FOODSTUFFS

Field of the Invention This invention relates to a method and apparatus for the sterilisation or disinfection of foodstuffs and in particular but not solely to meat.

Background of the invention The shelf life of food is substantially shortened due to the presence of micro-organisms in the food, which can cause the food to deteriorate. Not only does shelf life affect the economic viability of food producers but it has a direct effect on public health, since the presence of certain micro-organisms in food can be hazardous if the food is ingested. These problems can be exacerbated if the food is not kept sufficiently refrigerated or undercooked, since the micro-organisms in the food can multiply rapidly. in order to overcome the above-mentioned problems, it has been proposed to pasteurise food. However, a disadvantage of pasteurisation is that the process is lengthy and can only be used on certain types of food. Furthermore, the pasteurisation process affects the taste of the food and is costly to perform, since it uses a substantial amount of energy, a great deal of which is discharged into the working environment. in one known method, the food is packaged in an atmosphere which inhibits the fast reproduction of micro-organisms. One such an approach is to package the food product within a carbon dioxide atmosphere. This has proved to be difficult to control, environmentally unfriendly and expensive to run. It also does not kill pathogenic microorganisms but merely slows down their reproduction rate.

Tests carried out by the inventor have shown that it is particularly difficult to control pathogens on chicken such as Campylobacter without affecting the organoleptic qualities of the product.

The micro-organisms which infect chicken are particularly difficult to disinfect because they use the surface of the chicken as protection to provide a defense against disinfectants by lodging in the micro-cracks, fissures and pores of the chicken and are very difficult to dislodge and kill. Strong chemicals and biocides are not acceptable to manufacturers and legislators because they impart objectionable tastes and or smells and can change the constituents of the meat.

At present European legislators have banned acids and production aids such as surfactants.

UV disinfection although being efficient and fast in killing micro-organisms is unable to thoroughly disinfect meat as it can only kill micro-organisms that are exposed to the UV light; unfortunately a high proportion of the micro-organisms are not exposed but hidden from the UV light.

Summary of the invention Aspects of the invention are as set out in the appended claims.

The solution to this problem is a process which removes the micro-organisms from the surface and pores of the meat without changing its organoleptic qualities into a medium (such as water) so that the micro-organisms can then be exposed to some form of benign disinfection and be deactivated or killed.

Preferably the process for removing the micro-organisms from the surface and pores of the meat is ultrasonic pressure waves in the water at frequencies between 20 kHz and 100 kHz. Preferably water is the medium at a temperature of between 60°C and 95 °C to provide the disinfection action. Preferably the immersion treatment time for the meat is between 2.5 seconds and 30 seconds.

Results have shown that the new process is particularly good at disinfecting the surface of meat and chicken in particular without affecting the organoleptic qualifies of the product.

Drawings Embodiments of the disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

Fig. 1A - shows a side cross-section view of an example deep ultrasonic narrow tank; Fig, 1 B - shows an end cross-section view of the example deep ultrasonic narrow tank of Fig. 1A;

Figs. 2A and B - show part sectional side views of an example entrance module for a deep ultrasonic narrow tank such as the tank of Fig. 1 A;

Figs. 3A and B - show part sectional side views of the exit module for a deep ultrasonic narrow tank such as the tank of Fig. 1 A:

Fig. 4 - shows a side view of an assembled modular assembly with a flat split top; and Fig. 5 - shows a side view of an assembled modular assembly with a canopy top.

Specific description Tests carried out by the inventor have shown that there is not a single process which satisfactorily disinfects meat rather it has been shown that two synergistic processes working together gives a good disinfection result (up to 5 log micro-organism reduction) whilst meeting the requirements of the manufacturers and the food legislators. Good results on whole chicken (up to 5 log micro-organism reduction) were obtained by using Ultrasonic pressure waves in water at an elevated temperature to remove the micro-organisms from the surface of the chicken into the hot water which were then killed by the temperature of the water. Chicken skin is a very poor conductor of heat and can sustain immersion in hot water without transmitting the heat through the skin to the surface of the chicken if the immersion time is relatively short hence avoiding deterioration in organoleptic qualities of the chicken. There are no chemicals or acids associated with this invention only ultrasonic vibration, heat and water, Embodiments of the claims relate to an apparatus for disinfecting products, such as the apparatus shown in Figs. 1 - 5.

