FOAMED, DOUGH-BASED FOOD AND APPARATUS AND METHOD FOR PRODUCTION THEREOF AND USE OF THE APPARATUS

Abstract

A dough-based food product, an apparatus and method for production thereof. A food product matrix to be foamed includes a proportion of a starch-containing raw material and a proportion of water. Gas that has been dissolved or is to be dissolved is introduced into the food product matrix to be foamed. The gas is dissolved under pressure in the food product matrix to be foamed. Gas bubbles are formed by expansion and increasing the volume with a resulting reduction in density of the dough as a result of bubble growth for formation of a foamed food product matrix of the food product to be produced. The foam is then stabilized. Gas is introduced into and dissolved in the aqueous component of the food product matrix to be foamed in a subcritical state below the critical point and at a pressure of 10 bar≤p<gas critical pressure.

Claims

1. An apparatus for production of a food product, comprising at least one device suitable to prepare dough for the production of a dough-based food product matrix to be foamed as well as a supply device for supplying a gas into the dough-based food product matrix to be foamed, wherein the apparatus is embodied in such a way that gas can be introduced into the aqueous portion of the food matrix to be foamed in a subcritical state below the critical point at a pressure of 10 bar≤p<critical pressure of the gas by means of the supply device, and wherein a dissolving of the introduced gas in a subcritical state below the critical point can be adjusted in the apparatus at a pressure of 10 bar≤p<critical point of the gas for attaining a foamed, dough-based food product.

2. The apparatus according to claim 1, wherein the apparatus comprises an extruder as device for the preparation of dough and is configured to carry out the steps of a providing a food product matrix to be foamed, comprising a proportion by weight of a starch-containing raw material (R) and a proportion by weight of water (W), b introducing a gas that is to be dissolved or has been dissolved into the food product matrix to be foamed, c dissolving the gas or introducing the dissolved gas under pressure in the aqueous portion of the food product matrix to be foamed, d forming gas bubbles by pressure relaxation and increasing the volume with a resulting reduction in density of the dough as a result of bubble growth for formation of the foamed food product matrix of the food product to be produced, e stabilizing the foam of the foamed food product matrix.

3. The apparatus according to claim 2, wherein the gas is introduced and dissolved in a subcritical state below the critical point at a pressure of 10 bar≤p<critical pressure of the gas in step b and/or step c.

4. The apparatus according to claim 2, wherein the foam stabilization of the foamed food matrix is attained by heat-induced solidification in step e.

5. The apparatus according to claim 2, wherein carbon dioxide (CO.sub.2) or noxious gas (N.sub.2O) is introduced as gas in each case in their subcritical state in step b and/or c.

6. The apparatus according to claim 4, wherein pressures of 25≤p≤65 bar and a temperature of <31° C. are present in the case of carbon dioxide (CO.sub.2) as subcritical gas in step b and c.

7. The apparatus according to claim 2, wherein the apparatus further comprises: a raw material supply device for supplying a starch-containing raw material into the extruder; and a liquid supply device, which is arranged downstream from the raw material supply device in the process direction of the extruder, for supplying liquid, in particular water, wherein the supply device is connected downstream from the liquid supply device in the process direction.

8. The apparatus according to claim 2, wherein the extruder is a twin-screw extruder designed in the same direction or in the opposite direction.

9. The apparatus according to claim 1, wherein the apparatus further comprises a container, which can be closed in a pressure-tight manner, as device for the dough preparation, wherein a relaxation nozzle is arranged in a discharge area, which is designated for the escape of the dough-based food product matrix, of the container, which can be closed in a pressure-tight manner, to attain a pressure relaxation and thus to form a foamed, dough-based food product matrix.

