Pasteurizing machine and method for treating liquid or semi-liquid food products

Abstract

To provide a pasteurizing machine for producing liquid or semi-liquid products and a pasteurizing method for reducing lumps of powder or solid material in the liquid mixture, thus obtaining a high-quality mixture.SOLUTION: A pasteurizing machine 1 includes: a container 2a adapted to allow liquid or semi-liquid base products to processed and treated by pasteurization; a stirring device 3a mounted inside the container and driven by drive means 4 to stir the mixture; drive means 4 configured to drive the stirring device; a thermal treatment system 5 provided with at least one exchanger 6 for heating the mixture inside the container 2a; and at least one control unit 10a adapted to control operation of the drive means 4. The drive means 4 is provided with a brushless electric motor 9 equipped with a rotor provided with permanent magnets for producing a magnetic field needed to generate movement.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a machine and method for processing liquid or semi-liquid food products, such as, without loss of generality, ice cream, sorbet, base mixes for frozen desserts, etc.

[0002] In particular, the present invention relates to the provision of a machine for mixing, pasteurizing and maturing food products.

[0003] For the sake of brevity, in the following reference will be made more frequently to pasteurization machines which are used to process a base product for the production of ice cream or the like and which are sometimes, but not necessarily, also equipped with means for subsequently dispensing the final product, without thereby limiting the scope of the invention to this particular example. [Background technology]

[0004] As is known, a pasteurization machine is a device configured to mix the ingredients of a food product during processing for its production, in order to reduce the bacterial load contained in the food product.

[0005] Pasteurization machines involve heating the product to a temperature preferably between 65°C and 85°C for a predetermined time to determine thermal restructuring and minimize health risks from heat-sensitive pathogenic microorganisms, such as vegetative bacteria, fungi and / or yeasts, while causing only minimal changes in the chemical, physical and organic properties of the treated product.

[0006] The mixture that constitutes the product being treated is heated and stirred inside the vessel in which the treatment takes place.

[0007] A pasteurization machine generally comprises a vessel configured to allow a liquid or semi-liquid base product to be processed or treated, and an agitator mounted therein and driven in rotation to mix the product at various stages of the treatment process.

[0008] The vessel is heated by a suitable heating system, which comprises a heat exchanger associated with said vessel, which is realized by a pipe wound in a spiral around the outer wall of the vessel in order to heat the product inside the vessel without interfering with the rotation of the agitator.

[0009] The agitator is driven in rotation by an electric motor connected to the agitator shaft by a transmission means, such as a reduction gear unit, belt, chain, gears or the like, which makes it possible to transmit motion to the agitator according to a predetermined reduction ratio via a mechanism which makes it possible to reverse the direction of rotation if necessary.

[0010] The applicant has experimentally observed that discrete speed changes or reversals of rotation direction are useful aspects to consider for the purpose of homogenizing the temperature of the mixture and are therefore very important for the pasteurization process.

[0011] However, such an operation, as applied in the prior art pasteurization machines mentioned above, does not allow increasing the proportion of air retained in the mixture and the dispersion of solids within the mixture.

[0012] These aspects are essential for the subsequent steps of processing a finished product such as ice cream.

[0013] In fact, it has been found that increasing the viscosity of the mixture ensures that a higher proportion of air (i.e., what is known as "overrun") can be retained within the mixture and finished product.

[0014] At the same time, it has been found that when powders are added to a liquid, they tend to form lumps or clump at the surface, especially if the powder is sticky or hydrophobic, and resist wetting by the liquid. As a result, optimized powder dispersion contributes to improving the final quality of the ice cream.

[0015] Furthermore, conventional motors, connected to the agitators they must drive, are characterized by a very low torque-to-inertia ratio, and therefore require high torques to start and obtain speed variations (at discrete intervals) within a reasonably acceptable time frame. This leads to the use of oversized motors that are not necessary (in terms of the required performance) under steady-state operating conditions, which implies unjustified cost and size.

[0016] It should also be noted that in prior art machines the presence of a mechanism for reversing the direction of rotation of the agitator entails greater structural complexity.

