refers to a slurry having an aqueous liquid as a continuous phase and containing solid particles of starch and / or flour. Typically, starch compositions can flow and be transported in a manner similar to a liquid when at a temperature between 5°C and 55°C. Such starch compositions can be subjected to a drying step, resulting in the aqueous starch composition becoming a dry starch composition.

[0017] The maximum weight percentage of solid particles that can be included in a starch composition while maintaining flowability and transportability properties depends, as is known, on the exact nature of the particles. Preferably, the solids content of the starch composition is between 20 and 60%, 25 and 55%, 30 and 50%, more preferably between 35 and 45 or 40% by weight.

[0018] The aqueous medium may have additional components in addition to water. Other compounds besides water may be present, and indeed this is the case in industrial applications of the present invention, where, for example, process water streams or other locally available and suitable water streams are used. However, the aqueous phase is preferably essentially free of other solvents, such as ethanol. The aqueous phase preferably comprises at least 80, 85, 90, or even at least 95, 96, 97, or 98% by weight of water. In one embodiment of the present invention, the aqueous phase consists essentially of water or even consists of water.

[0019] The temperature of the aqueous phase can vary within wide limits and is preferably from 5 to 50°C, more preferably from 10 to 30°C or even from 15 to 25°C.

[0020] In the pregelatinization process, the starch composition is heated using a drum dryer while the drum is rotating to form pregelatinized starch and / or flour. During the pregelatinization process, the starch composition is dried using a drum dryer. Preferably, in the pregelatinization process, the starch composition is heated using a drum dryer by applying steam to the drum dryer.

[0021] Drum dryers are well known to those skilled in the art, and it is also known that both pregelatinization and drying can occur in a single pass through the drum dryer. It has been found by the inventors that drum dryers can be used in combination with other features of the present invention to form pregelatinized starch and / or flour, and the resulting pregelatinized starch and / or flour can exhibit improved properties, such as, for example, relatively high low-temperature viscosity and enhanced high-shear stability.

[0022] In principle, the starch and / or flour used can be any type of starch.

[0023] In a preferred embodiment, the method comprises at least one of a physical modification step and a chemical modification step before the mixing step, wherein the starch and / or flour is physically modified or chemically modified, and the starch and / or flour used in the mixing step is physically modified starch and / or flour or chemically modified starch and / or flour.

[0024] In a preferred embodiment, the starch is physically modified, preferably thermally inhibited. In said embodiment, the method comprises a physical modification step prior to the mixing step, the physical modification step being a thermal inhibition step for thermally inhibiting the starch and / or flour, and the starch and / or flour used in the mixing step is a thermally inhibited starch and / or flour. Preferably, the starch composition formed in the mixing step has a pH in the range of 4.0 to 7.5, more preferably 4.0 to 6.5.

[0025] In an alternative preferred embodiment, the starch and / or flour is a chemically modified starch and / or flour. In said embodiment, the method comprises a chemical modification step for chemically modifying the starch and / or flour before the mixing step, and the starch and / or flour used in the mixing step is a chemically modified starch and / or flour. Preferably, the starch composition formed in the mixing step has a pH in the range of 4.0 to 6.5.

[0026] Chemically modified starch and / or flour can be obtained, for example, via chemical cross-linking. Chemical cross-linking treatments of starch and / or flour are known in the art.

[0027] Commonly known chemical modification processes for chemically modifying starch and / or flour include, but are not limited to: - crosslinking reactions such as using any one of phosphorus oxychloride, trimetaphosphoric acid and a mixture of adipic acid and acetic anhydride; substitution reactions, such as any one of acetylation, octenylsuccinylation, phosphorylation and hydroxypropylation, and - Conversion reactions such as any one of acid hydrolysis, oxidation and bleaching, thermal conversion and enzymatic conversion.

[0028] In yet other embodiments, the starch and / or flour is selected from native starches and / or flours. As used herein, the term "native" starch has the meaning of a starch found in nature.

[0029] Most preferably, the starch and / or flour is derived from waxy starch and / or waxy flour. It has been found that waxy varieties of starch and / or flour can provide beneficial properties.

[0030] In embodiments, the starch and / or flour may include maize (i.e., corn), wheat, rice, sorghum, barley, rye, tapioca, potato, and any mixtures thereof.

[0031] Preferably, the starch and / or flour is selected from maize (ie, corn), wheat, rice, sorghum, barley, rye, and any mixture thereof.

[0032] In a preferred embodiment, the starch and / or flour is derived from rice, preferably glutinous rice.

