WO2006126870A1

WO2006126870A1 - Apparatus and method for processing food products, drying and/or cooling unit and processed food product

Info

Publication number: WO2006126870A1
Application number: PCT/NL2005/000386
Authority: WO
Inventors: Matheus Johannes Hof; Rinze Wassenaar
Original assignee: Gti Koudetechniek B.V.
Priority date: 2005-05-26
Filing date: 2005-05-26
Publication date: 2006-11-30

Abstract

Apparatus for processing, such as cooling and/or drying, food products. The apparatus has a conveyor structure including a conveying surface extending along a processing path in a processing space, for conveying the food products through the processing space. A cooling and/or drying unit for supplying a flow of a cooling and/or drying medium, such as a gas or a gas mixture, to the food products in the processing space is present. The cooling and/or drying unit at least includes a fluid outlet in a first zone of the processing path for supplying a flow of said medium which moves at least a part of the food products away from the conveying surface.

Description

Title: Apparatus and method for processing food products, drying and/or cooling unit and processed food product.

FIELD AND BACKGROUND OF THE INVENTION

The invention relates to an apparatus and method for processing, such as cooling and/or drying, of food products.

From European patent publication 945 077 an apparatus for freezing food products is known. The apparatus comprises at least one freezing space and one conveying track for moving the food products through the freezing space. Blowing means are provided for blowing a cooled medium over the products present on the conveying track. The blowing means comprise blowing openings, at least above at least a portion of the at least one conveying track. The blowing openings are arranged for blowing out the cooled medium at least substantially at right angles to the conveying direction of the at least one conveying track.

However, a disadvantage of the prior art system known from this European patent publication is that, during the freezing process, food products tend to adhere to each other and form lumps of frozen food products. Especially for small food products, such as sliced vegetables, shrimp, shredded fish, etc, this tendency to adhere to each other is disadvantageous. Without wishing to be bound to any theory, it is believed that the formation of lumps results in a prolonged cooling time of the food products and, in case of freezing, the formation of large crystals. Large crystals in the products will cause damage to the cell membranes and drip losses and will consequently adversely affect the storage lives of the products. Furthermore, processing the lumps of food products is difficult since, e.g. in case separate food products are required in the further processing, individual food products have to be removed from a lump. In addition, this bears a high risk of unwanted damage to the food products.

In the art, another apparatus for freezing food products is known, which is provided with a conveyer belt for moving the food products through a freezing space. The conveyor belt is provided with a shaking device, for mechanically shaking the conveyor belt. The shaking of the conveyor belt separates the food products from each other, and thus prevents the formation of lumps of food products.

However, a disadvantage of this other prior art system is that the mechanical shaking damages the food products. Furthermore, the shaking device requires a relatively large amount of maintenance, since the mechanical moving parts are subject to wear. Also, the mechanical parts are subject to fouling and difficult to clean, which is a particular disadvantage because of hygiene requirements with regard to the processing of food products.

SUMMARY OF THE INVENTION

It is one goal of the invention to provide an apparatus for processing, such as cooling and/or drying, of food products in which the formation of lumps of food products during processing is reduced. In order to achieve this goal, the invention provides an apparatus according to claim 1.

In an apparatus according to claim 1, the formation of lumps of food products is reduced, because the cooling and/or drying unit includes a fluid supply in a first zone of the processing path for supplying a flow which moves at least a part of the food products away from the conveying surface. Thus, in operation, the food products are moved away from the conveying surface at the first zone of the processing path. The movement separates food products clogged together and the formation of lumps is, at least partially, suppressed.

The invention further provides a method according to claim 17. In such a method, the formation of lumps is reduced. The invention also provides a cooling and/or drying unit according to claim 24. Such a unit reduces the formation of lumps when food products are processed. In addition, the invention provides a food product according to claim 25 and a container according to claim 26. Such a food product has a reduced amount of lumps. Likewise, the food products in the container exhibit a reduced formation of lumps. Specific embodiments of the invention are set forth in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Further details, aspects and embodiments of the invention will be described, by way of example only, with reference to the attached drawings. Fig. 1 schematically shows a cut-away side view of an example of an arrangement of examples of embodiments of apparatuses according to the invention. Fig. 2 schematically shows a cross-section view of the example of fig. 1 along the line II-II in fig. 1.

Fig. 3 schematically shows a cross-sectional view of the example of fig. 1 along the line III-III in fig. 1. Fig. 4 schematically shows a cross- sectional view of the example of fig. 1 along the line IV-IV in fig. 1.

Fig. 5 schematically shows a cut-away side view of a part of the example of an embodiment of an IQF apparatus according to the invention shown in fig. 1.

Fig. 6 schematically shows a cut-away top view of the example of fig. 5 with removed cover.

Fig. 7 schematically shows a cut-away top view of the example of fig. 5 with conveyor and deflector removed.

Fig. 8 schematically shows a cross-sectional view of the example of fig. 5 along the line VIII-VIII in fig. 5. Fig. 9 schematically shows a side view of a part of the processing path of the example of fig. 5.

Fig. 10 schematically illustrates the flow of air in the part of the example of figs. 5-

9 indicated with reference number X in fig. 9.

Fig. 11 schematically shows a part of the conveyor and flow passages in the example of figs. 5-9.