The first 2 modules will be described in detail with the aid of Figs 1 - 3. A first embodiment of the disclosure is shown in Figs 1 A and 1 B which show a part section through a main module 25 of a modular system comprising a rectangular tank 1 with two vertical wails with a bottom and two flanges 2 rigidly fixed to each of its ends producing an open ended tank 1 . The top of the vertical walls are formed into a turned over edge for safety reasons. Preferably the tank 1 is made of a food grade material. Preferably the food grade material is a food grade stainless steel such as 304 or 316. Preferably the walls and bottom of the tank 1 are formed from sheet metal bent or folded into shape. Preferably the bottom has a "V" form to allow easy drainage. Preferably the flanges 2 are welded to each end of the walls of the tank. The flange 2 has a series of holes placed around its profile to enable it to be connected to another flange 2 with the same hole profile. The purpose of the flanges 2 are so a number of module 25 can be arranged in a serial manner with other modules 25 and bolted together with a suitable food grade seal 29 in between the flanges 2 to produce one long watertight tank. Preferably the fiange 2 is made of a food grade material. Preferably the food grade material is a food grade Viton, silicon rubber or some other food grade rubber. Preferably all of the flanges are substantially the same dimensions.

Each wall of the tank 1 has a recess 26 to accommodate two ultrasonic transducers 3; four in total which when energized will produce the required ultrasonic pressure waves in the tank 1 . In the case of a very hot water tank (above 80 °C) then instead of a recess 26 a "cut out" (not shown) is made in the wall of the tank 1 to allow the rear of the ultrasonic transducer 3 to protrude through the wail of the tank 1 for cooling purposes. Preferably the ultrasonic transducers 3 are of the piezo-electric type. Preferably the ultrasonic transducers 3 are of the "drop in" submergib!e type. Preferably the ultrasonic transducers 3 are sized to provide 12-30 wafts per liter of ultrasonic power. The Ultrasonic transducers are powered by a power electronic control unit (not shown) whose parameters are very closely matched to the transducer's characteristics to keep the transducers 3 at peak performance all of the time. Preferably the control unit has a variable power control. Preferably the control unit has customizing wave shape control. Preferably the control unit has local closed loop control to maintain the frequency of ultrasonic pressure waves to the desired specification. Preferably the control unit has variable frequency and sweep frequency control. Preferably the control unit has the ability to communicate with a PLC with master and slave capability.

Above the recess 26 are situated two heaters 4, one on each wall of the tank. These heaters heat the water when the tank 1 is full up to the water line 7. A small recirculating pump and pipework (not shown to aid fig clarity) is fitted to pull hot water from higher up the tank and deliver if info the bottom of the tank to aid heating efficiency. This is counter intuitive as heaters are normally placed in the bottom of a tank to allow the heat to rise and the cold water to fail. The inventor has found that heaters when energized create localized boiling at the heater surface which manifests itself as small bubbles of steam in the water which in turn collapse the ultrasonic bubbles in the water reducing the ultrasonic cleaning effect. This effect is solved by positioning the heaters 4 at the top of the tank and placing a heater guard 5 over the heater which doubles as a chimney, guiding the steam bubbles to the surface of the water and minimizing any significant dispersion of the steam bubbles in the main body of the wafer. The guard 5 also prevents the chicken 12 from getting burnt by the heaters 4 as they pass through the tank 1 .

The heaters 4 are controlled by a temperature controller {not shown) and two or more temperature probes 16 are situated in the top and bottom in the tank 1 , fixed through the wail of the tank 1 to provide fast and accurate water temperature control. Preferably the heater 4 is the rod type suitably fixed to the side of the tank. Preferably the heater 4 is controlled by a temperature controller to a tight tolerance. Preferably the temperature controller is part of an overall PLC which controls the whole treatment process. A heat exchanger arrangement would also be perfectly adequate to provide water at the required temperature and those skilled in the art of water heating are able to provide suitable schemes. Situated on the water line 7 is an oil and fat skimmer 6 which is of a box type construction with one open side and three closed sides. The height of the box is positioned equally above and below the water line 7. Protruding from the bottom of the rear side is a pipe 10 which is suitably sealed through the wall of the tank 1 . Attached to the pipe is a valve 27 which is normally closed when de-energized which when energized fakes any fats and oils which have accumulated on the surface of the water to drain by gravity therefore minimizing any carry through on the chicken 12 as it leaves the tank. The oil and fat skimmer is operated by a solenoid valve 27 which is automatically opened on a time cycle as a small amount of water is simultaneously fed into the tank 1 to slightly raise its level. Preferably the oil skimmer 6 is made of a food grade material. Preferably the food grade material is a food grade stainless steel such as 304 or 318. Preferably the walls of the oil skimmer 6 are formed from sheet metal bent or folded into shape. Preferably the oil skimmer 6 is of welded construction.

