OVEN AND METHOD FOR BAKING CHEESE-BASED FOOD PRODUCTS

Abstract

A method and baking oven (1) for baking food products comprising cheese or constituted by cheese are described. The baking oven comprising a baking chamber (2), a conveyor belt (3) movable in a continuous way in the baking chamber for supplying the ingredients and for unloading the food products, heating means (4) to heat the ingredients in the baking chamber and extracting means (9) to extract air and vapor from the baking chamber, which are configured to obtain a food product having residual humidity of less than 5% by weight and a consequent shelf-life longer than 4 months.

Claims

1. A baking oven (1) for baking food products comprising cheese or constituted by cheese, the oven comprising: a baking chamber (2), a conveyor belt (3) movable in the baking chamber (2) for supplying and unloading food products, heating means (4) to heat the food products in the baking chamber, said heating means being selected selected from the group consisting of: microwave heating, infrared heating, electric resistance heating, and combinations thereof, extracting means (9) to extract air and vapor from the baking chamber, wherein the baking chamber is insulated from the outside, except for an inlet (5) and an outlet (6) of the conveyor belt (3), and a control unit (17) comprising program means programmed to adjust the flow rate of said extracting means (9) so that said extracting means (9) extract, from the baking chamber, a flow rate Q of air and vapor equal to or higher than: $Q=\frac{V}{{\left(U_{\mathrm{OUT}}-U_{\mathrm{IN}}\right)}^{*}.Math.d_A}$ where: Q is the volumetric flow rate of air and vapor to be withdrawn from the baking chamber (2) per each kilogram of food products passing through the baking chamber (2) itself, V is the amount of vapor to be removed per each kilogram of food product passing through the baking chamber (2), U.sub.IN is the specific humidity of the air entering the baking chamber (2), U.sub.OUT is the specific humidity of the air withdrawn from the baking chamber (2), d.sub.A is the air density, wherein the vapor amount V is the difference between the water content X.sub.IN in each kilogram of food product to be baked, inserted in the baking chamber (2), and the water content X.sub.OUT being in each kilogram of baked food product extracted from the baking chamber (2), where V=X.sub.INX.sub.OUT, with X.sub.OUT<50 grams, to obtain a baked food product having residual moisture lower than 5% by weight and shelf-life longer than four months at room temperature.

2. The baking oven (1) according to claim 1, wherein the extracting means (9) extract a minimum of 20 m.sup.3 of air and vapor per each kilogram of food product passing through the baking chamber (2).

3. The baking oven (1) according to claim 1, wherein d.sub.A is equal to 1.225 kg/m.sup.3.

4. The baking oven (1) according to claim 1, further comprising air inflow means (12) for the air inflow into the baking chamber (2), which are preferably arranged next to at least one inlet (5) of the baking chamber (2).

5. The baking oven (1) according to claim 4, wherein the air inflow means direct, onto the surface of the conveyor belt (3), an inlet air flow intercepting the whole width of the conveyor belt (3), and the extracting means (9) are configured to extract an air and vapor flow by intercepting the whole width of the conveyor belt (3).

6. The baking oven according to claim 4, wherein the air inflow means (12) comprise at least one inflow port (13) fluidically connected with a fan (14) and the extracting means (9) comprise at least one outflow port (10) fluidically connected with at least one suctioning device (11), said inflow and outflow ports intercepting the whole width of the conveyor belt (3) and being spaced from one another so that the air and vapor flow extends onto the surface of the conveyor belt (3) at the whole width thereof and at least for half the length of the baking chamber (3).

7. The baking oven (1) according to claim 6, wherein said inlet air flow and said outlet air and vapor flow are laminar.

8. The baking oven (1) according to claim 4, wherein adjusting means to adjust the flow rate of the air entered by the inflow means and the flow rate of the air and vapor extracted by the extracting means, are provided, and wherein air filtering means (15) are combinable with the inflow means, the extracting means, or both the inflow means and the extracting means.

