METHOD FOR PRODUCING THERMALLY MODIFIED STARCH BLENDS

Abstract

Preparing a blend of at least two thermally modified starches of different botanical origins, consisting in: (i) preparing a starch milk containing at least two starches of different botanical origins, having total solids content of between 30 and 40%, and preferably between 35 and 37% by weight, (ii) adding an alkaline agent to obtain a final conductivity of the powder resuspended to 20% solids content of between 0.5 and 5 mS/cm, (iii) ensuring a contact time of between 0.5 and 5 hours, (iv) filtering and drying the starch milk to a moisture content of between 10.5 and 15%, to obtain a starch powder having a conductivity of between 0.5 and 2.5 mS/cm and a pH of between 9 and 10.5,

(v) heating the dried starch powder to a temperature higher than 130° C., preferably between 130 and 220° C., for a residence time of between 10 minutes and 6 hours.

Claims

1. A method for preparing a blend of at least two thermally modified starches, in which the starches are granular starches of different botanical origins, which comprises the steps consisting in: (i) preparing a starch milk containing at least two starches of different botanical origins, having total solids content of between 30 and 40%, and preferably between 35 and 37% by weight, (ii) adding an alkaline agent so as to obtain a final conductivity of the powder resuspended to 20% solids content of between 0.5 and 5 mS/cm, (iii) ensuring a contact time of between 0.5 and 5 hours, (iv) filtering and drying the starch milk to a moisture content of between 10.5 and 15%, so as to obtain a starch powder having a conductivity of between 0.5 and 2.5 mS/cm and a pH of between 9 and 10.5, (v) heating the dried starch powder so as to bring it to a temperature higher than 130° C., preferably between 130 and 220° C., for a residence time of between 10 minutes and 6 hours.

2. The method according to claim 1, wherein the botanical origin of the starches is selected from the group consisting of corn, waxy corn, amylomaize, wheat, waxy wheat, pea, faba bean, potato, waxy potato, tapioca, waxy tapioca, rice, konjac and is more preferentially potato starch and waxy corn starch.

3. The method according to claim 1, wherein the alkaline agent is selected from the group consisting of sodium hydroxide, sodium carbonate, tetrasodium pyrophosphate, ammonium orthophosphate, disodium orthophosphate, trisodium phosphate, calcium carbonate, calcium hydroxide, potassium carbonate, and potassium hydroxide, taken alone or in combination, and even more preferentially sodium carbonate.

4. The method according to claim 3, wherein the rise in temperature of the dry starch obtained in step (v) is carried out in continuous turbo-dryer type devices, for which the setpoint temperature is set to more than 190° C., preferably between 200 and 210° C., for a residence time of between 10 and 60 minutes, even more preferentially between 15 and 35 minutes and the delta T, defined as the difference in temperature between the setpoint temperature and the temperature of the product at the outlet of the reactor, is of between 17 and 27° C.

5. The method according to claim 3, wherein the rise in temperature of the dry starch obtained in step (v) is carried out in devices of the reaction fluidized bed type, for which the setpoint temperature is set to more than 130° C., preferably between 130 and 200° C., for a residence time of between 30 minutes and 6 hours, even more preferentially between 2 hours and 4 hours.

6. A use of a thermally modified starch produced by the method according to claim 1, as a thickening agent or texturizing agent in food applications, in particular in soups and sauces, and in dairy products.

Description

DESCRIPTION OF THE INVENTION

[0065] According to the invention, the method for preparing a blend of at least two thermally modified starches, in which the starches are granular starches of different botanical origins, comprises the steps consisting in:

[0066] (i) preparing a starch milk containing at least two starches of different botanical origins, having total solids content of between 30 and 40%, and preferably between 35 and 37% by weight,

[0067] (ii) adding an alkaline agent so as to obtain a final conductivity of the powder resuspended to 20% solids content of between 0.5 and 5 mS/cm,

[0068] (iii) ensuring a contact time of between 0.5 and 5 hours,

[0069] (iv) filtering and drying the starch milk to a moisture content of between 10.5 and 15%, so as to obtain a starch powder having a conductivity of between 0.5 and 2.5 mS/cm and a pH of between 9 and 10.5,

[0070] (v) heating the dried starch powder so as to bring it to a temperature higher than 130° C., preferably between 130 and 220° C., for a residence time of between 10 minutes and 6 hours.