A pair of level defectors 17 and 37 are situated at the desired water level 7 and at a minimum water level which operates a valve which when open adds water to the tank to compensate for water loss through carry-out on the chicken and any evaporation. The whole outside of the tank is heat insulated with a suitable heat insulator 13 to minimize heat loss from the tank 1 . Situated on the top of the tank 1 is a hinged heat insulated two piece lid 14 designed to allow the chicken support bracket 1 1 to pass through the flexible flaps 15 whilst substantially maintaining the heat inside the tank. The split lid 14 is hinged to allow access to the tank 1 if required. Preferably the flexible flaps 15 are made of a food grade material. Preferably the food grade material is viton, silicon rubber or some other food grade rubber. Placed in the bottom of the tank is an outlet pipe 9 and placed adjacent to one of the heaters 4 is an inlet pipe 8. The water in the tank gets dirty as the volume of treated chicken 12 rises and needs to be cleaned. The dirty wafer is taken out via the outlet 9 and cleaned with a proprietary water filtering system (not shown) which includes a filter and an in line heater in its return pipe to compensate for any heat lost through the cleaning operation. The clean hot water is returned to the tank 1 through inlet 8 and through the heater section to maximize heat retention. Preferably the pipework 8 and 9 is made of a food grade material. Preferably the food grade material is a food grade stainless steel such as 304 or 316. Preferably the filter is of the self-cleaning type.

An inlet module 20 and exit module 22 is required to ease inlet and outlet of the chicken 12 and form a watertight tank with the modular section 25. The inlet module and exit modules 20 and 22 will be described in detail with the aid of Figs 2 and 3.

Figs. 2A and B show the inlet module 20 which is a triangular tank with 2 fiat vertical triangular shaped side walls 34 and a fiat third wail 28 inclined at 45 degrees to the vertical. The 2 vertical walls and the base of the 45 degree inclined wall are rigidly attached to a flange 19. The top of the vertical walls are formed into a turned over edge for safety reasons. The flange 19 has a series of holes placed around its profile to enable it to connected to another flange with the same hole profile. Placed in the fiat third wall 28 is a recess or pocket 39 to house an ultrasonic transducer 3 to provide the ultrasonic pressure waves in the inlet module. Preferably the inlet module 20 is made of a food grade material. Preferably the food grade material is a food grade stainless steel such as 304 or 316. Preferably the walls of the inlet module 20 are formed from sheet metal bent or folded into shape.

Figs. 3A and B show the exit module 22 and is an exactly the same as the inlet module 20 only rotated 180 degrees. The outlet module 22 shows is a triangular tank with 2 fiat vertical triangular shaped side walls 32 and a flat third wall 33 inclined at 45 degrees to the vertical. The 2 vertical walls and the base of the 45 degree inclined wall are rigidly attached to a flange 21 . The top of the vertical walls are formed into a turned over edge for safety reasons. The flange 21 has a series of holes placed around its profile to enable it to connected to another flange with the same hole profile. Placed in the fiat third wail 33 is a recess or pocket 38 to house an ultrasonic transducer 3 which provides the ultrasonic pressure waves in the inlet module. Preferably the outlet module 22 is made of a food grade material. Preferably the food grade material is a food grade stainless steel such as 304 or 316. Preferably the walls of the outlet module 22 are formed from sheet metal bent or folded into shape. Preferably the outlet module 22 is of welded construction.

In a second embodiment of the invention and referring to Figs 4 and 5 shows all of the modules are put together to form a process. Fig 4 shows an inlet module 20 which is rigidly fixed to two main modules 25 which are also rigidly fixed together with an exit module 22 rigidly fixed to the last main module 25. Preferably the modules 20, 25 and 22 are rigidly attached together using bolts (not shown). Preferably the modules have a food grade seal 29 between the module flanges 19 - 2, 2 - 2 and 2 - 21 . Preferably the food grade seal is viton, silicone rubber or some suitable food grade rubber to form a watertight seal. This assembly is rigidly attached to a base 23 with angle brackets 40 and levelled with anti-vibration feet or pads (not shown).

