Patent Application
20150157033
A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the reproduction of the patent document or the patent disclosure, as it appears in the U.S. Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
This application claims benefit of the following patent application(s) which is/are hereby incorporated by reference: None
Not Applicable
Not Applicable
The present invention relates to a seafood processing apparatus and methods of processing seafood.
It is known to process packaged seafood by pasteurization or sterilization. Pasteurization usually involves heating the packaged seafood to temperatures of around 85 to 90° C. and then cooling prior to storing the packages in refrigerated conditions. Sterilization usually involves heating the seafood to temperatures of around 115 to 121° C. Sterilized seafood does not need to be stored in refrigerated conditions.
In known pasteurization apparatus and methods, seafood is packaged in sealed packages. The packages may be metal cans, plastics tubs that have an aluminium easy open lid or plastics pouches. The packaged seafood is loaded into baskets and placed in an unpressurised cooking tank. The baskets are submerged in water in the cooking tank. The water is heated to bring it up to the cooking temperature. The cooking temperature is typically 85 to 90° C. Once the cooking process is complete, the baskets are removed from the cooking tank and submerged in cooling water in an unpressurised cooling tank. Once the cooling process is complete, the pasteurized seafood packages are removed from the pasteurization apparatus and stored in refrigerated conditions.
The invention provides a method of pasteurizing seafood comprising disposing a sealed package containing seafood in a seafood processing chamber; providing a liquid in said processing chamber in which liquid said package is submerged; heating said liquid to a pasteurization temperature to pasteurize said seafood; providing a controlled pressure gas in said processing chamber; and controlling the pressure P1 of said controlled pressure gas such that during pasteurization of the seafood an internal pressure P2 in said package is at least one of: not greater than said pressure P1 by more than a predetermined amount; equal to said pressure P1; and less than said pressure P1.
The invention also includes seafood processing apparatus comprising: a seafood processing chamber to receive a liquid in which sealed packages containing seafood are to be submerged; a heating system to deliver heat to said liquid in said processing chamber to heat said liquid to a pasteurization temperature to pasteurize the seafood in said sealed packages; a gas supply system to supply pressurized gas to said processing chamber; and a control system configured to control the pressure P1 of the pressurized gas in said processing chamber such that during pasteurization of the seafood an internal pressure P2 in said seafood package is at least one of: not greater than said pressure P1 by more than a predetermined amount; equal to said pressure P1; and less than said pressure P1.
Referring to
The metal body 12 comprises a cylindrical side wall 20 closed at one end by a transverse bottom wall 22. Although not essential, in the illustrated example the side wall 20 and bottom wall 22 are integral and may be formed by a metal pressing process, such as drawing. Alternatively, the side wall 20 and bottom wall 22 may be separate and joined by seaming. The metal body 12 may be formed from a suitable plated steel, such as tin plated steel. In another example, the metal body may be formed of tin free steel, which may be produced by applying an electrolytic chromic acid treatment of sheet steel.
The opening 16 is defined in the region of the free end of the side wall 20 by an annular member 24 that is secured to the side wall. The annular member 24 may be secured to the metal body 12 by a crimping or rolling process, or by means of a suitable soldering or adhering process. The annular member 24 may be a metal member and is preferably made of a metal having the same, or a similar, coefficient of thermal expansion as the metal from which the metal body 12 is made.
The annular member 24 comprises an upstanding outer side wall 26, an annular ledge 28 extending radially inwardly of the side wall 26 and a downwardly extending annular lip 30 at the radially inner edge of the ledge. The lip 30 defines the opening 16. The ledge 28 is disposed below the free, or upper, end of the outer side wall 26 so that the annular member 24 defines a recess to receive the closure member 18. An annular recess 32 may be provided in the upper face of the ledge 28 where it meets the lip 30 so as to ensure that there are no upward bulges, or discontinuities, at the inner periphery of the ledge that might interfere with sealing between the ledge and the closure member 18. An annular groove 38 (
The closure member 18 is a plastics member with a circular profile configured to allow the closure member to seat on the ledge 28 with its outer periphery disposed radially inwardly of and adjacent the outer side wall 26 of the annular member 24. The upper side of the closure member 18 may be provided with a pull tab 32 (
Although not essential, in the illustrated example, the closure member 18 is a plastics laminate. As best seen in
a layer 50 of polyethylene terephthalate (PET)
a printed layer 52
a layer 54 of PET SiOx
a layer 56 of PET
a polymer peel layer 58.