[0033] In one embodiment, the method includes a thermal inhibition step prior to the mixing step, and the starch and / or flour used in the mixing step is a thermally inhibited starch and / or flour. When a thermally inhibited starch or flour is mixed with water, the pH of the resulting starch composition is often greater than 7.0 or 8.0. The tendency of starch compositions to have an alkaline pH is believed to be caused by typical thermal inhibition processing conditions for thermally inhibiting starch or flour, i.e., high temperatures (such as temperatures of 100-200°C) and alkaline pH conditions are used. The inventors have discovered that the changes in starch and / or flour achieved by thermal inhibition can be at least partially reversed if the pH of the starch composition is not reduced in accordance with the present invention.

[0034] The preparation of heat-inhibited starches and / or flours is known per se. Heat-inhibited starches and flours have the advantage that they are not generally considered chemically modified starches or flours and do not need to be labeled with a European Union "E" number or equivalent, and therefore can be part of a "clean label" approach to food ingredients.

[0035] As is known, thermal inhibition of starch involves heat treatment at temperatures between 100 and 200°C. In a preferred embodiment, thermal inhibition is carried out at an alkaline pH (above 8.0), thereby ensuring that the starch has a moisture content of less than 1% by weight. As a result, upon completion of thermal inhibition, the moisture content of the thermally inhibited starch can be, and in a preferred embodiment is, less than 1% by weight.

[0036] As is known, the thermal inhibition of flour involves heat treatment at temperatures between 100 and 200°C.

[0037] When first prepared, heat-inhibited starches and flours have moisture contents below, and typically significantly below, their equilibrium values, which as used herein are values ​​at 21° C. and 50% relative humidity.

[0038] In a preferred embodiment, the required pH of the starch composition is achieved by providing an acidic aqueous medium before it enters the mixing step. The pH of the aqueous medium is selected, for example, in the range of -1.0 to 7.5 or 1.0 to 5.0. The desired pH value of the aqueous medium can be established by routine experimentation using small samples of the relevant starch and / or flour. Most preferably, the pH of the aqueous medium is determined so that no further pH adjustment is necessary. In the case of heat-inhibited starches and / or heat-inhibited flours with significant alkalinity, it may prove necessary to bring the pH of the aqueous medium to a value below 2.0.

[0039] In a further embodiment, the pH of the starch composition is brought to the desired value following combining the starch and / or flour with the aqueous medium, in which the pH of the starch composition is brought to a value of 3.0 to 7.0 or a value of 4.0 to 6.5 within 90 minutes, preferably within 60 or 30 or 15 minutes, more preferably within 10 minutes, after combining the starch and / or flour with the aqueous medium in the mixing step.

[0040] In general, it is quite possible, and sometimes preferred, to add an acidic aqueous composition to the starch and / or flour or starch composition to further adjust and optimize towards the desired value.

[0041] The adjustment of pH per se is well known to those skilled in the art and can be achieved, for example, by adding bases such as sodium hydroxide or acids such as sulfuric acid and citric acid, or by means of buffers such as citrate buffers and phosphate buffers.

[0042] As used herein, the pH of a solid material such as starch and / or flour is determined at 21°C and is measured as follows: 10 g of the dry test material to be measured is placed in a beaker containing 100 ml of demineralized water, followed by stirring. The pH of the suspension is then measured using a calibrated standard pH measuring device. The measured pH is considered to be the pH of the test material.

[0043] The pH of the starch composition according to the invention is preferably at least 2.0 to prevent the glycosidic bonds between the sugar moieties of the starch from being hydrolyzed, a process known to occur at an accelerated pace at pH values ​​below 2.0. More preferably, the pH of the starch composition is at least 2.5, 3.0, 3.5 or even at least 4.0.

[0044] The pH of the starch composition according to the invention should be at most 7.9, since beneficial effects on the properties of the pregelatinized starch and / or flour have been found to occur when the pH of the starch composition is less than 7.9. In a preferred embodiment, the pH of the starch composition is between 4.0 and 7.5, more preferably between 4.0 and 6.5. It has been found that by controlling the pH of the starch composition to less than 7.5, preferably less than 6.5, the shear stability of the pregelatinized starch and / or flour can be at least maintained or even enhanced. More preferably, the pH of the starch composition is at most 7.2, 7.1, 7.0, 6.9, 6.8, 6.7, 6.6, 6.5, 6.4, 6.3, 6.2, 6.1, or even at most 6.0.

