THAWING PLANT AND THAWING METHOD OF RAW FROZEN MEAT PRODUCTS IN A DRUM TUMBLER

Abstract

Thawing plant comprising a drum tumbler (10) hermetically sealable; a vacuum pump (11) connected to said drum tumbler (10) to create a partial vacuum defined below 125 mbars; a water steam injector (12) connected to said drum tumbler (10); a rotating device (13) connected to the drum tumbler (10) to produce its continuous or intermittent rotation; wherein it further comprises a deep diathermy heating applicator (20) including multiple directional emitter antennas (21) configured to apply radiofrequency waves in a medium frequency range configured and focused to produce an uneven heating of the meat product (30) maximizing the heating of an inner volume (33) of the meat product (30) at a predefined depth below an external surface (31) of said meat product (30).

Claims

1. A thawing plant for raw frozen meat products, comprising: A hermetically sealable drum tumbler; a vacuum pump connected to said drum tumbler and configured to reduce the air pressure inside said drum tumbler below 125 mbars creating a partial vacuum; a water steam injector connected to said drum tumbler and configured to inject water steam inside said drum tumbler; a rotating device connected to said drum tumbler and configured to produce a continuous or intermittent rotation of said drum tumbler; a deep diathermy heating applicator including multiple directional emitter antennas each one configured to apply radiofrequency waves in a medium frequency range; and said radiofrequency waves selected within the medium frequency range to heat an inner volume of the raw frozen meat products at a predefined depth below an external surface of said raw frozen meat products, and configured to leave an outer volume unheated or less heated than said inner volume, producing an uneven heating of the raw frozen meat products.

2. The thawing plant according to claim 1 wherein said deep diathermy heating applicator is configured to apply radiofrequency waves in a range between 300 kHz and 1000 kHz or preferably between 400 kHz and 600 kHz and/or said deep diathermy heating applicator being configured to deliver between 20 kW and 50 kW of power.

3. Thawing plant according to claim 1 further comprising a conveyor and a pre-heating enclosure external to said drum tumbler, said multiple directional emitter antennas disposed on said pre-heating enclosure and said conveyor configured to introduce into and to extract from said pre-heating enclosure the raw frozen meat products in a single row or in a single layer alignment along a transport path.

4. The thawing plant according to claim 3 wherein said pre-heating enclosure is a Faraday cage closeable by one or more gates configured to contain said radiofrequency waves produced by the multiple directional emitter antennas contained therein when said one or more gates are closed.

5. The thawing plant according to claim 3 wherein the multiple directional emitter antennas included in the pre-heating enclosure are arranged in different angular positions around said transport path defined by said conveyor and in successive axial positions along said transport path defined by said conveyor; all of said multiple directional emitter antennas focused to said transport path.

6. The thawing plant according to claim 1 wherein said multiple directional emitter antennas of the deep diathermy heating applicator are contained within said drum tumbler and are arranged in different angular positions and in successive axial positions on an inner surface of said drum tumbler and/or on mixing blades attached to said inner surface of the drum tumbler.

7. The thawing plant according to claim 1 wherein said multiple directional emitter antennas of the deep diathermy heating applicator are contained within said drum tumbler and are supported in a stationary position in the upper half of said drum tumbler and focused to emit said medium range waves downwards.

8. The thawing plant according to claim 1 wherein said drum tumbler further comprises: a heat carrier fluid circuit filled with a heat thermal fluid and disposed in thermal contact with said drum tumbler, said heat carrier fluid circuit being connected to a heat carrier fluid pump and to a thermal unit adapted to modify the temperature of said heat carrier fluid; and/or a tilting chassis articulated around a horizontal shaft, said tilting chassis supporting said drum tumbler.