9. The baking oven (1) according to claim 4, wherein the air entered in the baking chamber (2) by the airflow means is ambient air and the inflow means are provided with means for measuring the specific humidity of the incoming air U.sub.IN or, alternatively, treating means to treat the air are combined with the inflow means, for the inflow of air having a given specific humidity U.sub.IN in the baking chamber (2).

10. The baking oven (1) according to claim 4, wherein the inlet air flow rate is lower than the outlet air and vapor flow rate, and the baking chamber (2) is maintained slightly depressurized to aid the vapor extraction and the expansion of the food products.

11. The baking oven (1) according to claim 1, wherein the extracting means comprise a plurality of outflow ports (10) fluidically connected with one or more suctioning devices (11), wherein each outflow port (10) withdraws a corresponding part of the air and vapor flow rate extracted from the baking chamber (2).

12. The baking oven (1) according to claim 1, wherein the air inflow means are combined with heating means to heat the inlet of air for the air inflow into the baking chamber (2), said heating devices being adjustable.

13. The baking oven (1) according to claim 1, wherein the conveyor belt (3) is of closed loop type and is combined with a first and a second movement roller (7, 8), the rollers being provided with actuators (16) to change their distance so that, during the baking, the conveyor belt (3) is always tensioned, thereby balancing possible expansions of the conveyor belt (3), and that the rollers are moved closer, thereby reducing the tension of the conveyor belt (3) when necessary.

14. The baking oven (1) according to claim 13, wherein one or more position sensors (18) are provided to detect the position of the conveyor belt (3), and wherein the actuators (16) of the rollers can be driven for feedback keeping the conveyor belt (3) centered, on the basis of the position signals the position sensors detected.

15. The baking oven (1) according to claim 1, wherein at the bottom part of the oven, at the return path of the conveyor belt (3), cleaning means (21), washing means (22) and drying means (23) of the conveyor belt (3) are combined.

16. A method of cooking food products comprising cheese or constituted by cheese, by a baking oven (1) comprising a baking chamber (2) closed except for an inlet (5) and an outlet (6), a conveyor belt (3) movable in the baking chamber for supplying food products to be baked and unloading baked food products, heating means (4) to heat the food products in the baking chamber (2), said heating means (4) being selected from the group consisting of: microwave heating, infrared heating, electric resistance heating means, and combinations thereof, extracting means (9) to extract air and vapor from the baking chamber (2) and a control unit (17) provided with program means programmed to adjust the flow rate of said extracting means (9), the method comprising the steps of: a) baking the food products in the baking chamber (2) by the heating means, by extracting moisture in the vapor form from them; b) programming, by the program means, the extracting means to extract an air and vapor flow rate Q from the baking chamber (2); wherein the air and vapor flow rate Q extracted during step b) is equal to or higher than: $Q=\frac{V}{{\left(U_{\mathrm{OUT}}-U_{\mathrm{IN}}\right)}^{*}.Math.d_A}$ where: Q is the volumetric flow rate of air and vapor to be withdrawn from the baking chamber (2) per each kilogram of food products passing through the baking chamber (2) itself, V is the amount of vapor to be removed per each kilogram of food product passing through the baking chamber (2), U.sub.IN is the specific humidity of the air entering the baking chamber (2), U.sub.OUT is the specific humidity of the air withdrawn from the baking chamber (2), d.sub.A is the air density, wherein the vapor amount V is the difference between the water content X.sub.IN in each kilogram of food product to be baked, inserted in the baking chamber (2), and the water content X.sub.OUT being in each kilogram of baked food product extracted from the baking chamber (2), where V=X.sub.INX.sub.OUT, with X.sub.OUT<50 grams, to obtain a baked food product having residual moisture lower than 5% by weight and shelf-life longer than four months at room temperature.

17. The baking method according to claim 16, wherein the flow rate Q is equal to at least 20 m.sup.3 per each kilogram of food product passing through the baking chamber (2).

