METHOD FOR PREPARING A HEAT-MODIFIED STARCH

Abstract

A method for producing a heat-modified starch, comprising the steps of: (i) preparing a starch milk having a solids content of between 20% and 45% by weight and adding an alkaline agent, so as to obtain a final conductivity of between 4 and 7 mS/cm (ii) filtering the starch milk so as to recover a starch cake; (iii) introducing the starch cake, continuously, into a dryer at the same time as a continuous stream of hot air in order to recover a dried powder; (iv) continuously supplying a turboreactor with the dried powder, and by setting parameters for the speed of rotation of the stirrer, so that the dried powder is continuously centrifuged and conveyed into the turboreactor; (v) recovering the heat-modified starch produced.

Claims

1-5. (canceled)

6. A method for producing a heat-modified starch, comprising the steps of: (i) preparing a starch milk with solids 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 and 35%, 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 and resuspended starch at 20% by weight of solids is between 0.7 and 2.5 mS/cm; (iii) introducing said starch cake continuously into a dryer together with a continuous flow of hot air having a temperature of between 130° C. and 185° C. to recover a dried powder having a moisture content of between 8% and 18% by weight; (iv) continuously feeding the dried powder into a turboreactor, the inner wall of the turboreactor being maintained at a temperature of between 180° C. and 240° C., and by setting the rotational speed of the stirrer to achieve a centrifugal acceleration of between 850 and 2100 m.Math.s.sup.2, so that said dried powder is continuously centrifuged and fed into said turboreactor for a total time of between 3 and 45 minutes; (v) recovering the heat-modified starch thus produced.

7. The method according to claim 6, wherein the origin of the starch is selected from the group consisting of corn, waxy corn, potato, cassava, pea, and faba bean.

8. The method according to claim 6, wherein 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, and even more preferentially sodium carbonate.

9. A heat-modified starch capable of being obtained by the method according to claim 6.

10. A use of a heat-modified starch obtained by the method according to claim 6, as a thickening agent or texturizing agent in food applications, in particular in soups, sauces, mayonnaises, in desserts such as yogurts, fruit preparations for yogurts, stirred fermented milks, thermized yogurts, dessert creams, beverages, ready meals, preparations based on meat or fish, such as surimi.

Description

DESCRIPTION OF THE INVENTION

[0047] Thus, the invention relates to a method for producing a heat-modified starch, from a starch milk, comprising the steps consisting in:

(i) preparing a starch milk with solids 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 25 and 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 and resuspended starch at 20% by weight of solids is between 0.7 and 2.5 mS/cm;
(iii) introducing said starch cake continuously into a dryer together with a continuous flow of hot air having a temperature of between 130° C. and 185° C. to recover a dried powder having a moisture content of between 8% and 18% by weight;
(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 the rotational speed of the turboreactor stirrer to achieve a centrifugal acceleration of between 850 and 2100 m.Math.s.sup.−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.

[0048] The starch to be used in the method of the invention may be of any origin, for example corn, waxy corn, amylomaize, wheat, waxy wheat, leguminous plants such as pea and faba bean, potato, waxy potato, cassava, tapioca, waxy tapioca, rice, konjac, etc.

[0049] Preferentially, corn starch will be chosen, more particularly waxy corn starch (with a high amylopectin content), potato starch, cassava, pea and faba bean, as will be demonstrated by way of examples below.

[0050] 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.

[0051] The method according to the invention requires first preparing a starch milk with solids 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 25 and 35% by weight, so as to obtain a final conductivity of between 4 and 7 mS/cm.

[0052] 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 weight concentration of between 25 and 35%, preferably of 30%, in order to obtain a conductivity, on the milk, of between 4 and 7 mS/cm.

[0053] Indeed, the Applicant company has found that: [0054] the addition of the alkaline agent, more particularly the sodium carbonate, directly on the starch in the milk phase makes it possible to more effectively reach the sought-after high pH values (that is between 10.2 and 10.8, preferably between 10.5 and 10.65) than spraying the starch in the dry phase with sodium carbonate, in the sense that the addition in the milk phase enables better migration of the carbonate within the starch granules compared to powder impregnation.