10. A foamed, dough-based and gluten-free food product, in particular gluten-free long-life baked goods, such as snack products or snack baked goods, respectively, or gluten-free fresh baked goods, produced from a dough prepared for the production of a dough-based food product matrix to be foamed and by supplying a gas into the dough-based food product matrix to be foamed, wherein the gas has been introduced into an aqueous portion of the food matrix to be foamed in a subcritical state below the critical point at a pressure of 10 bar≤p<critical pressure of the gas, wherein a dissolving of the introduced gas in a subcritical state below the critical point was adjusted at a pressure of 10 bar≤p<critical point of the gas for attaining the foamed, dough-based and gluten free food product; and wherein the food product comprises a proportion by weight of a starch-containing raw material, as well as a proportion by weight of water for the formation of the food product matrix to be foamed.

11. The food product according to claim 10, wherein the food product has been produced by the steps of a. providing the food product matrix to be foamed, comprising the proportion by weight of the starch-containing raw material and the proportion by weight of water, b. introducing the gas that is to be dissolved or has been dissolved into the food product matrix to be foamed, c. dissolving the gas or introducing the dissolved gas under pressure in the aqueous portion of the food product matrix to be foamed, d. forming gas bubbles by pressure relaxation and increasing the volume with a resulting reduction in density of the dough as a result of bubble growth for formation of the foamed food product matrix of the food product to be produced, and e. stabilizing the foam of the foamed food product matrix.

12. The food product according to claim 10, wherein the dough-based food product matrix to be foamed is yeast-free.

13. The food product according to claim 10, wherein the food product has a porosity with average densities ≤0.5 g/cm.sup.3 for long-life baked goods and ≤0.3 g/cm.sup.3 for fresh baked goods.

14. The food product according to claim 10, wherein the food product has a porosity with average bubble diameters for long-life baked goods of ×50.3≤0.5 mm and of ×50.3≤3 mm for fresh baked goods.

15. The food product according to claim 11, wherein the gas is introduced and dissolved in a subcritical state below the critical point at a pressure of 10 bar≤p<critical pressure of the gas in step b and/or step c.

16. The food product according to claim 11, wherein the foam stabilization of the foamed food matrix is attained by heat-induced solidification in step e.

17. The food product according to claim 11, wherein carbon dioxide (CO.sub.2) or noxious gas (N.sub.2O) is introduced as gas in each case in their subcritical state in step b and/or c.

18. The food product according to claim 17, wherein pressures of 25≤p≤65 bar and a temperature of <31 C are present in the case of carbon dioxide (CO.sub.2) as subcritical gas in step b and c.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0069] A preferred exemplary embodiment of the subject matter of the invention will be described below in connection with the enclosed drawings.

[0070] FIG. 1 shows a schematic illustration of the method steps for the production of the foamed, dough-based food product according to the invention;

[0071] FIG. 2 shows a schematic setup of a preferred embodiment of the apparatus according to the invention for the continuous production of the food product according to the invention by means of an extruder;

[0072] FIG. 3 shows a schematic view of preferred mixing elements of the worm configuration of the preferred embodiment shown in FIG. 2 for the production of foamed doughs;

[0073] FIGS. 4A, 4B, and 4C show comparative photographs of cross sections through a gluten-containing fresh baked good, which is produced conventionally, a gluten-free fresh baked good, which is produced conventionally, and a gluten-free fresh baked good according to the invention; and

[0074] FIG. 5 shows a μ-computer tomographic image of a pretzel stick as food product according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0075] FIG. 1 shows a schematic illustration of the method steps for the production of the foamed, dough-based food product according to the invention according to a particularly preferred method according to the invention. The compressed gas foaming according to the invention of gluten-free doughs substantially consists of the three steps of (i) gas dissolution, (ii) bubble nucleation/foam formation, and (iii) foam stabilization under moderate pressure and temperature conditions in the subcritical range.

[0076] In section 0, a provision of a dough-based food product matrix to be foamed, comprising a proportion by weight of starch-containing raw material as well as a proportion by weight of water, i.e. the actual dough preparation, takes place in a method step a).

