WO2006105957A1

WO2006105957A1 - Process and plant for the production of meals containing poorly digestible starch

Info

Publication number: WO2006105957A1
Application number: PCT/EP2006/003112
Authority: WO
Inventors: Giuseppina Cerea
Original assignee: Vomm Chemipharma SRL
Current assignee: Vomm Chemipharma SRL
Priority date: 2005-04-06
Filing date: 2006-04-05
Publication date: 2006-10-12
Anticipated expiration: 2007-10-06
Also published as: CN1843163A; WO2006105957A8; ITMI20050577A1

Abstract

Process for treating a dietary meal containing starch, so as to make the latter poorly digestible, comprising the steps of: feeding a continuous flow of a starch-containing meal into a turbo- reactor (A) comprising a horizontal-axis cylindrical tubular body (1), provided with at least one inlet opening (5, 6), at least one discharge opening (7) for the treated product, a heating jacket (4), a bladed rotor (8) put into rotation at peripheral speeds comprised between 15 and 40 m/s, feeding into the turbo-reactor (A), cocurrently with the starch flow, a continuous and finely divided flow of a reactant consisting of a concentrated aqueous hydrogen peroxide solution, centrifuging the meal particles and the reactant against the turbo- reactor inner wall heated at a temperature of at least 100°C, with formation of a thin, dynamic, highly turbulent tubular fluid layer, reacting the meal and the reactant into the thin layer while it progresses in substantial contact with said inner wall of the turbo-reactor (A) towards the discharge opening (7), continuously discharging a flow of treated meal, having a humidity content of 30-50%, sending the flow of treated meal on to a maturation step for a time varying between 30 minutes and 24 h, at a temperature of 60-90°C, and to a subsequent drying step to bring the humidity content of the end meal to 10-16%.

Description

Title: Process and plant for the production of meals containing poorly digestible starch

DESCRIPTION

Field of application The present invention relates to the field of the food and dietetics industry and, in particular, it concerns a process for treating starch- containing meals to obtain products characterized by a poor assimilation by the body.

Prior art It is known that obesity is steadily increasing in the developed countries, especially in North America and in Europe, due to eating habits which are excessive in quantity and unbalanced in quality, as well as to insufficient exercise.

Correcting bad food habits is often anything but easy and above all, it is difficult to obtain a quick reduction of the calorie intake, as this also implies a drastic reduction in the amount of food eaten.

To obtain a reduction in the calorie intake without the person under treatment feeling strong food deprivation, part of the glucidic and lipidic components of food can be replaced with products that are poorly assimilated by the body. Examples of such poorly assimilated products are both soluble and insoluble dietary fibers, glycans, glucomannans, fructosanes, amylase resistant starches, etc.

These products can be eaten as such or, rather, added in suitable proportions to the flours and the semolinas used for bakery products and pasta and other foods.

Several processes are known for obtaining poorly digestible modified starches; for example, a process which comprises the treatment of native starch with phosphorylating agents so as to obtain phosphorylated distarch phosphodiesters is described in patent application EP 986307.

A process for preparing an amylase resistant granular starch is described in US patent US 5 902 410, and includes a heat treatment (60-160⁰C) of starch having an amylose content of at least 40%, in the presence of a swelling inhibiting agent, in particular an inorganic salt.

Of course, these are products having quite a high cost, also because they are obtained from a starting material, starch, which is in itself more costly than the flours it is obtained from. The addition of such products to the flours used in the production of bakery products or pasta thus considerably increases the cost of the end products.

The Applicant is not aware of any available cereal flours or semolinas, which are poorly assimilated by the body, nor of any treatments having been applied to cereal flours or semolinas that are apt to making them poorly assimilated with respect to their glucidic fraction.

Summary of the invention An object of the present invention is to provide a dietary starch- containing meal, wherein the starch is poorly assimilated by the body.

Such an object is achieved, according to the invention, by a process for treating a meal containing starch, so as to make the latter poorly digestible, comprising the steps of:

feeding a continuous flow of a starch-containing meal into a turbo- reactor comprising a horizontal-axis cylindrical tubular body, provided with at least one opening for introducing reactants and for discharging the treated product, a heating jacket for bringing the inner wall of the tubular body to a predetermined temperature, a bladed rotor, rotatably supported in the cylindrical tubular body where it is put into rotation at peripheral speeds comprised between 15 and 40 m/s, so as to disperse said continuous meal flow into a meal particle flow,

feeding into said turbo-reactor, cocurrently with said meal flow, a continuous and finely divided flow of a reactant consisting of a concentrated aqueous hydrogen peroxide solution,

centrifuging said meal particles and said reactant against the inner wall of the turbo-reactor, heated at a temperature of at least 100⁰C, with formation of a thin, dynamic, highly turbulent tubular fluid layer wherein the meal particles and said reactant are mechanically kept in close contact by the blades of said bladed rotor,

reacting said meal and said reactant into said thin layer while progressing in substantial contact with said inner wall of the turbo- reactor towards the discharge opening,

continuously discharging a flow of treated meal, having a humidity content of 30-50%,

sending said flow of treated meal on to a maturation step for a time varying between 30 minutes and 24 h, at a temperature of 60-90⁰C, and to a subsequent drying step to bring the humidity content to the values typical of starch-containing meals, that is, 10-16%.

