Patent Application
20220213230
The invention relates to the production of heat-modified starch, which starch has stabilized viscosity following this heat treatment. Such heat-modified starches can then be used as texturizing and thickening agents in numerous food applications, in particular in soups, sauces, in desserts such as yogurts, stirred fermented milks, thermized yogurts, dessert creams, but also beverages, ready meals, and preparations based on meat or fish, such as surimi.
Synthesized biochemically, a source of carbohydrates, starch is one of the most widespread organic materials in the plant kingdom, where it constitutes organisms' nutrient reserves.
Starches have always been used in the food industry, not only as a nutritional ingredient but also for their technical properties, as a thickening agent, binder, stabilizer or gelling agent.
For example, native starches are used in preparations requiring cooking. Corn starch, in particular, forms the basis of “powders for flan”.
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 custards.
However, those cannot be used in pastries intended to be frozen since, on defrosting, the phenomenon of syneresis, which is reflected in the expulsion of water, destroys the texture of the custard.
Thus, in its native state, starch has limited applicability due to syneresis, but also due to:
Thus, in order to meet today's demanding technical requirements, the properties of starch have to be optimized by various methods known as “modification”.
These main modifications therefore aim to adapt the starch to the technical constraints resulting from cooking, but also from freezing/thawing, from appertization or sterilization, and to make it compatible with modern food (microwaves, instant meals, “high temperatures”, etc.).
Starch modification therefore aims to correct one or more of the abovementioned defects, thereby improving its versatility and meeting the needs of consumers.
Techniques for modifying starch have generally been classified into four categories: physical, chemical, enzymatic and genetic, the ultimate goal being to produce various derivatives with optimized physicochemical properties.
Chemical and physical modifications are most commonly implemented.
Chemical treatment consists of introducing functional groups into the starch, which alters its physicochemical properties in a noteworthy manner.
Indeed, such modifications of granular native starches profoundly alter their behavior in terms of gelatinization, bonding and retrogradation.
Generally, these modifications are made by chemical derivatization, such as esterification, etherification, crosslinking or grafting.
However, chemical modifications are less sought-after by consumers in food applications (also for environmental reasons), even if some modifications are considered to be safe.
Various physical modifications are thus proposed, for example:
The starch goes from type B to type A after treatment, thereby acquiring a gelatinization temperature which increases significantly;
An alternative to “thermal inhibition” treatment has been proposed in the solvent phase and consists of heating a non-pre-gelatinized granular starch in an alcohol-based medium in the presence of a base and salts at a temperature of 120° to 200° C. for 5 minutes to 2 hours.
Regardless, the thermal inhibition process thus leads to obtaining a starch paste having properties of increased resistance to viscosity breakdown, and a non-cohesive texture.
The technical field to which the invention belongs is that of thermal inhibition treatment of starch without an aqueous-alcoholic solvent.
In this particular technical field, mention may more particularly be made of U.S. Pat. No. 6,221,420, which describes a thermally inhibited starch obtained by dehydration then heat treatment.
The main steps are:
Preferentially, before the step of dehydrating the starch, it is recommended to perform a step of alkalinization of the starch, making it possible to bring the pH of the starch suspension to a value of between 7 and 10, preferably of between 8 and 10.
At this stage, before the step of dehydration proper which precedes the inhibition step, the water content of the starch (as demonstrated by way of examples) is then between 8 and 10%.
US 2001/0017133 describes a similar method, wherein the starch is also dehydrated below 125° C. before the inhibition process is begun (at a temperature of more than 100° C., preferentially of between 120 and 180° C., more preferentially of between 140 and 160° C.) for a duration of up to 20 hours, preferentially of between 3 hours 30 and 4 hours 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 of between 8 and 9.5%, and a water content of between 2 and 15%.
A variant was proposed in patent application WO 2014/042537, which variant relates to heating an alkaline starch at temperatures of between 140 and 190° C. while ensuring that the inhibition method is initiated and carried out in the presence of a sufficient amount of water, that is more than 1% water.
