EP4288462A1

EP4288462A1 - Thermally modified starches

Info

Publication number: EP4288462A1
Application number: EP22703836.1A
Authority: EP
Inventors: Solène BOCK; Jacques Legrand
Original assignee: Roquette Freres SA
Current assignee: Roquette Freres SA
Priority date: 2021-02-04
Filing date: 2022-02-03
Publication date: 2023-12-13
Also published as: CN116806227A; CA3206210A1; WO2022167152A1; FR3119392A1; FR3119392B1; US20240141076A1

Abstract

The invention relates to a thermally modified starch produced via the acid route, characterized in that it has a free citrate content of less than 0.05% and a fixed citrate content of between 0.12 and 0.16%, and/or a reduction of between 2 and 10°C of the gelatinization temperature at RVA peak viscosity, and/or a sedimentation volume of between 15 and 35 ml.

Description

Title: Thermally Modified Starches

The invention relates to a thermally modified starch produced by an acid route, characterized in that it has a free and fixed citrate level, a lowering of the bursting temperature at the viscosity peak and a level of sedimentation quite special.

[0002] The invention also relates to a thermally modified starch produced by the acid route, having a coloration, expressed in L* (clarity) and in Yie (yellow), of the order of that of native starches.

The invention also relates to a particular process for the production at acid pH of such thermally modified starches, starch whose viscosity is stabilized following this heat treatment.

[0004] The treatment by acid means here a treatment of the starch in the dry phase at pH 4, with a powder of sodium citrate and citric acid.

[0005] Such thermally modified starches then find use as texturizing and thickening agents in numerous food applications.

Background of the invention

[0006] Biochemically synthesized, a source of carbohydrates, starch is one of the most widespread organic materials in the plant world, where it constitutes the nutritional reserve of organisms.

[0007] Starches have always been used in the food industry, not only as a nutritious ingredient but also for their technological properties, as a thickening, binding, stabilizing or gelling agent.

[0008] For example, native starches are used in preparations requiring cooking. Corn starch, in particular, is the basis of "custard powders". [0009] Since it is rich in amylose, it retrogrades and therefore gels strongly. It makes it possible to obtain firm flans after cooking and cooling. It is also suitable for pastry creams.

[0010] But these cannot enter pastries intended to be frozen because, on defrosting, the phenomenon of syneresis, which results in the expulsion of water, destroys the texture of the cream.

[0011] Thus, in the native state, starch is of limited application due to syneresis, but also due to:

- its low resistance to shear stresses and heat treatments,

- its low processability and

- its low solubility in common organic solvents.

[0012] As a result, to meet today's demanding technological needs, the properties of starch must be optimized by various so-called “modification” methods.

[0013] These main modifications then aim to adapt the starch to the technological constraints resulting from cooking, but also from freezing/thawing, canning or sterilization, and to make it compatible with modern food (micro- waves, instant preparations, "high temperatures"...).

[0014] The modification of the starch then aims to correct one or some of the defects mentioned above, thus improving its versatility and satisfying consumer demand.

Starch modification techniques have been broadly classified into four categories: physical, chemical, enzymatic and genetic, the purpose being to produce various derivatives with optimized physicochemical properties.

[0016] Chemical and physical modifications are those most often implemented. The chemical treatment consists in introducing functional groups into the starch, which remarkably alters its physico-chemical properties. Such modifications of native granular starches indeed profoundly alter the behavior in gelatinization, sticking and retrogradation.

[0018] Generally, these modifications are carried out by chemical derivatization, such as esterification, etherification, crosslinking or grafting.

[0019] However, chemical modifications are less sought after by the consumer in food applications (also for environmental reasons), even if certain modifications are considered safe.