[0017] Bulky pasteurization machines are therefore relatively inflexible, have poor performance and, above all, are unable to increase the viscosity of the food product (and therefore the overrun rate of the mixture) and are unable to prevent the formation of solid lumps or agglomerates within the liquid mixture.

[0018] There is a need for a pasteurization machine that can prevent the formation of lumps and agglomerates when powder needs to be added to the mixture.

[0019] Furthermore, there is a particularly strong need for pasteurization machines that can significantly increase the overrun rate of the mixture, thereby improving the quality of the final product. Summary of the Invention

[0020] The object of the present invention is to meet the above-mentioned needs, namely to provide a pasteurization machine and a pasteurization method for producing liquid or semi-liquid products, which makes it possible to reduce the agglomerations of powder or solid material in the liquid mixture, thus obtaining a high-quality mixture.

[0021] Another object of the present invention is to provide, generally speaking, a pasteurization machine and method for producing liquid or semi-liquid food products that provides improved processing efficiency and end product quality.

[0022] According to the present invention, these objects are achieved by a pasteurization machine and a pasteurization method for producing liquid or semi-liquid food products, said machine and method comprising the technical features set out in one or more of the appended claims. [Brief explanation of the drawings]

[0023] With the above objects in mind, the features of the present invention are clearly set forth in the following claims, and the advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate, by way of example, preferred, non-limiting embodiments of the invention. [Figure 1] 1 shows a schematic representation of a pasteurization machine in a first embodiment of the invention; [Figure 2] 2 shows a schematic representation of a pasteurisation machine in a second embodiment of the invention; [Figure 3] 1 shows a schematic cross-sectional view of a motor used in a machine of the present invention; [Figure 4] 1 shows a perspective view of some of the components of the machine of the present invention; [Figure 5] 5 shows a schematic plan view of the motor shown in FIG. 4. DETAILED DESCRIPTION OF THE INVENTION

[0024] With reference to the accompanying drawings, the numeral 1 indicates a pasteurization machine for thermally treating (i.e. pasteurizing) liquid or semi-liquid food products.

[0025] Pasteurization machines are generally intended to be used for the thermal treatment of products such as ice creams, sorbets, frozen desserts, etc., but also savory creams, sauces, soups, mixes, etc. in general, i.e. all such liquid or semi-liquid products which require a pasteurization treatment during the manufacturing process.

[0026] Although machine 1 is generally represented diagrammatically in Figures 1 and 2, showing only its outer casing 11 (or outer frame), it should be understood that such representation is illustrative of an exemplary embodiment and is not intended to limit the scope of the invention.

[0027] 4, on the other hand, shows some of the components of the machine shown in FIG.

[0028] The pasteurization machine 1 is represented in two possible structural configurations within the frame 11, both of which are shown merely as examples and the differences between them will be made clear below.

[0029] In both Figures 1 and 2, the pasteurization machine 1 comprises containers 2a, 2b adapted to allow processing of a liquid or semi-liquid base product, not shown, to which the product is fed either directly or, preferably, via conveying means (e.g. a hopper) accessible from outside the casing 11 and not shown as it is not relevant to the present invention.

[0030] Processing of the liquid or semi-liquid base product inside the containers 2a, 2b allows a pasteurization treatment to be carried out to obtain a liquid or semi-liquid finished product.

[0031] For this purpose, the vessels 2a, 2b are provided therein with stirrers 3a, 3b driven by drive means 4 for stirring the mixture of liquid or semi-liquid base products.

[0032] More particularly, according to the invention, the drive means 4 are realized by a brushless electric motor 9, the rotor 7 of which is provided with permanent magnets 18 for generating the magnetic field necessary to generate the movement of the rotor 7 (when a magnetic field is applied).

[0033] According to another embodiment, the rotor 7 is connected directly to the stirring device 3a, 3b.

[0034] The brushless electric motor 9 has a simplified mechanism and is fully electronically controlled, and is capable of providing torque that is independent of rotation speed and remains high even at low speeds.

[0035] According to the present invention, the agitators 3 a, 3 b are driven to rotate by the rotor 7 of the direct drive motor 9 .