[0055] Moreover, since impregnation in the powder phase requires adjusting the moisture content of the starch to high values, part of the energy intended for treating the product will therefore be lost to ensure the evaporation of the residual water. [0056] the addition of the alkaline agent in solution from a solution containing a weight concentration of between 25 and 35%, preferably of 30%, enables total dissolution of the alkaline agent in the starch milk, a quicker and more precise pH adjustment, and makes it possible to prevent deposition of solid alkaline agent at the bottom of the dryer in the event of it not dissolving. [0057] controlling the level of impregnation of the starch via conductivity measurements makes it possible to achieve the required precision for said high pH values.

[0058] The following step entails 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 and resuspended starch at 20% by weight of solids is between 0.7 and 2.5 mS/cm.

[0059] After this alkalinization step, the starch is dried to reduce its moisture content.

[0060] The following step therefore consists of introducing said starch cake obtained in the previous step continuously into a dryer together with a continuous flow of hot air having a temperature of between 130° C. and 185° C. to recover a dried powder having a moisture content of between 8% and 18% by weight.

[0061] This step can be carried out in a flash dryer, well known to the skilled person.

[0062] Said dried powder is then continuously fed into a turboreactor the inner wall of which is maintained at a temperature of between 180° C. and 240° C., by setting the rotational speed of the stirrer so as to achieve a centrifugal acceleration of between 850 and 2100 m.Math.s.sup.−2, in such a way that the said dried powder is continuously centrifuged and fed into said turboreactor for a total period of between 3 and 45 minutes.

[0063] In this step of implementation of the method of the invention, the setting of the rotational speed of the stirrer is determined by calculation, with regard to the centrifugal acceleration to be achieved, that is comprised according to the invention between 850 and 2100 m.Math.s.sup.−2.

[0064] The calculation is as follows, considering that a turboreactor is composed of a stirrer shaft 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): [0065] The centrifugal velocity is defined as the linear velocity at the blade tip “v” squared, divided by the radius R (distance between the stirrer shaft and the blade tip) and therefore expressed in m.Math.s.sup.−2.

{right arrow over (a)}=v.sup.2/R  [Math. 1] [0066] The linear speed at the blade tip is defined by the constant π multiplied by the diameter and the rotational speed of the stirrer shaft in rpm all divided by 60.

[00001]$\begin{array}{cc}v=\frac{\pi \times D\times \mathrm{Rotational}\mathrm{speed}}{60}& \left[\mathrm{Math}.2\right]\end{array}$

[0067] As illustrated below, for a VOMM ES350 turboshaft dryer, the linear velocity at the blade tip can be easily calculated from the values given by the manufacturer: [0068] diameter: 0.35 m; [0069] rotational speed of the stirrer shaft: 1000 rpm.

[0070] The mechanical action thus exerted by the rotor of the turboreactor provides a high quantity of kinetic energy, which encourages the intra- and intermolecular reactions between the polyglucosylated chains of the starch, thus leading to a higher degree of branching than the starting starch, placing it in a more “cross-linked” state.

[0071] Moreover, the formation of a thin, dynamic layer of starch circulating inside the turboreactor allows for a shortened reaction time, between 3 and 40 minutes, which is less than the treatments of the prior art, and particularly suitable for a continuous industrial application.

[0072] According to a preferred way, the heating jacket of the turboreactor is generally intended to be traversed by a heating fluid, such as a diathermic oil or steam.

[0073] By means of the double heating jacket of the turboreactor, it is possible to ensure precise temperature control inside the turboreactor, so that the thin, dynamic starch layer is kept in the optimal temperature range for the intimate mixing step, encouraging its physical transformation.

[0074] The last step consists in recovering the heat-modified starch thus obtained.

[0075] The invention further relates to heat-modified starches capable of being obtained according to the above method of the invention.

[0076] The heat-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, in particular in soups, sauces, beverages and ready meals, and in desserts such as yogurts and stirred fermented milks, and thermized yogurts.

[0077] Due to their texturizing and gelifying properties, they also have numerous applications in widely varying fields such as: [0078] acidic soups and sauces (pasteurized and sterilized), [0079] pasta sauces containing meat juices, [0080] desserts such as yogurts, stirred fermented milks, thermized yogurts, dessert creams, [0081] mayonnaise and hot vinaigrette, [0082] pie filling, fruit or meat filling or stable meat filling, either sweet or savory, dinners (short-life ready meals), [0083] pudding (dry mix to be cooked), [0084] baby food/preparations for infants, [0085] beverages, [0086] ready meals, preparations based on meat or fish, such as surimi. [0087] animal feed

[0088] The invention will be better understood with the aid of the following examples, which are intended to be illustrative and non-limiting.