Fig 5 shows an optional hood 24 over the tank assembly otherwise the tank assembly is the same as described in Fig 4 without the base (not shown).

This forms the process which will now be described in detail, initial conditions - The assembly is filled with water up to the required water level 7. When the water reaches to the required water level heaters 4 on the main modules 25 are switched on and the water is heated to the required temperature between 60 degrees Celsius and 95 degrees Celsius. As the water is heating up the ultrasonic transducers 3 are switched on and set to the precise settings programmed info the PLC (not shown). The ultrasonic transducers 3 degas the water to ensure that the ultrasonic pressure waves are at maximum efficiency before any chicken 12 is introduced. The process - when the water is up to temperature chicken 12 carcasses supported on a conveyor carrier system 1 1 which is usually an existing part of the chicken production process enter 35 the ultrasonic process at the inlet module 20, proceed through the ultrasonic tanks 25 and exit 36 through the outlet module 22. As the chicken 12 goes through the process the ultrasonic pressure waves in the water generated by the ultrasonic transducers removes the micro-organisms from the microcracks, fissures and pores of the chicken 12 skin info the water and the elevated temperature of the water kills the microorganisms in a sufficiently fast treatment time as to not affect the organoleptic qualities of the product.

Embodiments of the disclosure provide an apparatus for disinfecting products, for example foodstuffs such as meat, vegetables and nuts. An example apparatus is shown in Figs 1A and 1 B. The apparatus shown in Figs. 1 A and 1 B comprises a tank 1 for holding a liquid such as wafer for bathing the products therein. The tank 1 comprises a channel for the liquid arranged to enable a product 12 to be carried into, along, and out of the channel. At least one ultrasonic transducer 3 is arranged to be at least partially submerged in the liquid for providing ultrasonic energy via the liquid to a product 12 bathed in the liquid in the channel for forcing microorganisms off the product 12 and into the liquid. A heater 4 is arranged to heat the liquid in the channel to a temperature for killing microorganisms in the liquid. in the example shown in Figs. 1 A and 1 B, the profile of the tank 1 is symmetrical about a central axis and comprises a U-shaped channel, in the example shown, the tank 1 is formed from a food grade stainless steel that has been bent/folded into shape.

The U-shaped channel is bounded by two opposing piezoelectric ultrasonic transducers 3 on either side of the channel, thus totalling four ultrasonic transducers 3 in the tank 1 extending along the length of the channel. Each ultrasonic transducer 3 is coupled to a wall of the tank 1 inside the tank 1 and is arranged to be at least partially submerged in the liquid in the tank 1 . In this way, each ultrasonic transducer 3 defines a boundary of the liquid in the tank 1 . in the example shown, the ultrasonic transducers 3 are located in matching recesses in the walls of the tank 1 , such that a face of each ultrasonic transducer 3 is flush with an interior surface of the tank 1 .

Also located in the tank 1 are a pair of opposing heaters 4. The heaters 4 are each longer (in the direction of the channel) than each of the ultrasonic transducers 3. The heaters 4 extend along the length of the channel in the tank 1 and are coupled to an interior wall of the tank 1 above the ultrasonic transducers 3. The heaters 4 are therefore at least partially submerged in the liquid at a shallower depth than that of the ultrasonic transducers 3. The heaters 4 are not recessed in a wall of the tank 1 and therefore protrude into the channel of the tank 1 , although of course in other examples the heaters 4 may be recessed info a wall of the tank 1 in a similar way to the ultrasonic transducers 3 described above, in the example shown the heaters 4 are immersion heaters, such as filament heaters, but it will be understood that other types of heater, such as a heat exchanger arrangement, may be used, in other examples the tank 1 may not comprise any heaters 4, and instead the liquid may be heated outside the tank 1 and circulated into the tank 1 as hot liquid. The heaters 4 are each surrounded by a respective guard 5 over each heater 4. Each guard 5 may be formed from sheet metal, such as food grade stainless steel, that has been bent/folded into a box type construction to surround each heater 4. The box type construction is open on one side (the top side) to provide a chimney and allow the passage of bubbles to flow to the surface of the liquid in the tank 1 . The tank 1 is further heat insulated with a suitable heat insulator 13 to minimise heat loss from the tank 1 .