The treated meal exiting the turbo-reactor generally has a temperature of about 60-80°C.

The above-mentioned concentrated hydrogen peroxide solution preferably consists of an aqueous solution of hydrogen peroxide of at least 40-volumes and, advantageously, of about 120-140 volumes.

When 120-140 V hydrogen peroxide is used, the weight ratio of hydrogen peroxide to meal generally varies between 1:4 and 1:20. The concentrated aqueous hydrogen peroxide solution can be introduced into the turbo-reactor right at the inlet, since in that case the bladed rotor carries out an effective nebulization and centrifugation thereof, thus ensuring its introduction into the turbulent dynamic thin layer of meal particles to be treated in a highly dispersed condition.

In this way, the closest possible contact between the particles and the hydrogen peroxide is promoted, and this considerably increases the efficacy of the treatment.

As an alternative or in addition to the above-mentioned introduction through an inlet opening, the hydrogen peroxide introduction may also be carried out through openings for the nebulization of hydrogen peroxide at different levels along the length of the cylindrical tubular body.

It can sometimes be advantageous to introduce a steam flow into the turbo-reactor cocurrently with the above-mentioned meal flow.

The mean residence time of the meal flow inside the turbo-reactor is of about 1-5 minutes.

The above-mentioned maturation step at 60-90⁰C can be carried out in static conditions, for example inside heating silos with plate-type heat exchangers such as those manufactured by the Bulkflow Technologies Inc. (Canada) company. Alternatively, and preferably, the maturation at 60-90⁰C is carried out in dynamic conditions, in order to prevent undesirable agglomeration and increase the homogeneity of the end product, for example by means of a slow continuous stirrer or a screw apparatus. This latter apparatus advantageously consists of a horizontal-axis cylindrical tubular body, provided with inlet and discharge openings, a heating jacket for bringing the inner wall of the tubular body to a predetermined temperature, and a screw supported in the cylindrical tubular body where it is put into rotation at low speeds.

The drying step mentioned above can be carried out with any apparatus commonly used for drying powdery substances but it is preferably carried out with the aid of a turbo-dryer, which is an apparatus structurally similar to the above-described turbo-reactor, also comprising a horizontal-axis cylindrical tubular body, provided with inlet and outlet openings, with a heating jacket and with a bladed rotor rotatably and coaxially mounted inside the cylindrical tubular body.

When such apparatus is used, the temperature of the heating wall is of about 140-180⁰C and, cocurrently with the flow of treated meal entering the turbo-dryer, a hot and dry air flow is optionally fed at a temperature of 140-180⁰C. The mean residence time of the treated meal inside the turbo-dryer is of about 1-5 minutes.

The expression "starch-containing meal" includes cereal flours and semolinas, such as for example wheat, barley, maize, oats, rye, rice, as well as meals consisting entirely of starch. Preferably, in the process according to the present invention, starches with a high amylose content or flours containing starch with a high amylose content are used.

Following the treatment with hydrogen peroxide carried out according to the process of the present invention, the starch contained in the meal becomes little vulnerable to attack by alpha- amylase and therefore it is poorly digestible.

If the meal in question is a cereal flour or semolina, the gluten in the treated product is at least partially de-texturised. The flours that have undergone the treatment according to the present invention thus exhibit a behavior, during the kneading and rising step, similar to that of cake flour.

When a flour treated according to the present process is mixed with water, the viscosity of the suspensions or of the mixtures thus obtained is considerably reduced compared to the viscosity of suspensions or mixtures obtained from conventional flours with the same amounts of water.

The main use of the treated meals obtained with the process according to the present invention is in the dietetics sector as additives to be incorporated into standard flours to reduce their calorie content.

In another aspect thereof, the present invention relates to a plant for carrying out the process illustrated above, which comprises a turbo- reactor of the type described above, a screw apparatus for the maturation of the treated meal as described above, and a dryer, preferably a turbo-dryer.