[0020] Various physical modifications are therefore proposed, for example:

- moist heat treatment (Anglo-Saxon term "Heat Moisture Treatment" or HMT), consisting in treating the starch at controlled humidity levels (22-27%) and at high temperature, for 16 hours, in order to alter the structure and physicochemical properties of starch;

- "annealing" (Anglo-Saxon term "annealing"), consisting in treating the starch in excess of water, at temperatures below the gelatinization temperature, in order to approach the glass transition temperature;

- ultra high pressure treatment (Anglo-Saxon term "High Pressure Processing" or HPP), by which the amorphous regions of the starch granule are hydrated, which leads to a distortion of the crystalline parts of the granule and promotes the accessibility of said water-crystalline regions;

- glow discharge plasma treatment, which generates, at room temperature, high energy electrons and other highly active species. Applied to starch, these active species excite the chemical groups of the starch and cause significant cross-linking of macromolecules;

- osmotic pressure treatment (English acronym “OPT”), carried out in the presence of solutions with a high salt content. The starch is suspended in sodium sulfate to produce a uniform suspension.

Starch changes from type B to type A after processing, thus acquiring a gelatinization temperature which increases significantly;

- treatment by “thermal inhibition”. In general terms, thermal inhibition means the dehydration of a starch until it reaches the anhydrous or substantially anhydrous state (i.e. < 1% humidity), then a heat treatment at more than 100°C for a sufficient period of time to "inhibit" the starch, in this case to give it properties of crosslinked starches. It is also necessary to place the starch in at least neutral to preferably alkaline pH conditions before proceeding to the advanced dehydration step.

An alternative treatment by "thermal inhibition" has been proposed in the solvent phase, which consists in heating a non-pregelatinized granular starch in an alcoholic medium, in the presence of a base and salts, at a temperature of 120° to 200°C, for 5 minutes to 2 hours.

[0021] Be that as it may, the thermal inhibition process then leads to obtaining a starch paste having properties of increased resistance to viscosity rupture, and a non-cohesive texture.

The technical field to which the invention relates is that of treatment by thermal inhibition of starch, without hydroalcoholic solvent.

In this particular technical field, mention may be made more particularly of US Pat. No. 6,221,420, which describes a thermally inhibited starch, obtained by dehydration then heat treatment.

The main steps are:

- the dehydration of the starch to a water content of less than 1% carried out at a temperature between 100 and 125°C, then

- the heat treatment of the dry starch thus obtained, at about 140°C, in a reaction fluidized bed, for a period of about 20 hours.

Preferably, before the starch dehydration step, it is recommended to carry out a starch alkalization step, making it possible to bring the pH of the starch suspension to a value between 7 and 10, preferably between 8 and 10. At this stage, before the actual dehydration step which precedes the inhibition step, the water content of the starch (as exemplified) is then between 8 and 10%.

[0026] IIS 2001/0017133 describes a similar process, in which the starch is also dehydrated below 125°C before the inhibition process is started (at a temperature of more than 100°C, preferably between 120 and 180° C., more preferably between 140 and 160° C.) for a period of up to 20 hours, preferably between 3 hours 30 and 4 hours 30.

Before the dehydration step, the conventional alkalization step results in a starch suspension having a pH value of between 7.5 and 11.2, preferably between 8 and 9.5, and a water content between 2 and 15%.

[0028] A variant has been proposed in patent application WO 2014/042537, a variant which relates to heating an alkaline starch to temperatures between 140 and 190° C., ensuring that the inhibition process either initiated and conducted in the presence of water in sufficient quantity, i.e. more than 1% water.

In other words, this method recommends thermally inhibiting a previously alkalized starch without carrying out a dehydration step.

The starch preparation where the starch is thus brought to a pH of between 9.1 and 11.2, preferably to a value of the order of 10, and the humidity is adjusted between 2 and 22% , preferably between 5 and 10%.

The thermal inhibition is then carried out directly on this powder or this starch, at a temperature of between 140 and 190° C., preferably between 140 and 180° C., for a period of 30 minutes.

Another variant has been proposed, by lowering, on the contrary, the pH of the treated starch before thermal inhibition. Indeed, a major drawback is that high pH levels tend to increase starch browning during the heating step. [0033] Thus, in patent application WO 2020/139997, a starch preparation step is described which successively consists of:

- prepare a starch milk,

- bring the starch milk thus prepared to a pH between 5 and 6.5, by neutralization if necessary,

- add an acid buffer, and

- adjust the pH.