Materials and Methods

[0089] Measurement of Conductivity

The method implemented here is adapted from the European Pharmacopoeia—current official edition—Conductivity (§ 2.2.38).

Materials:

[0090] KNICK 703 electronic conductivity meter, also equipped with its measuring cell and verified according to the procedure described in its instruction manual.

Procedure:

[0091] 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.Math.cm is prepared.
The measurement is carried out at 20° C. using the conductivity meter, referring to the procedure indicated in the instrument's user manual.
The values are expressed in microSiemens/cm (μS/cm) or milliSiemens/cm (mS/cm).

[0092] Measuring the Viscosity of a Starch Suspension Using the Rapid Viscometer Analyzer (RVA)

This measurement is carried out at acid 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

[0093] The following are added to a 1 liter beaker containing 500 mL of demineralized water: [0094] 91.0 g of citric acid monohydrate (purity >99.5%), and homogenization is carried out, [0095] 33.0 g of sodium chloride (purity >99.5%), and homogenization is carried out until complete dissolution, [0096] 300.0 g of 1 N sodium hydroxide.
The contents are decanted into a 1 L volumetric flask and demineralized water is added to reach 1 L.

Buffer B

[0097] 100 g of buffer A are mixed with 334.0 g of demineralized water.

[0098] The product to be analyzed is prepared in the following manner:

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

TABLE-US-00001 TABLE 1 Time Temperature Rotational speed hh:mm:ss ° C. Revolutions/min (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

[0099] End of test: 00:20:05 (hh:mm:ss)

Initial temperature: 50° C.±0.5° C.
Data acquisition interval: 2 seconds

Sensitivity: low

[0100] 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).

As a reminder, 1 cP=1 mPa.Math.s.
The results will therefore be presented in mPa.Math.s.
The measurements will be of the viscosity 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.

EXAMPLES

Example 1: Preparation of Heat-Modified Starches “A” from Potato Starch

[0101] i) The alkalinization of the potato starch is carried out according to the following steps: [0102] Prepare a potato starch suspension at 36.5% by weight of solids (S) [0103] Prepare a solution of sodium carbonate at 30% weight concentration and heat to 40-50° C. to promote the dissolution of the carbonate [0104] Add the solution of sodium carbonate so as to obtain a conductivity on the milk of between 4 and 6 mS/cm; [0105] Ensure a contact time of 0.5 h;
ii) Filter through a horizontal wringer with a scraper blade to separate the water and starch so that the final conductivity on the resuspended starch at 20% solids weight is between 0.7 and 1.1 mS
iii) Dry the starch to a moisture content of 12% by weight in a flash dryer where the air flow is at a temperature of 150° C.
iv) Heat treatment
The product thus obtained is heat-treated in continuous VOMM turboreactors in series type ES350, whose centrifugal acceleration is set at 1700 m.Math.s.sup.−2, whose setpoint temperature is fixed at 210° C. and whose air flow rate is fixed at 300 Nm.sup.3h.

[0106] The continuous turboreactors of VOMM type ES350 in series are configured to subject the product to a total residence time between 30 and 45 min, 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 20-22° C.

The process parameters are given in the following table.

TABLE-US-00002 TABLE 2 Conductivity on product after Moisture impregnation, content of resuspended the product at 20% by before heat weight of S, treatment Setpoint Residence Exp in mS/cm in % by weight Delta T T° C. time (min) Potato 0.11 15.7 0 0 0 starch base A-1 0.96 12 21 210 30 A-2 0.96 12 21 210 40 A-3 0.96 12 22.5 210 45

[0107] The RVA viscosity measurements are carried out and presented in the table below.

Results

[0108]

TABLE-US-00003 TABLE 3 Drop RVA Peak RVA Tests (mPa .Math. s) (mPa .Math. s) Potato 554 877 starch base A-1 −226 654 A-2 −382 451 A-3 −427 305

[0109] The heat-modified starches A-1, A-2 and A-3 obtained from potato starch have an improved stability compared to the native starch: less viscosity gain and retrogradation are observed when using these inhibited starches.

[0110] This can be seen by measuring the fall with the RVA viscometer: the more negative the fall, the more resistant the inhibited starch will be to shearing, to the acidity of the media and to heat treatments.