The advantages and features of this invention will appear more clearly from the description of an embodiment of a process for treating meals containing starch, in order to make the latter poorly digestible, hereinafter provided with reference to the annexed drawing, given for illustrative and non-limiting purposes.

Brief description of the drawings

Figure 1 schematically shows a plant for the production of meals containing poorly digestible starch according to the process of the invention.

Detailed description of a preferred embodiment

With reference to figure 1, the turbo-reactor A essentially consists of a cylindrical tubular body 1, closed at the opposed ends by end walls 2, 3 and coaxially provided with a heating jacket 4 intended to be run through by a fluid, for example diathermic oil, for keeping the inner wall of body 1 at a predetermined temperature. The tubular body 1 is provided with inlet openings 5, 6 for the starch- containing meal to be treated and for the concentrated aqueous hydrogen peroxide solution, respectively, as well as a discharge opening 7 for the treated meal.

In the tubular body 1, is rotatably supported a bladed rotor 8, the blades 9 of which are helically arranged and are oriented for centrifuging and concurrently conveying the meal subjected to treatment towards the outlet.

A motor M is provided for driving the bladed rotor at peripheral speeds varying between 20 and 40 meters per second.

Openings 10 are provided in the inner wall of the cylindrical tubular body 1 for introducing concentrated aqueous hydrogen peroxide solution in nebulized form.

A plant for producing meals containing poorly digestible starches according to the process of the invention comprises, in addition to the turbo-reactor A, a maturation apparatus B and a turbo-dryer C.

The maturation apparatus B, depicted in a very schematic manner, comprises a cylindrical tubular body 21, closed at the opposed ends by end walls 22, 23 and coaxially provided with a heating jacket 24 intended to be run through by a fluid, for example diathermic oil, for keeping the inner wall of the body 1 at a predetermined temperature. The tubular body 21 is provided with an inlet opening 25 for the starch- containing meal coming from the turbo-reactor A and with a discharge opening 27 for the meal at the end of the maturation step.

A screw 28 is rotatably supported in the tubular body 21, driven in rotation at low speed by a motor N and intended for conveying the meal subjected to maturation towards the outlet.

Finally, the turbo-dryer C is not described in detail as it has a structure totally similar to that of turbo-reactor A, except for the absence of openings for the introduction of liquid reactants. The components of turbo-dryer C that are the same as those of the turbo-reactor A are indicated with the same reference numerals increased by 100.

EXAMPLE

In a turbo-reactor A wherein the bladed rotor is made to rotate at a peripheral speed of about 30 m/s and wherein the inner wall is kept at 140⁰C, a flow of wheat flour is continuously fed, having a 25% amylose content calculated on the total content of starch, which is 60% of the total product (humidity content of about 10%), at a flow rate of 100 kg/ hour. At the same time, 40 I/hour of a 1: 1 mixture of 130 V aqueous hydrogen peroxide and water is continuously fed through opening 6 and openings 10.

Right at the inlet of the turbo-reactor A, the flour flow is mechanically dispersed into very small particles, which are immediately centrifuged against the inner wall of the turbo-reactor itself, where they form a dynamic tubular thin layer.

At the same time, the aqueous hydrogen peroxide solution entering through opening 6 is mechanically finely nebulized by the blades 9 of rotor 8, which also readily centrifuge the very small droplets obtained. These are thus introduced into the dynamic tubular thin layer of flour particles with which they can interact.

The hydrogen peroxide solution introduced in nebulized form through the openings 10 further increases the hydrogen peroxide interaction with the flour particles.

After a residence time of about 2 minutes in the turbo-reactor A, a treated flour is continuously discharged from opening 7 with a humidity content of about 40% and a temperature of about 70⁰C.

The flow of treated flour exiting the turbo-reactor A is continuously fed to the maturation device B, through the inlet opening 25. The flour is made to slowly move forward by the slowly rotating screw 28, up to the discharge opening 27, after a mean residence time of about 2 hours at a temperature of about 70°C (which is also the temperature at which the inner wall is stabilized by the heating jacket 24).

At this point, the flour flow coming out of the maturation device B is continuously fed into the turbo-dryer C, through the inlet opening 105, along with a cocurrent air flow at about 160°C. After a mean residence time of about 1 minute inside the turbo-dryer, in which the bladed rotor 108 is put into rotation at a peripheral speed of 30 m/s and the heating jacket 104 stabilizes the temperature of the inner wall at about 160⁰C, the flour is discharged through the discharge opening 107.

The resulting flour has a humidity content of about 10% and the amylose contained therein has a degree of crystallization of more than 50% so as to bring the calculated degree of crystalline starch over the total close to 15%.

