EP3966256A1

EP3966256A1 - Method for preparing a heat-modified starch

Info

Publication number: EP3966256A1
Application number: EP20768083.6A
Authority: EP
Inventors: Claude Quettier; Vincent Wiatz; Solène BOCK; Jacques Legrand
Original assignee: Roquette Freres SA
Current assignee: Roquette Freres SA
Priority date: 2019-05-07
Filing date: 2020-05-06
Publication date: 2022-03-16
Also published as: CN113795517A; WO2020225512A1; CA3137486A1; US20220213230A1

Abstract

The invention relates to a method for producing a heat-modified starch, comprising the steps consisting in: (i) preparing a starch milk having a solids content of between 20% and 45% by weight, preferably between 30% and 40% by weight and adding an alkaline agent at a weight concentration of between from 25% to 35% by weight, so as to obtain a final conductivity of between 4 and 7 mS/cm; (ii) filtering said starch milk so as to recover a starch cake having a moisture content of between 30% and 45% by weight and so that the conductivity of the filtered starch, resuspended at a solids content of 20% by weight, is between 0.7 and 2.5 mS/cm; (iii) introducing said starch cake, continuously, into a dryer at the same time as a continuous stream of hot air having a temperature of between 130°C and 185°C in order to recover a dried powder having a moisture content of between 8% and 18%; (iv) continuously supplying a turboreactor with the dried powder, the internal wall of the turboreactor being maintained at a temperature of between 180°C and 240°C, and by setting parameters for the speed of rotation of the stirrer in order to achieve a centrifugal acceleration of between 850 and 2100 m.s ^-2, so that said dried powder is continuously centrifuged and conveyed into said turboreactor for a total time of between 3 and 45 minutes; (v) recovering the heat-modified starch thus produced.

Description

Process for preparing a thermally modified starch

The invention relates to the production of thermally modified starch, starch whose viscosity is stabilized following this heat treatment. Such thermally modified starches then find use as texturing and thickening agents in many food applications, in particular in soups, sauces, in desserts such as yoghurts, stirred fermented milks, thermized yoghurts, dessert creams, but also drinks. , prepared meals, meat or fish preparations, such as surimi.

Background of the invention

[0002] 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.

[0003] Starches have always been used in the food industry, not only as a nutritive ingredient but also for their technological properties, as a thickening agent, binder, stabilizer or gelling agent.

[0004] For example, native starches are used in preparations requiring cooking. Corn starch in particular is the basis for "custard powders".

[0005] As it is rich in amylose, it retrogrades and therefore strongly gels. It makes it possible to obtain firm blanks after cooking and cooling. It is also suitable for pastry creams.

[0006] However, these cannot be used in 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.

[0007] 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.

[0008] Therefore, to meet today's demanding technological needs, the properties of starch must be optimized by various so-called "modification" methods.

[0009] 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 a modern diet (micro- waves, instant preparations, "high temperatures" ...).

The modification of the starch then aims to correct one or some of the faults mentioned above, thus improving its versatility and meeting consumer demand.

The 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.

[0012] The chemical and physical modifications are those most often implemented.

[0013] The chemical treatment consists in introducing functional groups into the starch, which remarkably alters its physicochemical properties. Such modifications of the native granular starches indeed profoundly alter the behavior in gelatinization, sticking and retrogradation.

[0014] Generally, these modifications are carried out by chemical derivatization, such as esterification, etherification, crosslinking or grafting.

[0015] However, chemical modifications are less sought after by the consumer in food applications (also for environmental reasons), even though some modifications are considered safe. [0016] Various physical modifications are therefore proposed, for example:

- treatment by moist heat (English term for "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" (English term for "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 (English term for "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 crystalline regions in water;

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

- osmotic pressure treatment (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.

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

- treatment by "thermal inhibition". In general, thermal inhibition means the dehydration of a starch until it reaches the anhydrous or substantially anhydrous state (ie <1% humidity), then a thermal treatment at more than 100 ° C for a period of time sufficient to "inhibit" the starch, in this case here 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 with the extensive 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 a medium. alcoholic, in the presence of a base and salts, at a temperature of 120 ° to 200 ° C, for 5 minutes to 2 hours.