The layer thicknesses may be:
In the illustrated example, the closure member 18 is substantially transparent across its entire major surface area, thereby making it easy to view the crabmeat 14. The only obstruction to sight of the crabmeat will be the printing of the printed layer 52. In general, it is likely to be preferable to minimize the amount of printing on the closure member 18 as this is likely to reduce the viewing area unnecessarily. In some examples, the printed layer 52 may comprise a solid band of color printed around the periphery of the closure member 18, thereby defining a centrally located viewing portion, or window.
In the example illustrated by
In other examples, the peel layer 58 may be omitted and a suitable adhesive or bonding material provided on at least one of the outer periphery of the underside of the closure member 18 and the ledge 28. The adhesive or bonding material would be one suitable for use in packaging foodstuffs and selected to provide sufficient adhesion to maintain a seal during transport, handling and storage, yet allow removal by pulling on the tab 32 to peel the closure member 18 away from the ledge 28 so as to provide access to the crabmeat 14.
In the illustrated example, the closure member 18 is a laminate comprising five layers. It is to be understood that this is not essential as one or more layers may be omitted or added. For example, one or both of a transparent ultra violet (UV) blocking and a vapor blocking layer may be included in the laminate structure. Normal plastics materials will leak vapors over time so it may be desirable to include one or more vapor blocking layers to reduce such leakage and potentially extend the shelf life of the packaged crabmeat product. The vapor blocking layer may comprise a transparent aluminum oxide. The silicon oxide component of the PET SiOx layer 54 of the example illustrated in
The inner walls of the metal body 12 may be coated with a suitable protective coating 60. The protective coating 60 may assist in isolating the crabmeat 14 from the metal body 12. The protective coating 60 may also provide a layer of protection in the event the plating is damaged or defective so that the crabmeat 14 will not be affected by any corrosion of the metal body 12 that might otherwise occur. The coating 60 may be a lacquer suitable for use in packaging foodstuffs, for example, polyethylene terephthalate.
A lining 62 may be provided between the metal body 12 and crabmeat 14. The lining 62 may cover the inner sides of the cylindrical side wall 20 and the bottom wall 22 and be provided as a one piece lining. The lining 62 may help to prevent metal from the metal body 12 leaching, or migrating, into the crabmeat 14 and adversely affecting its flavor. In the illustrated example, the lining 62 comprises a layer of parchment.
A vegetable oil such as olive or sunflower oil may be added to the crabmeat. The vegetable oil may be added after the crabmeat has been placed in the metal body 12. The vegetable oil, especially olive oil, may improve the flavor of the crabmeat 14. The vegetable oil may also assist in providing a barrier to metal leaching, or migrating, from the metal body 12 into the crabmeat.
Although not essential, the crabmeat 14 typically comprises chunks and similarly large portions of meat, rather than flakes or shredded crabmeat. Although not limited to this use, the metal body 12 and closure member 18 are particularly suitable for packaging premium crabmeat products such as colossal or jumbo chunks. This is because the metal body 12 provides the chunks with protection against damage during handling and storage of the packaged crabmeat product, while the crabmeat 14 can readily be inspected through the closure member 18 to allow a consumer to confirm the presence of undamaged chunks of crabmeat, rather than cheaper, less desirable, flakes and shredded crabmeat. However, it is to be understood that the crabmeat 14 may include any grade of crabmeat, including flakes and shredded crabmeat.
