Food defrosting machine and method of use

Abstract

A food defrosting machine 100 comprises a multi-level conveyor assembly 104 having an upper conveyor 106 for conveying portions 1 of foodstuff in a first direction and a lower conveyor 110 for conveyi

Description

FIELD OF THE INVENTION Embodiments of the present invention relate to a food defrosting machine and method of use. In particular, they relate to a food defrosting machine and method of use, for defrosting portions of foodstuffs to a refrigerated temperature. BACKGROUND TO THE INVENTION An example of a food defrosting machine is a batch defrosting room, comprising a room with a false ceiling and a plurality of fans above the false ceiling. Pallets of frozen foodstuff are placed in the room, along with temperature sensors (skin probes). Warm air is blown through the room to remove the boundary layer of cold air surrounding the portions of foodstuff. If one of the temperature sensors records a temperature greater than a threshold, the fans may shut off. Heaters shut off and a refrigeration system is activated to reduce the temperature. When temperature is lower than a set point the heaters are activated again. This recurs several times during a defrosting cycle, using energy to repeatedly heat up and cool down the room. A batch defrosting room consumes high amounts of energy, and can corrupt the outer surface of the portions of foodstuff that are most exposed to the airflow due to the time taken to warm up the portions that are in the centre of each pallet. This can lead to variability of taste and texture. BRIEF DESCRIPTION OF VARIOUS EMBODIMENTS OF THE INVENTION According to various, but not necessarily all, embodiments of the invention there is provided a food defrosting machine comprising: a multi-level conveyor assembly comprising an upper conveyor for conveying portions of foodstuff in a first direction and a lower conveyor for conveying the portions in a second opposite direction; and a forced air assembly comprising ducting and a fan, the fan being located within the ducting, the ducting configured to direct airflow from the fan along the upper and lower conveyors in a direction parallel to the first and second directions. An advantage of the conveyors is thawing the portions in a quicker time than a batch defroster - 45 minutes as opposed to 12 to 24 hours and a consistent finished product temperature, while significantly saving energy and causing less corruption or blood loss to the foodstuff and temperature abuse. An advantage of the parallel airflow direction is improved aerodynamic efficiency and reduced noise, especially when the machine is in a confined space. By comparison, transverse fan designs are noisier and less efficient. Optionally, the forced air assembly is configured to direct an upper portion of the airflow along the upper conveyor and a lower portion of the airflow along the lower conveyor. An advantage is improved defrosting for a given footprint area of the machine, because both levels of the conveyor assembly receive high airflow. Therefore, the overall length of the machine can be minimised. Optionally, the forced air assembly is configured to direct the upper and lower portions of the airflow in a common direction along the upper and lower conveyors. Optionally, the upper conveyor is air permeable to allow air exchange with the lower conveyor. An advantage is improved aerodynamic efficiency and material efficiency because the upper and lower conveyors do not need to be fluidly isolated from each other as would be required if the airflow travelled in opposite directions. This allows an open design in which air can permeate between the levels. Optionally, the ducting comprises at least one port (e.g., outlet or inlet) arranged relative to the upper and lower conveyors to split the airflow into the upper and lower portions. Optionally, both the upper and lower conveyors share airflow from the same fan. An advantage is improved energy efficiency and material efficiency because the number of fans is minimised, allowing for example one fan to blow the air over both levels. Optionally, the upper and lower conveyors are arranged for the portions of foodstuff to fall from the upper conveyor to the lower conveyor. An advantage is exposing other parts of the portion of foodstuff to the air flow, as the portion may land on the lower conveyor in a different orientation. Optionally, the ducting comprises an