A system for sterilization and aseptic packaging of solid food using atmospheric pressure water and a method for preservation.

Abstract

This invention discloses a system and method for sterilizing and packaging solid food under normal pressure using water, as well as for preservation. The method includes: steam sterilization of the system interior; introducing sterile gas into a sealed enclosure to maintain a slight positive pressure; pasteurizing the food using hot water at 90-95°C, followed by cooling with cold water to 8-12°C; loading the food into a pre-formed and sterilized packaging box within the sterile chamber; heat-sealing; cutting; and then outputting the food. This invention can achieve effective sterilization and aseptic packaging of solid food at temperatures below 100°C. Depending on the packaging material, the shelf life can be extended to 60-180 days, while preserving the original flavor and texture of the food and significantly reducing energy consumption.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology, specifically relating to an atmospheric pressure water sterilization and aseptic packaging system for solid foods, and a preservation method using this system for food sterilization and packaging. This invention is particularly applicable to the processing and preservation of solid cooked foods such as braised foods (e.g., braised goose, braised duck, braised beef, braised pork), poached chicken, salted duck, and seafood (e.g., shrimp, fish, shellfish). Background Technology

[0002] Refrigeration and preservation technology for cooked foods is an important branch of the modern food industry. Its core objective is to extend the shelf life of food, reduce food waste, and ensure food safety while preserving the original flavor and texture of food to the greatest extent possible.

[0003] Currently, commercially available refrigerated cooked foods are mainly packaged using two methods: manual packaging and cleanroom packaging. Manually packaged refrigerated cooked foods, due to the greater human intervention in the packaging process, are prone to microbial contamination, and their shelf life is typically only 2-3 days. While cleanroom packaging reduces airborne particle and microbial contamination to some extent, the non-completely sealed sterile environment of a cleanroom still presents a risk of contamination during the packaging process, limiting its shelf life to approximately 7 days. This short shelf life presents significant challenges to production, sales, and operational management, hindering mass production and long-distance distribution, resulting in substantial food waste due to expiration.

[0004] To address these issues, some food processing companies have attempted to use freezing technology to extend the shelf life of food. However, freezing technology has significant drawbacks: First, during the freezing process, water inside food cells forms ice crystals, which can puncture cell membranes, leading to cytoplasm loss upon thawing, resulting in a poorer taste and a softer texture. Second, freezing and frozen transportation processes consume a large amount of energy, increasing production costs and carbon emissions. Furthermore, frozen foods must be consumed as soon as possible after thawing and cannot be repeatedly frozen and thawed, causing inconvenience for consumers.

[0005] Another technology for extending the shelf life of food is high-temperature canning sterilization. This technology uses high temperature and high pressure exceeding 100°C to sterilize food, killing all microorganisms, including spores, thus enabling long-term preservation at room temperature. However, high-temperature treatment can destroy heat-sensitive nutrients in food and cause the food to develop a "canned flavor"—an unpleasant change in taste and flavor caused by high-temperature heating, resulting in the food losing its original freshness and texture, leading to lower consumer acceptance.

[0006] Therefore, how to effectively extend the shelf life of solid cooked foods while maintaining their original flavor and texture is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a system and method for sterilizing and packaging solid food with atmospheric pressure water and preserving it. This invention uses atmospheric pressure water below 100°C to directly pasteurize the food, combined with fully automated aseptic packaging technology, which can extend the refrigerated shelf life to 60-180 days or more without damaging the original quality of the food.

[0008] In a first aspect, the present invention provides a system for sterilizing and aseptically packaging solid food with atmospheric pressure water.

[0009] In one overall implementation, the system includes: The basket conveyor chain is used to carry and transport solid food. This conveyor chain passes sequentially through each processing station, enabling continuous production.

[0010] A hot water tank, located on the conveyor path of the basket conveyor chain, is used to hold hot water for pasteurizing the solid food. The temperature of the hot water is controlled below 100°C, preferably 90-95°C, at which temperature the vegetative cells of bacteria can be effectively killed without damaging the food quality.

[0011] A cold water tank, located downstream of the hot water tank on the conveyor chain of the basket, is used to hold cold water for rapid cooling of the sterilized solid food. The purpose of cooling is to quickly lower the food temperature to the refrigeration temperature range to prevent the germination of residual spores.