18. The baking method according to claim 16, wherein the baking oven (1) comprises air inflow means (12) for the inflow of air into the baking chamber (2), and wherein the method further comprises: programming, by the program means, the inflow means for the inflow of air into the baking chamber, the air flow rate of the inlet of the inflow means being adjusted on the basis of the volumetric air and vapor flow rate withdrawn from the baking chamber (2) by the extracting means.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0067] Further characteristics and advantages of the invention will be better highlighted by the review of the following specification of a preferred, but not exclusive, embodiment illustrated for illustration purposes only, and without limitations, with the aid of the accompanying drawings, wherein:

[0068] FIG. 1 is a schematic view of a baking oven according to the present invention;

[0069] FIG. 2 shows a perspective view of part of the oven in FIG. 1;

[0070] FIG. 3 is a front view of a component of the oven shown in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0071] FIG. 1 is a schematic view of a baking oven 1 according to the present invention for baking food products containing cheese or entirely constituted by cheese.

[0072] FIG. 2 is a schematic, perspective and partially transparent view of a baking oven 1 according to the present invention.

[0073] Specifically, the baking oven 1 is configured to bake and dehydrate food products having a high initial moisture content and, in particular, cheese; the baked food product produced by the oven 1 is entirely constituted by, or comprises a high percentage ofat least 40% of the weightbaked or dehydrated cheese.

[0074] The oven 1 comprises a baking chamber 2, a conveyor belt 3 movable in a continuous way in the baking chamber 2 for supplying the food product and for unloading the baked food product, and heating means 4 for baking the food products passing through the baking chamber 2 on the conveyor belt 3.

[0075] The baking chamber 2 has an inlet 5 and an outlet 6 to allow the passage of the conveyor belt 3; for the rest, it is completely closed, i.e. insulated from the outside environment. In order to facilitate the inspection and cleaning, the baking chamber 2 can have one or more openable portions, not shown. In addition, the baking chamber 2 can be a single block or subdivided in sub-chambers.

[0076] The conveyor belt 3 can be constituted of trays movable in the baking chamber 2 by movement means, for example chains or belts, oras shown in the figuresclosed-loop shaped and provided with molds, combined with a first movement roller 7 and with a second movement roller 8, at least one of which is motorized. The first roller 7 and the second roller 8 are respectively arranged upstream and downstream of the baking chamber 2. The conveyor belt 3 is movable in a continuous way or intermittently in the baking chamber, and its speed can be adjusted as needed.

[0077] The heating means 4 are suitable for the baking and dehydration of the food products, thus causing the outflow of moisture, in the vapor form, from the cheese. Preferably, the heating means 4 are of the microwave type and/or can comprise electric resistances and/or infrared heating means.

[0078] According to the invention, the oven 1 is provided with extracting means 9 to withdraw air and vapor from the baking chamber 2 during the operations of the oven 1. The extracting means comprise at least one outflow port 10 connected to at least one suctioning device 11, two outflow ports 10 are visible in FIG. 1. The outflow ports 10 withdraw the air mixed to the vapor in several points of the baking chamber 2, by removing the vapor as it gradually forms. Preferably, an outflow port 10 is provided at the outlet of the baking chamber 2 and at least one outflow port 10 is provided in an intermediate position; in case of more outflow ports 10, a suctioning device 11 can be provided connected to several outflow ports 10, as shown in FIGS. 1 and 2, or a suctioning device 11 can be provided for each outflow port 10.

[0079] The extracting means 9 are configured so that to withdraw the flow rate of air and vapor from the baking chamber 2 that is suitable for preventing the vapor extracted from the cheese being baked from saturating the baking chamber 2.

[0080] Specifically, the extracting means are sized so that to extract at least of 20 m.sup.3 of air and vapor per each kilogram of cheese passing through the baking chamber. In fact, the sizing of the suctioning means depend on the amount and zo initial moisture of the cheese, or anyhow of the ingredients of the food product passing through the baking chamber 2, on the amount of residual moisture in the food product after baking 2 and on the amount of humidity that can be contained in each m.sup.3 of air extracted from the baking chamber 2, amount that can be determined by using a psychrometric diagram and from the amount of cheese that can pass in the baking chamber 2. In order to obtain a food product with stable characteristics over time, it was detected that the optimal residual moisture must be equal to or lower than 5% of its weight.