9. A raw frozen meat-products thawing method in a thawing plant, the method comprising thawing the raw frozen meat products by: hermetically sealing the raw frozen meat products within a drum tumbler and reducing the air pressure inside the drum tumbler creating a partial vacuum; injecting water steam in the drum tumbler while the drum tumbler is under the partial vacuum and while the drum tumbler rotates continuously or intermittently; creating the partial vacuum below 125 mbars; and previous and/or during the thawing of the raw frozen meat products in the drum tumbler, unevenly heating the raw frozen meat products with a deep diathermy heating process including applying radiofrequency waves in a medium frequency range with multiple directional emitter antennas, the radio frequency waves being selected, within the medium frequency range, to heat an inner volume of the raw frozen meat products at a predefined depth below an external surface of the meat products leaving the outer volume unheated or less heated than the inner volume, producing an uneven heating of the meat products.

10. The method according to claim 9 wherein the multiple directional emitter antennas are configured to apply radiofrequency waves in a range between 300 kHz and 1000 kHz or preferably between 400 kHz and 600 kHz and/or are configured to deliver between 20 kW and 50 kW of power.

11. The method according to claim 9 wherein the deep diathermy heating process is applied to the raw frozen meat products before the raw frozen meat product is introduced in the drum tumbler.

12. The method according to claim 9 wherein the deep diathermy heating process is applied to the raw frozen meat products while the raw frozen meat products remains in the drum tumbler and while the drum tumbler rotates continuously or intermittently.

13. The method according to claim 12 wherein each directional emitter antenna rotates with the drum tumbler and emits medium frequency waves only while the emitter directional antenna remains in the lower half of the drum tumbler and/or when the directional emitter antennas remain in the upper half of the drum tumbler in a stationary position while the drum tumbler rotates continuously or intermittently and emits medium range waves focused in a downwards direction.

14. The method according to claim 9 wherein the method further includes: calculating the energy to be delivered to the inner volume of the raw frozen meat products during the deep diathermy heating process to reach a predefined increase in the temperature of the inner volume considering the initial temperature of the raw frozen meat products and the weight and/or size of the raw frozen meat products, and delivering the calculated energy on the raw frozen meat products by the deep diathermy heating process.

15. The method according to claim 9 wherein the diathermy heating process is configured to delivery simultaneously or successively radiofrequency waves with different characteristics adapted to produce the heating of different types of tissues of the raw frozen meat products without producing an overheating thereof and/or adapted to produce a heating at different predefined depths.

16. The method according to claim 9 further comprising pumping a heat carrier fluid with a controlled temperature, or with a controlled temperature that is cooler than the meat products, through a heat carrier fluid circuit in thermal contact with the drum tumbler while the drum tumbler is continuously or intermittently rotated during the thawing process.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0119] The foregoing and other advantages and features will be more fully understood from the following detailed description of an embodiment with reference to the accompanying drawings, to be taken in an illustrative and non-limitative manner, in which:

[0120] FIG. 1 shows a schematic view of the proposed thawing plant, according to a first embodiment including a pre-heating enclosure and a drum tumbler;

[0121] FIG. 2 shows a schematic cross section of the pre-heating enclosure transversal to the transport path according to said first embodiment;

[0122] FIG. 3 shows a schematic cross section of the pre-heating enclosure traversal to the transport path according to a second embodiment;

[0123] FIG. 4 shows a schematic cross section of the drum tumbler traversal to its rotation axis, according to a third embodiment;

[0124] FIG. 5 shows a schematic cross section of the drum tumbler traversal to its rotation axis, according to a fourth embodiment;

[0125] FIG. 6 shows a schematic cross section of the drum tumbler traversal to its rotation axis, according to a fifth embodiment;

[0126] FIG. 7 shows a schematic longitudinal section of the drum tumbler along its rotation axis, according to a sixth embodiment;

[0127] FIG. 8 shows a schematic lateral view of the drum tumbler having a heat carrier fluid circuit attached to outer surface of the drum tumbler, surrounding it, said heat carrier fluid circuit being connected, through a rotative connection, to a heat carrier fluid pump and to a thermal unit.

[0128] In the above schematic figures, the radio frequency emitted by the antennas of the directional emitter has been schematically drawn as parallel arc segments, indicating the direction and approximate range of those emissions, making it clear where the emissions of several directional transmitting antennas overlap.