The sealed package 10 may be provided with a paper label (not shown) wrapped around the metal body 12 and carrying details of the supplier and product contained in the package. Alternatively, the package 10 may be provided with a shrink wrap film wrapper (not shown) that may wrap around the metal body 12 and at least partially cover the closure member 18. The shrink film wrapper may be a PET shrink film wrapper. The shrink film wrapper may be printed with details of the supplier and product contained in the package. The engagement of the shrink film wrapper with the metal body 12 and closure member 18 may provide securing of the closure member to the metal body. When a shrink film wrapper is used, it is preferable to avoid printing on parts that will rest against the closure member so as not to reduce the viewing area unnecessarily.
Referring to
not greater than the pressure P1 by a predetermined amount;
equal to the pressure P1; and
less than said pressure P1.
Referring to
Referring to
As shown in
The sealed packages 114 may be stacked one upon another in the baskets 138. Alternatively a layer of packages 114 may be placed in a basket 138 and covered by a separation member such as the separation members 144, 146 illustrated in
The separation member 144 comprises a sheet of metal, or suitably heat resistant plastics material, provided with through-holes 148 to allow for circulation of the liquid 118 during the pasteurization of the seafood in the packages 114. The separation member 146 comprises a frame 150 with a plurality of wires 152 attached to the frame and arranged to form a grid or mesh. The frame 150 and wires 152 may be made of stainless steel.
The separation members 144, 146 may seat directly on the sealed packages 114. Alternatively, separation member supports (not shown) may be secured to the sides of the basket, or spacers disposed between adjacent separation members so that the separation members do not contact the sealed packages 114 below them.
Referring to
The liquid supply system 160 may comprises a water inlet pipe 162 that may be directly connected to a source of mains pressure water, or to a header tank. The liquid supply system 160 may further comprise a water inlet valve 164 to permit control of the supply of water to the water tank 130. The water inlet valve 164 may be an electrically controlled valve, such as a solenoid valve. The water inlet pipe 162 joins and forms a T with water distribution piping 166. The water distribution piping 166 comprises left and right branches that enter the tank 130 at the end 142 and extend in parallel spaced apart relation along the tank to the access opening 132, where they are connected by a transverse section so that in plan the water distribution piping has a generally rectangular profile. Water distribution holes (not shown in the drawings) are provided in the water distribution piping 166 so that when the water inlet valve 164 is opened and water flows through the piping, it sprays out from the water distribution piping into the tank 130. Although not essential, the water distribution holes may be evenly distributed along the length of the portion of the water distribution piping 166 that is within the tank 130. Although not essential, in the illustrated example the water distribution piping 166 is disposed adjacent the top of the tank 130 and as shown in
Referring to
Referring to
Referring to
The cooling system 200 may also comprise a cooling water return pipe 214, which branches from the water inlet pipe 202 to return cooling water to the cooling water tank 208. The cooling water return pipe 214 may be connected with flexible piping 216 (
Referring to
Referring to
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Referring to
The processing chamber at 112 is provided with a pressure release valve (not shown) configured to vent air 114 from the processing chamber 112 if the pressure P1 exceeds a predetermined pressure PMAX.
Referring to
As shown in
In use of the seafood processing apparatus 110, an operator loads sealed packages 114 containing seafood into the processing chamber 112. The packages 114 may be loaded into the processing chamber 112 in one or more of the baskets 138. The baskets 138 may be positioned on the guide rails 136 so that they are supported by the rails and can be moved along the processing chamber 112 guided by the rails. Once the processing chamber 112 is loaded with the desired number of packages 114, the operator seals the access opening 132 by means of the cover 134 and inputs a start command to the controller 260. The controller 260 may initiate operation of the seafood processing apparatus 110 by sending a signal to the water inlet valve 164 to cause the valve to open and allow water to flow through the water inlet pipe 162 into the water distribution piping 166. The water is conveyed into the processing chamber 112 by the water distribution piping 166 where it is output into the tank 130.