[0045] In one embodiment, the starch and / or flour is heated in the pregelatinization process by applying steam to a drum dryer. The advantage is the controlled heating of the starch composition on the drum dryer.

[0046] In one embodiment, the gelatinization step is carried out so that the resulting gelatinized starch and / or gelatinized flour has a moisture content of 0% to 30% by weight, preferably 2% to 20% by weight, more preferably 3 to 15% by weight. The gelatinization step is carried out using a drum dryer. The conditions for the gelatinization step using a drum dryer can be selected appropriately to dry the gelatinized starch and / or gelatinized flour.

[0047] In a specific example, the resulting pregelatinized starch and / or flour is characterized by a loss factor value of at most 0.99, measured on a pH 3.6 gel obtained from the starch and / or flour subjected to successive mixing steps at room temperature: 1200 rpm for 8 minutes, 900 rpm for 5 minutes, 300 rpm for 5 minutes, and 5000 rpm for 1 minute, the loss factor being measured using an amplitude sweep at a frequency of 1 Hz with a deformation of 0.01% to 1000%. The loss factor value (loss tangent) measured after high shear conditions has been recognized by the inventors as an important measure of the high shear stability of pregelatinized starch and / or flour. The loss factor provides a ratio between the elastic and viscous properties of the starch. A loss factor of 1 equates to the elastic and viscous properties. The smaller the loss tangent, the more elastic the starch material.

[0048] In a specific example, the pregelatinized starch is rice starch, and even more preferably, heat-inhibited rice starch. This material is characterized in that after subjecting the gel to successive mixing steps of 8 minutes at 1200 rpm, 5 minutes at 900 rpm, and 5 minutes at 300 rpm at room temperature, and applying a shear rate of 5000 rpm for 1 minute, the gel has a shear-dependent viscosity (V5) of at least 2,000 mPa·s measured at 20°C and a shear rate of 0.88 s-1. A shear-dependent viscosity (V5) of at least 2,000 mPa·s has been found to be a beneficial property for the use of pregelatinized rice starch in food manufacturing.

[0049] In a specific example of the resulting pregelatinized rice starch, the gel has a loss factor value of at most 0.30 and a shear dependent viscosity (V5) of at least 11,000 mPas.

[0050] In a preferred embodiment of the pregelatinized rice starch and / or pregelatinized rice flour, the pregelatinized rice starch and / or pregelatinized rice flour is obtainable according to the method according to the invention.

[0051] As a result of the method of the present invention, pregelatinized rice starch and / or pregelatinized rice flour can be obtained, which is heat-inhibited prior to the gelatinization process, and the level of inhibition of the pregelatinized rice starch and / or pregelatinized rice flour is similar to the level of inhibition of the originally heat-inhibited starch or heat-inhibited flour used in the gelatinization process. The level of inhibition of a particular starch or flour can be indicated by the viscosity and / or loss factor value of the starch or flour. In a specific example, the pregelatinized heat-inhibited rice starch and / or pregelatinized heat-inhibited rice flour obtained according to the method of the present invention has a loss factor value that is at most 20% higher, preferably at most 10% higher, even more preferably at most equal, and most preferably at least 10% lower than the same non-pregelatinized heat-inhibited starch and / or heat-inhibited flour, said loss factor values ​​being measured on a gel of pH 3.6 obtained from said starch and / or flour subjected to successive mixing steps at room temperature of 1200 rpm for 8 minutes, 900 rpm for 5 minutes and 300 rpm for 5 minutes, and a shear rate application step of 5000 rpm for 1 minute, said loss factor being measured using an amplitude sweep at a frequency of 1 Hz with a deformation of 0.01% to 1000%.

[0052] As used herein, unless otherwise specified, the terms "essentially," "consisting essentially of," "essentially all," and their equivalents have their ordinary meaning in relation to a composition or process step that deviations in the composition or process step may occur, but only to the extent that the essential properties and effects of the composition or process step are not materially affected by such deviations.

[0053] The starch and / or flour may constitute the entirety of any solid material used in the mixing step, or may be present in the form of a mixture with other compounds. In the case of a mixture, the starch and / or flour is the largest dry matter component in the mixture, preferably representing at least 40, 50, 60, 70, 80, 90, or at least 95% of the mixture entering the mixing step. Examples of possible other compounds in the mixture are other carbohydrates, proteins, and lipids.

[0054] Upon completion of the pregelatinization process, the pregelatinized starch and / or flour is typically recovered and further processed, for example, by packaging the pregelatinized starch and / or flour.