In other words, this method recommends the thermal inhibition of a starch which has been alkalinized beforehand without carrying out a dehydration step.
The starch preparation or the starch is thus brought to a pH of between 9.1 and 11.2, preferentially to a value of the order of 10, and the humidity is adjusted to between 2 and 22%, preferentially between 5 and 10%.
The thermal inhibition is subsequently carried out directly on this powder or this starch, at a temperature of between 140 and 190° C., preferentially between 140 and 180° C., for a duration of 30 minutes.
From the foregoing, it is noted that the methods for thermal inhibition implemented in order to stabilize the viscosity of starches employ methods requiring:
There is therefore a need for a novel method 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 be “thermally inhibited”.
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·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.
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.
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.
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.
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.
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.
Indeed, the Applicant company has found that:
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.
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.
After this alkalinization step, the starch is dried to reduce its moisture content.
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.
This step can be carried out in a flash dryer, well known to the skilled person.
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·s−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.
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·s−2.
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):
{right arrow over (a)}=v
2
/R [Math. 1]
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:
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.
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.
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.
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.
The last step consists in recovering the heat-modified starch thus obtained.
The invention further relates to heat-modified starches capable of being obtained according to the above method of the invention.
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.
Due to their texturizing and gelifying properties, they also have numerous applications in widely varying fields such as:
The invention will be better understood with the aid of the following examples, which are intended to be illustrative and non-limiting.
Measurement of Conductivity
The method implemented here is adapted from the European Pharmacopoeia—current official edition—Conductivity (§ 2.2.38).
KNICK 703 electronic conductivity meter, also equipped with its measuring cell and verified according to the procedure described in its instruction manual.
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.
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).
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:
The following are added to a 1 liter beaker containing 500 mL of demineralized water:
100 g of buffer A are mixed with 334.0 g of demineralized water.
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:
End of test: 00:20:05 (hh:mm:ss)
Initial temperature: 50° C.±0.5° C.
Data acquisition interval: 2 seconds
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·s.
The results will therefore be presented in mPa·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.
i) The alkalinization of the potato starch is carried out according to the following steps:
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.
The RVA viscosity measurements are carried out and presented in the table below.
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.
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.
i) The alkalinization of the cassava starch is carried out according to the following steps:
The product thus obtained is heat-treated in continuous VOMM type ES350 turboreactors in series, whose centrifugal acceleration is set at 1700 m·s−2, whose setpoint temperature is fixed at 210° C. and whose air flow rate is fixed at 300 Nm3h. 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.
The process parameters are given in the following table.
The RVA viscosity measurements are carried out and presented in the table below.
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.
i) The alkalinization of the pea starch is carried out according to the following steps:
The product thus obtained is heat-treated in continuous VOMM type ES350 turboreactors in series, whose centrifugal acceleration is set at 1700 m·s−2, whose setpoint temperature is fixed at 210° C. and whose air flow rate is fixed at 300 Nm3h. 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.
The RVA viscosity measurements are carried out and presented in the table below.
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.
i) The alkalinization of waxy corn starch is carried out according to the following steps:
The product thus obtained is heat-treated in continuous VOMM type ES350 turboreactors in series, whose centrifugal acceleration is set at 1700 m·s−2, whose setpoint temperature is fixed at 200° C. and whose air flow rate is fixed at 300 Nm3h. 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.
The process parameters are given in the following table.
The RVA viscosity measurements are carried out and presented in the table below.
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.
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);
The product thus obtained is heat-treated in continuous VOMM turboreactors in series, whose centrifugal force is set at 1700 m·s−2, whose setpoint temperature is fixed at 210° C. and whose air flow rate is fixed at 300 Nm3h.
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.
The process parameters are given in the following table.
The RVA viscosity measurements are carried out and presented in the table below.
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 19 04787 | May 2019 | FR | national |
| 19 07333 | Jul 2019 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/FR2020/050754 | 5/6/2020 | WO | 00 |