It is only then that the actual heat treatment step is carried out, comprising a dehydration step and a thermal inhibition step.

In this patent application, it is essential first of all to bring the starch milk to a pH value between 5 and 6.5. Either the starch already has this pH value, considered to be its natural pH value, or a “neutralization” step (by adding acid or base) is carried out to reach this pH range. This step can take up to 24 hours.

Next, a citrate or citric acid pH buffer is added in order to bring the pH of the starch milk to a pH value of between 4 and 6. This step may take up to 24 hours.

Finally, to manufacture a thermally inhibited starch, it is taught in this patent application to carry out the dehydration and the thermal inhibition of the starch milk thus treated. This step can take up to 4 hours to react.

Finally, it has been established that this process makes it possible to obtain thermally inhibited starches that are whiter and have an improved taste compared to thermally inhibited starches prepared by the conventional method, i.e. after alkaline impregnation.

[0039] The fact remains that this method of preparing thermally inhibited starches can be improved. In fact, it has the drawback, from the point of view of its method used, of having to carry out the impregnation of the starch milk in an acid medium only after finely controlling the initial pH of the starch.

Then, as will be demonstrated below, a treatment of this type leads to the production of thermally inhibited starches having a high level of fixed citrate, of the order of more than 0.2%, reflecting a degree of functionalization important.

From all the above, there therefore remains a need to have an original process for inhibiting starch, making it possible to further reduce the reaction time, by carrying out the impregnation directly on the starch, and by reducing the actual thermal inhibition time, in order to lower the citrate level to values well below 0.2%, reflecting a sufficient degree of functionalization for the targeted applications.

Description of the invention

Thus, the invention relates to a thermally modified starch produced by the acid route, characterized in that it has a free citrate level of less than 0.05% and a fixed citrate level of between 0.12 and 0, 16%.

Advantageously, the thermally modified starch according to the present invention has:

- a lowering of the bursting temperature at the RVA viscosity peak between 2 and 10°C,

-and/or a sedimentation volume of between 15 and 35 ml.

More particularly, this thermally modified starch has a coloration expressed as an L* value of between 96 and 98, and as a Yie value of between 6 and 13.

The dosage of the citrates of the thermally modified starches of the invention is carried out by HPLC on the washed and hydrolyzed product, according to the conditions as presented below.

The dosage of free citrates makes it possible to validate the use of said starches thermally in "Clean Label" applications, and that of fixed citrates makes it possible to determine the degree of functionalization expressed by the products of the thermal reaction by acid route on the starches.

The products of the invention have a free citrate content of less than 0.05%, which is lower than the free citrate content of products of the same category of the state of the art (such as those obtained according to the process taught by international patent application WO 2020/139997 or marketed), the measured value of which is between 0.07 and 0.09%.

[0048] They need significant washing for their free citrate level to drop to a value of less than 0.01%.

As for the dosage of fixed citrates, obtained after washing and hydrolysis, the thermally modified starches in accordance with the invention have a fixed citrate rate of between 0.12 and 0.16%, whereas the products of the same category of the state of the art (such as those obtained according to the method taught by international patent application WO 2020/139997 or marketed) have values of the order of 0.24 to 0.39%.

The viscosity measurements of the thermally modified starches in accordance with the invention are carried out on an RVA 4800 device and allow a lowering of the bursting temperature at the RVA viscosity peak between 2 and 10° C.

The thermally modified starches in accordance with the invention are also characterized by their sedimentation capacity.

The test is carried out in test specimens, and the lower the settling volume, the higher the level of functionalization.

The settling volume of the products in accordance with the invention is between 15 and 35 ml, which reflects a high level of crosslinking.

The thermally modified starches in accordance with the invention are finally characterized by a coloration equivalent to that of the native starches which served as the basis for their manufacture. This translates into an L* value of between 96 and 98, and a Yie value of between 6 and 13.