[0036] It has been experimentally observed that the use of a brushless type motor 9 in the pasteurization process increases what is known as the overrun rate (increases the amount of air retained within the product) and improves powder dispersion for ice cream type products.

[0037] This aspect is explained in more detail below, including the physical details underlying the technical effect.

[0038] The agitators 3 a and 3 b are rotatable around a first rotation axis 8 .

[0039] The rotor 7 has a second axis of rotation (preferably coinciding with the first axis of rotation).

[0040] It should be noted that in the first structural variant, the two rotation axes, the first and second, are coaxial with each other.

[0041] Furthermore, preferably, the first and second two rotation shafts are directly connected to each other.

[0042] Advantageously, according to the embodiment just mentioned, no intermediate gears are used, i.e. the ratio is direct and reversal of the rotational movement of the motor is easily achieved.

[0043] According to this embodiment, the agitators 3 a , 3 b have a respective first rotating shaft 8 directly connected to the rotor 7 of the motor 9 .

[0044] Continuing with the description of the pasteurization machine 1, the pasteurization machine 1 comprises a heat treatment system 5 (for heating and / or cooling).

[0045] Preferably, the thermal treatment system 5 is of the thermodynamic type (ie configured to operate according to a thermodynamic cycle).

[0046] The system 5 comprises a heat exchanger 6 associated with the vessels 2a, 2b.

[0047] One of the functions of the heat treatment system 5 is to heat the mixture of liquid or semi-liquid base products inside the vessels 2a, 2b.

[0048] Preferably, heating is carried out at a temperature between 65°C and 85°C for a preset time while the agitators 3a, 3b agitate the mixture.

[0049] The heat treatment system 5 includes an additional heat exchanger 12 , a compressor 13 and a pressure reducing valve 14 .

[0050] The heating system 5 may also comprise another bypass branch for implementing what is known as a hot gas cycle (which allows heating to take place).

[0051] In other words, according to the embodiment just mentioned, the thermal treatment system 5 is configured to selectively perform a reverse Carnot cycle (saturated vapor compression cycle) and what is known as a hot gas cycle.

[0052] Preferably, the heat treatment system 5 comprises a duct 15 for containing a heat exchange fluid.

[0053] Preferably, the thermal treatment system 5 operates according to at least one thermodynamic cycle (eg, a vapor compression cycle and a hot gas cycle of heat exchange).

[0054] The heat exchanger 6 to which the duct 15 is connected may consist of a pipe 20 wrapped around the outer surface of the vessels 2 a, 2 b and connected to the heat treatment system 5 .

[0055] Alternatively, the heat treatment system 5 is an electric heating system.

[0056] According to this embodiment, the heat exchanger 6 comprises one or more electrical resistors.

[0057] The machine 1 comprises a control unit 10 which regulates in particular the operation of the drive means 4, ie the operation of the motor 9, starting it and determining its direction of rotation and speed of operation.

[0058] Preferably, therefore, the control unit 10 is arranged to control the drive means 4 , ie the motor 9 .

[0059] In a first structural variant shown in FIG. 1, the vessel 2a is arranged so that the stirring device 3a and the rotor 7 of the motor 9 mounted therein are both arranged with their axes of rotation horizontal.

[0060] In FIG. 1, the container 2a is a cylinder.

[0061] In this case, the end of the container 2 a opposite the motor 9 abuts the side wall of the frame 11 .

[0062] According to another embodiment, the machine 1 comprises a dispenser 16 making it possible to withdraw a quantity of product from the container 2a, 2b.

[0063] Preferably, the dispenser 16 is provided with a lever 17 which, when operated, allows the product to be dispensed.

[0064] In a second structural variant shown in FIG. 2, the vessel 2b is arranged so that the stirring device 3b and the rotor 7 of the motor 9 mounted therein are both arranged with their axes of rotation vertical.

[0065] In Figure 2, the container 2b is a tub-type container.

[0066] In this case, as shown in FIG. 2, the top of the container is flush with the top wall of the frame 11, and the dispenser 16 is installed, for example, on the side wall (located at the height of the container 2b).

[0067] Instead of the dispenser 16, a conveyor or duct (not shown) may be provided to transport the pasteurized product from the containers 2a, 2b to other devices or equipment for further processing of the product.