The liquid level sensor 272 outputs signals to the controller 260 indicating the level of the water 118 in the tank 130. When the signals indicate that a predetermined level has been reached, the controller 260 sends a signal to the recirculation pump 192 to start up. The predetermined level may be approximately 50% of the tank height, for example 52%. The recirculation pump 192 then operates to draw water from the tank 130 and pump it through the re-circulation piping 194 and back into the tank to create a recirculating flow of the water, thereby agitating the water in the tank. When the controller 260 receives signals from the liquid sensor 272 indicating that a predetermined fill level has been reached, a signal is sent to the water inlet valve 164 to cause it close and prevent the flow of water through the water inlet pipe 162. The fill level may be around 90% of the tank height, for example 92%.
When the tank 130 is filled to the required fill level, the controller 260 activates the heating system 116 by sending a signal to the steam inlet valve 182. The signal causes the steam inlet valve 182 to open and allow steam to flow through the steam supply piping 174 into the steam distribution piping 172. Heat from the steam distribution piping 172 is output into the water 118 progressively heating the water to raise its temperature to the pasteurization temperature. The pasteurization temperature may be around 85 to 95° C. The controller 260 is able to monitor the temperature of the water 118 utilizing signals received from the temperature sensor 262 and cause the steam inlet valve 182 to open and close in such a way as to bring the temperature of the water up to the pasteurization temperature as quickly as possible and then maintain the pasteurization temperature during the pasteurization (cooking) process. This may involve causing the steam inlet valve 182 to remain continuously open while the temperature of the water 118 is raised to the pasteurization temperature and then causing the valve to close once the required temperature is reached. Since the processing chamber 112 is closed and sealed, the temperature in the chamber should remain relatively steady and not fluctuate, even though the supply of steam is halted. If the temperature of the water 118 as sensed by the temperature sensor 262 approaches or falls below a predetermined lower limit, for example 85° C., the controller 260 may send a signal to the steam inlet valve 182 to cause it to open and admit more steam into the processing chamber 112.
While steam is being admitted into the processing chamber to raise the temperature of the water at 118, the controller 260 sends a signal to the gas inlet valve 252 to cause the valve to open and admit pressurized air into the processing chamber 112 to provide a controlled pressure P1 volume of air 124 in the processing chamber. If the pressurized air is supplied by a compressor 254 associated with the seafood processing apparatus 110, rather than a centralized compressed air supply system, it may be necessary for the controller 260, or an operator, to start the compressor earlier so as to allow a build-up of air pressure prior to the issue of the signal by the controller to the gas inlet valve 252.
The controller 260 may be configured to provide signals that cause the pressure P1 of the air 124 to be controlled such that the internal pressure P2 in the sealed packages 114 is at least one of:
not greater than the pressure P1 by more than a predetermined amount;
equal to the pressure P1; and
less than said pressure P1.
The controller 260 may control the pressure P1 utilizing:
The internal pressure P2 in the sealed packages 114 should be proportional to the temperature of the water 118 as sensed by the temperature sensor 262. This knowledge can be used to develop relationship data for the lookup tables based on measurements of the pressure P2 and corresponding water temperature obtained during trials using the seafood processing apparatus 110 or a suitable apparatus arranged for conducting trials to obtain suitable data. The pressure P2 data may be obtained using a mini, wireless, pressure sensor placed in a sealed package containing seafood during trials. The data obtained can be tabulated in combination with a pressure P1 that is selected to provide the desired pressure P2 against pressure P1 relationship as shown, for example, in the tables below.
A lookup table enabling control based on the pressure P1 against time relationship need only contain the time (T) and pressure P1 data. A lookup table enabling control based on the P1 against temperature relationship need only contain the sensed temperature (t) and pressure P1 data.