[0071] By choosing to blend starches of different botanical origins before the alkaline impregnation and the actual thermal treatment, the applicant company goes against the teachings of the state of the art.

[0072] It is indeed known to produce blends of starches in order to optimize their functional properties, but this is done by blending thermally modified starch varieties with native starches as described in international application WO 2020/018061.

[0073] Furthermore, the thermal modification of a blend of starches of different botanical origins makes it possible to ensure the same level of modification of the two (or more) components of the blend.

[0074] This international application indeed protects a starched composition comprising [0075] a heat moisture treated (HMT) potato starch in an amount varying between 60 and 70 percent by weight of the total starched composition and [0076] a native tapioca starch in an amount of between 30 and 40 percent by weight of the composition of the starch.

[0077] Or else, if the blend is thermally treated, it is especially recommended for blends of starches with binding agents. As described for example in patent application EP 3,345,932, wherein a starch of a given botanical origin is selected, mixed with a starch of the same origin but treated enzymatically or chemically.

[0078] To the knowledge of the applicant company, there is no prior disclosure of thermal treatment methods on a prior blend of at least two starches of different botanical origins.

[0079] The starches to be used in the method of the invention may be of any origin, for example corn, waxy corn, amylomaize, wheat, waxy wheat, pea, faba bean, potato, waxy potato, tapioca, waxy tapioca, rice, konjac, etc.

[0080] Preferentially, it is selected to blend a potato starch with a corn starch, more particularly waxy corn starch (with high amylopectin content).

[0081] According to a particular embodiment, the method according to the invention may relate to the preparation of a blend of two thermally modified starches, wherein the starches are granular starches of different botanical origin, present in the blend in equal amounts, thus forming a 50/50 blend by weight.

[0082] The method according to the invention requires preparing a starch milk of at least two different botanical origins having total solids content of between 30 and 40%, preferably between 35 and 37% by weight. As will be demonstrated by way of examples below, the solids content is set to 36.5% by weight.

[0083] The next step then consists in controlling the alkaline impregnation of the blended starches.

[0084] The alkaline agent is preferentially selected from the group consisting of sodium hydroxide, sodium carbonate, tetrasodium pyrophosphate, ammonium orthophosphate, disodium orthophosphate, trisodium phosphate, calcium carbonate, calcium hydroxide, potassium carbonate, and potassium hydroxide, taken alone or in combination, even more preferentially sodium carbonate.

[0085] Alkaline impregnation with sodium carbonate is carried out by adding the alkaline agent, for example in powder form, to obtain a final conductivity on the powder resuspended to 20% solids content of between 0.5 and 5 mS/cm.

[0086] A contact time of between 0.5 and 5 hours, preferably between 0.5 and 1 hour, is then ensured.

[0087] The actual thermal treatment is then carried out. As will be described below, the embodiment is carried out in a ventilated oven at 170° C., but these conditions are entirely transposable to an implementation in a continuous turbo-dryer or reaction fluidized bed device.

[0088] In these industrial devices, the conductivity and pH setpoints of the blended starch powder before thermal treatment are as follows: [0089] Conductivity: of between 0.5 and 2.5 mS/cm, [0090] pH: between 9.5 and 10.5.

[0091] In a first embodiment of the method according to the invention, the next thermal treatment step itself can be carried out in thermal treatment devices combining the heat exchanges by conduction and by convection, a device of the turbo-dryer type, for example at least one VOMM-type continuous turbo-dryer, which thus makes it possible, depending on the size of said VOMM, to achieve a very short reaction time, of the order of a few minutes, i.e. less than 5 minutes per thermal treatment stage.

[0092] The temperature setpoints are then set to values of more than 190° C., preferably of between 200 and 210° C., for a residence time of between 10 and 60 minutes, even more preferentially between 15 and 35 minutes.

[0093] The delta T, defined as the difference in temperature between the setpoint temperature and the temperature of the product at the outlet of the reactor, is between 17 and 27° C.

[0094] In a second embodiment of the method according to the invention, the actual thermal treatment can be carried out in devices of the “reaction fluidized bed” type.