The thermally modified starches can be obtained by a process comprising the steps consisting in:

(i) determining the amount of water to add to the powdered starch to achieve a total moisture content of 20% by weight,

(ii) add sodium citrate and citric acid powder to this quantity of water so as to obtain a buffer solution with a pH of 4,

(iii) mix the powdered starch and the buffer solution thus obtained and leave to stabilize for a period of the order of 30 minutes to 24 hours,

(iv) drying to an equilibrium humidity of around 13%,

(v) heating to a temperature of 170°C,

(vi) resuspending, adjusting the pH, washing and again drying the thermally modified starches thus obtained.

The starch to be used in the method of the invention can be of any origin, for example corn, waxy corn, amyloma, wheat, waxy wheat, peas, fava beans, beans, potato, waxy potato, tapioca, waxy tapioca, rice, konjac, taken alone or in a mixture.

Preferably, corn starch will be chosen, more particularly waxy corn starch (with a high amylopectin content, as will be exemplified below.

The method in accordance with the invention requires determining the quantity of water to be added to the starch so as to reach a total humidity of the mixture of 20% by weight, then adding the powder of sodium citrate and citric acid so as to obtain a buffer solution having a pH of 4. As will be exemplified below, half of the water added is used to dissolve the citric acid and the sodium citrate dihydrate beforehand. .

[0060] It is then left to stabilize for a period of the order of 30 min to 24 hours.

The preparation is dried to an equilibrium humidity of the order of 13%. The drying can be done at 60° C. in a Retsch laboratory dryer, but also in a hood with its natural ventilation at ambient temperature, or in a pilot/industrial dryer, at a temperature of more than 100° C.

After grinding and drying at 60° C., the actual heat treatment is carried out.

As will be exemplified below, the heat treatment is carried out at a temperature of 170° C., for a period ranging from 0.5 to 3 hours of reaction. These kinetics make it possible to vary the degree of functionalization of the thermally modified starches thus prepared (the more the starches are functionalized the more they are resistant to restrictive conditions of use, i.e. acid pH, high shear, high temperature).

The heating can be carried out in a ventilated oven, or in a pilot or industrial device of the VOMM Turbodryer type or in a fluidized reaction bed.

After heat treatment, the products are resuspended at 36% by weight of dry matter. The pH is rectified with soda between 5.5 and 6, then is finally filtered, dried and ground.

The thermally modified starches thus obtained will be advantageously used, depending on their respective properties, as thickening agent or texturizing agent in food applications.

The invention will be better understood using the following examples, which are intended to be illustrative and not limiting.

[0069] Materials and methods

[0070] Substrates

Waxy maize starch marketed by the applicant company under the brand name WAXILYS® produced on its Beinheim site.

Its characteristics are:

- water content: 12.4%

- pH: 5.4

- conductivity: 223 pS

- Coloring: L* = 97.6; Yie = 8.11 Below are the two products used for the pH 4 buffer.

[0072] Measurement of conductivity and pH

Conductivity

The method implemented here is adapted from the European Pharmacopoeia - official edition in force - Conductivity (§ 2.2.38).

Materials:

KNICK 703 electronic conductivity meter also equipped with its measurement cell and checked according to the procedure described in the related instruction manual.

Procedure:

A solution containing 20 g of sample in powder form and 80 g of distilled water having a resistivity greater than 500,000 ohms is prepared. cm.

The measurement is carried out at 20°C using the conductivity meter, referring to the procedure indicated in the user manual of the device.

The values are expressed in microSiemens/cm (pS/cm) or miliSiemens/cm (mS/cm).

pH

The method implemented here is adapted from the European Pharmacopoeia - official edition in force - pH (§ 2.2.3).

A suspension of the sample to be analyzed is prepared at 20% (W/W) and the pH value is determined using a laboratory pH meter, referring to the procedure indicated in the user manual of the device. The pH is expressed to the nearest 0.01 unit. [0073] Measurement of oarHPLC citrates

The citrate assay is carried out:

- directly after heat treatment, on washed and dried products, (measurement of free citrates) then,

- after hydrolysis (measurement of fixed citrates) according to the following methods.