[0077] In section 1, the introduction for example of carbon dioxide as gas in the subcritical state takes place in a method step b) and the dissolution of a gas under pressure in a dough matrix takes place in a subsequent method step c). The pressure, the type of gas, the temperature, the dough characteristic (viscosity) and the mixing are relevant for the kinetics of the dissolving process, as will be described below using the example of a fresh baked good as well as a long-life baked good. It is significant for the foam quality that the desired amount of gas does in fact dissolve. A pure dispersion or fine distribution, respectively, of the gas in the dough is not sufficient, because this would lead to an uneven gas bubble distribution in the dough foam. This is an essential difference as compared to applications, in which gas/air is mechanically folded and distributed into dough masses.

[0078] According to the invention, the dissolving process of the gas in method step c) takes place under pressure, but in the subcritical range (e.g. in the case of carbon dioxide: p<73.8 bar/T<+31° C.). The advantage in the case of subcritical conditions is that high pressures are not necessary with lower wear of the apparatus components and that less effort has to be expended for safety measures.

[0079] The dissolving of gases in static material systems is a diffusion-controlled process. On principle, the diffusion of a gas into a dough matrix can be approximated as follows as a function of temperature, pressure and gas concentration:

D=D.sub.0 exp(−ΔE.sub.D/R T)  (diffusion coefficient in solids)

wherein D is the diffusion coefficient, D.sub.0 is the diffusion constant, and ΔE.sub.D is the activation energy for the diffusion of a gas into a dough matrix.

[0080] Due to the fact that diffusion is a very slow process, the dissolving of gases would take a very long time in a static system. In contrast, a method is described in the present invention, in which gas is dissolved in a dough matrix within a short period of time, so that the application is relevant for industrial processes. This is why, in addition to the diffusion, an additional convective material transport takes place in method step c) by means of an additional intensive mixing of the gas with the dough material. The duration of the dissolving of the gas is reduced significantly through this.

[0081] Due to the fact that gluten-free doughs often have an increased water portion and a lower viscosity as compared to gluten-containing doughs, the dissolution rate of the gas is increased in the cases of gluten-free doughs in a particularly advantageous manner and the desired amount of gas can dissolve more quickly.

[0082] The amount of gas to be dissolved depends on the desired degree of loosening of the baked good and preferably lies between 0.05 and 1.5% by weight (percent by weight), particularly preferably is 0.5% by weight.

[0083] In section 2 for method step d), the nucleation of gas bubbles and the formation of a dough foam structure associated therewith occur by means of selective pressure drop. A special role is assigned to this section, because after the complete relaxation, the structure is mainly responsible for the textural and sensory properties of the final product. The key to a finely distributed foam structure lies in a high nucleation rate (#/s), i.e. in the formation of many gas bubbles/cells within a short period of time. To be able to control the nucleation in a selective manner, it is preferred to embody the apparatus according to the invention in such a way that the gas type, the amount of gas, the pressure difference, the pressure drop rate, the viscosity and the shear can be adjusted. A tailored pressure drop takes place in method step d) through a nozzle or a pressure-controlled valve. On principle, a sudden pressure drop effects an intensive gas bubble nucleation, but it must be ensured as a function of the amount of gas and the dough viscosity that the dough matrix does not tear.

[0084] According to method step e), section 3 provides for the foam stabilization or the solidification, respectively, of the foam structure by means of thermal coagulation or gelatinization, respectively, of the pore walls as a result of structural changes of the polymeric egg white and starch molecules, for example at a temperature in the range of 200°. In other words, the pre-foamed structure is solidified by means of a subsequent baking process by means of the input of thermal energy.

[0085] In section 3, a preferred embodiment of the invention provides for the filling of the attained dough foam into baking molds.

[0086] The solidification preferably takes place immediately after the foam production, because longer interims between foaming and solidification can lead to a breakdown of the structure or to a coarsening of the foam structure, because the dough foams are thermodynamically unstable material systems.

[0087] The temperature/time combinations can be chosen similarly as in the case of the traditional production. In the case of highly low-viscos and highly foamed doughs, higher temperatures are preferred. No further foam destabilization or change of the gas bubble structure, respectively, takes place after the solidification.

[0088] FIG. 2 shows a preferred embodiment of the apparatus according to the invention for carrying out the method according to the invention described in FIG. 1.