[0095] As is known to the skilled person, this device consists of a reactor which makes it possible to suspend a divided solid by means of a gas, in this case an air/nitrogen blend. The speed of the gas is adjusted depending on the raw material.

[0096] The thermal treatment temperature (temperature of the product) is between 130 and 200° C. with a reaction time varying between 30 min and 6 h, preferentially between 2 and 4 hours.

[0097] The thermally modified starches according to the invention will advantageously be used, based on their respective properties, as a thickening agent or texturizing agent in food applications, especially in soups, sauces, and dairy products.

[0098] One of the main limitations of thermally modified starches manufactured from a single botanical source is a developed viscosity slightly lower than that of the commercially available chemically modified starches, requiring overdosing in the event of replacement in the context of a solution that is 100% natural and “with the least possible chemical transformation”. (“clean label”).

[0099] These blends are therefore inscribed as a simple and efficient solution for industries that manufacture, for example, sauces.

[0100] More particularly, these blends appear to meet the technological requirements for pasteurization, average shear and acidic pH.

[0101] The invention will be better understood with the aid of the following examples, which are intended to be illustrative and non-limiting.

EXAMPLES

Materials and Methods

Measurement of Conductivity

[0102] The method implemented herein is adapted from the European Pharmacopoeia—current official edition—Conductivity (§ 2.2.38).

Equipment:

[0103] KNICK 703 electronic conductivity meter, also equipped with its measuring cell and verified according to the procedure described in its instruction manual.

Procedure:

[0104] A solution containing 20 g of sample in powder form and 80 g of distilled water having a resistivity of greater than 500,000 ohms.cm is prepared.

[0105] The measurement is carried out at 20° C. using the conductivity meter, referring to the procedure indicated in the instrument's user manual.

[0106] The values are expressed in millisiemens/cm (mS/cm).

Measuring the Viscosity of a Starch Suspension Using the Rapid Viscometer Analyzer (RVA)

[0107] This measurement is carried out under predetermined concentration conditions and according to a suitable temperature/time analysis profile.

[0108] Two buffer solutions are prepared:

Buffer A

[0109] The following are added to a 1 liter beaker containing 500 mL of demineralized water: [0110] 91.0 g of citric acid monohydrate (purity >99.5%), and homogenization is carried out, [0111] 33.0 g of sodium chloride (purity >99.5%), and homogenization is carried out until complete dissolution, [0112] 300.0 g of 1N caustic soda.

[0113] The contents are decanted into a 1L volumetric flask and demineralized water is added to reach 1 L.

Buffer B

[0114] 100 g of buffer A are mixed with 334.0 g of demineralized water.

[0115] The product to be analyzed is prepared in the following manner:

[0116] A mass of 1.37 g of the dry product to be analyzed, obtained in this way, is directly introduced into the receptacle of the viscometer, and buffer solution B is introduced until a mass equal to 28.00±0.01 g is obtained. Homogenization is carried out using the stirrer blade of the Rapid Visco Analyzer (RVA-NewPort Scientific).

[0117] The time/temperature and speed analysis profile in the RVA is then carried out as follows:

TABLE-US-00001 TABLE 1 Rotational speed Time Temperature Revolutions/min hh:mm:ss ° C. (RPM) 00:00:00 50 100 00:00:10 50 500 00:00:20 50 960 00:00:30 50 160 00:01:00 50 160 00:05:00 92 160 00:17:00 92 160 00:20:00 50 160

[0118] End of test: 00:20:05 (hh:mm:ss)

[0119] Initial temperature: 50° C.±0.5° C.

[0120] Data acquisition interval: 2 seconds

[0121] Sensitivity: low

[0122] The results of the measurements are given in RVU (unit used to express the viscosity obtained on the RVA), it being known that 1 RVU unit=12 cPoises (cP).

[0123] As a reminder, 1 cP=1 mPa.s.

[0124] The results will therefore be presented in mPa.s.

[0125] The viscosity measurements will be taken “at the peak”, i.e. the maximum viscosity value between 4 and 6 minutes, and “at the drop”, i.e. the difference between the viscosity value at the peak and that measured at 17 minutes.