Claims

1. Process for treating a dietary meal containing starch, so as to make the latter poorly digestible, comprising the steps of:

feeding a continuous flow of a starch-containing dietary meal into a turbo-reactor (A) comprising a horizontal-axis cylindrical tubular body

(1), provided with at least one opening (5, 6) for introducing said meal and reactants, at least one discharge opening (7) for the treated product, a heating jacket (4) for bringing the inner wall of the tubular body (1) to a predetermined temperature, a bladed rotor (8), rotatably supported in the cylindrical tubular body where it is put into rotation at peripheral speeds comprised between 15 and 40 m/s, so as to disperse said continuous meal flow into a meal particle flow,

feeding into said turbo-reactor (A), cocurrently with said meal flow, a continuous and finely divided flow of a reactant consisting of a concentrated aqueous hydrogen peroxide solution,

centrifuging said meal particles and said reactant against the inner wall of the turbo-reactor, heated at a temperature of at least 100⁰C, with formation of a thin, dynamic, highly turbulent tubular fluid layer wherein the meal particles and said reactant are mechanically kept in close contact by the blades (9) of said bladed rotor (8),

reacting said meal and said reactant within said thin layer while progressing in substantial contact with said inner wall of the turbo- reactor (A) towards the discharge opening (7),

sending said flow of treated meal on to a maturation step for a time varying between 30 minutes and 24 h, at a temperature of 60-90°C, and to a subsequent drying step to bring the humidity content of the end meal to 10-16%.

2. Process according to claim 1, wherein said concentrated hydrogen peroxide solution consists of aqueous hydrogen peroxide of at least 40 volumes.

3. Process according to claim 2, wherein said concentrated hydrogen peroxide solution consists of aqueous hydrogen peroxide of 120-140 volumes.

4. Process according to claim 3, wherein the weight ratio of hydrogen peroxide to meal varies between 1:4 and 1:20.

5. Process according to any one of the previous claims, wherein said maturation step at 60-90⁰C is carried out in an apparatus (B) comprising a horizontal- axis cylindrical tubular body (21) provided with at least one inlet opening (25), at least one discharge opening (27), a heating jacket (24) for bringing the inner wall of the tubular body (21) at a predetermined temperature comprised between 60 and 90⁰C, and a screw (28) supported in rotation in the cylindrical tubular body (21).

6. Process according to any one of the previous claims, wherein said drying step is carried out in a turbo-dryer (C) comprising a horizontal- axis cylindrical tubular body (101) provided with openings (105, 106) for introducing said treated and matured meal, discharge openings (107) for the end product, a heating jacket (104) for bringing the inner wall of the tubular body (101) to a temperature of 140-180⁰C, a bladed rotor (108), rotatably supported in the cylindrical tubular body where it is put in rotation at peripheral speeds comprised between 15 and 40 m/s.

7. Process according to claim 6, wherein an air flow at a temperature of 140-180⁰C is fed into the turbo-dryer (C), cocurrently with said flow of treated and matured meal.

8. Process according to any one of the previous claims, wherein said starch-containing meal consists of starch and preferably, of a high amylose content starch.

9. Process according to any one of claims from 1 to 7, wherein said meal consists of a cereal flour or semolina, preferably having a high amylose content.

10. Plant for carrying out the process according to any one of the previous claims, comprising:

- a turbo-reactor (A) comprising a horizontal-axis cylindrical tubular body (1), provided with at least one opening (5, 6) for introducing said meal and reactants, at least one discharge opening (7) for the treated product, a heating jacket (4) for bringing the inner wall of the tubular body (1) to a predetermined temperature, a bladed rotor (8), rotatably supported in the cylindrical tubular body;

- a maturation apparatus (B) comprising a horizontal-axis cylindrical tubular body (21) provided with at least one inlet opening (25), at least one discharge opening (27), a heating jacket (24) for bringing the inner wall of the tubular body (21) to a predetermined temperature, and a screw (28) supported in rotation into the cylindrical tubular body (21)

- a dryer.

11. Plant according to claim 10, wherein said dryer consists of a turbo-dryer (C) comprising a horizontal-axis cylindrical tubular body

(101), provided with at least one opening (105, 106) for introducing said treated and matured meal, at least one discharge opening (107) for the end product, a heating jacket (104) for bringing the inner wall of the tubular body (101) to a predetermined temperature, a bladed rotor (108), rotatably supported in the cylindrical tubular body.

12. Cereal flour or semolina containing poorly digestible starch obtained with the process according to claim 9.

13. Flour or semolina according to claim 12, obtained from a starting meal selected among wheat, rice, maize, oats, rye flour or semolina, and mixtures thereof.