[0089] According to the preferred embodiment of the invention, the gas dissolution takes place in section 1, the relaxation at a nozzle 25 on the end side to an extruder 3 takes place in section 2, and the foam stabilization in a baking oven takes place in section 3 (not shown in FIG. 2).

[0090] According to the invention, overcritical conditions can be avoided in an advantageous manner as a result of an intensive mixing, combined with a sufficiently long dwell time in the apparatus according to the invention and as a result of a selective relaxation through a nozzle or a valve.

[0091] As limitation to the method according to the invention and the apparatus according to the invention, the U.S. patents (Rizvi) only consider overcritical gases, namely overcritical CO2. It is not disclosed, however, to what extent the gas is dissolved in the dough matrix. The bubble formation is also not discussed in more detail. Here, the dissolving of gas occurs exclusively via the use of high pressure. The dwell time of the gas and the conditions of the mixing and of the relaxation are not considered. Only conveying elements are used.

[0092] Convection plus diffusion can be implemented effectively in an advantageous manner in an extruder, which is why an enrichment of the doughs with gas preferably takes place in an extruder 3 as shown in FIG. 2.

[0093] The extruder 3 shown in FIG. 2 is divided into individual segments (S) or treatment zones, respectively. In section 0, a supply device 5 for supplying starch-containing raw material R, is arranged at the beginning of the process line P. A supply device 10 for supplying water W is furthermore arranged downstream in the direction of the process line P.

[0094] One temperature control device 6 is in each case operatively connected per segment in the segments S downstream from the supply device 10, wherein the temperature control devices 6 can be controlled via a control unit 3. In the method according to the invention, temperature control devices are preferably adjusted to a temperature in the range of between 20° C. and 30° C.

[0095] In section 1 of the process line, FIG. 2 shows a supply device 15 for supplying the gas to be dissolved. The mass flow of the gas significantly influences the dough density and thus also the pastry volume. The dough density can be adjusted selectively by means of the regulation with a suitable flow valve 16 for gases.

[0096] Only as much gas as can in fact be dissolved in the dough, should ideally be metered out. An excess of gas would lead to the intensification of blow-by effects and to the formation of unwanted large cavities in the dough foam matrix. This would result in a coarse and uneven porosity in the finished product. To prevent such blow-by effects, the metered-out amounts of gas or the mass flow, respectively, of the gas for carbon (CO.sub.2) particularly preferably lie for example between 0.1 and 0.4 g/h.

[0097] In contrast to the known methods and apparatuses, a combination of mixing intensity, dwell time, as well as temperature and pressure is considered in the present invention. The dissolving of the gas preferably takes place via kneading and mixing elements (see FIG. 3), which input little energy into the product, with a simultaneously high distributive and dispersive mixing effect, which is why the apparatus according to the invention preferably comprises at least one screw element with suitable kneading and mixing elements.

[0098] Due to the high back-mixing attained by means of a screw element configuration with suitable kneading and mixing elements, a dwell time of between 30 s and 300 s is already sufficient in an advantageous manner to dissolve a specified amount of gas at a pressure/temperature combination of between 25 and 65 bar and between 20 and 30° C. Compared to the extrusion under overcritical conditions, this approach is advantageous from a safety perspective. The gentle temperatures in the case of such subcritical conditions are furthermore advantageous with regard to potential temperature-sensitive dough components, for example as compared to the known method from the U.S. patents (Rizvi), which equals a cooking extrusion.

[0099] In contrast to foaming methods, as they are used notoriously in low-viscous dough masses, the present invention differs significantly in that the gas is dissolved and is not only dispersed or finely distributed. Only with the gas dissolution can it be ensured that the desired bubble distribution is created in response to a selective relaxation.

[0100] In the case of approaches, in which a dough is mixed with gas without gas dissolution, the bubble size depends on the ratio of destabilizing inertia forces to stabilizing surface forces and can be described by the Weber number. If, in contrast, the gas is present in the dissolved form in the aqueous portion of the dough matrix, the bubble size is substantially by the pressure difference and relaxation rate in consideration of the fluidic conditions. The nucleation or, in other words, the gas bubble formation, respectively, is highly relevant, i.e. the step in which microscopically small gas bubbles form. The goal is a uniform formation of the bubbles in large numbers.