Example 1: Obtaining the Thermally Modified Starch Blend in a Ventilated Oven

[0126] These first tests are carried out on the laboratory scale, in an oven, so as to select the best proportions of potato starch and waxy corn starch in the blend, before proceeding with the industrial tests.

Preparation of the Blend of Starches and Impregnation with Sodium Carbonate.

[0127] Native starches (waxy corn starch and potato starch) are products sold by the applicant company under these same names.

[0128] Waxy corn starch and powdered potato starch are introduced in the proportions indicated in Table 2 below.

[0129] This blend of powder is then suspended in demineralized water so as to obtain total solids content of 36.5% by weight.

[0130] The pH and the conductivity of the suspension are then measured.

[0131] Sodium carbonate is added to this milk under the following alternative conditions: [0132] If sodium carbonate is added in powder form: in a sufficient amount to obtain a final conductivity measured on a powder resuspended to 20% of solids of between 0.5 and 1 mS/cm. A contact time of 2 hours is allowed, [0133] If sodium carbonate is added in solution at 30% weight concentration: in a sufficient amount to obtain a conductivity, on the milk, of between 2 and 4 mS/cm. A contact time of 30 minutes is sufficient, given that the sodium carbonate is already dissolved in solution at 30%.

[0134] It is filtered and dried at a starch equilibrium moisture of between 10 and 14%.

TABLE-US-00002 TABLE 2 Tests % by weight of waxy corn starch % by weight of potato starch E-1* 100 0 E-2 94 6 E-3 90 10 E-4 70 30 E-5 50 50 E-6* 0 100 *Tests E-1 and E-6 are the starch controls of a single botanical source.

Thermal Treatment in an Oven

Equipment Used:

[0135] MEMMERT ventilated oven. [0136] Aluminum cup for METTLER LJ16 (moisture measurement scale). [0137] Scale.

Procedure:

[0138] Weigh ˜40 g per aluminum cup of the starch base to be tested. [0139] Place the cups in the MEMMERT oven previously set to 170° C. [0140] Start the chronometer after inserting the cups into the oven. [0141] Then remove a cup from the oven at each point of the reaction kinetics.

Neutralization and Washing of the Products Obtained

[0142] After the reaction at 170° C., the test with 36% solids is resuspended in demineralized water.

[0143] The pH is corrected between 5.5 and 6 by HCI.

[0144] It is filtered and washed by percolation so as to obtain, on the final product resuspended to 20% of solids, a conductivity <500 mS/cm.

[0145] The “cake” obtained is dried under a ventilated hood for one night at ambient temperature.

[0146] It is coarsely ground on a basic IKA A11 grinder and then sieved on a 315 μm screen.

Example 2: Analyses of the Properties of the Thermally Modified Starch Blends

[0147] The RVA viscosity measurements at 92° C. are carried out and presented in Table 3 below.

TABLE-US-00003 TABLE 3 Reaction time Peak RVA Drop RVA Tests (h) (mPa .Math. s) (mPa .Math. s) E-1 1 328.7 −184 2 48 −126 E-2 1 206.3 −265 1.5 110.2 −220 E-3 1 530.7 −91 1.5 319.2 −246 2 148.0 −244 E-4 0.5 854.7 452 1 649.2 −30 1.5 434.4 −358 2 209.8 −436 2.5 104.0 −333 E-5 0.5 755.8 328 1 848.7 131 1.5 549.9 −292 2 342.1 −441 E-6 2 659.5 −338

[0148] The thermally modified starches according to the invention have improved stability during the process of use with respect to native starch: less viscosity gain and retrogradation are observed when using these starches. On this point, it is indeed observed that the more the RVA drop tends towards 0 or becomes negative, the more the product will therefore be functionalized, the more resistant it will be and the less retrogradation it will express.

[0149] A comparison is established with a modified chemical starch (CLEARAM® CH2020) and waxy thermally inhibited starches (NOVATION® 2600, NOVATION® 2300 and CLARIA® PLUS), commercially available. The results are presented in Table 4.