[0081] More in detail, the flow rate Q of air and vapor to be extracted from the baking chamber per each kilogram of food product passing through the baking chamber 2 can be determined according to the following values: [0082] amount of vapor V to be removed from each kilogram of food product passing through the baking chamber 2; this amount is obtained as the difference between the moisture of the cheese X.sub.IN and the moisture of the food product X.sub.OUT, which, as described above, must be 5% maximum. For example, for a cheese-only food product with moisture of 35%, i.e. a water content of 350 grams per each kilogram, at least 300 grams of water must be evaporated to obtain a food product with a water content of 50 grams maximum. [0083] difference between the specific humidity of the outflow air U.sub.OUT from the baking chamber 2 and the specific humidity of the incoming air U.sub.IN in the baking chamber 2; in other words, in order to know how many grams of vapor V emitted from the food product being baked can be contained in each kilogram of air extracted from the baking chamber, the amount of vapor already present in the inlet air flow of the air inflow in the baking chamber 2 and the maximum vapor amount that can be contained in the air extracted by the baking chamber 2 must be considered in order to avoid reaching the saturation point at which the vapor would condense. In turn, the values of U.sub.OUT and U.sub.IN depend on the temperature and humidity of the outlet and inlet air flow. [0084] density of air d.sub.A corresponding to the ratio between the air mass and volume it occupies; it is expressed in kilograms per cubic meter and assumed to be equal to 1.225 kg/m.sup.3 in standard conditions, i.e. at the pressure of 1 atm, 0% of humidity and temperature of 15 C.

[0085] The flow rate Q of air and vapor extracted from the baking chamber 2 per each kilogram of food product can be calculated with the formula described in the summary of the invention:

[00003]$Q=\frac{V}{{\left(U_{\mathrm{OUT}}-U_{\mathrm{IN}}\right)}^{*}.Math.d_A}$

to obtain a food product with a moisture of 5% maximum by weight. This way, once packaged, the food product can be preserved for at least four months outside of the refrigerator, maintaining high organoleptic properties over time.

[0086] The inflow of air in the baking chamber can be caused by the same extracting means 9 and can occur through the inlet 5 and outlet 6 of the baking chamber. Preferably, however, the oven 1 also comprises air inflow means 12 that introduce an air flow into the baking chamber 2, represented by the arrows in FIG. 2. The air inflow means comprise at least one air inflow port 13 connected to at least one fan 14 in order to push the air into the baking chamber 2 through the inflow port 13 arranged in proximity of the inlet 5 of the baking chamber.

[0087] The inflow 13 and outflow 10 ports are configured to generate a flow of air covering the whole width of the conveyor belt 3 so that to mix with the moisture leaving the food product being baked at the level of the whole width Y of the belt. In addition, the ports 10 and 13 are arranged so that the flow of air extends along at least one half, preferably along the whole length X of the conveyor belt 3 in the baking chamber 2. Preferably, laminar air flows are established to remove moisture more effectively from the whole surface of the food product being baked, with respect to the so-called turbulent flows, in which vortex structures, which could put the vapor extracted back in contact with the food product on the conveyor belt 3, are formed.

[0088] Respective filtering means 15 can be combined with each inflow and outflow port for the inflow of air in the baking chamber 2 that is suitable for coming into contact with the food product and to withhold the fat particles and/or cheese particles from the air extracted from the baking chamber 2.

[0089] The extracting means 9 and possibly the inflow means 12 are provided with means for adjusting the flow rate of the air extracted and introduced according to need, depending on the recipe being baked or on the baking conditions. This way, it is also possible to adjust the inlet and outlet air flow so that to slightly depressurize the baking chamber 2; in fact, this condition favors the expansion of the food product and the formation of little air cavities that make it particularly crunchy.

[0090] The heating means 4 can be of the microwave type to quickly obtain the removal of high amounts of humidity from the food product, typically between 4 and 10 minutes. This allows to suitably dehydrate the food product while preventing the cheese from curing/burning. Alternatively or in addition, the heating means can comprise electric resistances and/or be of the infrared type.