outlet for providing the airflow to the upper and lower conveyors, and an inlet for receiving the airflow from the upper and lower conveyors, wherein the inlet and outlet are located towards opposite ends of the multi-level conveyor assembly. An advantage is improved accessibility because the upper and lower conveyors can be located outside the ducting to allow access for cleaning and maintenance. Optionally, the inlet is located above the upper and lower conveyors. Optionally, the outlet is orientated to define an airflow direction from the outlet parallel to the upper and lower conveyors, and the inlet is orientated to define an airflow direction transverse to the upper and lower conveyors into the inlet. Optionally, the inlet is orientated to define an upwards airflow direction into the inlet. An advantage is reducing the probability of portions of foodstuffs being sucked into the inlet, because the inlet is located above the upper and lower conveyors and pulls air upwards. Optionally, the upper conveyor comprises an air permeable belt to allow airflow from the lower conveyor to reach the inlet through the air permeable belt. Optionally, the air permeable belt comprises a wire belt or a mesh. An advantage is that the inlet can be located above the conveyors and draw air from the upper and lower conveyors without sucking portions of foodstuffs into the inlet. Optionally, the ducting comprises an enclosed tunnel for recirculation of the airflow from one end region of the multi-level conveyor assembly to the other end region of the multi-level conveyor assembly. An advantage is aerodynamic efficiency when the airflow is transported through the fan to the other end of the conveyors. Optionally, the enclosed tunnel is located above the multi-level conveyor assembly. An advantage is that the enclosed tunnel may at least partially enclose the upper conveyor for reducing air leakage, or may extend at a greater height such as above ceiling level for reduced noise. 4 Optionally, the enclosed tunnel fluidly connects the inlet and the outlet. Optionally, the enclosed tunnel extends for most or substantially all of a length of the multi-level conveyor assembly to circulate the airflow from the inlet to the outlet. Optionally, at least one of the upper and lower conveyors is semi-enclosed, or mostly enclosed, for inhibiting leakage of the airflow from the multi-level conveyor assembly. An advantage is improved aerodynamic and defrosting efficiency. Optionally, the multi-level conveyor assembly comprises side walls for inhibiting air leakage out of the semi-enclosed / mostly enclosed one of the conveyors. An advantage is improved aerodynamic and defrosting efficiency because the airflow is constrained between the side walls. Optionally, the side walls comprise hand access apertures. Optionally, the hand access apertures collectively extend along substantially a whole length of the semi-enclosed / mostly enclosed conveyor. An advantage is that the hand access apertures enable ease of maintenance and cleaning, without disassembly. They may have minimal effect on air leakage. Optionally, the lower conveyor is semi-enclosed / mostly enclosed by the upper conveyor and a lower pair of the side walls. An advantage is improved aerodynamic and defrosting efficiency because the airflow is vertically and horizontally constrained. 5 Optionally, the upper conveyor is semi-enclosed / mostly enclosed by an upper boundary (e.g., the ducting) and an upper pair of the side walls, or wherein the upper conveyor is open topped. Optionally, the upper conveyor is semi-enclosed / mostly enclosed at least by an underside of the ducting. An advantage is improved aerodynamic and defrosting efficiency because the airflow is vertically and horizontally constrained. Optionally, one or more baffles are mounted to an upper boundary of at least one of the upper and lower conveyors, and are arranged to direct airflow downwardly towards a surface of the respective conveyor. An advantage is improved defrosting efficiency because the airflow rate is highest close to the portions of foodstuff. Optionally, the food defrosting machine comprises a loading extension allowing the portions of foodstuff to be loaded onto one of the upper and lower conveyors, wherein the loading extension extends beyond the forced air assembly and is separated from the forced air assembly by a partition such as a wall. An advantage is that the fan noise and aerodynamic