The tank 1 is arranged to hold a liquid in use. The tank 1 is arranged to hold the liquid to a liquid level 7, Either side of the liquid level 7, slightly above the heaters 4, are a pair of liquid level detectors 17 and 34 coupled to an interior surface of the tank 1 . The tank 1 also comprises a pair of temperature sensors 16 coupled to an interior surface of the tank 1 that are below the liquid level 7 and are arranged to be submerged by the liquid in use.

The bottom of the tank 1 has a v-shaped profile, and an outlet 9 is coupled to the tank 1 at the apex of the v-shape, at the deepest part of the tank 1 . The outlet 9 is coupled to a drain. The tank 1 is capped with a hood 14 that comprises a pair of abutting flexible flaps 15 running along the centre of the hood 14. Extending through the flexible flaps 15 is a conveyor 1 1 for carrying a product 12 into, through, and out of the liquid in the channel of the tank 1 . The conveyor 1 1 has a carrier, for example hooks or baskets, for carrying the products 12. For example, each carrier may carry a respective product 12.

As can be seen in Fig. 1 B, on one side of the tank 1 there is an oil and fat skimmer 6 located at the liquid level 7 and above one of the heaters 4. The oil and fat skimmer 6 is of a box type construction with one open side and three closed sides and comprises a filter. In the example shown, the oil and fat skimmer 6 is formed from a food grade stainless steel that has been bent/folded into shape. The height of the box is positioned equally above and below the liquid level 7. The oil and fat skimmer 6 protrudes into the tank 1 and is coupled to a pipe 10 extending through the wall of the tank 1 , which is in turn coupled to a valve 27 located outside the tank 1 . The valve 27 is coupled to a pipe leading to a drain source. On an opposite side of the tank 1 , at approximately the same height as the oil and fat skimmer 6, is an inlet pipe 8 that acts as a feeder and extends through the wail of the tank 1 and is coupled to a source of liquid.

The heater 4, the ultrasonic transducers 3, the conveyor 1 1 , the liquid level detectors 17 and 34, the temperature sensors 18 and optionally the valve 27 and inlet pipe 8/feeder are coupled to and operable by a controller (not shown), such as a programmable logic circuit, PLC.

The tank 1 is arranged to hold a liquid such as water for bathing the products 12 therein. The ultrasonic transducers 3 are arranged to be at least partially submerged by the liquid and are operable to provide ultrasonic energy to the products 12 through the liquid in the channel. In some examples, the ultrasonic transducers 3 are each arranged and/or collectively arranged to provide 12 - 30 watts per litre of ultrasonic energy, for example at least 12 and less than 30 watts per litre. Additionally or alternatively, in other examples the ultrasonic transducers 3 are each arranged and/or collectively arranged to provide at least 30 watts per litre of ultrasonic energy to the liquid. The channel and hood 14/f!aps 15 are arranged so that the conveyor 1 1 carrying the product 12 can carry the product into, through and out of the liquid in the channel, as shown in Fig. 1 B. The position of the ultrasonic transducers 3 and/or the arrangement of the conveyor 1 1 may be selected to provide ultrasonic energy to the centre of the products 12 when the products 12 are submerged in the liquid of the channel of the tank 1 .

The controller is arranged to operate the conveyor 1 1 to control the length of bathing/dwell time of the products 12 in the liquid in the tank 1 . For example, the conveyor 1 1 may be configured to bathe the product in the liquid for at least 2.5 seconds, for example at least 5 seconds, and for less than 30 seconds, for example less than 25 seconds, for example less than 20 seconds. The controller may also be arranged to operate the heaters 4 to control the temperature of the liquid. For example, the heaters 4 may be arranged to heat the liquid in the channel to a temperature for killing microorganisms in the liquid, for example to at least 60 °C, for example at least 80 °C. The heaters 4 may be arranged to heat the liquid in the channel to a temperature that is selected to kill microorganisms but minimise any effect on the organoleptic properties of the product 12 being carried through the liquid. For example, the heaters 4 may be arranged to heat the liquid to less than 95 °C.