In any event, the thermal inhibition process then results in a starch paste exhibiting properties of increased resistance to viscosity breaking, and a non-cohesive texture.

[0018] The technical field to which the invention relates is that of treatment by thermal inhibition of starch, without hydro-alcoholic solvent.

In this particular technical field, mention may be made more particularly of US 6.221.420 which describes a thermally inhibited starch obtained by dehydration followed by heat treatment.

The main stages 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 alkalinization step, making it possible to bring the pH of the starch suspension to a value between 7 and 10, preferably between 8 and 10.

[0021] 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%.

US 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 3:30 and 4:30.

Before the dehydration step, the conventional alkalinization step leads to 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%.

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

[0025] In other words, this method recommends thermally inhibiting a starch previously alkalized without proceeding to a dehydration step.

The starch preparation or 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%.

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

From all of the above, we see that the thermal inhibition processes implemented to stabilize the viscosity of the starches involve processes that require:

- the implementation of long treatment times, i.e. up to 20 hours, and

- control of the water content of the starches to be treated, according to the processes proposed in the state of the art, whether at values of less than 1% or on the contrary between 2 and 22%.

[0029] There therefore remains a need for an original process for inhibiting starch, making it possible to further reduce the reaction time, and without it being necessary to control the water content of the starch. to “thermally inhibit”.

Description of the invention

[0030] Thus, the invention relates to a process for producing a thermally modified starch from a starch milk comprising the steps of:

(i) prepare a starch milk having a dry matter of between 20 and 45% by weight, preferably between 30 and 40% by weight and add an alkaline agent at a mass concentration of between 25 to 35% by weight, so as to obtain a final conductivity of between 4 and 7 mS / cm;

(ii) carrying out the filtration of said starch milk so as to recover a starch cake having a moisture content between 30 and 45% by weight and in such a way that the conductivity of the filtered and resuspended starch at 20% by weight of dry matter is between 0.7 and 2.5 mS / cm;

(iii) introducing said starch cake continuously into a drier together with a continuous flow of hot air having a temperature between 130 ° C and 185 ° C in order to recover a dried powder having a content of humidity between 8% and 18% by weight;

(iv) continuously supplying a turbojet with the dried powder, the internal wall of the turbojet being maintained at a temperature between 180 ° C and 240 ° C, and by setting the speed of rotation of the turbojet agitator in order to achieve a centrifugal acceleration of between 850 and 2100 ms ² , so that said dried powder is continuously centrifuged and fed into said turbojet for a total period of between 3 and 45 minutes;

(v) recovering the thermally modified starch thus produced.

The starch to be used in the method of the invention can be of any origin, for example corn, waxy corn, amylomaïs, wheat, waxy wheat, legumes, such as peas and field beans. , potato, waxy potato, cassava, tapioca, waxy tapioca, rice, konjac, etc.

Preferably, corn starch will be chosen, more particularly waxy corn starch (with a high amylopectin content), potato starch, cassava, peas and field beans, such as it will be exemplified below.

The alkaline agent is preferably chosen from the group consisting of sodium hydroxide, sodium carbonate, tetrasodium pyrophosphate, ammonium orthophosphate, disodium orthophosphate, trisodium phosphate, calcium carbonate , calcium hydroxide, carbonate potassium, and potassium hydroxide taken alone or in combination, more preferably sodium carbonate.

The method according to the invention firstly requires the preparation of a starch milk having a dry matter of between 20 and 45% by weight, preferably between 30 and 40% by weight, and add a alkaline agent at a mass concentration of between 25 to 35% by weight, so as to obtain a final conductivity of between 4 and 7 mS / cm.

The next step then consists in controlling the alkaline impregnation of the starch by adding the alkaline agent in the form of a solution at a mass concentration of between 25 and 35%, preferably 30% to obtain a conductivity, on milk, between 4 and 7 mS / cm.