[0055] The industrial implementation of the method of the present invention can be in the form of a batch process, a continuous process, or a mixture thereof. [Example]

[0056] Preparation of gel Specific properties of starch or flour were determined by preparing gels with the starch or flour. The experiments shown in Comparative Experiments A and B and Examples 1 and 2 are performed using a heat-inhibited rice starch. The experiments shown in Comparative Experiments C and D and Examples 3-5 are performed using a different heat-inhibited rice starch. The other heat-inhibited rice starch has a lower level of inhibition than the heat-inhibited rice starch of Experiments C, D, 1, and 2.

[0057] Comparative Experiments E and F and the experiments shown in Examples 6 and 7 are carried out using heat-inhibited cornstarch.

[0058] The experiments shown in comparative experiments G and H and examples 8 and 9 are carried out using chemically modified glutinous rice starch.

[0059] Comparative experiments I and J and the experiments shown in Example 10 are carried out using heat-inhibited rice flour.

[0060] Non-gelatinized starch or non-gelatinized flour gels were prepared using 135 g (dry weight) starch or 225 g (dry weight) flour in a Stephan UMSK5 cooker equipped with a mixing insert with two round blades. In the next step, the water was acidified with citric acid and trisodium citrate, buffered to pH 3.6, and enough water was added to bring the total weight to 2,500 g, thereby combining the citric acid and trisodium citrate with the water, before adding the starch.

[0061] Non-gelatinized starch or non-gelatinized flour gels were further prepared by heating the starch compositions at 94°C for 4.5 minutes via indirect heating at 0.6 bar steam pressure in a double jacket Stephan UMSK5 cooker with simultaneous mixing at 300 rpm. After cooling the resulting gels to 25°C, the gels were subjected to further processing, including a high shear step, as described below.

[0062] Pregelatinized starch or pregelatinized flour gels were prepared in a Stephan UMSK5 cooker equipped with a mixing insert with two rounded blades using 135 g (dry weight) starch or 225 g (dry weight) flour. In the next step, 250 g of ethylene glycol (10 wt. % based on the total weight of the solution) was added to the dry starch or flour before adding water or other ingredients. Water was acidified using citric acid and trisodium citrate, buffered to pH 3.6, and enough water was added to bring the total weight to 2,500 g, thereby combining the citric acid and trisodium citrate with the water before adding it to the starch or flour. Ethylene glycol was used only in Comparative Experiments D, F, H, and J and Examples 3-10.

[0063] A homogeneous gel of pregelatinized starch or flour was obtained by subjecting the mixture to three successive mixing steps in a Stephan UMSK5 at room temperature: 1200 rpm for 8 minutes, 900 rpm for 5 minutes and 300 rpm for 5 minutes.

[0064] A 500 mL portion of the resulting gel was then subjected to a vigorous shearing process by means of a Silverson L4RT mixer using a square-hole (2.4 mm) high-shear screen mixer head at a predetermined shear rate (rpm) for 1 minute.

[0065] The selection of the rpm for the intensive shear step is performed based on the properties of the gel, and therefore in the further examples below, a different rpm may be chosen to gain the most meaningful insight into the behavior of the material. The rpm used for the intensive shear step (always 1 min) is reflected in the notation of the viscosity parameter V by a subscript, whereby V0 indicates no intensive shear step (i.e., 0 rpm) and V 1.5 V indicates 1,500 rpm, V3 indicates 3,000 rpm, V5 indicates 5,000 rpm, V7 indicates 7,000 rpm, etc. The sheared gel is allowed to stand overnight at a temperature of 4°C.

[0066] Measurement of viscosity characteristics The viscosity and loss factor of gels made from the relevant starches first subjected to an intensive shear process were determined at a temperature of 20°C by means of an Anton Paar rheometer (parallel plate-plate configuration; plate diameter was 40 mm). In the context of this specification, the term loss factor is used in its usual sense of being the loss tangent in the linear viscoelastic region. It represents the ratio between the viscosity and elasticity of the system, indicating which is dominant. A loss factor of 1 equals the elastic and viscous properties of the material. The smaller the loss tangent, the more elastic the material.

[0067] 0.88s -1 The viscosity at 100°C was determined by viscosity curve measurement, where the shear rate was varied from 0.1 to 100 s along a logarithmic ramp with 20 measurement points. -1 It fluctuated.

[0068] The loss factor was determined from the LVR range obtained via amplitude sweep measurements with the following characteristics: 0.01 to 1000% deformation following a logarithmic ramp with six measurement points per decade.

[0069] In the examples and comparative experiments herein, loss factor and viscosity are always determined first on gels subjected to shear forces as described above at the rpm indicated for each example or comparative experiment.