[0068] These other devices or appliances may be followed by another suitable type of dispenser or distributor.

[0069] The pasteurization machine 1 described so far allows for the implementation of a method for pasteurizing liquid or semi-liquid food products, said method comprising supplying a liquid or semi-liquid base product to a container 2a, 2b, where it is treated by pasteurization to obtain a liquid or semi-liquid finished product.

[0070] In the vessels 2a, 2b the mixture consisting of the liquid or semi-liquid base product is mixed (ie stirred) by the stirrers 3a, 3b by means of a brushless electric motor 9 connected to the stirrers 3a, 3b.

[0071] The agitator 3a, 3b comprises at least one blade and / or at least one scraping element and / or at least one spiral element.

[0072] During mixing, the method comprises heating the mixture of liquid or semi-liquid base product inside the containers 2a, 2b to a temperature preferably between 65°C and 85°C for a preset time (preferably between 1 minute and 50 minutes, more preferably between 2 minutes and 30 minutes) to obtain a pasteurized finished product.

[0073] According to another embodiment, during the step of stirring the mixture, the electric motor 9 can be instructed to reverse the direction of rotation of the rotor 7 to perform multiple stirring cycles in which the direction of rotation of the stirrers 3a, 3b is reversed.

[0074] Referring to FIG. 3, the brushless motor 9 comprises an (outer) ring rotor which is the rotor 7 of the motor.

[0075] The rotor 7 comprises a number of permanent magnets 18 facing a corresponding number of (electrical) stator windings 19 (forming part of the motor 9), which are driven by the control unit 10 according to a predetermined switching sequence to cause the rotor 7 (i.e. the permanent magnet ring) to rotate in one direction D or the other direction S, thereby causing a corresponding rotation of the agitators 3a, 3b.

[0076] FIG. 5 shows a specific embodiment of the motor 9 .

[0077] The stator windings 19 are disposed within a stator casing 21 (which can be fixed to the frame 11).

[0078] It should be noted that the permanent magnets 18 (not shown in FIG. 5) are disposed within the rotor casing 22 .

[0079] More precisely, the permanent magnets 18 are arranged on the side walls of the rotor casing 22 .

[0080] Rotor casing 22 is cylindrical and, in particular, lacks one of its base surfaces, thereby defining an internal cavity.

[0081] In practice, the rotor casing 22 houses (in its internal cavity) the stator casing 21 (which is fixed to the frame 11 in use).

[0082] The rotor casing 22 also has a hole in its center from which extends a shaft 23 which is connected (directly or indirectly) to the agitators 3a, 3b.

[0083] The ability to easily switch the stator windings 19 makes it equally easy and very fast to change the speed of rotation of the rotor 7 and, if necessary, to reverse its direction of rotation.

[0084] The switching of the stator windings 19 is controlled by the control unit 10 .

[0085] The structural mechanism of the brushless motor 9 is much lighter and smaller than that of a conventional electric motor.

[0086] High torque can be maintained even at low rotational speeds, thus optimizing the process and further improving performance.

[0087] This allows, for example, the helical element to undergo a rotation cycle at different operating speeds in a very short time.

[0088] The applicant has experimentally observed that the application of a brushless motor 9 to the agitator of the pasteurization machine 1 optimizes the overrun obtained by the mixture being processed.

[0089] The effect of increasing the proportion of air retained within the base mixture is important for many types of liquid or semi-liquid food products, particularly for ice cream type products, as it improves their quality.

[0090] Therefore, there are clear advantages to using this type of motor in a pasteurization process.

[0091] Generally speaking, the quality of the resulting pasteurized mixture is radically improved.

[0092] Described below are some specific advantages that the applicant has discovered through experimental tests carried out on a pasteurization machine made in accordance with the invention, i.e. a machine equipped with a brushless motor 9.

[0093] Advantageously, the brushless electric motor 9 makes it possible to transmit to the stirring devices 3a, 3b an intermittent pulsed movement known as "discontinuous rotation".

[0094] With regard to the pasteurization machine 1 of the present invention, the primary advantage of such intermittent pulsing (i.e. cogging effect) concerns the dispersion of the powder in the liquid.