DETAILED DESCRIPTION OF AN EMBODIMENT

[0129] The foregoing and other advantages and features will be more fully understood from the following detailed description of an embodiment with reference to the accompanying drawings, to be taken in an illustrative and not limitative.

[0130] The present invention is directed to a thawing plant for raw frozen meat products 30.

[0131] Thawing raw frozen meat products 30 is tricky because the thawing requires heat, but any part of the raw meat products 30 has to be over-heated or it will be cooked, and its color will change. An additional complication is that the pieces of meat product 30 are frequently quite big making difficult to thaw its inner volume.

[0132] The pieces of raw frozen meat product 30, which usually are pieces of whole muscle such ribs, hindquarters or other animal parts. Each piece of frozen meat product 30 have an external surface 31, an outer volume 32 immediately bellow the external surface 31 and having a predefined thickness and an inner volume 33 surrounded by said outer volume 32 and therefore being under a predefined depth below the external surface 31 of each piece of the frozen meat product 30.

[0133] In this example the typical piece of meat product has an average general thickness of approximately between 15 and 25 cm. In this case, the outer volume 32 is defined as the volume of meat that forms the 5 cm closest to the external surface 31 of the piece of the meat product 30, and the volume of meat surrounded by the outer volume 32 and placed deeper than 5 cm is defined as the inner volume 33. This inner volume 33 is the most difficult and the last part of the meat product to be thawed by the methods commonly used.

[0134] According to a first embodiment of the present shown on FIGS. 1 and 2, the proposed thawing plant includes a deep diathermy heating applicator 20, including multiple directional emitter antennas 21 integrated in a pre-heating enclosure 40, and a cylindrical drum tumbler 10 connected to a vacuum pump 11 and to a water steam injector 12.

[0135] The drum tumbler 10 includes a cylindrical section mostly horizontal, the bottom end closed and a front end including a tapered conical section including an opening with a sealable door through which the meat product 30 can be introduced to and extracted from the inside of the drum tumbler 10.

[0136] Said drum tumbler 10 is supported on bearings permitting its rotation along a longitudinal axis concentric with said cylindrical section, and a rotating device 13 which includes a motor cinematically connected with the drum tumbler to produce its rotation along the longitudinal axis, for example through gears or a belt.

[0137] The inner surface of the drum tumbler 10 includes mixing blades 14 protruding inwards in a radial direction to produce the tumbling of the meat product 30 stored in the drum tumbler 10 while the drum tumbler 10 rotates.

[0138] In the exemplary embodiment shown on the drawings six mixing blades 14 are drawn in a symmetrical radial arrangement. A different number of mixing blades 14, with a different shape or arrangement are also contemplated.

[0139] It is also proposed to support the drum tumbler 10 in a tilting chassis 50 articulated around a horizontal shaft 51 which is perpendicular to an axis parallel to the longitudinal axis adjacent to the front end of the drum tumbler 10. Pistons connected to the bottom end of the tilting chassis 50 allow changing the inclination of the longitudinal axis of the drum tumbler 10, tilting said drum tumbler 10 frontwards or backwards to facilitate the insertion, extraction or mixing of the meat product contained therein. This embodiment is shown on FIG. 1 where the tilting movement of the drum tumbler 10 is shown in dashed lines.

[0140] In the example shown on FIG. 1 the pre-heating enclosure 40 is a tunnel with an entrance opening and an exit opening, both including a gate 42 for its closure. A conveyor 41, in this example a conveyor belt, passes through the pre-heating enclosure 40 for the transport of the pieces of frozen meat product along a transport path TP going through the pre-heating enclosure 40.

[0141] An alternative embodiment is also contemplated according to which the pre-heating enclosure 40 has only one opening and the conveyor 41 introduces the meat products 30 therein and extracts therefrom through said singe opening.