noise are reduced in the area where the workers load and unload the portions. Optionally, the loading extension is for one of the upper and lower conveyors. Optionally, the loading extension comprises a portion of the upper conveyor. Optionally, the loading extension comprises a sloped portion of the respective conveyor, changing height from a loading height to a conveyor height of the respective conveyor. An advantage is that the upper and lower conveyor heights are optimised for cleaning and maintenance, while the loading height for loading foodstuff is optimised and may be different than the conveyor heights. Optionally, an exit end of the other one of the upper and lower conveyors is proximal to the loading extension. Optionally, the exit end is located to eject the portions of foodstuff into a space to the same side of the partition as the loading extension. Optionally, a chute is provided at the exit end to direct the portions of foodstuff in a predetermined direction, optionally into a container. Optionally, the food defrosting machine comprises a temperature control device configured to control a temperature of the airflow to a temperature value within the range 5 to 20 or 10 to 20 Celsius, while the conveyor speed and temperature sensors ensure that all parts of the product are less than 3 Celsius. Optionally, the fan is a bifurcated fan. An advantage is improved maintenance because the fan motor is protected from debris or dust from the foodstuff, as well as corrosive cleaning chemicals. The fan is out of the air stream so does not require as much cleaning. According to various, but not necessarily all, embodiments of the invention there is provided a method of operating the food defrosting machine, the method comprising: placing portions of foodstuff on a multi-level conveyor assembly comprising an upper conveyor that conveys the portions of foodstuff in a first direction and a lower conveyor that conveys the portions in a second opposite direction; and activating a fan of a forced air assembly, the forced assembly comprising ducting and the fan, the fan being located within the ducting, the ducting directing airflow from the fan along the upper and lower conveyors in a direction parallel to the first and second directions. Optionally, the method further comprises activating the temperature control device (e.g., heater) to control the temperature of the airflow to a value within the range 5 - 20 or 10 -20 Celsius. BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of various examples of embodiments of the present invention reference will now be made by way of example only to the accompanying drawings in which: FIG. 1 schematically illustrates a side view of an example food defrosting machine; and FIG. 2 schematically illustrates a longitudinal cross-section view of the example food defrosting machine. DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS OF THE INVENTION FIGS. 1 and 2 show a non-limiting example of a food defrosting machine 100 for defrosting portions 1 of foodstuff. In some examples, the portions 1 of foodstuff comprise frozen chicken fillets. It would be appreciated that the food defrosting machine 100 may be used for alternative foodstuffs including meats as well as non-meats. The machine 100 comprises a multi-level conveyor assembly 104. The multilevel conveyor comprises an upper conveyor 106 and a lower conveyor 110. The conveyors 106, 110 are belt-type conveyors. 8 A front portion of the upper conveyor 106 is sloped down to define a loading extension 118. A person or robot in front of the loading extension 118 deposits the portions 1 on the loading extension 118. The loading extension 118 of the upper conveyor 106 transports the portions 1 upwardly to a height of the upper conveyor 106, and then horizontally along the upper conveyor 106 in a rearward first horizontal direction away from the loading extension 118. The loading extension 118 extends through an aperture in a partition wall 102. The partition wall 102 may comprise a wall panel extending from floor level to at least a height of a top of the machine 100, or to ceiling height. The partition wall 102 can acoustically separate the person depositing the portions 1 from the noise-generating parts of the machine 100, and protect the person from stray airflow. The lower conveyor 110 is located directly beneath the upper conveyor 106, and when portions 1 reach an end of the upper conveyor 106 