DETAILED DESCRIPTION

Figs. 1-4 schematically show an arrangement 1 of apparatuses 10-13 for processing food products. The apparatuses 10-13 are constructed to dry or cool food products, which prolongs the lifetime, in particular the storage life. The food products to be processed by the arrangement 1 may be raw food products or have been subjected to preparation steps, such as (deep) frying or cooking. The food products may have an initial temperature above, at or below room temperature. The food products to be processed may be pre-processed, for example the product may be (deep) fried and may for example have an initial temperature up to 100⁰C.

The apparatuses 10-13 may for example, in operation, cool the food products from a first temperature to a second temperature lower than the first temperature. The first temperature may for example be below 40 ⁰C, such as 30⁰C. The first temperature may be above or at the freezing point of the food products. The first temperature may for example be above O⁰C and/or below 10⁰C. The second temperature may for example be at or below the freezing point of the food products. The second temperature may for example be about or below O⁰C and/or above -5O⁰C. The apparatuses 10-13 may also, or alternatively, be constructed to perform another processing step which prolongs the lifetime of the food products, and for example be constructed to dry the food products. To that end, for example the apparatuses may reduce the humidity to below 10% Rv at a temperature below 100 ⁰C.

In the example of figs. 1-4, the arrangement 1 is constructed to freeze the food products, that is to cool at least the outside of the food product from a temperature above the freezing point of the food products, e.g. above O⁰C, to a temperature below the freezing point, e.g. -2O⁰C. In this example, the arrangement 1 freezes the food products in successive stages.

The arrangement includes, in a processing direction P of the food products from an entrance 31 to an exit 32, a pre-cooling apparatus 10, an individual quick freeze (IQF) apparatus 11, a fast freezing apparatus 12, and a post-freezing apparatus 13. The arrangement 1 is separated from the outside environment by means of a wall W. The inside environment is partitioned in rooms with different ambient temperatures by means of partitioning walls Wl and W2. The pre-cooling apparatus 10 is placed in a room in which the ambient air has a temperature near, or slightly above the freezing point of the food products, e.g. 0⁰C. The IQF apparatus 11 is placed in a room in which the ambient air has a temperature below the freezing point of the food products, e.g. -20⁰C. The fast freezing apparatus 12 and post-freezing apparatus 13 are placed in a room in which the ambient air has a temperature lower than in the room of IQF apparatus 11, e.g. -42°C.

In the arrangement 1, an overall processing space 3 is formed by the processing spaces of the individual apparatuses 10-13, which are in communication with each other. The processing space 3 has a processing entrance 31 and a processing exit 32. A conveyor structure 2 extends from the processing entrance 31 to the processing exit 32 through the overall processing space 3. In this example, the conveyor structure 2 includes two endless conveyor belts 20. The top sides of the conveyor belts 20 constitute a conveying surface 22, for conveying the food products from the processing entrance 31 to the processing exit 32. In operation, the conveyor belt 20 is moved by a driving unit 23, such that the conveying surface 22 moves in a processing direction P, carrying the food products along in the processing direction P through the processing space 3. However, the invention is not limited to the shown way of moving the food products through the processing direction P, and the conveying surface 22 may be implemented in any suitable manner.

In this example, the arrangement 1 is separated in a first line of apparatuses 10-12 and a second line of apparatus 13. The apparatuses 10- 12; 13 in each line are directly connected to each other, i.e. the processing exit of an upstream apparatus of the respective line lies directly adjacent to the processing entrance of an apparatus downstream of the upstream apparatus. The processing exit 34 of the most downstream apparatus 12 in the first line lies adjacent to processing entrance 33 of the most upstream apparatus 13 in the second line, but a spacing 37 is present between the processing exit 34 of the most downstream apparatus 12 in the first line and the processing entrance 33 of the most upstream apparatus 13 in the second line. In the example, the overall processing space 3 thus includes the spacing 37 and two processing passages, extending through, respectively, the first line and the second line.

The apparatuses in the example of figs. 1-4 are further provided with a cooling and/or drying unit for supplying a flow of a cooling and/or drying medium, such as a gas or a gas mixture, to the food products in the processing space. In this example, the cooling units use air as a cooling and/or drying medium. The cooling and/or drying unit of the respective apparatuses 10-13 includes a separate means for generating a flow of the cooling medium and a means for cooling and/or drying the air.

As is explained below in more detail, the pre-cooling apparatus 10 and the IQF apparatus 11 are provided with examples of cooling and/or drying units according to the invention. As schematically shown in figs. 1-4, and explained below in more detail, the processing space 3 of the pre-cooling apparatus 10 and the IQF apparatus 11 includes pulse zones. In the pulse zones, fluid outlets are provide which provide a flow of cooling and/or drying medium sufficient to move the food products away from the conveying surface 22. The movement of the food products may be limited in a direction away from the conveying surface 22 by a first limiter 41, as schematically shown in figs. 1-4. The movement of the food products may be limited in a direction parallel to the conveying surface by a second limiter 42, as schematically shown in figs. 1 and 3.

Arranged on top of each of the pre-cooling apparatus 10, the fast freezing apparatus 12 and the post-freezing apparatus 13 is a series of fans 5 for displacing relatively substantial streams of air from outside of the apparatuses 10-13 to the inside 7 of the apparatuses. The IQF apparatus 11 is provided on top thereof with high pressure blowers 4 for providing a high pressure stream of air to the inside of this apparatus 11.