If the controller 260 is configured to control the pressure P1 based on the pressure P1 against time relationship, at each time interval, corresponding to the time intervals (T) used in obtaining the data for the lookup tables, the controller 260 compares the sensed pressure P1 as indicated by signals received from the pressure sensor 264 against the respective value for the desired pressure P1 stored in the lookup table. If the pressure P1 indicated by the signals received from the pressure sensor 264 is not sufficiently high for that time interval, the controller 260 sends a signal to the gas inlet valve 252 to cause the valve to open and admit compressed air into the processing chamber 112 to raise the pressure P1 of the air 124. If the pressure is greater than the required pressure P1 indicated in the lookup table by a predetermined amount, the controller 260 may send a signal to the gas outlet valve 256 to cause the valve to open and release air 124 from the processing chamber 112 to reduce the air pressure.
If the controller 260 is configured to control the pressure P1 based on the pressure P1 against temperature relationship, the controller periodically determines what the pressure P1 should be by matching the temperature of the water 118 as indicated by signals received from the temperature sensor 262 with the temperature values stored in the lookup table. The pressure P1 value indicated in the lookup table can then be compared with the actual pressure P1 indicated by signals received from the pressure sensor 264. If the pressure P1 indicated by the signals received from the pressure sensor 264 is not sufficiently high for that sensed temperature, the controller 260 may send a signal to the gas inlet valve 252 to cause the valve to open and admit compressed air into the processing chamber 112 to raise the pressure P1 of the air 124. If the pressure is greater than the required pressure P1 indicated in the lookup table by a predetermined amount, the controller 260 may send a signal to the gas outlet valve 256 to cause the valve to open and release air 124 from the processing chamber 112 to reduce the air pressure.
In the illustrated example, the controller 260 is configured to control the pressure P1 based on both a pressure P1 against temperature relationship and a pressure P1 against time relationship. During a phase of operation of the seafood processing apparatus 110 in which the heating system 116 is operating to raise the temperature of the water 118 in the processing chamber 112 to the pasteurization temperature, the controller 260 may control the pressure P1 based on a pressure P1 against temperature relationship. Once the pasteurization temperature has been reached and is being maintained during pasteurization of the seafood in the sealed packages 114, the control of the pressure P1 may be based on the pressure P1 against time relationship.
The controller processor 266 may set a pasteurization process commenced flag when signals from the temperature sensor 262 to indicate that the water temperature has reached the pasteurization temperature. The processor 266 may then use its internal clock, or another counter associated with the controller 260, to measure a set time period required for the pasteurization (cooking) phase to complete. When the processor 266 determines that the pasteurization phase is complete, the controller 260 may send signals to the discharge pipe valve 232 to cause the valve to open and allow the heated water 118 to discharge from the tank 130 via the discharge pipe 230. When the controller 260 receives signals from the liquid level sensor 272 indicating that a predetermined low water level has been reached, the controller signals the cooling system 200 to activate the cooling water pump 206 and the regulating valve 218. The cooling water pump 206 pumps cooling (iced) water from the cooling water tank 208 into the cooling water inlet pipe 202. Initially, the regulating valve 218 is fully open and the pressure in the cooling water inlet pipe 202 is insufficient to open the check valve 204. Consequently, the pumped cooling water is returned to the cooling water tank 208 via the cooling water return pipe 214 and flexible piping 216. As the regulating valve 218 is progressively closed, the pressure in the cooling water inlet pipe 202 builds up until there is sufficient pressure to open the check valve 204. Cooling water then flows through the check valve 204 into the water distribution piping 166 which discharges the cooling water into the tank 130.