[0095] It should be noted that the process of dispersing solid particles in a liquid medium should be carried out in as short a time as possible so that the powder sinks into the liquid rather than floating on the surface.

[0096] In brushless type motors 9, the cogging phenomenon, which is particularly pronounced when the motor is a "direct drive" motor, advantageously promotes the dispersion and dissolution of the powder for reasons explained below.

[0097] When powders are added to liquids, especially if the powder is sticky or hydrophobic, the powder has a tendency to form clumps or agglomerate on the surface and resist wetting by the liquid.

[0098] When the agitator is rotated continuously, as in the prior art, the lumps are displaced but not effectively broken down.

[0099] Instead, the machine 1 of the invention advantageously makes it possible to improve the wettability of the powder in the liquid mixture, especially in the case of sticky or hydrophobic powders in the liquid.

[0100] The discontinuous rotation of the motor 9 (due to the cogging effect of a brushless motor) means that the stirring action starts and stops at short intervals.

[0101] The intermittent operation of the motor 9 is therefore characterized by "on" and "off" steps, with the rotation starting and stopping in micro-pulses due to a cogging effect, which is particularly effective in stirring the mixture during the active phase by breaking down powder agglomerates.

[0102] This intermittent operation advantageously prevents the formation of new agglomerates during the rest phase and ensures a uniform dispersion of the particles in the liquid.

[0103] In practice, during the start of motor 9 ("on" step), i.e., during the start pulse of motor 9, the agitator rapidly stirs the mixture, generating shear forces that serve to break up powder agglomerates. When the agitation action stops ("off" step), i.e., during the stop pulse of motor 9, the agglomerates are given the possibility to disperse in the liquid, since they are not constantly exposed to shear forces that could leave them whole.

[0104] Preferably, according to one embodiment, the motor 9 has a cogging effect of between 1% and 10%, preferably between 2% and 5% of the peak torque / force of the motor.

[0105] It should also be noted that continuous stirring as in the prior art can lead to the formation of new agglomerates when the powder particles, i.e. the solid material, collide with each other.

[0106] On the other hand, the intermittent stirring applied by the motor 9, with start and stop cycles due to the cogging effect, can advantageously separate the powder particles and prevent them from re-agglomerating.

[0107] Furthermore, the machine 1 of the present invention advantageously allows a high degree of control of the mixing process.

[0108] In practice, intermittent agitation allows for accurate and precise control of the duration and intensity of the agitation cycle, which can be optimized for the particular combination of liquid and powder being processed.

[0109] In summary, the discontinuous rotation (pulsating due to the cogging effect) of the agitators 3a and 3b obtained via the motor 9 is - Facilitates dispersion of powders in liquids through a more controlled and efficient mixing process; - Helps break down agglomerates in the product being processed, - Prevents re-agglomeration, - Allows you to customize the mixing profile, ultimately leading to better dispersion and a more uniform mixture.

[0110] Other notable advantages of the present invention are:

[0111] The intermittent pulsating motion of the brushless motor 9, and therefore of the agitators 3a, 3b (due to the cogging effect mentioned above), advantageously promotes overrun by creating gaseous cavities within the liquid mixture being processed.

[0112] In fact, during stirring, sudden pressure changes create momentary low pressure areas within the liquid mixture, thus favoring the formation of small gas bubbles.

[0113] Additionally, during the agitation cycle, fluctuations in motion speed or changes in direction can temporarily trap air bubbles within the liquid.

[0114] This temporary bubble entrapment further contributes to the retention of air within the liquid.

[0115] As already mentioned, the higher the percentage of air retained in the product, especially in the case of ice cream-type foods, the higher the overrun, which, as is known, is one of the parameters that defines the indicator of product quality, i.e., contributes to creating a high-quality product with an optimal texture.

[0116] It is therefore clear how machine 1 brings numerous benefits to the quality of the final product.