The Applicant company has in fact found that:

- the addition of the alkaline agent, more particularly the sodium carbonate directly to the starch in the milk phase makes it possible to achieve the desired high pH values more effectively (are between 10.2 and 10.8, preferably between between 10.5 and 10.65) than spraying sodium carbonate on the starch in the dry phase, in the sense that the addition in the milk phase allows better migration of the carbonate inside the starch granules in comparison to a powder impregnation.

In addition, as the powder phase impregnation requires adjusting the humidity of the starch to high values, part of the energy dedicated to the treatment of the product will therefore be lost to ensure the evaporation of the residual water. .

- the addition of the alkaline agent in solution from a solution at a mass concentration of between 25 and 35%, preferably 30% allows total dissolution of the alkaline agent in the starch milk, a faster and finer pH adjustment, and avoid a deposit of solid alkaline agent in the bottom of the reactor in the event of non-solubilization.

- controlling the level of starch impregnation via conductivity measurements makes it possible to achieve the precision required for said high pH values.

The following step leads to carrying out the filtration of said starch milk so as to recover a starch cake having a moisture content included between 30 and 45% by weight and so that the conductivity of the starch filtered and resuspended at 20% by weight of dry matter is between 0.7 and 2.5 mS / cm.

[0038] After this alkalization step, the starch is dried so as to reduce its moisture content.

The next step therefore consists in introducing the starch cake obtained in the previous step, continuously, in a dryer at the same time as a continuous flow of hot air having a temperature between 130 ° C and 185 ° C, in order to recover a dried powder having a moisture content between 8% and 18% by weight.

[0040] This step can be carried out in a flash dryer type, well known to those skilled in the art.

Said dried powder is then continuously fed into a turbojet whose inner wall is maintained at a temperature between 180 ° C and 240 ° C, by setting the speed of rotation of the agitator in order to achieve centrifugal acceleration between 850 and 2100 ms ² , so that said dried powder is continuously centrifuged and fed into said turbojet for a total period of between 3 and 45 minutes.

In this step of carrying out the method of the invention, the setting of the speed of rotation of the agitator is determined by calculation, with regard to the centrifugal acceleration to be achieved, that is to say included according to invention between 850 and 2100 ms ² .

The calculation method is as follows, considering that a turbojet is composed of a stirring shaft provided with blades having a certain orientation defined by the manufacturer (in this case, we can consider the device marketed by the company VOMM under the brand name ES350):

- The centrifugal speed is defined as the linear speed at the end of the blade "v" squared, divided by the radius R (distance between the stirring shaft and the end of the blade) and therefore expressed in ms ² .

[0044] [Math. 1] a = V ² / R

[0045] The linear speed at the end of the blade is in turn defined by the constant P multiplied by the diameter and the speed of rotation of the stirring shaft in rpm, the whole divided by 60.

[0046] [Math. 2]

As exemplified below, for a VOMM type ES350 turboshaker, the linear speed at the end of the blade is easily calculated from the values given by the manufacturer:

- diameter: 0.35 m;

- speed of rotation of the stirring shaft: 1000 rpm.

The mechanical action thus exerted by the rotor of the turbojet engine brings about the large amount of kinetic energy making it possible to promote the intra and intermolecular reactions between the polyglucosylated chains of the starch, and thus lead to a degree of branching greater than the starting starch, thus placing it in a more "crosslinked" state.

Furthermore, the formation of a thin and dynamic layer of starch circulating inside the turbojet allows a shortened reaction time, between 3 and 40 minutes, shortened compared to the treatments of the state of the art, particularly suitable for continuous industrial application.

[0050] According to a preferred manner, the heating jacket of the turbojet engine is generally intended to be traversed by a heating fluid, such as diathermic oil or steam.

Thanks to the heating jacket of the turbojet engine, it is possible to ensure precise control of the temperature inside said turbojet engine, so that the thin and dynamic layer of starch is kept within the range of optimum temperature for the intimate mixing step favoring its physical transformation. The last step consists in recovering the thermally modified starch thus obtained.

[0053] The invention also relates to the thermally modified starches obtainable according to the process of the above invention.