TABLE-US-00004 TABLE 4 Peak RVA Drop RVA Product (mPa .Math. s) (mPa .Math. s) CLEARAM ® CH2020 760 6 NOVATION ® 2600 603 30 NOVATION ® 2300 276 −186 CLARIA ® PLUS 399 −132

[0150] The products presented in this table are produced from a single botanical source, in this case waxy corn starch.

[0151] Thermally inhibited starches, such as NOVATION® 2600, NOVATION® 2300 and CLARIA® PLUS, as well as thermally modified starches E-1 and E-6, have in common the fact that they all have a lower peak viscosity than CLEARAM® CH2020, which is a chemically modified starch.

[0152] By producing a blend of potato starch and waxy corn starch, the peak viscosities are higher than those of the modified starches obtained from a single botanical source.

[0153] The 50/50 blend offers the best compromise between its peak viscosity, which represents the viscosity developed by the product, and its drop viscosity, which represents its level of resistance.

[0154] The 50/50 blend makes it possible to benefit from the advantages of the two raw materials in terms of texture, resistance and viscosity development.

Example 3: Preparation of a Thermally Modified Starch Blend A in a VOMM Continuous Turbo-Dryer.

[0155] 1) The alkalinization of the starch blend is carried out according to the following steps: [0156] Preparing a suspension of 50/50 wt. % waxy corn starch and potato starch, with 36.5% solids; [0157] Adding sodium carbonate in powder form in order to obtain a final conductivity on the powder resuspended to 20% solids of between 0.5 and 1 mS/cm; [0158] Ensuring a contact time of 2 h; [0159] Filtering and drying to a starch equilibrium moisture content of between 10 and 14% [0160] It is quite possible, instead of adding sodium carbonate in powder form, to: [0161] Prepare an aqueous solution of sodium carbonate at 30% weight concentration and heat to 40-50° C. to promote the dissolution of the carbonate; [0162] Add the solution of sodium carbonate at 30% weight concentration so as to obtain a conductivity on the milk of between 2 and 4 mS/cm; [0163] Ensure a contact time of 30 min.

[0164] This makes it possible to reduce the contact time since the carbonate is already well dissolved in solution at 30%.

[0165] (2) Thermal treatment

[0166] The product obtained in this way is heat-treated in VOMM-type continuous turbo-dryers in series, the setpoint temperature of which is set to 210° C. and which are configured to subject the product to a residence time of 30 min and such that the temperature difference between the setpoint and the temperature of the product at the outlet of the reactor, referred to as delta T, is a value of the order of 21° C.

Process Parameters

[0167]

TABLE-US-00005 TABLE 5 Conductivity Moisture on the content product after of the impregnation, product resuspended to before Residence 20% solids, in thermal Setpoint time Exp mS/cm treatment Delta T T ° C. (min) A-1 0.626 10 21 210 30

[0168] The RVA viscosity measurements are carried out and presented in the table below.

Results

[0169]

TABLE-US-00006 TABLE 6 Drop RVA Peak RVA Exp (mPa .Math. s) (mPa .Math. s) 50/50 waxy starch/ 990 1169 potato starch base A-1 −158 577

[0170] The 50/50 blend here also offers the best compromise between its peak viscosity which represents the viscosity developed by the product and its drop viscosity which represents its level of resistance.

Example 4: Preparation of a Thermally Modified Starch Blend B in a VOMM Continuous Turbo-Dryer.

[0171] 1) The alkalinization of the starch blend is carried out according to the following steps: [0172] Preparing a suspension of 50/50 wt. % waxy corn starch and potato starch, with 36.5% solids; [0173] Adding sodium carbonate in powder form in order to obtain a final conductivity on the powder resuspended to 20% solids of between 0.5 and 1 mS/cm; [0174] Ensuring a contact time of 2 h; [0175] Filtering and drying to a starch equilibrium moisture content of between 10 and 14%.

[0176] It is quite possible, instead of adding sodium carbonate in powder form, to: [0177] Prepare a solution of sodium carbonate at 30% weight concentration and heat to 40-50° C. to promote the dissolution of the carbonate; [0178] Add the solution of sodium carbonate at 30% weight concentration so as to obtain a conductivity on the milk of between 2 and 4 mS/cm; [0179] Ensure a contact time of 30 min.

[0180] This makes it possible to reduce the contact time since the carbonate is already well dissolved in solution at 30%.