The flow of air inside and outside of the apparatuses 10-13 is schematically indicated in figs. 2-4 with arrows. As shown in figs. 2-4, the inside 7 of the apparatuses 10-13 forms a channel for providing the cooling and/or drying medium, in this example air from the fans 5 or high pressure blowers 4, to the conveying surface 22 and hence to the food products. The air displaced to the inside 7 causes a flow of air at the conveying surface 22

The apparatuses 10-13 are further provided with a cooling means 6 downstream of the blowers 4 and the fans 5, for cooling the air inside the apparatuses. Downstream of the cooling means 6, the channel formed by the inside 7 of the apparatuses has a constriction 71 which mouths in a box-like chamber 9 extending below the conveying surface 22. The box-like chamber 9 is provided with openings (not shown in figs. 1-4) at the side of the chamber 9 which faces the conveying surface 22. Via the openings, the cooled air can be discharged from the inside 7 into the processing space 3, and be guided over the food products to be cooled.

In the pre-cooling apparatus 10, a series of fans 8 is provided between the constriction 71 and the chamber 9, for locally increasing the flow and pressure of the cooling medium in the vicinity of fluid outlets in the processing path, and more particularly in the vicinity of the pulse zones in the processing path in which, in operation, the food products are moved away from the conveying surface. Since the flow and/or pressure of the cooling and/or drying medium is increased only locally, the energy consumption is relatively low. As shown in fi.gs.1 and 2, the fans 8 of the pre-cooling apparatus 10 are positioned at the entrance of a sub-chamber 94 in the chamber 9. The sub-chamber 94 is separated from other parts of the chamber 9 by sub-chamber walls 93. The entrance of the sub-chamber 94 is positioned in fluid communication with the constriction 71. The fan 8 sucks the cooling and/or drying medium from the constriction 71 and blows the medium into the sub-chamber 94. The fan 8 thus increases the flow and pressure of the cooling medium in the sub-chamber 94. The sub-chamber 94 has fluid outlets, not shown in figs. 1-4, which mouth in the processing space 3 near the conveying surface 22. The fluid outlets provide a flow of cooling and/or drying medium in a direction away from the conveying surface 22.

The apparatuses 10-13 shown in the arrangement 1 are able to perform one or more processing steps of a four-stage cooling process. However, depending on the specific implementation, the cooling process may instead be performed in more or less stages, such as in a single cooling stage. To that end, more or less apparatuses than shown in figs. 1-4 may be present in the arrangement. Furthermore, upstream or downstream of the apparatuses 10-13, additional apparatuses may be present to perform further processing steps before or after the cooling process, such as washing, glazing, pre-cooling, after-freezing, packaging etc.

The pre-cooling apparatus 10 is able to perform a pre-cooling step. During pre- cooling, the food product is cooled from a temperature at or above room temperature to a temperature close or closer to the freezing point, e.g. from about 20⁰C to below 10⁰C. In this example, the pre-cooling apparatus 10 pre-cools the food products entering the processing space 3 to the freezing point of the food product, which in this example is about O⁰C. In the pre-cooling apparatus 10, the food products are also, at least partially, dried.

During operation of the pre-cooling apparatus, the food products are moved away from the conveying surface 22 in the pulse zones, which are in this example present between the conveying surface 22 and the first h^'miters 41. In the pulse zones, the force exerted on the food products by the cooling and/or drying medium is increased with respect to outside the pulse zones, in this example by means of the fans 8 and sub-chambers 94. Due to the exerted force, in the pulse zones, the food products are moved away from the conveying surface by the flow of cooling and/or drying medium. The movement separates food products adhered together, as explained below in more detail, and hence reduces the formation of lumps as well. Furthermore, the movement provides an enhanced drying of at least the surface of the food products, thus reducing the formation of the lumps in the further processing of the food products.

The IQF apparatus 11 is able to perform an individual quick freezing (IQF) step. In the IQF step, at least the surface temperature of the food products is brought to a temperature below the freezing point. In this example, the IQF step is performed on the food products leaving the pre-cool apparatus 10, which thus have a temperature of about 0⁰C. The IQF apparatus freezes at least the outside of the pre- cooled food product, for example to a few degrees below the freezing point. The IQF step reduces the adherence of food products, and hence the formation of lumps downstream in the processing path, since a significant amount of the formation of lumps is believed to be caused by freezing of moisture on the outside of the food products.

The IQF apparatus 11 is provided with pulse zones, as is shown in figs. 5-8 in more detail. In operation, the food products are moved away from the conveying surface 22 by means of the flow of cooling and/or drying medium. This movement separates food products adhered together. Furthermore, the movement accelerates the freezing of the outside of the food products, thus reducing reformation of lumps after the food products have been separated. Hence, the formation of lumps is reduced in the IQF step. It is believed that lumps are mostly formed during freezing of the outside of the food products. Hence, the reduction of lump formation before and during IQF results in a significant reduction of the formation of lumps in the overall processing of the food products.