Example 2: Preparation of Heat-Modified Starches “B” from Cassava Starch

[0111] i) The alkalinization of the cassava starch is carried out according to the following steps: [0112] Prepare a cassava starch suspension at 36.5% by weight of solids (S) [0113] Prepare a solution of sodium carbonate at 30% weight concentration and heat to 40-50° C. to promote the dissolution of the carbonate; [0114] Add the solution of sodium carbonate so as to obtain a conductivity on the milk of between 4 and 6 mS/cm; [0115] Ensure a contact time of 0.5 h;
ii) Filter through a horizontal wringer with a scraper blade to separate the water and starch so that the final conductivity on the resuspended starch at 20% solids weight is between 0.7 and 1.1 mS.
iii) Dry the starch to a moisture content of 10% in a flash dryer where the air flow is at a temperature of 150° C.
iv) Heat treatment

[0116] The product thus obtained is heat-treated in continuous VOMM type ES350 turboreactors in series, whose centrifugal acceleration is set at 1700 m.Math.s.sup.−2, whose setpoint temperature is fixed at 210° C. and whose air flow rate is fixed at 300 Nm.sup.3h. The VOMM continuous turboreactors in series are configured to subject the product to a residence time between 17 and 32 min, 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 22-27° C.

[0117] The process parameters are given in the following table.

TABLE-US-00004 TABLE 4 Conductivity on product after Moisture impregnation, content of resuspended the product at 20% by before heat weight of S, treatment, Setpoint Residence Exp in mS/cm in % by weight Delta T T° C. time (min) Cassava 0.10 12.5 0 0 0 starch base B-1 0.95 10 27 210 17 B-2 0.95 10 24 210 27 B-3 0.95 10 25 210 32

[0118] The RVA viscosity measurements are carried out and presented in the table below.

Results

[0119]

TABLE-US-00005 TABLE 5 Drop RVA Peak RVA Tests (mPa .Math. s) (mPa .Math. s) Cassava 480 603 starch base B-1 60 438 B-2 −97 269 B-3 −155 147

[0120] The heat-modified starches B-1, B-2 and B-3 obtained from cassava starch have an improved stability compared to the native starch: less viscosity gain and retrogradation are observed when using these inhibited starches.

Example 3: Preparation of Heat-Modified Starches “B” from Pea Starch

[0121] i) The alkalinization of the pea starch is carried out according to the following steps: [0122] Prepare a pea starch suspension at 33% by weight of solids (S) [0123] Prepare a solution of sodium carbonate at 30% weight concentration and heat to 40-50° C. to promote the dissolution of the carbonate; [0124] Add the solution of sodium carbonate so as to obtain a conductivity on the milk of between 4 and 6 mS/cm; [0125] Ensure a contact time of 0.5 h;
ii) Filter through a horizontal wringer with a scraper blade to separate the water and the starch so that the final conductivity on the resuspended starch at 20% solids weight is between 0.7 and 1.1 mS.
iii) Dry the starch to a moisture content of 10% by weight in a flash dryer where the air flow is at a temperature of 135° C.
iii) Heat treatment

[0126] The product thus obtained is heat-treated in continuous VOMM type ES350 turboreactors in series, whose centrifugal acceleration is set at 1700 m.Math.s.sup.−2, whose setpoint temperature is fixed at 210° C. and whose air flow rate is fixed at 300 Nm.sup.3h. The VOMM continuous turboreactors in series are configured to subject the product to a residence time between 6 and 21 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 23-24° C.

The process parameters are given in the following table.

TABLE-US-00006 TABLE 6 Conductivity on product after Moisture impregnation, content of resuspended the product at 20% by before heat weight of S, treatment, Setpoint Residence Exp in mS/cm in % by weight Delta T T° C. time (min) Pea 0.09 12.9 0 0 0 starch base C-1 0.9 10 24 210 6 C-2 0.9 10 24 210 15 C-3 0.9 10 23.5 210 21

[0127] The RVA viscosity measurements are carried out and presented in the table below.

Results

[0128]

TABLE-US-00007 TABLE 7 Drop RVA Peak RVA Tests (mPa .Math. s) (mPa .Math. s) Pea 76 285 starch base C-1 −54 302 C-2 −140 97 C-3 −132 60

[0129] The heat-modified starches C1, C-2, and C-3 have improved stability during the process of use compared to native starch: less viscosity gain and retrogradation are observed when using these inhibited starches.