Claims

1. A pasteurization machine (1) for processing liquid or semi-liquid food base products, comprising: - a container (2a, 2b) adapted to allow said liquid or semi-liquid base product to be treated and processed by pasteurization; - a stirring device (3a, 3b) mounted inside said container (2a, 2b) and driven by a driving means (4) to stir the mixture of said liquid or semi-liquid base product; - drive means (4) adapted to drive said stirring devices (3a, 3b); a thermal treatment system (5) comprising at least one exchanger (6) associated with said vessels (2a, 2b) for heating said mixture of said liquid or semi-liquid base product inside said vessels (2a, 2b); at least one control unit (10) adapted to control the operation of said drive means (4), The pasteurization machine (1), wherein the drive means (4) comprises a brushless electric motor (9) comprising a rotor (7) provided with a permanent magnet (18) for generating the magnetic field required to generate the movement.

2. 2. Pasteurization machine according to claim 1, wherein the electric motor (9) is a direct drive motor.

3. 3. Pasteurization machine according to claim 1 or 2, wherein the rotor (7) is directly connected to the agitator (3a, 3b).

4. 4. Pasteurization machine (1) according to any one of claims 1 to 3, wherein the agitator (3a, 3b) has a first rotation axis (8) and the rotor (7) of the motor (9) has a second rotation axis, the first rotation axis and the second rotation axis being coaxial.

5. 5. Pasteurization machine (1) according to claim 4, wherein the first and second rotary shafts are directly connected to each other.

6. 6. Pasteurization machine (1) according to any one of claims 1 to 5, wherein the agitator devices (3a, 3b) comprise at least one blade and / or one scraping element and / or one helical element, the first rotation shaft (8) of each of which is connected to the rotor (7) of the motor (9).

7. 7. Pasteurization machine (1) according to any one of claims 1 to 6, wherein the heat exchanger (6) comprises a pipe (20) wrapped around the outer surface of the vessel (2a, 2b) and connected to the heat treatment system (5).

8. 8. Pasteurization machine (1) according to any one of claims 1 to 7, wherein both the agitator (3a) and the rotor (7) of the motor (9) are arranged so that their axes of rotation are horizontal.

9. 8. Pasteurization machine (1) according to any one of claims 1 to 7, wherein both the agitator (3b) and the rotor (7) of the motor (9) are arranged so that their axes of rotation are vertical.

10. 10. Pasteurization machine (1) according to any one of the preceding claims, comprising dispenser means (16) connected to said containers (2a, 2b) for dispensing said liquid or semi-liquid product.

11. 11. Pasteurization machine (1) according to any one of claims 1 to 10, wherein the motor (9) comprises a stator body (21) accommodating an electric stator winding (19), the rotor (7) and the stator body (21) being coaxial, the stator body (21) being at least partly arranged inside the rotor (7).

12. 12. Pasteurization machine (1) according to any one of claims 1 to 11, wherein the motor (9) comprises a stator body (21) housing an electric stator winding (19) and a rotor body (22) to which the permanent magnets (18) are fixed, the stator body (21) being at least partly housed in the rotor body (22).

13. 1. A method for pasteurizing a liquid or semi-liquid food product, comprising: - placing said liquid or semi-liquid base products in containers (2a, 2b) adapted to allow them to be processed; - stirring the mixture of liquid or semi-liquid base products by means of stirring devices (3a, 3b) mounted inside the containers (2a, 2b) and simultaneously heating the mixture of liquid or semi-liquid base products inside the containers (2a, 2b), The method, wherein the stirring step comprises driving the stirring devices (3a, 3b) via a brushless electric motor (9) comprising a rotor (7) with a permanent magnet (18) for generating the magnetic field necessary to generate rotational movement of the stirring devices (3a, 3b).

14. 14. The method according to claim 13, wherein during the stirring step, the rotor (7) of the electric motor (9) is directly connected to the stirring device (3a, 3b).

15. 15. The method according to claim 13 or 14, wherein the step of heating the mixture comprises heating the mixture of the liquid or semi-liquid base product inside the container (2a, 2b) at a temperature between 65°C and 85°C for a preset time.

16. 16. The method according to any one of claims 13 to 15, comprising stirring the mixture of the liquid or semi-liquid base product inside the container (2a, 2b) via a stirring device (3a, 3b) comprising at least one blade and / or one scraping element and / or one spiral element.

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