[0101] In the present invention, the relaxation preferably takes place through a nozzle 25, which is arranged on the end side of the extruder 3, according to FIG. 2. Such a cylindrical nozzle 25 is preferably chosen with an L/D ratio of between 0.2 and 200. Small L/D ratios of between 2 and 30 are chosen even more preferably to attain pressure drop rates of >60 bar/min.

[0102] FIG. 3 shows a schematic view of preferred mixing elements 20; 21; 22 of the screw element configuration of the first preferred embodiment shown in FIG. 2 for the production of the dough-based, foamed food product according to the invention, wherein the dissolving rate is increased by means of the mixing elements 20; 21; 22 shown in FIG. 3, which are to be attached to an eccentric screw (not shown in FIG. 3). The mixing elements 20; 21; 22 shown in FIG. 3 are preferably attached in section 1 of the apparatus according to the invention shown in FIG. 2, in which method step c) takes place. Mixing element 20 is a so-called “Igel” screw (for example from Extricom) comprising such a structure that the dough-based food product matrix is at least partially cut, whereby a distributing (distributive) mixing effect is attained.

[0103] Mixing element 21 is a so-called barrier screw (for example from Extricom) comprising such a structure that a distributive mixing is attained. Mixing elements thereby has a barrier section, which provides for an extensional flow of the dough-based food product matrix.

[0104] Mixing element 22 is a so-called T-element (for example from Extricom) comprising such a structure that a distributive mixing effect as well as a shifting of the dough-based food product matrix is attained.

[0105] It has been discovered in an advantageous manner that less pressure is necessary and that overcritical conditions can be avoided by means of the improved mixing by means of the mixing elements 20; 21; 22.

[0106] The resulting mixing increases the diffusion of gas into the dough matrix, so that a single-phase system forms. As a result of the worm element configuration according to FIG. 3, a treatment zone-specific, mechanical treatment of the mass is attained in an advantageous manner in sections 0 to 3. It has been discovered in an advantageous manner that as a result of such a screw element configuration, the specific mechanical energy input into the dough-based food product matrix to be foamed is comparatively low and gentle with values of around 100 kJ/kg.

[0107] As can be seen in FIGS. 4A, 4B, and 4C, dough-based food products, which are traditionally produced in a gluten-free manner, have a comparatively coarsened bubble structure or porosity, respectively, which was created by means of coalescence, as summarized in Table 1, wherein A shows a traditionally produced, gluten-containing fresh baked good, B shows a traditionally produced, gluten-free fresh baked good, and C shows a gluten-free fresh baked good produced according to the invention.

[0108] The present invention relates to the selective structuring of foamed dough-based food products and baked goods resulting therefrom. To be able to assess the quality as well as the characteristic, structural properties of the food product according to the invention as compared to conventionally produced baked goods in a relevant manner, the pastry volume, the pore image and the crumb texture, for example, need to be analyzed.

[0109] The dough-based food products according to the invention are preferably divided into fresh baked goods and long-life baked goods.

[0110] To analyze the pore morphology, the cross section of slices of fresh baked goods are scanned with a resolution of 4800 dpi and are statistically analyzed by means of image processing software (see FIGS. 4A, 4B, and 4C).

[0111] In the case of long-life baked goods, the density and the pore morphology are determined by means of microcomputer tomography with a resolution of 7 μm. In addition to porosity, pore size and number are measured as well (see FIG. 5).

[0112] The baking volume and the pastry density are determined by means of a volume scanner. The measuring principle of a volume scanner is based on a contact-free distance measurement by means of a laser sensor. The circumference of the pastry is measured along the axis at defined distances. The volume and the density are calculated by means of the measured data (see Tables 1 and 2 below).