they fall onto the lower conveyor 110. This has the added benefit of exposing other parts of the portion to the air flow, as the portion may land on the lower conveyor 110 in another orientation. The lower conveyor 110 transports the portions 1 in a forward second horizontal direction towards a front of the machine 100. The lower conveyor 110 extends up to the same aperture or a different aperture in the partition wall 102 and ejects the portions 1, now defrosted, into a chute 3 of the machine 100 that points at a container 2 such as a wheeled trolley. The exit end of the lower conveyor 110 is directly beneath the entrance end (loading extension 118) of the upper conveyor 106. Therefore, a person loading the portions 1 can also supervise the ejection of portions 1 into the container 2. In case a person needs access to the parts of the machine 100 beyond the partition wall 102, the partition wall 102 may comprise a doorway with an optional door, to allow access to a corridor running alongside the machine 100. In order to defrost the portions 1 on the upper and lower conveyors 106, 110, the machine 100 comprises a forced air assembly 120. The forced air assembly 120 comprises a bifurcated fan 134 (motor outside airflow) or other fan / air driving device. The forced air assembly 120 further comprises ducting 122, fluidly connecting a front end region of the conveyor assembly 104 to an opposite rear end region of the conveyor assembly 104, and wherein the fan 134 is located within the ducting 122. Furthermore, the forced air assembly 120 further comprises a temperature control device 136, comprising a heater for example. In the context of defrosting portions 1 of foodstuffs to a refrigerated temperature, the temperature control device 136 may be configured to control a temperature of the airflow to a value within the range 5 or 10 Celsius to less than 20 Celsius. One or more temperature sensors (not shown) may be coupled to a control system (not shown) for controlling the temperature control device 136 and / or the fan 134 in dependence on temperature information from the one or more temperature sensors. In summary, the fan 134 circulates the airflow in a loop comprising the ducting 122 and the conveyor assembly 104. The airflow loses heat to the portions 1 of foodstuff, and the heater of the temperature control device 136 replaces the lost heat. The ducting 122 and fan 134 are positioned above the conveyor assembly 104, with an underside 130 of the ducting 122 spaced above the upper conveyor 106. In some examples, the ducting 122 may extend above a ceiling level of a room in which the conveyor assembly 104 is situated, to reduce noise. In other 10 examples, the ducting 122 may be within 10-50 centimetres height above the upper conveyor 106 to partially enclose the upper conveyor 106 and reduce upwards air leakage therefrom. The ducting 122 comprises an inlet 126 aligned with the front end region of the conveyor assembly 104, then an elongate horizontal section extending to the rear end region of the conveyor assembly 104, then a C-shaped bend to reverse an airflow direction in the ducting 122, and finally an outlet 124 aligned with the rear end region of the conveyor assembly 104. In other examples, the inlet 126 and outlet 124 may swap ends. Having the inlet 126 at the front reduces the chance of air spilling out of the room, and makes it easier to get the air to channel over both conveyors. The outlet 124 of the ducting 122 is upright and configured to blow airflow horizontally along the upper and lower conveyors 106, 110 simultaneously, in a common forward direction parallel to the plane of the lower and upper conveyors 110,106. The airflow from the outlet 124 is therefore divided into: an upper portion travelling longitudinally, forwardly, and horizontally along the upper conveyor 106; and a lower portion travelling longitudinally, forwardly, and horizontally along the lower conveyor 110. The upper and lower portions of the airflow travel in a common direction. The outlet 124 is shown as a single large aperture. Alternatively, the outlet 124 can comprise an upper aperture for the upper conveyor 106, and a separate lower aperture for the lower conveyor 110. A lower edge of the outlet 124 is at or below an upper surface of the lower conveyor 110, and an upper edge of the outlet 124 is at or above an upper surface of the upper conveyor 106. The inlet 126 of the ducting 122 is a horizontal