Dosing method

After separation by ion exchange chromatography, the citrate ion is detected by conductimetry. Quantification is done by the internal calibration method. We use as equipment a set of high performance liquid chromatography composed of:

- An ICS 2100 Thermofisher system;

- A sampler allowing the samples to be kept at 10°C (type TSP AS-AP);

- An AERS 500-ultra suppressor;

- A Thermo AS11 HC 250*4 mm column with AG11-HC 4*50 mm pre-column.

- filters for ion chromatography - IC 0.45 pm- Pali.

We use as reagents:

- HPLC quality water

- Sigma tribasic sodium citrate dihydrate

- Trifluoroacetic acid from Sigma

- Internal standard solution: 400 mg/L trifluoroacetic acid solution

- 2N hydrochloric acid from Merck

- EGC-KOH cartridge from Thermo.

The procedure is as follows:

- Solvent A: HPLC quality water,

- Elution program: 77 | 1,3 | 1.5 |

- Volume injected: 25 pL

- Column temperature: 36°C

- Analysis time: 77 min

- Sample temperature: 10°C

- ASRS: 193mA

Calibration

Prepare 6 curve points.

- Weigh x mg of sodium citrate, i.e. x between 10 and 250 mg and adjust to 500 mL of water. Shake.

- Take 0.5 mL, add 0.5 mL of internal standard and make up to 20 mL with 1 mM sodium hydroxide.

- Filter and inject.

- Calculate the weight of the standards in chloride (weight in sodium chloride (Mw of the ion/ Mw of salt)).

Plot the calibration curve: ratio of peak heights (= weight of chloride standard/weight of internal standard).

Sample

Weigh 100 mg of sample + 0.5 mL of internal standard into 20 mL of water. Filter . Inject.

[0074] Washing and drying

In a 250 ml beaker, approximately 20 g of the sample to be analyzed and 200 ml of demineralized water are introduced. Covered with a watch glass and stirred for 20 minutes using a magnetic stirrer. It is then filtered in a Buchner funnel with a diameter of 150 mm equipped with a Durieux n°111 white band filter, with a diameter of 150 mm or equivalent.

The filtrate is returned to a 250 ml beaker, dispersed in 200 ml of deionized water and stirred for 20 minutes. Filtered again and rinsed with 200 ml of demineralized water.

The filtered product is dried in a laboratory oven overnight, then ground so as to avoid lumps. [0075] Hydrolysis

Into the 250 ml flask with a flat bottom and ground-in neck, a test sample “P” is introduced, exactly weighed of the sample to be analyzed. A quantity of distilled water equal to (100 - P), 100 ml of 2N hydrochloric acid and some boiling regulators (granular pumice stone) are added. Place in the electric mantle under reflux condenser and leave for 45 minutes from boiling. Cool then neutralize with 40% sodium hydroxide solution to pH 7.

[0076] Expression of the results

The citrate ion content in % is determined by the following equation:

Q/Px100 where:

Q = quantity of citrate read on the curve (mg)

P = sample weight in mg.

[0077] Measurement of the viscosity of a starch suspension using the Rapid Viscosimeter Analyzer (RVA) 4800

This measurement is carried out at pH 4 under determined concentration conditions and following an appropriate temperature/time analysis profile.

Preparation of Citrate buffer at pH 4

- prepare 800 ml of distilled water,

- add 9.838 g of sodium citrate,

- add 12.782 g of citric acid,

- adjust the solution with NaOH or HCl to reach a pH of 4,

- top up to 1 liter with distilled water.

The product to be analyzed is prepared as follows:

A mass of 1.37 g of the dry product to be analyzed is placed directly in the bowl of the viscometer, and pH 4 buffer solution is introduced until a mass equal to 28.00 ± 0.01 g is obtained. .