The thermally modified starches according to the invention will advantageously be used, depending on their respective properties, as thickening agent or texturizing agent in food applications, in particular in soups, sauces, drinks and prepared meals and in desserts such as stirred yoghurts and fermented milks and thermized yogurts.

By their texturizing and gelling properties, they will also find numerous applications in fields as varied as:

- sour sauces and soups (pasteurized and sterilized),

- pasta sauces with meat juice,

- desserts such as yoghurts, stirred fermented milks, thermized yogurts, dessert creams,

- hot mayonnaise and vinaigrette,

- pie filling, fruit or stable and sweet or savory meat or meat filling, dinners (ready meals with short shelf life),

- pudding (dry mixture to cook),

- baby jars / infant formula,

- drinks,

- prepared meals, preparations made from meat or fish, such as surimi.

- Food for animals

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

Material and methods

[0057] Measurement of the 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 measured and checked according to the procedure described in the relevant instruction manual.

Procedure:

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

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

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

[0058] Measuring the viscosity of a starch suspension using the Rapid Viscosimeter Analyzer (RVA)

This measurement is carried out at acidic pH (between 2.5 and 3.5) under determined concentration conditions and according to a suitable temperature / time analysis profile.

Two buffer solutions are prepared:

Buffer A

In a 1 liter beaker containing 500 ml of demineralized water, add

- 91.0 g of citric acid monohydrate (purity> 99.5%) and homogenized,

- 33.0 g of sodium chloride (purity> 99.5%), and homogenize until complete dissolution,

- 300.0 g of 1N soda.

It is transferred to a 1 L volumetric flask and complete with 1 L demineralized water.

Buffer B

100 g of Buffer A are mixed with 334.0 g of deionized water.

The product to be analyzed is prepared as follows:

A mass of 1.37 g of the dry product to be analyzed thus obtained is introduced directly into the bowl of the viscometer, and Buffer B solution is introduced until a mass equal to 28.00 ± 0.01 is obtained. g. The Rapid Visco Analyzer (RVA-NewPort Scientific) is homogenized with the stirring paddle. The time / temperature and speed analysis profile in the RVA is then carried out as follows:

[0060] [Table 1]

[0061] End of test: 00:20:05 (hh: mm: ss)

Initial temperature: 50 ° C ± 0.5 ° C

Data acquisition interval: 2 seconds

Sensitivity: low (low)

The results of the measurements are given in RVU (unit used to express the viscosity obtained on the RVA), knowing that 1 RVU unit = 12 cPoises (cP).

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

The results will therefore be presented in mPa.s.

The measurements will be of viscosity taken “at peak”, i.e. maximum viscosity value between 4 and 6 minutes, and “at drop”, i.e. the difference between the value of the viscosity at the peak and that measured at 17 minutes.

Examples

Example 1: preparation of thermally modified starches "A" from potato starch

i) The alkalization of the potato starch is carried out according to the stages following:

- Prepare a suspension of potato starch at 36.5% by weight of dry matter (DM)

- Prepare a sodium carbonate solution at 30% mass concentration and heat to 40-50 ° C to promote dissolution of the carbonate

- Add the sodium carbonate solution so as to obtain a conductivity on the milk of between 4 and 6 mS / cm;

- Ensure a contact time of 0.5h;

ii) Filter using a horizontal scraper-knife wringer to separate the water and the starch and so that the final conductivity on the starch resuspended at 20% by weight of dry matter is between 0.7 and 1.1 mS iii) Dry the starch at a humidity of 12% by weight in a flash dryer type where the air flow is at a temperature of 150 ° C

iv) Heat treatment

The product thus obtained is heat-treated in continuous turbofan type VOMM series type ES350, the centrifugal acceleration of which is set at 1700 ms-2, the set point temperature of which is set at 210 ° C and the flow rate of which air is set at 300 Nm ³ h.

The continuous VOMM type ES350 type turbojets in series are configured to subject the product to a total residence time between 30 and 45 min, and so that the temperature difference between the setpoint and the temperature of the product at the outlet of the reactor, called Delta T, or a value of the order of 20-22 ° C.

The process parameters are given in the following table.

[0065] [Table 2]

The RVA viscosity measurements are carried out and are presented in the table below.