aperture located in or mounted to the flat underside 130 of the ducting 122, and so is configured to draw in air upwardly from the upper conveyor 106 at the front end region of the conveyor assembly 104. Furthermore, the upper or each conveyor comprises a highly air permeable belt 108 such as a wire form or perforated plastic mesh, allowing air to be drawn from the lower conveyor 110, through the air permeable belt 108 of the upper conveyor 106, and into the inlet 126. The upper conveyor 106 therefore does not present much of an obstruction to airflow. Due to the air permeability of the belts 108 of the conveyors 106, 110, and the positioning of the inlet 126, it is useful that the airflow along the upper and lower conveyors 106, 110 travels in a common direction rather than in opposite directions. This ensures smooth laminar circulating airflow. The ducting 122 may be relatively aerodynamically enclosed compared to the conveyor assembly 104. The ducting 122 may comprise an enclosed tunnel 128 extending from the inlet 126 to the outlet 124. Optionally, the ducting 122 may be continuously enclosed from the inlet 126 to the outlet 124. The fan 134 and temperature control device 136 may be located within the elongate horizontal section of the enclosed tunnel 128. A single fan 134 provides all the airflow for the machine 100. In other examples, multiple fans may be provided. In some examples, separate left and right fans and ducting 122 may be provided. As best shown in FIG. 2, the conveyors 106, 110 are less aerodynamically enclosed than the ducting 122, in cross-section. The lower conveyor 110 is mostly aerodynamically enclosed by an upper boundary and left and right boundaries, wherein the upper boundary comprises 12 the air permeable upper conveyor 106, and the left and right boundaries comprise an upper pair of side walls 114 comprising hand access apertures 116. The hand access apertures 116 extend along each side wall 114 from the front end region to the rear end region of the conveyor assembly 104. The hand access apertures 116 are at least 3cm tall and at least 10cm long, for example, to allow insertion of a human hand for cleaning or maintenance. The hand access apertures 116 collectively make up a small enough area of the side walls 114 that the side walls 114 effectively constrain the airflow to within the cross-section. Hand access apertures 116 may be implemented as a series of elongate slots along a side wall 114, and / or as a continuous slot above the top edge of a side wall 114. The upper conveyor 106 is mostly aerodynamically enclosed by the flat underside 130 of the elongate horizontal section of the enclosed tunnel 128 of the ducting 122, and by left and right boundaries comprising a lower pair of side walls 114 with the hand access apertures 116. In other examples, the upper boundary is provided by something other than the ducting 122. In further examples, the upper conveyor 106 is open topped with at least 1 metre of clearance above it, wherein said section of the ducting 122 is positioned much higher such as above a ceiling level. In the example of FIG. 1 where an upper boundary is located above the upper conveyor 106, FIG. 1 shows that baffles 132 in the form of diagonal plates may be mounted to the upper boundary. In this case, the baffles 132 are mounted to the flat underside 130 of the elongate horizontal section of the enclosed tunnel 128 of the ducting 122. The baffles 132 are sloped downwardly in a 13 direction of the airflow, to direct the airflow down towards the upper surface of the upper conveyor 106. Therefore, the baffles 132 collectively increase the average airflow velocity proximal to the conveyor surface. In some examples, similar baffles 132 may be provided for the lower conveyor 110. The side walls 114 and the ducting 122 may be formed from a hygienic material such as stainless steel, or another metal with a hygienic coating, for example. Although embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed. Features described in the preceding description may be used in combinations other than the combinations explicitly described. Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not. Although features have been described with reference to certain embodiments, those features may also be present in other embodiments whether described or not. Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and / or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