The fast freezing apparatus 12 is able to perform a fast freezing step. In the fast freezing process, the temperature of the core of the IQF food products is brought below the freezing point, and in this example is brought to a temperature which is less than 1O⁰C below the freezing point of the respective food products. The fast freezing apparatus 12 thus ensures that the food products are frozen at their inside as well, and not only at the outside. The fast freezing is believed to reduce the formation of the formation of large crystals, and accordingly reduces drip losses. The post-freezing apparatus 13 is able to perform an post-freezing step. In the post-freezing step, the temperature of the frozen food products is lowered, to further enhance the lifetime of the food products. In the post-freezing, the temperature of the food products can for example be brought from a temperature between O⁰C and —20 ⁰C to a lower temperature between, e.g. between -15°C and -5O⁰C. In the example of figs. 1-4, the frozen food products are passed from the fast freezing apparatus 12 to the post-freezing apparatus 13. The average temperature of the frozen food is brought further down by the post-freezing apparatus 13, for example to -20 degrees Celsius. The post-freezing further prolongs the storage life of the food products. The storage life of the food products is believed to be substantially independent of the period of time required to perform the post-freezing. Accordingly, the post- freezing can be performed relatively slow, thus using with a relatively low amount of energy without affecting the storage life.

Figs. 5-8 show views of the example of the IQF apparatus 11. Each of the apparatuses 10-13 of figs. 1-4 may be implemented in a similar manner as the example of figs. 5-7. However, different implementations are also possible. The shown example of an IQF apparatus 11 is positioned in a chamber confined by a wall W. The IQF apparatus 11 includes a frame 101 which is provided with a conveyor structure 2. By means of the conveyor structure 2, food products can be conveyed through the processing space 3 in a processing direction P. The conveyor structure 2 may like in the example, include an endless conveyor belt 20 with a topside 22 which forms a conveying surface, and a bottom side 21. In this example, the conveyor belt 20 extends along a processing path in the processing space 3 from the processing entrance to the processing exit (both not shown in figs. 5-8). At the entrance and the exit, the conveyor belt 2 projects with terminal ends slightly out of the processing space 3. The conveyor belt 2 can be moved in a circulating manner by a driving unit 23.

The IQF apparatus 11 has a cooling and/or drying unit which is constituted to provide the cooling and/or drying medium to the conveying surface 22. The unit includes fluid outlets 90,91A-C via which the cooling and/or drying medium is discharged from the unit. As shown in this example, the fluid outlets 90,91A-C may be arranged to supply a flow at a conveying surface side of the food products only. Thereby, an improved control over the movement of the food products is obtained, since it is prevented that the food products are blown away in a sideways direction, e.g. by a flow of cooling medium towards the conveying surface 22 which is deflected by the conveying surface 22 in a sideways direction.

The fluid outlets 90,91A-C may for instance be positioned to provide a flow which is substantially perpendicular with respect to the conveying surface 22. Thereby, the movement of the food products in the processing direction is not influenced by the cooling and/or drying medium.

In this example, the conveying surface 22 is positioned substantially horizontally and, in operation, the flow of cooling and/or drying medium will be substantially upwards. Thereby, the movement of the food products can be controlled accurately, because the force exerted by the cooling and/or drying medium is at least partially counteracted by the gravitational force acting on the food products. For example, in case the force exerted by the flow is larger than the gravitational force, the food products are moved away from the conveying surface 22 , while if the force is smaller than the gravitational force, the food products move towards the conveying surface 22 or remain on the conveying surface 22.

The processing space 3 has zones 36 in which the flow of air exerts a force on the food products sufficient to move at least a substantial part of the food products away from the conveying surface 22. From hereon, these zones 36 are referred to as the pulse zones 36. In the example, the force exerted by the flow in the pulse zones 36 exceeds the gravitational force on the food products. Because of the moving force exerted by the flow, the food products move away from the conveying surface. The amount of force may have any value suitable for a specific implementation. The amount of force may e.g. be dependent on the size and/or shape and/or specific weight of the food products to be processed.

The movement of the food products in the direction away from the conveying surface 22 separates food products stuck together. Thereby, the formation of lumps of food products clogged together is reduced. Furthermore, the volume of air flowing per second is increased in the pulse zones 36. The cooling and/or drying of the food products is thus increased. Thereby, the separated food products are dried and/or cooled more quickly, before adhering together again, and the formation of lumps is reduced even further. Outside the pulse zones 36, in second or non-pulse zones 35, the force exerted by the flow is lower than in the pulse zones 36. In this example, in the non-pulse zones 35 the force exerted by the flow is lower than the gravitational force acting on the food products. Thus, as indicated with arrow C in fig. 10, the food products, blown away from the conveyor belt in the pulse zones 36, return back to the conveying surface 22 in the non-pulse zone 35 downstream of a pulse zone 36.

The processing space 3 may include any suitable configuration of pulse zones 36 and/or non-pulse zones 35. For example, the processing space 3 may include two or more pulse zones 36 and one or more non-pulse zones 35 which separate the first zones from each other. In the example of figs 5-8, the processing space 3 includes pulse zones 36, and non-pulse zones 35 in an alternating arrangement.