[0113] The crumb texture of fresh baked goods is determined for example by means of a texture analyzer. Analogous to the defined standard according to AACC 74-09, the firmness (in g or N) of the crumb is analyzed by means of a compression punch (see Table 1 below).

[0114] In the case of long-life baked goods (e.g. snacks), the breaking strength is analyzed instead of the crumb firmness as texture parameter by means of a texture analyzer. The breakage behavior of snacks is measured in a compression test by means of 3-point bending apparatus.

[0115] The test provides statements with regard to hardness and flexibility of the sample (see Table 2 below).

[0116] Table 1 shows a comparison of a traditionally produced fresh baked good as compared to the gluten-free food product according to the invention, attained by means of the method shown in FIG. 1 and the apparatus according to the invention shown in FIG. 2, using a fresh baked good (bread).

[0117] The production of the food product according to the invention shown in Table 1 using the example of bread as fresh baked good by means of an apparatus shown in FIG. 2 in the pilot scale is described in an exemplary manner below: [0118] a) a food product matrix to be foamed is provided in section 0 of the apparatus shown in FIG. 2 at the beginning of the process line P by adjusting the supply device 5 to a mass flow of 4.2 kg/h for the flour and by adjusting the supply device 10 to a mass flow of 4.08 kg/h for the water; [0119] b) in section 1 of the apparatus shown in FIG. 2, the carbon dioxide (CO.sub.2) is furthermore introduced into the food product matrix to be foamed as gas G to be dissolved via a gas inlet nozzle 18 comprising a length/diameter ratio L/D of 32, wherein a mass flow of the gas G in the range of 0.1 kh/g is adjusted by means of the flow valve 16, which corresponds to an advantageous adjustment to attain a desired dough density. The measurable pressure of the gas to be dissolved thereby lies in the range of between 30 and 35 bar at the gas inlet nozzle 18; [0120] c) the introduced gas then dissolves in the aqueous portion of the food product matrix to be foamed during a dwell time in the range of 120 s at a temperature of 30° C., which is adjusted by means of the temperature control devices 6, and at a pressure of between 30 and 35 bar; [0121] d) gas bubble formation by means of pressure relaxation at the nozzle 25; [0122] e) in an immediately following method step, a foam stabilization takes place by means of baking the attained, foamed, dough-based food product at 200° C. for 30 minutes.

TABLE-US-00001 TABLE 1 structure parameters of foamed fresh baked goods in comparison Gluten-free Traditional Traditional according to wheat gluten-free the invention Structure parameters Unit (A) (B) (C) Volume Volume V mm.sup.3 Density ρ g/ml 312 ± 15 365 ± 4 310 ± 3 Overrun OR % 203 135 177 Texture Breaking g 900 950 300 Force F Pore mean x μm 1116 1685 996 structure x.sub.10, 3 μm 330 545 330 x.sub.50, 3 μm 870 1340 750 x.sub.90, 3 μm 2220 3330 2060 span Sp — 2.17 2.08 2.3 density#/mm.sup.3 mm.sup.−3 porosity — 0.67 0.57 0.64

[0123] The production of the food product according to the invention shown in Table 2 using the example of pretzel sticks (snack product) as long-life baked good in the pilot scale will be described below in an exemplary manner: [0124] a) a food product matrix to be foamed is provided in section 0 of the apparatus shown in FIG. 2 at the beginning of the process line P by adjusting the supply device 5 to a mass flow of 4.75 kg/h for the flour and by adjusting the supply device 10 to a mass flow of 3.25 kg/h for the water; [0125] b) in section 1 of the apparatus shown in FIG. 2, the carbon dioxide (CO.sub.2) is furthermore introduced into the food product matrix to be foamed as gas G to be dissolved via a gas inlet nozzle 18 comprising a length/diameter ratio L/D of 32, wherein a mass flow of the gas G in the range of 0.1 kh/g is adjusted by means of the flow valve 16, which corresponds to an advantageous adjustment to attain a desired dough density. The measurable pressure of the gas to be dissolved thereby lies in the range of between 27 and 32 bar at the gas inlet nozzle 18; [0126] c) the introduced gas then dissolves in the aqueous portion of the food product matrix to be foamed during a dwell time in the range of 120 s at a temperature of 20° C., which is adjusted by means of the temperature control devices 6, and at a pressure of between 27 and 32 bar; [0127] d) gas bubble formation by means of pressure relaxation at the nozzle 25 with an L/D ratio of 22; [0128] e) in an immediately following method step, a foam stabilization takes place by means of baking the attained, foamed, dough-based food product at 200° C. for 7 minutes.