The controller 260 may signal the discharge pipe valve 232 to close at substantially the same time as it signals the cooling system 200 to activate the cooling water pump 206 and regulating valve 218. Alternatively, the discharge pipe valve 232 may be kept open for a predetermined period following the activation of the cooling water system 200 to allow some residual heat to be removed from the processing chamber 112 in a flow of discharging cooling water. When the controller 260 signals the discharge pipe valve 232 to close, the tank 130 fills with cooling water. The rising water level is monitored by the controller 260 using signals received from the water level sensor 272. When a predetermined fill level is reached, the controller 260 signals the cooling water pump 206 to cease pumping. The predetermined fill level may be around 90% of the tank height, for example 92%. Either when a predetermined level is reached during the filling process, or when the fill process is complete and the cooling water pump 206 is commanded to cease pumping, the controller 260 may signal the recirculation pump 192 to commence pumping so that cooling water from the tank 130 is pumped through the recirculation piping 194. The recirculation pump 192 then operates to draw cooling water from the tank 130 and pump it through the recirculation piping 194 and back into the tank to create a recirculating flow of the water thereby agitating the cooling water in the tank. If the recirculation pump 192 is activated at a predetermined level, the level may be approximately 50% of the tank height, for example 52%.
During the discharge of heated water 118 from the tank 130, the pressure P1 in the processing chamber 112 would ordinarily start to reduce as the air 124 expands to occupy the volume previously occupied by the water. However, the internal pressure P2 in the sealed packages 114 may remain high due to the high temperature within the packages. In order to maintain the desired pressure relationship between the internal pressure P2 and pressure P1, the controller 260 may send signals to the gas inlet valve 252 to open and allow more compressed air to flow into the processing chamber 112. The controller 260 may be configured to use the pressure P1 against time relationship or pressure P1 against temperature relationship as described above to control the opening of the gas inlet valve 252 to maintain the desired pressure relationship. Once the cooling process commences and the sealed packages 114 are exposed to the cooling water, the internal pressure P2 should reduce as the temperature of the packages and their contents falls. As the internal pressure P2 reduces, the controller 260 may operate to control the pressure P1 so that it is also reduced so as to maintain a desired relationship between the internal pressure P2 and the pressure P1. To reduce the pressure P1 the controller 260 sends signals to the gas outlet valve 256 to cause it to open and allow air 124 to vent from the tank 130. The controller 260 may be configured to use the pressure P1 against time relationship or pressure P1 against temperature relationship as described above to control the opening of the gas outlet valve 256 to maintain the desired pressure relationship. In the illustrated example, the controller 260 is configured to use the pressure P1 against time relationship to control the opening and closing of the gas inlet and outlet valves 252, 256 during the emptying of the heated water 118 from the tank and during cooling process.
When signals from the pressure sensor 264 indicate that the pressure in the tank 130 has fallen to atmospheric pressure, the controller 260 deems cooling process complete. The cooling process may take between six and twenty minutes. When the controller 260 has determined that the cooling process is complete, it may send a signal to the recirculation pump 192 to cease pumping and command the discharge pipe valve 232 to open and allow discharge of the cooling water from the tank 130. The cover 134 may then be opened and the baskets 138 containing the sealed packages 114 transferred from the processing chamber 112 to the cooling water tank 208, which may contain iced water. At this stage the seafood in the sealed packages 114 will still be warm. The packages 114 are left in the cooling water tank 208 to completely cool prior to the transfer of the packages to a refrigerated environment. In the meantime, the seafood processing apparatus 110 can be prepared for another pasteurization process by loading further baskets 138 containing sealed packages 114 into the tank 130.
The seafood processing apparatus 110 is configured so that a predetermined relationship can be maintained between the internal pressure P2 in the sealed packages and the pressure P1 of the gas in the processing chamber 112. In some examples the relationship is maintained such that the internal pressure P2 does not exceed the pressure P1 by more than a predetermined amount or is substantially equal to the pressure P1. In currently preferred examples, the pressure P1 is maintained so that it is above the internal pressure P2. The pressurization of the processing chamber with the gas may prevent stressing of the seals, or seams, of the sealed packages. In an unpressurised processing chamber, there would be insufficient resistance to the build up of pressure in the sealed packages to prevent stressing of the seals, or seams, of the package, potentially leading to a breach of the package. For example, in the case of a sealed package as illustrated by
In the illustrated example, the rails for the baskets are disposed in an upper region of the processing chamber such that the baskets are suspended from the rails and hang down into the water 118. This is not essential. In some examples a single rail may be provided and the baskets configured to engage and run on a single rail. In other examples, rails may be provided in a lower region of the processing chamber, including along the bottom of the processing chamber.