The fluid outlets 90,91A-C may be implemented in any manner suitable for the specific implementation. The fluid outlets can for example be arranged below the conveying surface 22. In figs. 5-8, to that end a cooling and/or drying unit includes a chamber 9 provided on the frame 101. The chamber 9 extends below the conveying surface in the space between the top side 22 and the bottom side 21 of the conveyor 20. The chamber 9 may be connected to a supply of a cooling or dried medium, for example in a manner as shown in figs. 1-4. The chamber 9 may have any suitable shape. In figs. 5-8, for instance, the chamber is shaped like a box, which is closed off at the bottom and the upright sides.

At the top side of the chamber 9, the fluid outlets 90,91A-C are provided. In the example, the fluid outlets include slit-shaped openings 90,91A-C at the top side of the chamber 9, as shown in more detail in figs. 9-11. By means of the slit-shaped openings 90,91A-C, the cooling and/or drying medium, e.g. cool or/and dry air, can be provided to the top side 22 of the conveyor belt 20.

In the examples, the cooling and/or drying medium discharged via the fluid outlets is able to flow through the conveyor belt 20 to the food products. In this example, the conveyor belt 20 has a plurality of passages 204 extending between a chamber side surface of the conveyor belt 20 and the topside surface 22, as shown in fig. 11. The conveyor belt 20 includes a plurality of similar shaped links 200 pivotally connected by pivots 201 to form a chain. Each link 200 rests on the top side of the chamber with a spacer 202 and the pivot 201. Between the spacer 202 and the pivot an air chamber 203 is obtained. The air chamber 203 is in fluid communication with the top side 22 by means of the passage 204 extending between the air chamber 203 and the top side-22.

To obtain the pulse zones 36, any suitable supply of cooling and/or drying medium may be used. In the example of figs. 5-8, the fluid outlets 90,91A-C are connected to a single supply, i.e. the chamber 9. However, the cooling and/or drying unit may include separate supplies of pressurized fluid operating at different pressures fluid, each supply being connected to a separate outlet mouthing in a respective zones 35,36. To that end, the chamber 9 may for instance be divided into different partitions each connected to a different source of fluid. However, other implementations are also possible.

In figs. 5-8, for example, respective wider slit-shaped openings 91A-91C of the top side of the chamber 9 are positioned below the pulse zones 36. In the processing direction P, a plurality of narrower slit-shaped openings 90 is positioned between successive wider slit-shaped openings 91A-91C. The narrow slit-shaped openings 90 are narrower than the wider slit-shaped openings 91A-91C. Hence, a larger flow of fluid will be present at the area of the conveying surface 22 above the wider slit- shaped openings 91A-91C than at the areas above the smaller slit shaped openings 90. Hence, in the pulse zones 36, the force exerted by the flow of a cooling and/or drying medium will be larger as well.

In this example, the narrower outlets 90 have an equal width, and may for instance be about 2 mm wide, whereas the width of the wider fluid outlets varies, and may for instance be between 5 and 15 mm. Accordingly, the amount of force exerted by the flow of cooling medium is about the same in the non-pulsed parts 35, whereas in operation, the amount of force exerted in the respective pulsed parts 36 differ. In this example, the width of the wider slit-shaped openings 91A-91C reduces in the processing direction P. Thus, the force exerted in the pulse zones downstream is lower than in the pulse zones upstream. This results in a lower energy consumption while the formation of lumps of food products is effectively reduced. In this example for instance, the most upstream opening 91C has a width of 15 mm, whereas the most downstream opening 91A has a width of 5 mm. However, the flow pattern may differ from the example and the invention is not limited to the shown example. For instance, the width of the fluid outlets 90,91A-C may be modified. E.g. the width of the narrower fluid outlets 90 may vary as well, or the wider fluid outlets may have an equal width.

The fluid outlets may be spaced apart. In figs. 5-8, for instance, the slit-shaped openings 90,91A-C are spaced by plates 92 at the top side of the chamber 9. The plates 92 inhibit the flow of fluid over the conveying surface at the areas directly above the plates 92. In the example, the plates 92 extend over substantially the width of the top side of the chamber, in a plane parallel to the conveying surface 22. The longitudinal direction of the plates 92 is oriented perpendicular to the processing direction P. In the processing direction P, the plates 92 are placed adjacent to each other, but separated by the slit-shaped openings 90,91A-C. The plates 92 include a flat part 921 substantially in parallel with the conveying surface 22.

At opposite sides of the flat part 921, the plates 92 have protruding sides 920 extending towards the chamber 9. The protruding sides 920 are placed at a non- perpendicular angle with respect to the flat part 921, and form side-walls of the slit- shaped passages 90,91A-C. The slit-shaped passages 90,91A-C have a tapered cross- section, which narrows towards the conveying surface 22. The tapered cross-section results in an advantageous flow profile of the cooling and/or drying medium.

Since the fluid outlets are spaced apart (in this example by the plates 92), in operation, the conveying surface 22 is alternately blown and not blown by streams of medium. Hence, an intermittent cooling pattern is obtained, which may also be achieved or enhanced by blowing cooled medium intermittently or in any other suitable manner. Due to the intermittent cooling pattern, a relatively small amount of cooled medium is used, while a good heat exchange between the food products and the surroundings, in particular the cooled medium, can be obtained. Without wishing to be bound to any theory, it is assumed that this occurs due to the fact that heat transfer from the core of the products to the cooled surface thereof does not decrease significantly when the cooling of the surface is omitted between the passing of successive slit-shaped passages 90,91A-C. Fig. 10 shows in more detail the flow of air in the processing space 3 of the example. As shown, the slit-shaped openings 91 A-C positioned below the pulse zones 36 are wider than the slit-shaped openings 90 in the non-pulse zones 35. Thus, near the slit-shaped openings 91 A-C, the amount of air flow is larger, and accordingly a larger force is exerted on the food products by the flow of air, as indicated with arrow A in fig. 10.