Results

[0067] [Table 3]

The thermally modified starches A-1, A-2 and A-3 obtained from potato starch exhibit improved stability compared to native starch: fewer phenomena of viscosity setting and retrogradation are observed during the use of these inhibited starches. This can be seen by measuring the drop with the RVA viscometer: the more negative the drop, the more the inhibited starch will be resistant to shearing, to the acidity of the media and to heat treatments.

Example 2: preparation of thermally modified starches "B" from cassava starch.

i) The alkalinization of the cassava starch is carried out according to the following steps: - Prepare a suspension of cassava starch at 36.5% by weight of dry matter (DM)

- Ensure a contact time of 0.5h;

ii) Filter using a horizontal scraper blade wringer to separate the water and the starch and so that the final conductivity on the starch resuspended at 20% by weight DM is between 0.7 and 1.1 mS.

iii) Dry the starch at a humidity of 10% in a flash dryer type where the air flow is at a temperature of 150 ° C.

iv) Heat treatment.

The product thus obtained is heat treated in continuous turbojets of the VOMM type of ES350 type in series, the centrifugal acceleration of which is set at 1700 ms ² , the setpoint temperature of which is set at 210 ° C. and the flow rate of which air is set at 300 Nm ³ h. VOMM type continuous turbojets in series are configured to subject the product to a residence time of between 17 and 32 min, and so that the temperature difference between the setpoint and the temperature of the product at the outlet of the reactor, that we call Delta T, i.e. a value of around 22-27 ° C.

The process parameters are given in the following table.

[0072] [Table 4]

Results

[0074] [Table 5]

The thermally modified starches B-1 B-2 and B-3 obtained from cassava starch exhibit improved stability compared to native starch: less viscosity setting and retrogradation phenomena are observed during the use of these starches inhibited. Example 3: preparation of thermally modified starches "B" from pea starch.

i) The alkalinization of pea starch is carried out according to the following steps:

- Prepare a suspension of pea starch at 33% by weight of dry matter (DM)

- Prepare a sodium carbonate solution at 30% mass concentration and heat to 40-50 ° C to promote the dissolution of the carbonate;

- Ensure a contact time of 0.5h;

ii) Filter using a horizontal scraper knife wringer to separate the water and the starch and so that the final conductivity on the starch resuspended at 20% by weight DM is between 0.7 and 1.1 mS

iii) Dry the starch at a humidity of 10% by weight in a flash dryer type where the air flow is at a temperature of 135 ° C

iii) Heat treatment

The product thus obtained is heat treated in continuous turbojets of the VOMM type of ES350 type in series, the centrifugal acceleration of which is set at 1700 ms-2, the setpoint temperature of which is set at 210 ° C and whose air flow rate is set at 300 Nm ³ h. The continuous VOMM type turbojets in series are configured to subject the product to a residence time of 6 to 21 min, and so that the temperature difference between the setpoint and the temperature of the product at the outlet of the reactor, that we call Delta T, i.e. a value of around 23-24 ° C.

The process parameters are given in the following table.

[0078] [Table 6]

Results

[0080] [Table 7]

Thermally modified starches C-1, C-2 and C-3 exhibit improved stability during the process of use compared to native starch: less viscosity setting and retrogradation phenomena are observed during the use of these starches inhibited.

Example 4: preparation of thermally modified starches "D" from waxy corn starch

i) The alkalinization of waxy corn starch is carried out according to the following steps:

- Prepare a suspension of waxy corn starch at 36.5% by weight of dry matter (DM)

- Prepare a sodium carbonate solution at 30% mass concentration and heat to 40-50 ° C to promote dissolution of the carbonate;

- Add the sodium carbonate solution at a mass concentration of 30% so as to obtain a conductivity on the milk of between 4 and 7 mS / cm;

- Ensure a contact time of 0.5h

ii) Filter using a horizontal scraper-knife wringer in order to separate the water and starch and so that the final conductivity on the powder resuspended at 20% by weight of DM is between 1, 75 and 2 mS.

iii) Dry the starch at a humidity of 11.8% in a flash dryer type where the air flow is at a temperature of 135 ° C

iii) Heat treatment.