[0181] 2) Thermal treatment

[0182] The product obtained in this way is heat-treated in VOMM-type continuous turbo-dryers in series, the setpoint temperature of which is set to 210° C. and which are configured to subject the product to a residence time of 35 to 40 min and such that the temperature difference between the setpoint and the temperature of the product at the outlet of the reactor, referred to as delta T, is a value of the order of 24 to 25° C.

Process Parameters

[0183]

TABLE-US-00007 TABLE 7 Conductivity Moisture on the content product after of the impregnation, product resuspended to before Residence 20% solids, in thermal Setpoint time Exp mS/cm treatment Delta T T ° C. (min) B-1 0.630 10 24 210 35 B-2 0.595 10.1 25 210 40

[0184] The RVA viscosity measurements are carried out and presented in the table below.

Results

[0185]

TABLE-US-00008 TABLE 8 Drop RVA Peak RVA Exp (mPa .Math. s) (mPa .Math. s) 50/50 waxy starch/ 990 1169 potato starch base B-1 −386 648 B-2 −497 469

[0186] The 50/50 blend here also offers the best compromise between its peak viscosity which represents the viscosity developed by the product and its drop viscosity which represents its level of resistance.

Example 5: Preparation of a Thermally Modified Starch Blend C in a VOMM Continuous Turbo-Dryer.

[0187] 1) The alkalinization of the starch blend is carried out according to the following steps: [0188] Preparing a suspension of 50/50 wt. % waxy corn starch and potato starch, with 36.5% solids; [0189] Adding sodium carbonate in powder form in order to obtain a final conductivity on the powder resuspended to 20% solids of between 0.5 and 1 mS/cm; [0190] Ensuring a contact time of 2 h; [0191] Filtering and drying to a starch equilibrium moisture content of between 10 and 14%.

[0192] It is quite possible, instead of adding sodium carbonate in powder form, to: [0193] Prepare a solution of sodium carbonate at 30% weight concentration and heat to 40-50° C. to promote the dissolution of the carbonate; [0194] Add the solution of sodium carbonate at 30% weight concentration so as to obtain a conductivity on the milk of between 2 and 4 mS/cm; [0195] Ensure a contact time of 30 min.

[0196] This makes it possible to reduce the contact time since the carbonate is already well dissolved in solution at 30%

[0197] 2) Thermal treatment

[0198] The product obtained in this way is heat-treated in VOMM-type continuous turbo-dryers in series, the setpoint temperature of which is set to 210° C. and which are configured to subject the product to a residence time of 45 to 50 min and such that the temperature difference between the setpoint and the temperature of the product at the outlet of the reactor, referred to as delta T, is a value of the order of 22 to 25° C.

Process Parameters

[0199]

TABLE-US-00009 TABLE 9 Conductivity Moisture on the content product after of the impregnation, product resuspended to before Residence 20% solids, in thermal Setpoint time Exp mS/cm treatment Delta T T ° C. (min) C-1 0.605 10.3 25 210 45 C-2 0.590 11 22 210 50

[0200] The RVA viscosity measurements are carried out and presented in the table below.

Results

[0201]

TABLE-US-00010 TABLE 10 Drop RVA Peak RVA Exp (mPa .Math. s) (mPa .Math. s) 50/50 waxy starch/ 990 1169 potato starch base C-1 −504 345 C-2 −457 181

[0202] The thermally modified starch blends C represent the products which are the most resistant to shearing, to acidity of the media and to thermal treatments.

[0203] The thermally modified starch blends B are a little less resistant than the thermally modified starch blends C and the thermally modified starch blends A are somewhat less resistant than the thermally modified starch blends B.

[0204] If the reaction times between the method in the oven and the method in VOMM-type turbo-dryers are compared, about 35 min of reaction time in VOMM-type turbo-dryers in series to obtain a product close to the functionalities of the product E-5 after 1.5 h of reaction time.

[0205] Likewise, between 40 and 45 min of reaction time in VOMM-type turbo-dryers in series is required to obtain a product close to the functionalities of the product E-5 after 2 h of reaction time.

[0206] The choice to use these starch blends will be made based on the intended application and thus on the shear, acidity and implementation temperature conditions.