1. A food defrosting machine comprising:a multi-level conveyor assembly comprising an upper conveyor for 5 conveying portions of foodstuff in a first direction and a lower conveyor for conveying the portions in a second opposite direction; anda forced air assembly comprising ducting and a fan, the fan being located within the ducting, the ducting configured to direct airflow from the fan along the upper and lower conveyors in a direction parallel to the first and second 10 directions.

2. The food defrosting machine of claim 1, wherein the forced air assembly is configured to direct an upper portion of the airflow along the upper conveyor and a lower portion of the airflow along the lower conveyor.

153. The food defrosting machine of claim 2, wherein the forced air assembly is configured to direct the upper and lower portions of the airflow in a common direction along the upper and lower conveyors.20 4. The food defrosting machine of claim 1, 2, or 3, wherein the ductingcomprises at least one port arranged relative to the upper and lower conveyors to split the airflow into the upper and lower portions.

5. The food defrosting machine of any preceding claim, wherein the ducting 25 comprises an outlet for providing the airflow to the upper and lower conveyors, and an inlet for receiving the airflow from the upper and lower conveyors, wherein the inlet and outlet are located towards opposite ends of the multi-level conveyor assembly.30 6. The food defrosting machine of claim 5, wherein the inlet is locatedabove the upper and lower conveyors.10 07 257. The food defrosting machine of claim 5 or 6, wherein the outlet is orientated to define an airflow direction from the outlet parallel to the upper and lower conveyors, and wherein the inlet is orientated to define an airflow direction transverse to the upper and lower conveyors into the inlet.

8. The food defrosting machine of claim 7, wherein the inlet is orientated to define an upwards airflow direction into the inlet.

9. The food defrosting machine of any one of claims 5 to 8, wherein the upper conveyor comprises an air permeable belt to allow airflow from the lower conveyor to reach the inlet through the air permeable belt.

10. The food defrosting machine of any preceding claim, wherein the ducting comprises an enclosed tunnel for recirculation of the airflow from one end region of the multi-level conveyor assembly to the other end region of the multilevel conveyor assembly.

11. The food defrosting machine of claim 10, wherein the enclosed tunnel is located above the multi-level conveyor assembly.

12. The food defrosting machine of any preceding claim, wherein at least one of the upper and lower conveyors is semi-enclosed for inhibiting leakage of the airflow from the multi-level conveyor assembly.

13. The food defrosting machine of claim 12, wherein the multi-level conveyor assembly comprises side walls for inhibiting air leakage out of the semi-enclosed one of the conveyors.

14. The food defrosting machine of claim 13, wherein the side walls comprise hand access apertures.10 07 2515. The food defrosting machine of claim 13 or 14, wherein the upper conveyor is semi-enclosed by an upper boundary and an upper pair of the side walls, or wherein the upper conveyor is open topped.

16. The food defrosting machine of claim 15, wherein the upper conveyor is semi-enclosed by at least an underside of the ducting.

17. The food defrosting machine of any preceding claim, wherein one or more baffles are mounted to an upper boundary of at least one of the upper and lower conveyors, and are arranged to direct airflow downwardly towards a surface of the respective conveyor.

18. The food defrosting machine of any preceding claim, comprising a loading extension allowing the portions of foodstuff to be loaded onto one of the upper and lower conveyors, wherein the loading extension extends beyond the forced air assembly and is separated from the forced air assembly by a partition.

19. The food defrosting machine of claim 18, wherein the loading extension is for one of the upper and lower conveyors, wherein the loading extension comprises a sloped portion of the respective conveyor, changing height from a loading height to a conveyor height of the respective conveyor.

20. The food defrosting machine of claim 18 or 19, wherein an exit end of the other one of the upper and lower conveyors is proximal to the loading extension.

21. The food defrosting machine of claim 20, wherein the exit end is located to eject the portions of foodstuff into a space to the same side of the partition as the loading extension, wherein a chute is provided at the exit end to direct the portions of foodstuff in a predetermined direction.2110 07 2522. The food defrosting machine of any preceding claim, wherein the food defrosting machine comprises a temperature control device configured to control a temperature of the airflow to a temperature value within the range 5 5 Celsius to less than 20 Celsius.

23. The food defrosting machine of any preceding claim, wherein the fan is a bifurcated fan.10 24. A method of operating the food defrosting machine of any precedingclaim, the method comprising:placing portions of foodstuff on a multi-level conveyor assembly comprising an upper conveyor that conveys the portions of foodstuff in a first direction and a lower conveyor that conveys the portions in a second opposite 15 direction; andactivating a fan of a forced air assembly, the forced assembly comprising ducting and the fan, the fan being located within the ducting, the ducting directing airflow from the fan along the upper and lower conveyors in a direction parallel to the first and second directions.2025. The method of claim 24, further comprising activating the temperature control device to control the temperature of the airflow to a value within the range 5 Celsius to less than 20 Celsius.

Images