The product thus obtained is heat-treated in continuous turbojets of the VOMM type of ES350 type in series, the centrifugal acceleration of which is set at 1700 ms-2, the setpoint temperature of which is set at 200 ° C and of which the air flow rate is set at 300 Nm ³ h. VOMM type continuous turbojets in series are configured to subject the product to a residence time of between 15 and 35 min, and so that the temperature difference between the setpoint and the temperature of the product at the outlet of the reactor, that Delta T is called, ie a value of the order of 17 to 20 ° C.

The process parameters are given in the following table.

[0085] [Table 8]

Results

[0087] [Table 9]

The thermally modified starches D-1, D-2 and D-3 exhibit improved stability during the process of use compared to native starch: less viscosity setting and retrogradation phenomena are observed during the use of these starches inhibited.

[0089] Example 5: Preparation of thermally modified starches "E" from bean starch.

i) The alkalinization of faba bean starch is carried out according to the following steps:

- Prepare a suspension of faba bean starch at 33% by weight of dry matter (DM);

- Ensure a contact time of 0.5h;

ii) Filter using, for example, a horizontal wringer with a scraper knife in order to separate the water and the starch and so that the final conductivity on the starch resuspended at 20% by weight DM is between 1, 5 and 2 mS;

iii) Dry the starch at a humidity of 14% by weight in a flash dryer type dryer where the air flow is at a temperature of 135 ° C;

iii) Heat treatment

The product thus obtained is heat treated in continuous turbojets of the VOMM type in series, the centrifugal force of which is set at 1700 ms ² , the set point temperature of which is set at 210 ° C. and the air flow rate of which is fixed at 300 Nm ³ h.

VOMM type continuous turbojets in series are configured to subject the product to a residence time of 13 to 25 min, and in such a way that the temperature difference between the setpoint and the temperature of the product at the outlet of the reactor, that we call Delta T, i.e. a value of around 23-24 ° C

The process parameters are given in the following table [0092] [Table 10]

[0093]

Results

[0094] [Table 11]

The thermally modified starches E-1 and E-2 exhibit improved stability during the use process compared to native starch: less viscosity setting and retrogradation phenomena are observed when using these inhibited starches. .

Claims

[Claim 1] A method of producing a thermally modified starch comprising the steps of:

(i) prepare a starch milk having a dry matter of between 20 and 45% by weight, preferably between 30 and 40% by weight and add an alkaline agent at a mass concentration of between 25 to 35%, so as to obtain a final conductivity of between 4 and 7 mS / cm;

(iv) continuously supplying a turbojet with the dried powder, the internal wall of the turbojet being maintained at a temperature between 180 ° C and 240 ° C, and by setting the speed of rotation of the agitator in order to achieve acceleration centrifugal between 850 and 2100 ms- ² , so that said dried powder is continuously centrifuged and fed into said turbojet for a total period of between 3 and 45 minutes;

(v) recovering the thermally modified starch thus produced.

[Claim 2] A method according to claim 1, characterized in that the origin of the starch is selected from the group consisting of corn, waxy corn; potatoes, cassava, peas and field beans.

[Claim 3] A method according to claim 1, characterized in that the alkaline agent is preferably chosen from the group consisting of sodium hydroxide, sodium carbonate, tetrasodium pyrophosphate, ammonium orthophosphate, l ' disodium orthophosphate, trisodium phosphate, calcium carbonate, calcium hydroxide, potassium carbonate, and sodium hydroxide potassium, taken alone or in combination, and even more preferably sodium carbonate.

[Claim 4] Thermally modified starch obtainable by the process according to any one of the preceding claims.

[Claim 5] Use of a thermally modified starch obtained by the process according to any one of claims 1 to 3, as a thickening agent or texturizing agent in food applications, in particular in soups, sauces, mayonnaise , in desserts such as yoghurts, fruit preparations for yoghurts, stirred fermented milks, thermized yoghurts, dessert creams, drinks, prepared meals, meat or fish preparations, such as surimi.