[0070] Comparative Experiment A The properties of the raw material, heat-inhibited glutinous rice starch, used in the following Comparative Experiment B and Examples 1-2 were measured without subjecting the starch to subsequent processing steps such as slurrying.

[0071] The starch had a moisture content of 7.0% by weight. The starch had a pH of 8.3 (determined in a 10% by weight starch solution in demineralized water). Viscosity properties were determined as follows: V514,500mPa.s Loss factor 0.29

[0072] Comparative Experiment B The sample of thermally inhibited glutinous rice starch used in Comparative Experiment A was used to form a slurry using demineralized water as the aqueous medium. The resulting slurry contained 30 wt. % thermally inhibited glutinous rice starch particles, expressed as a percentage of the dry matter of the thermally inhibited glutinous rice starch based on the total weight of the slurry. The slurry had a pH of 8.0. The slurry was then dewatered on a drum dryer (Andritz single drum dryer, model E5 / 5) using steam at 5.5 bar and 5 rpm to form a slurry-dried starch with a moisture content of 4.4 wt. %.

[0073] The slurried dry starch had a pH of 8.3 (determined in a 10% by weight starch solution in demineralized water).

[0074] Viscosity characteristics were determined as follows: V59,750mPa.s Loss factor 0.36

[0075] Example 1 A starch composition was formed using the sample of thermally inhibited glutinous rice starch used in Comparative Experiment A, using as the aqueous medium demineralized water acidified to a pH of 2.5 with sulfuric acid prior to contacting with the rice starch. The resulting starch composition had a pH of 7.3 and contained 30% by weight of thermally inhibited glutinous rice starch particles, expressed as a percentage of dry matter of the thermally inhibited glutinous rice starch based on the total weight of the starch composition.

[0076] The starch composition was then dried on a drum dryer using 5.5 bar steam and 5 rpm to form a pregelatinized starch having a moisture content of 4.6% by weight.

[0077] The pregelatinized starch had a pH of 7.7 (determined in a 10% by weight starch solution in demineralized water).

[0078] Viscosity characteristics were determined as follows: V511,900mPa.s Loss factor 0.28

[0079] Example 2 A starch composition was formed using the sample of thermally inhibited glutinous rice starch used in Comparative Experiment A, using as the aqueous medium demineralized water acidified to a pH of 2.1 with sulfuric acid prior to contacting with the rice starch. The resulting starch composition had a pH of 6.2 and contained 30% by weight of thermally inhibited glutinous rice starch particles, expressed as a percentage of the dry matter of the thermally inhibited glutinous rice starch based on the total weight of the slurry.

[0080] The starch composition was then dried on a drum dryer using steam at 5.5 bar and 5 rpm to form a pregelatinized starch having a moisture content of 5.0% by weight.

[0081] The pregelatinized starch had a pH of 6.5 (determined in a 10% by weight starch solution in demineralized water).

[0082] Viscosity characteristics were determined as follows: V512,300mPa.s Loss factor 0.28

[0083] The V5 and loss factor results show that the shear stability of Examples 1 and 2, which have starch compositions with a pH of less than 7.9, was significantly higher than that of Comparative Example B.

[0084] Comparative Experiment C The properties of this alternative heat-inhibited glutinous rice starch, the raw material used in Comparative Experiment D and Examples 3, 4 and 5 below, were measured without subjecting the starch to subsequent processing steps such as slurrying.

[0085] The starch had a moisture content of 10.0% by weight. The starch had a pH of 8.1 (determined in a 10% by weight starch solution in demineralized water). Viscosity properties were determined as follows: V55600mPa.s Loss factor 0.50

[0086] Comparative Experiment D A sample of the thermally inhibited glutinous rice starch used in Comparative Experiment C was used to form a slurry using demineralized water as the aqueous medium. The resulting slurry contained 36% by weight of thermally inhibited rice starch particles, expressed as a percentage of the dry matter of the thermally inhibited rice starch based on the total weight of the slurry. The slurry had a pH of 8.2. The slurry was then dewatered on a drum dryer (Andritz single drum dryer, model E5 / 5) using steam at 6 bar and 6 rpm to form a slurry-dried starch with a moisture content of 3.5% by weight.