[0091] In addition, air heating devicesnot showncan be combined with the inflow means so that to obtain the inflow of hot air in the chamber in order to assist the baking and removal of the vapor, and to carry out a combined hot air and microwave baking. The air heating devices can comprise electric resistances. Alternatively or in addition, an air treatment unit, suitable for an inflow of air of the desired temperature and humidity in the baking chamber, can be combined to the inflow means.

[0092] Respective actuators 16 can be combined with the first and/or second roller 7, 8, preferably of the pneumatic type and which operate to maintain the conveyor belt 3 tensioned while baking in order to avoid the rollers from slipping. In fact, while baking, due to the heat, the conveyor belt can suffer expansions, which are compensated by a displacement of the rollers caused by the actuators 16. Moreover, the actuators 16 can be driven to bring the rollers 7, 8 closer to one another, once the baking has been completed, to bring the conveyor belt 3 in a resting condition, in which it is not tensioned in order to prevent it from wearing.

[0093] The baking oven 1 further comprises a control unit 17 provided with program means to adjust the flow rate of the air inflow means and air extraction means, the temperature of the air to be introduced into the baking chamber 2, the power of the heating means, the movement speed of the conveyor belt 3 and the actuators 16.

[0094] In addition, position sensors 18 can be provided at the conveyor belt 3 to detect its position and to send the values detected to the control unit 17, which reprocesses them through the program means to check for any possible side displacements of the belt 3 with respect to its centered position. This way, if the belt 3 is not correctly centered, the control unit 17 can act on the actuators 16, by driving them so that to maintain the belt in the correct position.

[0095] The conveyor belt 3 can comprise a plurality of molds 19 for containing the initial ingredients and arranged so that to form a plurality of longitudinal lines L.sub.1, L.sub.2 . . . L.sub.n extending along the whole length of the belt and side by side to one another in the direction of the width of the belt. The molds 19 are practically useful whenever the initial ingredient is grated cheese, mixed or not with other ingredients, but also in case of cheese pieces in order to confer a regular shape to the food product.

[0096] With reference to FIG. 3, correspondingly at the level of the outer surface of the first and second rollers 7, 8, a plurality of grooves S.sub.1, S.sub.2 . . . S.sub.n are obtained, each shaped and sized to receive a respective line of molds.

[0097] The grooves of the second roller 8 can also have a raised portion 20 in one of their intermediate positions and which deforms the lower surface of the molds in order to facilitate the unloading of the product from the mold by overturning it on the roller itself.

[0098] Returning to FIGS. 1 and 2, the oven can comprise cleaning means 21, washing means 22 and drying means 23 arranged on its lower part, at the return path of the belt 3 between the second and first roller. The cleaning means 21 can comprise at least one scraper, the washing means 22 can be constituted by a series of nozzles for the outflow of vapor and the drying means 23 can be constituted by a series of hot air outflow channels.

[0099] The baking oven 1 described above can be used for baking the food products according to the following steps: [0100] baking the cheese and possible other ingredients in the baking chamber 2 through the heating means 4; [0101] extracting a flow rate Q of air and vapor by the extracting means 9 from the baking chamber 2 in an amount equal to or higher than:

[00004]$Q=\frac{V}{{\left(U_{\mathrm{OUT}}-U_{\mathrm{IN}}\right)}^{*}.Math.d_A}$

[0102] wherein the flow rate Q is preferably equal to at least of 20 m.sup.3 of air and vapor per each kilogram of food product in the baking chamber 2; [0103] repeating the preceding steps until obtaining a food product with a maximum residual moisture equal to 5% of its weight, in order to obtain a food product that can be preserved for at least 4 months outside of the refrigerator.

[0104] The parameters V, U.sub.OUT, U.sub.IN and d.sub.A correspond to the above description with reference to the baking oven.

[0105] Whenever the oven is provided with air inflow means for the air inflow into the baking chamber, the method can provide a further step of adjusting the flow rate of air inflowing in the baking chamber as the flow rate of air extracted varies. In fact, on the basis of an increase/decrease of the value of the flow rate of air extracted, it is possible to vary, in the sense of increasing/decreasing, also the flow rate of the air introduced, preferably so that the flow rate of the air introduced is lower than the flow rate of the air extracted, in order to maintain the baking chamber slightly depressurized.