The guards 5 are arranged to convey any bubbles produced by the heaters 4 in the liquid away from the channel, and away from the ultrasonic transducers 3. In some examples, the guards 5 may extend to the surface of the liquid, thereby forming two regions in the tank 1 - a first region in which a heater 4 is submerged, and a second region providing the channel for the products 12 to pass therethrough.

The inlet pipe 8/feeder arrangement is arranged to top-up the level of the liquid in the tank 1 in response to the liquid level sensors 17, 37 indicating that the level of the liquid in the tank 1 fails below a selected threshold, and may be operated by the controller.

The controller is arranged to turn off at least one of the heaters 4 and at least one of the ultrasonic transducers 3 in response to the liquid level sensors 17, 37 indicating that the level of the liquid in the tank 1 falls below a selected threshold. The threshold may be selected by the controller and/or programmed by an operator. The controller is also arranged to switch on at least one of the heaters 4 and at least one ultrasonic transducer 3 in response to the liquid level sensors 17, 37 indicating that the level of the liquid in the tank 1 is above a selected threshold. The oil and fat skimmer 6 is arranged to syphon off some of the liquid in the tank 1 from a region near the top of the tank, for example a region near the top of the channel, at selected intervals, and is configured to remove oils, fats and/or other debris from the liquid. The intervals may be selected by the controller and/or programmed by an operator, for example the intervals may be triggered by the controller, for example based on signals received from sensors in the tank 1 such as the liquid level detectors 17, 37 and/or temperature sensors 16. The apparatus is also arranged to replenish the liquid in the tank 1 as liquid is removed by the skimmer 6 and/or the liquid level drops, for example due to evaporation or carry over (for example, some liquid may be carried out of the tank 1 on the product 12). For example, the controller may receive signals from the liquid level detectors 17, 37 indicating that the liquid level in the tank 1 is low, and operate the inlet pipe 8/feeder arrangement to supply more liquid to the tank 1 . in some examples, the replenished liquid is heated prior to circulation into the tank 1 .

The outlet 9 at the bottom of the tank 1 is arranged to drain the liquid from the tank 1 , and in some example, it is arranged to filter and/or heat the liquid drained from the tank 1 and recirculate the filtered and/or heated liquid to the tank 1 , for example via inlet pipe 8. in operation, products 12 are loaded onto the conveyor 1 1 , The conveyor 1 1 carries the products into, through and out of the liquid in the channel of the tank 1 . The conveyor 1 1 passes through the flexible flaps 15 which are forced apart by the movement of the conveyor 1 1 , but which return to their original, abutting, configuration once the conveyor 1 1 has passed so as to retain heat inside the tank 1 and to reduce evaporation of the liquid from the tank.

As the conveyor 1 1 carries the products 12 through the tank 1 , the ultrasonic transducers 3 impart ultrasonic energy to the products 12 via the liquid and force microorganisms off the products 12 and into the liquid. Because the liquid has been heated to a temperature for killing microorganisms, the microorganisms forced off the products 12 are then killed by the heat of the liquid. The dwell time of the products 12 in the liquid of the tank 1 is selected so as to minimise any change to the organoleptic properties of the product 12 caused by the temperature of the hot liquid.

Any bubbles produced by the heaters 4 in the tank 1 are funnelled/conveyed away from the ultrasonic transducers 3 by the guards 5. This may improve the efficacy of the transmission of ultrasonic energy to the products 12.