[0087] Viscosity characteristics were determined as follows: V57,200mPa.s Loss factor 0.47

[0088] Example 3 A starch composition was formed using the sample of thermally inhibited glutinous rice starch used in Comparative Experiment C, using as the aqueous medium demineralized water acidified to pH 2.1 with citric acid prior to contacting with the rice starch. The resulting starch composition had a pH of 5.0 and contained 36% by weight of thermally inhibited glutinous rice starch particles, expressed as a percentage of dry matter of the thermally inhibited glutinous rice starch based on the total weight of the slurry.

[0089] The starch composition was then dried on a drum dryer using steam at 5.5 bar and 5 rpm to form a pregelatinized starch having a moisture content of 5.0% by weight.

[0090] Viscosity characteristics were determined as follows: V59,300mPa.s Loss factor 0.31

[0091] Example 4 A starch composition was formed using the sample of thermally inhibited glutinous rice starch used in Comparative Experiment C, using as the aqueous medium demineralized water acidified to pH 4.0 with citric acid prior to contacting with the rice starch. The resulting starch composition had a pH of 6.0 and contained 36% by weight of thermally inhibited glutinous rice starch particles, expressed as a percentage of dry matter of the thermally inhibited glutinous rice starch based on the total weight of the slurry.

[0092] The starch composition was then dried on a drum dryer using steam at 6 bar and 6 rpm to form a pregelatinized starch having a moisture content of 2.3% by weight.

[0093] Viscosity characteristics were determined as follows: V59,000mPa.s Loss factor 0.36

[0094] Example 5 A starch composition was formed using the sample of thermally inhibited glutinous rice starch used in Comparative Experiment C, using as the aqueous medium demineralized water acidified to pH 4.3 with citric acid prior to contacting with the rice starch. The resulting starch composition had a pH of 7.0 and contained 36% by weight of thermally inhibited glutinous rice starch particles, expressed as a percentage of dry matter of the thermally inhibited glutinous rice starch based on the total weight of the slurry.

[0095] The starch composition was then dried on a drum dryer using steam at 6 bar and 6 rpm to form a pregelatinized starch having a moisture content of 3.7% by weight.

[0096] Viscosity characteristics were determined as follows: V58,800mPa.s Loss factor 0.41

[0097] The V5 and loss factor results show that the shear stability of Examples 3, 4, and 5, which have starch compositions with a pH of less than 7.9, was significantly higher than that of Comparative Example B.

[0098] Comparative Experiment E The properties of the raw material, heat-inhibited waxy corn starch, used in Comparative Experiment F and Examples 6-7 below were measured without subjecting the starch to subsequent processing steps such as slurrying.

[0099] The starch had a moisture content of 10.2% by weight. The starch had a pH of 7.2 (determined in a 10% by weight starch solution in demineralized water). The viscosity properties were determined as follows: V513,500mPa.s Loss factor 0.44

[0100] Comparative experiment F A sample of the thermally inhibited waxy corn starch used in Comparative Experiment E was used to form a slurry using demineralized water as the aqueous medium. The resulting slurry contained 36% by weight of thermally inhibited waxy corn starch particles, expressed as a percentage of the dry matter of the thermally inhibited corn starch based on the total weight of the slurry. The slurry had a pH of 8.2. The slurry was then dewatered on a drum dryer (Andritz single drum dryer, model E5 / 5) using steam at 6 bar and 6 rpm to form a slurry-dried starch with a moisture content of 2.9% by weight.

[0101] Viscosity characteristics were determined as follows: V58,200mPa.s Loss factor 0.43

[0102] Example 6 A starch composition was formed using the sample of thermally inhibited waxy corn starch used in Comparative Experiment E, using as the aqueous medium demineralized water acidified to a pH of 3.3 with citric acid prior to contacting with the corn starch. The resulting starch composition had a pH of 5.0 and contained 36% by weight of thermally inhibited corn starch particles, expressed as a percentage of the dry matter of the thermally inhibited corn starch based on the total weight of the starch composition.

[0103] The starch composition was then dried on a drum dryer using 5.5 bar steam and 5 rpm to form a pregelatinized starch having a moisture content of 3.4% by weight.

[0104] Viscosity characteristics were determined as follows: V511,100mPa.s Loss factor 0.30

[0105] Example 7 A starch composition was formed using the sample of thermally inhibited waxy corn starch used in Comparative Experiment E, using as the aqueous medium demineralized water acidified to a pH of 3.4 with citric acid prior to contacting with the corn starch. The resulting starch composition had a pH of 5.5 and contained 36% by weight of thermally inhibited corn starch particles, expressed as a percentage of the dry matter of the thermally inhibited corn starch based on the total weight of the starch composition.