It is to be understood that complete cooling of the sealed packages may take place in the processing chamber prior to transferring the cooled packages to a refrigerated environment, such as a refrigerated store or refrigerated transportation container. In examples in which complete cooling takes place in the processing chamber, a separate cooling chamber, such as the cooling tank 208, may be unnecessary. However, it may be advantageous to have a first stage cooling process take place in the processing chamber to partially cool the packages followed by a second stage cooling process in a separate cooling chamber to complete the cooling of the packages. By reducing the time the packages spend in the processing chamber, it is possible to increase the throughput of the seafood processing apparatus. In examples in which the packages are only partially cooled in the processing chamber, the cooling should be such as to reduce the internal pressure P2 in the packages to atmospheric pressure.
In the illustrated example, a thermocouple is used to provide indications of water temperature that are used to indicate pressure. It is to be understood that this is not essential. For example, other types of temperature sensor such as thermistors or infra red temperature sensors may be used. Alternatively, pressure sensors or a combination of pressure sensors and temperature sensors may be used. Since suitable pressure and temperature sensors will be known to persons skilled in the art, an exhaustive list of such is not provided herein.
In the illustrated example, the processing chamber is configured to receive a plurality of containers that can each contain a plurality of sealed packages containing seafood. It is to be understood that this is not essential. A seafood processing apparatus according to the invention may be configured to hold just one container containing such packages.
The invention includes methods of processing seafood and seafood processing apparatus in which sealed packages containing seafood are submerged in a liquid in a processing chamber during a cooking process and the pressure of a volume of gas in the processing chamber is controlled such that as the internal pressure in the packages varies due to changes of temperature in the processing chamber the resultant forces acting on the seals, or seams, of the packages will at least not exceed a predetermined value. The pressure of the gas may be controlled such that the internal pressure does not exceed the gas pressure by more than a predetermined amount. The pressure of the gas may be controlled such that the internal pressure and gas pressure are substantially equal and there is substantially no net force acting to separate the seals or seams. The pressure of the gas may be controlled such that the internal pressure is lower than the gas pressure. In some examples, the gas pressure may be controlled such that during certain phases of a cooking process in which the internal pressure is relatively low, the gas pressure is not more than a predetermined amount less than the internal pressure and during increased temperature phases during which the internal pressure is relatively high, the gas pressure is greater than the internal pressure.
In some examples in which the gas pressure is maintained above the internal pressure, it may be desirable to ensure that the gas pressure is not too much greater than the internal pressure, either to avoid damage to the package contents or damage to a seal or seam of the package. For example, in the case of a sealed package such as that illustrated by
Control of the gas pressure based on a predetermined P1 against time relationship may require that the desired pressure P1 is set higher than the internal pressure in the sealed packages to provide a factor of safety in case the process conditions vary too greatly from the test conditions under which the data representing the relationship was obtained. Control based on data representing a pressure P1 against temperature relationship may facilitate more accurate control requiring a lesser, or no safety factor.
It is to be understood that the illustrated and described examples are given to aid understanding of the invention and changes and modifications to the specifically-described examples may be carried out without departing from the principles of the present invention, which is intended to be limited only by the scope of the appended claims, as interpreted according to the principles of patent law, including the doctrine of equivalents.
Thus, although there have been described particular embodiments of the present invention of a new and useful SEAFOOD PROCESSING APPARATUS AND METHODS OF PROCESSING SEAFOOD it is not intended that such references be construed as limitations upon the scope of this invention except as set forth in the following claims.