A deflector may be positioned in the pulse zones 36 which deflects the flow of cooling and/or drying medium towards the conveying surface 22. The deflector may be implemented in any suitable manner. The deflector may for instance include one or more fluid outlets which supply a flow of fluid which deflects the flow of cooling and/or drying medium towards the conveying surface. The deflector may also include a mechanical deflector, e.g. a surface which deflects the flow. In the examples, for instance, curved plates 41 are arranged above the conveying surface 22. The curved plates 41 act as deflectors, for deflecting the flow from the fluid outlet towards the conveying surface 22, as is indicated with the arrow B in fig. 10. By deflecting the flow back towards the conveying surface, the movement of the food products is directed back towards the conveying surface in a controlled manner, as shown with arrow C in fig. 10.

In fig. 10, in the non-pulsed zone 35 outside the pulsed zone 36, the air guided along the deflector flows in a direction away from the conveying surface 22, as shown with arrows D. This flow of air carries along a finer fraction of the mass to be processed. Thereby, e.g. dust and crumbles of food products are removed from the food products. The air moving away from the conveying surface is discharged to the outside of the IQF apparatus 11 via an air duct 43 positioned above the processing space3, as shown in fig. 5-8. In this example, the pressure outside the apparatus 11 is lower than inside the apparatus. Thus, the cooling and/or drying medium will flow from the outlets to the outside environment of the apparatus II. The curved plates 41 further limit the movement of the food products in a direction away from the conveying surface 22. Downstream of the curved plates, upright plates 42 are positioned which act as second limiters, which limit in operation the movement of the food products in a direction parallel to the conveying surface 22. Because of the limiters, the free movement of the food products in a respective direction is limited to a confined area, thus reducing fouling of the apparatus outside the confined area. In this example, in operation, at least a part of the food products will collide with the plates 41,42 on an impact surface of the plates 41,42. This collision will also separate at least a part of the adhered food products. Accordingly, the impact surface further reduces the formation of lumps of food products adhered together. In this example, as shown in more detail in fig. 10, the curved plates 41 each include a first planar end part 410 extending in a first direction away from the conveying surface 22, a second planar end part 411 extending in a second direction towards the conveying surface, and an intermediate curved part 412 connecting the first and second end parts 410,411. Such a shape provides a flow profile which reduces the formation of lumps effectively. In addition, the shown profile can be cleaned easily, and in use exhibits a low degree fouling in time.

Furthermore, the angle of incidence of the food products on the curved plate is small, resulting in a relatively low amount of damage to the food products. In particular, it is found that a first planar end part 410 positioned at an angle larger than or 70 degrees and/or smaller than or equal to 80 degrees, such as for instance 76 degrees, with respect to the conveying surface 22, results in a good separation of adhered food products, with a limited amount of damage to the food products. In addition, a second planar end part 411 positioned at an angle larger than or equal to 30 degrees and/or smaller than or equal to 40 degrees, such as about 34 degrees, with respect to the conveying surface 22 guides the flow and the food products towards the conveying surface 22 without significant interference with the flow away from the conveying surface 22. The intermediate curved part 412 can for example have a radius below 10 cm and/or above 2 cm, in the example of about 5 cm. It is found that such a radius contributes to a low amount of damage to the food products as well. In the example, the edge of the first planar end part 410 lies closer to the conveyor than the edge of the second planar end part 411. Thereby, the freedom of movement of the flow or food products moving away from the conveyor is effectively limited to a direction perpendicular to the conveying surface (or at least not against the processing direction P) while the cooling and/or drying medium used in the pulsed zone 36 can be lead away from the conveying surface, without being returned to conveying surface (and hence the food products) in the non-pulse zone 35. Thus, a flow of fresh cooling and/or drying medium over the food products is ensured. However, the invention is not limited to the shown deflector and limiters, The deflector and/or limiters may be implemented in any manner suitable for the specific implementation. For instance, the first limiter may be implemented as a substantially flat plate extending in parallel to the conveying surface 22, and/or the second limiter as a substantially flat plate oriented perpendicular to the conveying surface 22.

In the example of figs. 5-8, in operation, adjacent the first end 31, products are placed on the top side 22 of the conveyor belt 20 and moved in the processing space 3. Simultaneously, cooled medium with a desired, relatively low temperature is drawn from outside into the chamber 9. The cooled medium may for instance be air or another suitable gas or gas/air mixture, optionally provided with, for instance, fungicidal and/or bactericidal additives. The cooled medium may for example have a temperature of between -55 and +40 degrees Celsius, whereby cooling and/or freezing of products can be effected, which products may or may not be pre-frozen or pre- cooled. Also, glazing may take place or other suitable conditioning treatments of the food products.