Example 4: Preparation of Heat-Modified Starches “D” from Waxy Corn Starch

[0130] i) The alkalinization of waxy corn starch is carried out according to the following steps: [0131] Prepare a waxy corn starch suspension at 36.5% by weight of solids (S) [0132] Prepare a solution of sodium carbonate at 30% weight concentration and heat to 40-50° C. to promote the dissolution of the carbonate; [0133] Add the solution of sodium carbonate at 30% weight concentration so as to obtain a conductivity between 4 and 7 mS/cm for the milk; [0134] Ensure a contact time of 0.5 h
ii) Filter through a horizontal wringer with a scraper blade to separate the water and starch so that the final conductivity on the resuspended powder at 20% solids weight is between 1.75 and 2 mS.
iii) Dry the starch to a moisture content of 11.8% in a flash dryer where the air flow is at a temperature of 135° C.
iii) Heat treatment.

[0135] The product thus obtained is heat-treated in continuous VOMM type ES350 turboreactors in series, whose centrifugal acceleration is set at 1700 m.Math.s.sup.−2, whose setpoint temperature is fixed at 200° C. and whose air flow rate is fixed at 300 Nm.sup.3h. The VOMM continuous turboreactors in series are configured to subject the product to a residence time between 15 and 35 min, such that the temperature difference between the setpoint and the temperature of the product at the outlet of the dryer, referred to as Delta T, is a value of the order of 17 to 20° C.

[0136] The process parameters are given in the following table.

TABLE-US-00008 TABLE 8 Conductivity on product after Moisture impregnation, content of brought to the product 20% by weight before heat of S, treatment, Setpoint Residence Exp in mS/cm in % by weight Delta T T° C. time (min) Waxy 0.04 11.5 0 0 0 corn starch base D-1 1.9 11.8 20 200 15 D-2 1.9 11.8 18 200 25 D-3 1.9 11.8 17 200 35

[0137] The RVA viscosity measurements are carried out and presented in the table below.

Results

[0138]

TABLE-US-00009 TABLE 9 Drop RVA Peak RVA Exp (mPa .Math. s) (mPa .Math. s) Waxy 914 1020 corn starch base D-1 −66 441 D-2 −127 284 D-3 −176 157

[0139] The heat-modified starches D1, D-2, and D-3 have improved stability during the process of use compared to native starch: less viscosity gain and retrogradation are observed when using these inhibited starches.

Example 5: Preparation of Heat-Modified Starches “E” from Faba Bean Starch

[0140] i) The alkalinization of the faba bean starch is carried out according to the following steps:—Prepare a faba bean starch suspension at 33% by weight of solids (S); [0141] Prepare a solution of sodium carbonate at 30% weight concentration and heat to 40-50° C. to promote the dissolution of the carbonate; [0142] Add the solution of sodium carbonate so as to obtain a conductivity on the milk of between 4 and 6 mS/cm; [0143] Ensure a contact time of 0.5 h;
ii) Filter for example through a horizontal wringer with a scraper blade to separate the water and starch and so that the final conductivity on the resuspended starch at 20% solids weight is between 1.5 and 2 mS;
iii) Dry the starch to a moisture content of 14% by weight in a flash dryer where the air flow is at a temperature of 135° C.;
iii) Heat treatment

[0144] The product thus obtained is heat-treated in continuous VOMM turboreactors in series, whose centrifugal force is set at 1700 m.Math.s.sup.−2, whose setpoint temperature is fixed at 210° C. and whose air flow rate is fixed at 300 Nm.sup.3h.

[0145] The VOMM continuous turboreactors in series are configured to subject the product to a residence time between 13 and 25 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 23-24° C.

[0146] The process parameters are given in the following table.

TABLE-US-00010 TABLE 10 Conductivity on product after Moisture impregnation, content of resuspended the product at 20% by before heat weight of S, treatment, Setpoint Residence Exp in mS/cm in % Delta T T° C. time (min) Faba bean 0.133 8 0 0 0 starch base E-1 1.9 14 24 210 13 E-2 1.9 14 23.5 210 25

[0147] The RVA viscosity measurements are carried out and presented in the table below.

Results

[0148]

TABLE-US-00011 TABLE 11 Drop RVA Peak RVA Tests (mPa .Math. s) (mPa .Math. s) Faba bean 82 323 starch base E-1 −79 229 E-2 −47 45
The heat-modified starches E-1 and E-2 have improved stability during the process of use compared to the native starch: less viscosity gain and retrogradation are observed when using these inhibited starches.