In some examples, the plurality of ultrasonic transducers 3 may be arranged either side of the channel, for example so that they mirror each other. In other examples, the ultrasonic transducers 3 may be arranged along only one side of the channel. The plurality of ultrasonic transducers 3 may be evenly spaced along the length of the channel. The plurality of ultrasonic transducers 3 may extend substantially the whole height of the tank 1 and/or channel. The plurality of ultrasonic transducers 3 may be phase linked and/or synchronised, for example synchronised in frequency. if will of course be understood that the heaters 4 need not be located inside the tank 1 , but that instead the liquid may be heated outside the tank 1 , and hot liquid fed into the tank 1 . in some examples, the tank 1 comprises a flow provider arranged to recirculate liquid from a region at the top of the tank to a region at the bottom of the tank. This may help to ensure that all parts of the tank 1 are at the correct temperature for killing the microorganisms. in some examples, the ultrasonic transducers 3 may comprise a heat sink for removing heat. For example, the heat sink may comprise a radiator for radiating heat away from the ultrasonic transducers 3. In some examples, the tank 1 may comprise a cut-out region exposing at least a portion of the ultrasonic transducers 3 outside the tank 1 . The portion of the ultrasonic transducers 3 outside the tank 1 may be a face of an assembly enclosing the ultrasonic transducers 3. in some examples, the tank 1 described above may form part of a modular system, in the example shown in Figs. 1A and 1 B, the tank 1 is arranged to be a module of a modular system, whereby a number of modules may be coupled together to form an assembly. Accordingly, at each end of the tank 1 there is flange 2 for coupling with an adjacent tank 1 . The flange 2 is made from a resilient material such as viton, silicone rubber or some other suitable food grade rubber, and is arranged to provide a water-tight seal between two tanks 1 to allow the passage of liquid and products 12 between the tanks 1 , However, in other examples, it will be understood that the tank 1 may be self- contained. In such examples the tank 1 may comprise end walls. The end walls may be sloped, for example at 45 degrees relative to the liquid level, to facilitate the entry and exit of products 12 into and out of the tank 1 .

An example assembly comprising such a modular system is shown in Figs. 4 and 5. The assembly of Figs. 4 and 5 comprises two main modules 25 coupled together in series via a flange 2, The assembly also comprises two end modules 20, 22 coupled to respective ends of the series of main modules 25 also via flanges; an inlet module 20 and an exit module 22, for example as shown in Figs. 2A, 2B and 3A, 3B respectively. The modules 20, 25, 22 of the assembly are arranged to couple together to allow the passage of products 12 and liquid through the modules 20, 25, 22.

The inlet and exit modules 20, 22 are substantially identical, and each comprises a triangular-shaped tank arranged to hold a liquid and forming a channel for the passage of liquid and products 12 therethrough. Each inlet and exit module 20, 22 has a respective flange 19, 21 arranged to couple with an end of a main module 25, such as the tank 1 shown in Figs. 1A and 1 B. in some examples, each inlet and exit module 20, 22 may comprise an ultrasonic transducer 3, for example seated in a recess or pocket 19, 38 in the bottom of the module and arranged to provide ultrasonic energy upwards towards products 12 in the channel from beneath the channel. in operation, products 12 may be loaded onto the conveyor 1 1 . The conveyor 1 1 carries the products 12 into, through and out of the liquid in the channel of the inlet module 20, through the channels of the two main modules 25, and through and out of the channel of the exit module 22. As the conveyor 1 1 carries the products 12 through the modules 20, 25, 22, the ultrasonic transducers 3 impart ultrasonic energy to the products 12 via the liquid and force microorganisms off the products 12 and into the liquid. Because the liquid has been heated to a temperature for killing microorganisms, the microorganisms forced off the products are then killed by the heat of the liquid. The dwell time of the products 12 in the liquid of the tank 1 is selected so as to minimise any change to the organoleptic properties of the product 12 caused by the temperature of the hot liquid, in some examples, a single controller may control operation of all of the modules 20, 25, 22 of the assembly and all elements thereof.

It will of course be understood that the length of the assembly can be adjusted by altering the number of modules 20, 25, 22, for example by adding or removing the number of main modules 25. This may be desirable if a longer dwell time of the product 12 in the liquid is desired, for example.

The above embodiments are to be understood as illustrative examples. Further embodiments are envisaged. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims. in some examples, one or more memory elements can store data and/or program instructions used to implement the operations described herein. Embodiments of the disclosure provide tangible, non-transitory storage media comprising program instructions operable to program a processor to perform any one or more of the methods described and/or claimed herein and/or to provide data processing apparatus as described and/or claimed herein.

The activities and apparatus outlined herein may be implemented with fixed logic such as assemblies of logic gates or programmable logic such as software and/or computer program instructions executed by a processor. Other kinds of programmable logic include programmable processors, programmable digital logic (e.g., a field programmable gate array (FPGA), an erasable programmable read only memory (EPROM), an electrically erasable programmable read only memory (EEPROM)), an application specific integrated circuit, ASIC, or any other kind of digital logic, software, code, electronic instructions, flash memory, optical disks, CD-ROMs, DVD ROMs, magnetic or optical cards, other types of machine-readable mediums suitable for storing electronic instructions, or any suitable combination thereof.