[0106] The starch composition was then dried on a drum dryer using steam at 5.5 bar and 5 rpm to form a pregelatinized starch having a moisture content of 3.2% by weight.

[0107] Viscosity characteristics were determined as follows: V510,600mPa.s Loss factor 0.31

[0108] The V5 and loss factor results show that the shear stability of Examples 6 and 7, which have starch compositions with a pH of less than 7.9, was significantly higher than that of Comparative Example F.

[0109] Comparative Experiment G The properties of the raw material, chemically modified glutinous rice starch, used in the following Comparative Experiment H and Examples 8-9 were measured without subjecting the starch to subsequent processing steps such as slurrying.

[0110] The starch had a moisture content of 12.8% by weight. The starch had a pH of 6.3 (determined in a 10% by weight starch solution in demineralized water). The viscosity characteristics were determined as follows: V513,800mPa.s Loss factor 0.33 V73,700mPa.s Loss factor 0.74

[0111] Comparative Experiment H A sample of the chemically modified glutinous rice starch used in Comparative Experiment G was used to form a slurry using demineralized water as the aqueous medium. The resulting slurry contained 36% by weight of chemically modified rice starch particles, expressed as a percentage of dry matter of the chemically modified rice starch based on the total weight of the slurry. The slurry had a pH of 8.0. The slurry was then dewatered on a drum dryer (Andritz single drum dryer, model E5 / 5) using steam at 6 bar and 6 rpm to form a slurry-dried starch with a moisture content of 3.1% by weight.

[0112] Viscosity characteristics were determined as follows: V57,200mPa.s Loss factor 0.62 V71,800mPa.s Loss factor 1.62

[0113] Example 8 A starch composition was formed using the sample of chemically modified glutinous rice starch used in Comparative Experiment G, using as the aqueous medium demineralized water acidified to pH 3.6 with citric acid before contacting with corn starch. The resulting starch composition had a pH of 5.0 and contained 36% by weight of chemically modified glutinous rice starch particles, expressed as a percentage of dry matter of the chemically modified glutinous rice starch based on the total weight of the starch composition.

[0114] The starch composition was then dried on a drum dryer using steam at 6 bar and 6 rpm to form a pregelatinized starch having a moisture content of 2.5% by weight.

[0115] Viscosity characteristics were determined as follows: V515,400mPa.s Loss factor 0.25 V75,700mPa.s Loss factor 0.61

[0116] Example 9 A starch composition was formed using the sample of chemically modified glutinous rice starch used in Comparative Experiment G, using as the aqueous medium demineralized water acidified to pH 4.1 with citric acid before contacting with corn starch. The resulting starch composition had a pH of 5.5 and contained 36% by weight of chemically modified glutinous rice starch particles, expressed as a percentage of dry matter of chemically modified glutinous rice starch based on the total weight of the starch composition.

[0117] The starch composition was then dried on a drum dryer using 5.5 bar steam and 5 rpm to form a pregelatinized starch having a moisture content of 3.4% by weight.

[0118] Viscosity characteristics were determined as follows: V517,400mPa.s Loss factor 0.25 V75,100mPa.s Loss factor 0.65

[0119] The results for V5 and loss factor at 5000 rpm and V7 and loss factor at 7000 rpm show that the shear stability of Examples 8 and 9, which have starch compositions with a pH of less than 7.9, was significantly higher than that of Comparative Example H.

[0120] Comparative Experiment I The properties of the raw material, heat-inhibited glutinous rice flour itself, used in Comparative Experiment J and Example 10 below were measured without subjecting the flour to subsequent processing steps such as slurrying.

[0121] The flour had a moisture content of 0.12% by weight. The flour had a pH of 8.0 (determined in a 10% by weight flour solution in demineralized water). Viscosity properties were determined as follows: V521,800mPa.s Loss factor 0.50 V74,700mPa.s Loss factor 1.22

[0122] Comparative Experiment J A sample of the heat-inhibited glutinous rice flour used in Comparative Experiment I was used to form a slurry using demineralized water as the aqueous medium. The resulting slurry contained 29 wt. % heat-inhibited glutinous rice flour particles, expressed as a percentage of the dry matter of the heat-inhibited glutinous rice flour based on the total weight of the slurry. The slurry had a pH of 8.0. The slurry was subsequently dewatered on a drum dryer (Andritz single drum dryer, model E5 / 5) using 6 bar steam and 6 rpm to form a slurry-dried flour with a moisture content of 5.0 wt. %.