The cooled medium is blown out of the slit-shaped outlets 90,91A-C via the conveying surface 22 over the food products. As the food products are moved through the processing space 3 by the conveyor belt 20, they pass the wider slits shaped openings 91A-C. The flow out of the wider slit shaped openings 91A-91C moves a substantial part of the food products away from the conveying surface 22 in the pulse zone 36. The flow may for example have a velocity of more than 10 m/s, such as between 15 m/s and 30 m/s, measured at the conveying surface 22 above the slit- shaped openings 91 A-C. As explained above, the movement by the flow of air separates food products stuck together. The portion of the food products moved away from the conveying surface 22 is then guided back to the conveying surface 22 via the curved plate 41, which also acts as a limiter for the food products in the direction away from the conveying surface 22. The movement of the airborne food products returning to the conveying surface 22 is limited in the processing direction P by the upright plate 42. The force exerted at impact on the curved plate 41, and optionally the upright plate 42, further loosens the food products. The air guided along the curved plate 41 is lead away, in this example upwards, from the processing space, taking a finer fraction of the matter to be processed, e.g. dust and crumbles along. The returned, loosened, food products are cooled further in the non-pulse space 35 by the flow of cooling medium at the narrower slit-shaped openings 90. The flow out of the narrower openings 90 may for example have a velocity of more than 5 m/s, such as between 5 m/s and 15 m/s , measured at the conveying surface 22 above the slit-shaped openings.

It should be noted that the invention can be applied to any suitable food products. In particular, the invention can be applied to obtain a quick individual frozen food product. The food products may be sliced, chopped or otherwise be divided into small pieces before freezing, and may for example include slabs, slices, chunks of food products. Examples of suitable products are e.g. sliced mushrooms, sliced banana, sliced carrot, shrimp or prawn, cockles or other small food products. However, the products may also be frozen or cooled as a whole, and for example be food products with a round shape, such as peas, and berries. Other suitable food products may likewise be processed.

Tables 1 and 2 show, by way of example, values of parameters used in experiments performed with an example of an apparatus according to the invention on a variety of food products using air as a cooling medium. A significant reduction of the formation of lumps has been observed in these experiments. In the experiments an apparatus of which the length of the processing space was 1.8 m has been used. The narrower slit-shaped openings had a width of 2 mm. The velocity of the air in m/s through these openings is represented by Vair (1) in table 1, while the successive wider slit-shaped openings had in the processing direction a width of 15, 10, and 6 mm with a velocity Vair(2), Vair (3), Vair (4) in m/s as listed in table 1, respectively. table 1

In table 2, T_prod(in) represents the initial core temperature of the food product in degrees Celsius. Tprod(out) represents the average product temperature of the food products leaving the conveyor. Tair represents the temperature of the air in degrees Celsius, tfreeze represents the period of time the food products reside in the flow of cooling medium in seconds. Qair represents the amount of air flow in m³ /s per square meter of conveying surface. P represents the pressure in the chamber 9 in Pascal. table 2

Table 3 illustrates an example of a method performed with the arrangement of figs. 1- 4 with sliced mushrooms. Initially, the temperature of the slices was 15°C. In table 3, lprocessing represents the length of the processing space in the respective apparatus 10- 13. M_prod/A_conveyor represents the amount of sliced mushrooms per area of the conveying surface, tprocessing represents the time the food products resided in the processing space of the respective apparatus. Tair represents the temperature of the air blown over the food products, pair represents the pressure of the air in the chamber 9. With respect to the pre-cooling apparatus 10, both the pressure for the sub-chambers 94 and the chamber 9 is listed. Qair represents the air flow in m³/s per square meter of conveying surface. Pcooimg represents the amount of cooling power of the apparatus. Tprod represents the average temperature of the products after they were processed in the respective apparatus 10-13. Pvent represents the power of the fans 5 resp. high pressure blowers 4. table 3

It should be noted that in the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word 'a' is used as equivalent to the term 'at least one'. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage.

Furthermore, the invention is by no means limited to the embodiments shown in the drawings. Within the framework of the invention as defined by the claims, many variations are possible. For instance, the invention may be applied in cooling, drying, combined cooling and drying, or other suitable processing of food products. The cooling and/or drying medium may be any suitable fluid, and for example be a gas or a gas mixture, such as air. Likewise, the medium may be provided with additives such as, for instance, fungicidal and/or bactericidal additives. Also, although in the drawings cooling apparatuses are disclosed, the invention can also be applied to drying apparatuses, and to that end, for instance the embodiments of figs. 1-4 can be modified by replacing the cooling unit 6 by a unit which removes vapor from the air. Also, depending on the specific implementation the distance in the longitudinal direction of the conveyor belts between the plates 92 and hence the width of the slit- shaped openings 90, 91 may varied for influencing the cooling pattern, while, moreover, through variation of the position of the blowing openings, the flow pattern of the cooled medium may be influenced. Further, within the framework of the invention, other means may be used for effecting the desired cooling and displacement of the cooled medium, for instance compressed air and the like. However, other alternatives and modifications are also possible.