The time/temperature and speed analysis profile in the RVA is then carried out as follows:

[0079] [Table 1]

End of test: 00:38:05 (hh:mm:ss)

Initial temperature: 30°C ± 0.5°C

Data acquisition interval: 2 seconds

Sensitivity: low (low) The measurement results are given in RVU (unit used to express the viscosity obtained on the RVA), knowing that 1 RVU unit = 12 ePoises (cP).

As a reminder, 1 cP = 1 mPa.s.

On the graphs, the results are expressed in cPoises.

The temperature at the peak of swelling between 2 and 17 minutes is added to the analysis profile.

[0080] Sedimentation test

The product is dispersed in an aqueous medium and the decanted volume is measured.

Solution A - Zinc chloride: 10 g

- Ammonium chloride: 26 g

- Distilled water: qsp 100 ml

In a 250 ml jar, introduce a test portion of 1.0 g of the anhydrous product at analyze. Add 100 ml of solution A, stopper, homogenize and place in a water bath for 10 min. Cool in a cold water bath, homogenize again, transfer to a 100 ml test tube and measure the decanted volume after 24 hours.

The decanted volume, expressed in ml, is given by the following formula:

(decanted volume of starch / total volume) x 100

[0081] Measurement of the coloration

Colorimetric measurement is based on opposing color theory which specifies that the responses of cones (cells in the retina of the human eye responsible for color vision) to the colors red, green and blue are recombined into opposing "black- white", "red-green" and "yellow-blue" when transmitted to the brain by the optic nerve.

This measurement is based on the color scales widely used in the food and polymer industries, called CIELAB's L*, a*, b* scales.

The L*, a* and b* type scales are defined as follows:

- "L*" axis (lightness): 0 corresponds to black, 100 corresponds to white

- “a*” axis (red-green): the positive values of which are attributed to red; negative values are assigned to green; 0 is neutral

- “b*” axis (yellow-blue): the positive values attributed to yellow; negative values are assigned to blue; 0 is neutrality.

The “L*” index therefore has a value between 0 and 100, while the “b*” and “a*” indices have no numerical limitations. The measuring device is typically a Colorflex EZ spectrocolorimeter, following the manufacturer's specifications (Manual version 1.2 of August 2013 for CFEZ firmware version 1.07 and higher - see pages 17 and 38).

The measurement is carried out in a 64 mm glass sample dish into which the sample is introduced so as to half fill the glass dish to have enough material to properly cover the surface in contact with the radii (for measurement homogeneity).

[0085] Example Example 1: preparation of thermally modified starches

In the bowl of THE RM 0 MIX 3300 VorWerk, place 500 g commercial WAXILYS® waxy corn starch. To reach a total humidity of 20% it is necessary to add 47.88 g of demineralised water. Half of this water is used to dissolve the sodium citrate and citric acid so as to obtain a pH of 4. This solution is sprayed on the starch while stirring, the rest of the water is then added to the Thermomix.

Leave to mature for 24 hours then dry on a RETSCH dryer at 60°C until an equilibrium humidity of about 13%

It is ground on a Thermomix grinder in order to break up the starch and prevent the formation of aggregates.

Measurements: Humidity, pH, conductivity, color (L*and Yie)

Heat treatment

Weigh 40 g of sample and place in an aluminum dish for METTLER LJ16 balance (moisture measuring balance).

The dish is introduced into the MEMMERT ventilated oven previously heated to 170°C. The stopwatch is started as soon as the cups are introduced, and they come out according to the chosen reaction kinetics.

Washing and rectification of the pH of the products after reaction by resuspension

- resuspension of the sample at 36% DM in demineralised water,

- rectification of the pH between 5.5 and 6 by NaOH,

- filtration on a frit of porosity 3,

- drying of the cake under a ventilated hood overnight at room temperature,

- Grinding (IKA) so as to decompose and make the sample homogeneous.

Measurements: Humidity, pH, conductivity, color (L* and Yie), RVA 4800 viscosity on washed products and sedimentation test.