TABLE-US-00002 TABLE 2 structure parameters of foamed long-life baked goods in comparison No foaming Foaming Structure parameters Unit (C) (D) Volume Volume V mm.sup.3 Density ρ g/ml 825 ± 10 717 ± 3 Overrun OR % 15 Texture Breaking N  36 ± 15  17 ± 5 Force F Pore mean x μm 205 189 structure x.sub.10, 3 μm 30 52 x.sub.50, 3 μm 211 182 x.sub.90, 3 μm 344 318 span Sp — 1.49 1.46 cell density #/mm.sup.3 mm.sup.−3 411 592 porosity — 0.34 0.53

[0129] FIG. 5 shows a μ-computer tomographic image of a long-life baked good of the dough-based food product according to the invention.

[0130] A possible production method will be described hereinafter in an exemplary manner by means of the method steps a) to e) shown in FIG. 1 using a pressure container, which can be closed in a pressure-tight manner, in particular a cream maker:

[0131] A dough-based food product matrix to be foamed comprising a proportion by weight of a starch-containing raw material, in particular a gluten-free cereal flour, as well as between 1 and 1.8 proportions by weight of water is provided in method step a) and is added into the pressure container, which can be closed in a pressure-tight manner.

[0132] In particular carbon dioxide (CO.sub.2) and/or noxious gas (N.sub.2O) is introduced into the food product matrix to be foamed in a subsequent method step b) by means of a gas cartridge in terms of a supply device for supplying a gas in the subcritical state.

[0133] The introduced gas is dissolved under pressure in the aqueous portion of the dough-based food product matrix in the subsequent method step c), wherein a mixing of the raw material containing water and starch and simultaneously a dissolving of the gas in the aqueous portion of the dough-based food product matrix is attained by shaking the pressure container. The shaking of the pressure container can take place by hand or for example by means of a vortex mixer or the like.

[0134] By actuating a relaxation nozzle, which is arranged in a discharge area of the container, which can be closed in a pressure-tight manner, for the discharge of the dough-based food product matrix, an escape of the dough-based food product matrix is attained in method step d), wherein a gas bubble formation is induced and a foamed food product matrix is created by means of the pressure relaxation, which occurs thereby. The created, foamed food product matrix can for example be poured into a suitable baking mold in method step d).

[0135] A foam stabilization is attained, and the dough-based, foamed food product is thus attained by means of a baking process in a further method step e).

[0136] The attained, foamed and gluten-free food product displays average pore diameters of 500 μm with an even pore image. A bread density of 360 g/l was furthermore attained, which surprisingly lies close to a conventional, yeast-loosened, gluten-containing wheat bread (200-350 g/l). In other words, a foamed, dough-based food product or baked good, respectively, which satisfies the high demands on the structure and pore characteristic, is attained by means of this method according to the invention, independent from the gas retention capacity.

LIST OF REFERENCE NUMERALS

[0137] 1 control unit [0138] 2 drive unit (extruder) [0139] 3 extruder [0140] 5 supply device for supplying a starch-containing raw material [0141] 6 temperature control device [0142] 10 supply device for supplying liquid (water) [0143] 11 eccentric screw pump [0144] 15 supply device (gas) [0145] 16 flow valve [0146] 17 gas pressure container [0147] 18 gas inlet nozzle [0148] 20 mixing element [0149] 21 mixing element [0150] 22 mixing element [0151] 25 nozzle (end side to the extruder) [0152] G gas [0153] P process direction (extruder) [0154] R raw material (containing starch) [0155] S segments [0156] W water