[0123] Viscosity characteristics were determined as follows: V512,500mPa.s Loss factor 0.67 V77,300mPa.s Loss factor 1.01

[0124] Example 10 A flour composition was formed using the sample of heat-inhibited glutinous rice flour used in Comparative Experiment I, using as the aqueous medium demineralized water acidified to pH 3.2 with citric acid before contacting with corn flour. The resulting flour composition had a pH of 5.0 and contained 29% by weight of heat-inhibited glutinous rice flour particles, expressed as a percentage of dry matter of the heat-inhibited glutinous rice flour based on the total weight of the flour composition.

[0125] The flour composition was then dried on a drum dryer using 5.8 bar steam and 10 rpm to form a pregelatinized flour having a moisture content of 5.1% by weight.

[0126] Viscosity characteristics were determined as follows: V516,800mPa.s Loss factor 0.49 V77,900mPa.s Loss factor 0.86

[0127] The results for V5 and Loss Factor at 5000 rpm and V7 and Loss Factor at 7000 rpm show that the shear stability of Example 10, which has a starch composition with a pH of less than 7.9, was significantly higher than that of Comparative Example J.

[0128] While the principles of the present invention have been described above in connection with specific embodiments, it should be understood that this description is made by way of example only and does not limit the scope of protection determined by the appended claims.

Claims

1. 1. A method for preparing pregelatinized starch and / or pregelatinized flour, comprising: Providing an aqueous medium having a pH in the range of -1.0 to 7.5; - mixing starch and / or flour with said aqueous medium in a mixing step to form a starch composition having a pH in the range of 2.0 to 7.9, preferably 4.0 to 7.5, more preferably 4.0 to 6.5, said starch composition having said aqueous medium as a continuous phase and containing 20 to 60% by weight, preferably 30 to 50% by weight, of starch and / or flour particles, expressed as a percentage of dry matter relative to the total weight of the starch composition; and - pregelatinizing the starch composition in a gelatinization step, wherein the composition is heated using a drum dryer while rotating a drum to form the pregelatinized starch and / or flour, and during the gelatinization step, the starch composition is dried using the drum dryer; - cooling the pregelatinized starch and / or pregelatinized flour to a temperature of up to 80°C; and storing the obtained pregelatinized starch and / or pregelatinized flour at a temperature of up to 60°C, preferably at a temperature in the range of -10°C to +50°C; A method comprising:

2. 2. The method according to claim 1, further comprising at least one of a physical modification step and a chemical modification step prior to the mixing step, wherein the starch and / or flour is physically modified or chemically modified, and the starch and / or flour used in the mixing step is the physically modified starch and / or flour or the chemically modified starch and / or flour.

3. 3. The method of claim 2, further comprising a physical modification step prior to the mixing step, the physical modification step being a thermal inhibition step for thermally inhibiting starch and / or flour, the starch and / or flour used in the mixing step being the thermally inhibited starch and / or flour, and the starch composition formed in the mixing step having a pH in the range of 4.0 to 7.5, more preferably 4.0 to 6.

5.

4. 3. The method according to claim 2, further comprising a chemical modification step for chemically modifying starch and / or flour before the mixing step, wherein the starch and / or flour used in the mixing step is the chemically modified starch and / or chemically modified flour, and the starch composition formed in the mixing step has a pH in the range of 4.0 to 6.

5.

5. 5. The method according to any one of claims 1 to 4, wherein the starch and / or flour is derived from a waxy starch and / or a waxy flour.

6. 6. The method according to any one of claims 1 to 5, characterized in that the starch and / or flour is selected from maize (i.e., corn), wheat, rice, sorghum, barley, rye and any mixture thereof.

7. 7. The method according to any one of claims 1 to 6, characterized in that the starch and / or flour is derived from rice, preferably glutinous rice.

8. 8. The method according to any one of claims 1 to 7, characterized in that the gelatinization step is carried out so that the obtained pregelatinized starch and / or pregelatinized flour has a moisture content lying between 0% and 30% by weight, preferably between 2% and 20% by weight, more preferably between 3 and 15% by weight.

9. 9. The method according to any one of claims 1 to 8, In the mixing step, the pH of the starch composition is brought to a value between 4.0 and 6.5 within 90 minutes, preferably within 15 minutes, more preferably within 10 minutes after mixing of the starch and / or flour with the aqueous medium. A method characterized by:

10. 10. The method according to any one of claims 1 to 9, wherein in the gelatinization step, the composition is heated using a drum dryer by applying steam to the drum dryer.

11. 11. The method according to any one of claims 1 to 10, characterized in that in the mixing step, the starch and / or flour is the largest dry matter component.