[0086] Results

Physicochemical measurements

On the samples taken during the reaction at 170°C, before washing, are measured:

- humidity - pH

- the conductivity in pS

- the coloring and presented in the following table 1 [0087] Table 1

We observe during the reaction with the citrate buffer (pH 4) powdered directly in a Waxy corn starch milk:

- an increase in pH which goes from 4.15 to 5.41 after 3 hours at 170°C.

- a drop in conductivity at the start of the reaction of about 174 pS, then a stabilization after 1 hour of reaction at about 327 to 332 pS.

- a slight increase in color after 3 hours of reaction at 170° C., which changes to Yie (yellow) from 8.18 to 13.31.

[0089] Washing of the products after reaction

The measurements are carried out on products washed according to the protocol indicated above and presented in Tables 2 and 3 below.

[0090] Table 2 [0091] Table s

Products are obtained after washing whose pH is between 5.6 and 6.5 and a conductivity between 204 pS and 390 pS.

The Yie (yellow) colorations are between 6.4 and 12.3. By comparison the native base Waxy a Yie of 8.11.

[0092] Measurement of RVA 4800 viscosity at 140°C on washed products

The results are represented in the graph of figure 1 .

It appears that the treatment at 170°C of waxy maize starch impregnated at pH 4 in a citrate/citric acid medium leads to a drop in the bursting temperature at the peak viscosity.

Figure 2 shows the measurement of the peak burst temperature between 2 and 17 minutes, and it is observed that the peak burst temperature decreases upon reaction at 170°C between 2 and 10°C .

Within the meaning of the invention, the thermally modified starches of interest are therefore obtained from 0.5 hour of reaction at 170°C.

[0093] Sedimentation test

The results are presented in the following table 4 and figure 3.

[0094] Table 4 After 0.5 hour of reaction, products which are already highly functionalized are obtained.

Beyond that, the degree of functionalization decreases, but remains constant.

[0095] Dosage of citrates

The results are presented in Table 5 below (compared to the contents of free and fixed citrates of products marketed by the company TATE

& LYLE and products according to the teachings of patent application WO 2020/139997).

[0096] Table s

Note that the free citrate content of the waxy starch base of 0.26% represents the quantity of citrate which has impregnated the starch and will be used for the heat treatment reaction.

The quantity of citrate fixed after reaction at 170° C., for the thermally modified starches of the invention is from 0.12 to 0.16, much lower than that of the inhibited starches obtained according to the process of the state of art.

Claims

[Claim 1] Thermally modified starch produced by the acid route, characterized in that it has a free citrate content of less than 0.05% and a fixed citrate content of between 0.12 and 0.16%.

[Claim 2] Thermally modified starch according to claim 1, characterized in that it has:

- and/or a sedimentation volume between 15 and 35 ml.

[Claim 3] Thermally modified starch according to Claim 1 or 2, characterized in that it has a coloration expressed as an L* value of between 96 and 98, and as a Yie value of between 6 and 13.

[Claim 4] Thermally modified starch according to any one of the preceding claims, characterized in that the botanical origin of the starch is chosen from the group consisting of maize, waxy maize, amylomaize, wheat, waxy wheat, pea, horse bean, bean, potato, waxy potato, tapioca, waxy tapioca, rice, konjac, taken alone or in a mixture and is more particularly corn waxy.

[Claim 5] Process capable of preparing the thermally modified starch of any one of the preceding claims, characterized in that it comprises the steps consisting in:

(iv) drying to an equilibrium humidity of around 13%,

(v) heating to a temperature of 170°C, (vi) resuspending, adjusting the pH, washing and again drying the thermally modified starches thus obtained.

[Claim 6] Process according to claim 5, characterized in that the botanical origin of the starch is chosen from the group consisting of maize, waxy maize, amylomaize, wheat, waxy wheat, pea, faba bean, bean, potato, waxy potato, tapioca, waxy tapioca, rice, konjac taken alone or in combination and is more particularly waxy maize.

[Claim 7] Use of the thermally modified starch of any one of Claims 1 to 4 or capable of being produced according to either of Claims 5 and 6, as a thickening agent or texturizing agent in food applications.