Claims

1. Apparatus for processing, such as cooling and/or drying, food products, including: a conveyor structure including a conveying surface extending along a processing path in a processing space, for conveying the food products through the processing space; and a cooling and/or drying unit for supplying a flow of a cooling and/or drying medium, such as a gas or a gas mixture, to the food products in the processing space, which cooling and/or drying unit at least includes a fluid outlet in a first zone of the processing path for supplying a flow of said medium which moves at least a part of the food products away from the conveying surface, and wherein the processing space includes at least one second zone outside the first zone, for returning the moved away food products to the conveying surface .

2. Apparatus according to claim 1, further including a deflector for deflecting the flow from the fluid outlet towards the conveying surface.

3. Apparatus according to claim 1 or 2, further including a first limiter for limiting the movement of the food products in a direction away from the conveying surface, and optionally a second limiter for limiting the movement of the food products in a direction parallel to the conveying surface.

4. Apparatus according to any one of the preceding claims, wherein at least one of the first and/or second limiter includes a impact surface, for separating adhered food products by means of collision of the adhered food products with the impact surface.

5. Apparatus according to any one of claims 2-4, wherein the deflector and/or limiter includes a guiding surface facing the conveying surface, for guiding the flow and/or the movement of the food products towards the conveying surface, and the apparatus further includes a space between the guiding surface and the conveying surface.

6. Apparatus according to claim 5, wherein the guiding surface and/or impact surface are provided on a side of a curved plate, said side facing the conveying surface.

7. Apparatus according to claim 6, wherein the curved plate includes a first planar end part extending in a first direction away from the conveying surface, a second planar end part extending in a second direction towards the conveying surface, and an intermediate curved part connecting the first and second end parts.

8. Apparatus according to any one of the preceding claims, wherein the conveyor structure comprises a conveyor belt provided with the conveying surface, which conveyor belt includes a plurality of passages for allowing the flow of gas through the conveyor belt towards the conveying surface, and the cooling and/or drying unit includes at least one fluid outlet positioned to provide the flow near the passages at a second surface of the conveyor belt directed away from the conveying surface.

9. Apparatus according to any one of the preceding claims, wherein the processing path further includes at least two first zones, and at least one second zone which separates the first zones from each other, at which second zone the fluid flow in operation, is absent or exerts a lower force on the food products than in the first zone.

10. Apparatus according to claim 9, wherein the second zone includes: at least one no-flow zone in which in operation the flow is absent, and at least one low flow zone in which said flow is present in operation but exerts a force on the food products insufficient to move the food products away from the conveying surface.

11. Apparatus according to claim 9 or 10, wherein the cooling and/or drying unit further includes a fluid outlet in the second zone of the processing path, for providing a gas flow of lower density and/or velocity than in the first zone.

12. Apparatus according to any one of the preceding claims, wherein the fluid outlet includes at least one slit-shaped passage extending in a direction perpendicular to a conveying direction of the food products over substantially the width of the conveying surface.

13. Apparatus according to any one of the preceding claims, wherein the cooling and/or drying unit includes a fluid supply chamber positioned at the second surface side of the conveying path, the fluid supply chamber having an outlet side surface extending in parallel to the second surface, said outlet side surface being provided with the slit-shaped passage, and optionally the outlet side surface is mechanically in contact with the second surface, for guiding and or supporting the conveyor belt at the second surface side.

14. Apparatus according to any one of the preceding claims, wherein the gas or gas mixture includes air.

15. Apparatus according to any one of the preceding claims, wherein the apparatus is arranged for cooling the outside surface and/or the inside mass of the food products from a first temperature above, at or below freezing point to a second temperature above, at or below freezing point, which second temperature is lower than said first temperature.

16. Apparatus according to any one of the preceding claims, wherein the fluid outlet is arranged to supply a flow at a conveying surface side of the food products only.

17. Method for processing, such as cooling and/or drying, food products, including: conveying the food products on a conveying surface along a processing path in a processing space; supplying a flow of a fluid cooling and/or drying medium, such as a gas or a gas mixture, to the food products, which in a first zone of the processing path moves at least a part of the food products away from the conveying surface; and returning the food products towards the conveying surface in a second zone of the processing path.

18. Method according to claim 17, wherein the food products are small, such as an average size smaller than 15 cm³ or an average mass of below 2 kg/1, such as lower than 1 kg/1 and optionally the food products include slices of food products.

19. Method according to claim 17 or 18, wherein the food products have an average mass of less than 10 grams per food product

20. Method according to any one of claims 17-19, wherein the food product is cooled from a first temperature above freezing point to a second temperature closer to the freezing point

21. Method according to any one of claims 17-20, wherein at least the outside surface of the food product is cooled from a first temperature above or at freezing point to a second temperature below to the freezing point.

22. Method according to any one of claims 17-21, wherein at least the outside surface of the food product is cooled from a first temperature below freezing point to a second temperature further below freezing point.

23. Method according to any one of claims 17-22, wherein the cooling and/or drying medium is air, optionally with addititives.

24. Cooling and/or drying unit for supplying a flow of a cooling and/or drying medium, such as a gas or a gas mixture, to food products in a processing space, said cooling and/or drying unit including a fluid supply positionable near or at a conveying surface in a first zone of a processing path in the processing space, for supplying a flow which moves at least a part of the food products away from the conveying surface.

25. Dried or cooled food product obtainable with a method according to any one of claims 17-23.

26. Container including a space provided with a plurality of dried or cooled food products according to claim 25.