[0142] The directional emitter antennas 21 are placed inside the pre-heating enclosure 40, surrounding the transport path TP and directed to a target area of that transport path intended to contain the inner volume 33 of the frozen meat products 30 transported on said conveyor 41.

[0143] To allow a precise and deep penetration of the radio frequency waves generated by the directional emitter antennas 21, it is proposed that the conveyor 41 transports the pieces of frozen meat product 30 in a single row alignment, allowing the directional emitter antennas 21 to be arranged in an array surrounding the pieces of meat product 30 transported in the conveyor 41, emitting the radio frequency waves on the meat product from different angular positions around the transport path TP.

[0144] All those radio frequency waves converge in the target area where the inner volume 33 of the meat product 30 is placed during its transport along the transport path TP, mainly heating said inner volume 33.

[0145] In the example shown on FIG. 2, the pre-heating enclosure 40 includes directional emitter antennas 21 placed under the conveyor 41 belt and configured to emit upwards through the conveyor 41, which has to be made of a material transparent to said radio frequencies, and directional emitter antennas 21 placed above the conveyor 41 belt and above the transport path TP and configured to emit downwards.

[0146] In the example shown on FIG. 3, three directional emitter antennas 21 are arranged around the transport path TP at three different angular positions spaced apart 120° to each other, the waves emitted by said three directional emitter antennas 21 converging in the inner volume 33.

[0147] The penetration of the radio frequencies on the meat product depends on the frequency used, being difficult to reach and heat the inner volume 33 using frequencies above the 300 MHz. It is proposed to configure the directional emitter antennas 21 to emit in a medium frequency, between the 300 kHz and the 3000 kHz, to ensure a deep penetration reaching said inner volume 33.

[0148] Those frequencies are also selected because they produce an interaction of the proteins and with the muscle tissues producing its heating.

[0149] In the examples shown on FIGS. 2 and 3 the directional emitter antennas 21 are configured and focused to emit waves of radio frequency which converge in the inner volume 33 of the meat products 30 transported through the pre-heating enclosure 40 producing its heating.

[0150] According to another embodiment of the present invention, the conveyor 41 is configured to transport the pieces of meat product 30 in a single layer alignment along the transport path TP. The features previously described can also be applied to this particular embodiment.

[0151] In the example shown on FIG. 1 the pre-heating enclosure 40 can be closed by gates 42, said pre-heating enclosure 40 actuating as a Faraday cage which content the radio frequency waves emitted by the directional emitter antennas 21. In this case, the directional emitter antennas 21 can only actuate when the gates 41 are closed producing the pre-heating on a batch of pieces of meat product contained in the pre-heating enclosure 40.

[0152] Despite the above an embodiment where the pre-heating enclosure 40 has no gates 42 and in which the conveyor can continuously transport pieces of meat product 30 there through producing a continuous treatment is also contemplated.

[0153] According to an alternative embodiment, shown on FIGS. 4, 5, 6 and 7, the directional emitter antennas 21 are located inside the drum tumbler 10, emitting against the meat product 30 contained therein.

[0154] In this embodiment the thawing plant lacks pre-heating enclosure 40, because the deep diathermia applicator 20 is contained in the drum tumbler 10.

[0155] Inside the drum tumbler 10 the deep diathermy heating process can be applied previous to the creation of the partial vacuum, while the partial vacuum is created, or previous to the injection of the water steam. But in any case, the deep diathermy heating process shall be applied while the drum tumbler 10 rotates continuously or intermittently to assure the uniform treatment of all the pieces of frozen meat product 30 stacked inside the drum tumbler 10.

[0156] According to the embodiment shown on FIG. 4, an array of multiple directional emitter antennas 21 are located on the inner surface of the hollow cylindrical drum tumbler 10, in different radial positions between the mixing blades 14 and also in different longitudinal positions along the rotation axis of the drum tumbler 10 and directed inwards. Those directional emitter antennas 21 are attached to the drum tumbler 10 and therefore they rotate together with the drum tumbler 10.

[0157] The pieces of meat product are stacked inside the drum tumbler 10 on top of the directional emitter antennas 21 placed in the lower half of the drum tumbler 10.

[0158] Those directional emitter antennas 21 located in the lower half of the drum tumbler 10 emits upwards, affecting the inner volume 33 of the pieces of meat product 30 located immediately on top of said directional emitter antennas 21.

[0159] It is proposed to configure the directional emitter antennas 21 of the drum tumbler 10 to emit only when are in the lower half of the drum tumbler 10, i.e. only when the meat product 30 is in direct contact with it, the directional emitter antennas 21 being disconnected when remain in the upper half of the drum tumbler 10.

[0160] According to an additional or complementary embodiment, the directional emitter antennas are located in the mixing blades 14 and directed towards the interior of the drum tumbler 10, for example being directed to affect the pieces of meat product 30 being located between the mixing blades 14. It is also proposed to locate said directional emitter antennas inside the mixing blades 14, said mixing blades 14 being made of a material transparent to the radio frequencies.

[0161] It is also proposed to locate the directional emitter antennas inside the drum tumbler 10, but supported in a stationary arm which remains in a stationary position within the drum tumbler 10 while the drum tumbler 10 rotates, the directional emitter antennas being directed downwards to emit the radio frequency waves against the upper layer of pieces of meat product 30 stacked inside the drum tumbler 30, heating its inner volume.

[0162] So, the inner volume 33 of the peat product 30 will be heated up using medium frequency waves emitted by the multiple directional emitter antennas 21, preferably using frequencies comprised between 400 kHz and 600 kHz.

[0163] This heating of the inner volume 33 can be performed previous to the introduction of the meat product 30 in the drum tumbler 10, and therefore previous to the thawing method using partial vacuum and water steam, performing the deep diathermia heating process in a pre-heating enclosure 40.

[0164] In this case the pieces of frozen meat product 30 are transported through the pre-heating enclosure 40 by the conveyor 41. Once the deep diathermia heating process is completed the inner volume 33 of each piece of meat product 30 will be hotter than the outer volume 32.

[0165] Then the prices of meat product are introduced in the drum tumbler 10, the drum tumbler 10 is sealed and the air is extracted therefore using the vacuum pump 11 establishing a partial vacuum under 125 mbars inside the drum tumbler 10.

[0166] Then the water steam injector 12 introduces water steam inside the drum tumbler 10 while the drum tumbler rotates continuously or intermittently and while the air pressure remains under 125 mbars, producing the condensation of the water steam in the external surface 31 of the pieces of meat product 30 at a temperature below 50° C., producing its heating and thawing and preventing the cooking of said external surface 31 of the pieces of meat product 30. This process is maintained until all the pieces of meat product 30 are completely thawed.

[0167] The drum tumbler 10 can be provided with a heat carrier fluid circuit 15 filled with a heat thermal fluid and in thermal contact with the drum tumbler 10, said heat carrier fluid circuit 15 being connected to a heat carrier fluid pump 16 and to a thermal unit 17 adapted to modify the temperature of the heat carrier fluid, as shown on FIG. 8.

[0168] During the thawing process performed in the drum tumbler 10, the temperature of the drum tumbler 10 can be adjusted modifying the temperature of the heat carrier fluid, permitting the heating and cooling of the drum tumbler 10. The heating of the drum tumbler 10 accelerates the heating of the external surfaces 31 of the pieces of meat product 30 contained in the drum tumbler 10, and the cooling thereof during the final part of the thawing process prevents the over-heating of the external surface 31 of the pieces of meat product 30 while the heat introduced in the pieces of meat product reaches the inner volume 33.

[0169] According to an alternative of the proposed method the deep diathermy heating process is performed inside the drum tumbler 10, previous o during the thawing process performed by the water steam. In this case the pre-heating enclosure 30 is not necessary.

[0170] It will be understood that various parts of one embodiment of the invention can be freely combined with parts described in other embodiments, even being said combination not explicitly described, provided there is no harm in such combination.