[0012] A sealed enclosure is installed over at least a portion of the basket conveyor chain to form a sterile cavity. This sealed enclosure isolates subsequent processes such as food filling and packaging from the external environment.

[0013] A sterile centrifugal fan is installed inside the sealed enclosure to further dry and cool the cooled solid food, removing surface moisture and facilitating subsequent heat-sealing packaging.

[0014] The loading position is located inside the sealed cover and is used to load the dried and cooled solid food into the packaging box.

[0015] A film supply unit is used to supply film for packaging boxes. The film supply unit includes a film unwinding mechanism, a film sterilization section, and a thermoforming machine connected in sequence. The film is first sterilized, and then thermoformed into a packaging box of a specific shape using the thermoforming machine.

[0016] A cap film supply unit is used to supply packaging cap film. The cap film supply unit includes a cap film unwinding mechanism and a cap film sterilization section connected in sequence. The cap film is sterilized before sealing to ensure the sterility of the sealing process.

[0017] A sealing section, located inside the sealing cover and downstream of the filling position, is used to heat-seal the cover film onto the packaging box containing the solid food.

[0018] The shearing section, located inside the sealing cover and downstream of the sealing section, is used to cut the sealed packaging box into individual finished products.

[0019] The finished product conveyor line is used to transport the sheared finished product out of the sealed cover.

[0020] In a preferred embodiment, the system further includes a steam pipe. The steam pipe is connected to the sealing cover, the hot water tank, and the cold water tank, and is used to perform overall steam sterilization of the system interior before system startup to ensure initial sterility.

[0021] In a preferred embodiment, the system further includes a temperature control circulation unit. Specifically, the temperature control circulation unit includes: a heat exchanger connected to the hot water tank and the cold water tank for heating or cooling the medium (such as water, brine, or brine); a chiller connected to the heat exchanger for cooling the medium in the cold water tank to 5-8°C; a diaphragm pump for driving the medium to circulate between the heat exchanger and the hot water tank or the cold water tank; and a filter disposed on the medium circulation pipeline for filtering the medium and removing impurities.

[0022] In a preferred embodiment, the sealing cover is provided with a sterile gas inlet for introducing sterile gas (such as sterile air or sterile nitrogen) into the sealing cover to maintain a slight positive pressure. The sealing cover is also equipped with a pressure sensor to monitor the pressure inside the sealing cover and ensure the stability of the slight positive pressure. This design effectively prevents microorganisms in the outside air from entering the interior of the sealing cover through gaps such as the discharge port.

[0023] In a preferred embodiment, the system further includes a traction unit. The traction unit is disposed inside the sealing cover and is used to traction the substrate and / or the cover film to move along the conveying direction, thereby realizing the continuous conveying of packaging materials.

[0024] In a preferred embodiment, the system further includes a waste winding mechanism for recycling the remaining packaging material after shearing by the shearing section, reducing waste and maintaining a clean production environment.

[0025] In a preferred embodiment, the system further includes a PLC central control system. The PLC central control system is electrically connected to the hot water tank, cold water tank, sterile centrifugal fan, various drive mechanisms, and various sensors. It is used to control the temperature and flow rate of the hot water, the synchronous control of the packaging material transfer, the filling and sealing of food, and the cutting control. Process parameters corresponding to different food types are verified through testing and coded into different numbers and stored in the system. During operation, only the corresponding number needs to be retrieved for one-button start, ensuring the repeatability and safety reliability of the process for similar foods.

[0026] Secondly, the present invention provides a method for sterilizing and aseptically packaging solid food with atmospheric pressure water using the above-mentioned system.

[0027] In one overall implementation, the method includes the following steps: (1) System sterilization steps: Steam is introduced into the sealed cover, hot water tank and cold water tank through steam pipes to sterilize the inside of the system and kill microorganisms on the inner surface of the system.

[0028] (2) Steps for establishing a sterile environment: After the system is sterilized, sterile gas is introduced into the sealed enclosure to maintain a slightly positive pressure sterile environment inside the sealed enclosure and prevent external air from backflowing and introducing contamination.

[0029] (3) Medium preparation steps: Heat the hot water in the hot water tank to 90-95℃ and cool the cold water in the cold water tank to 5-12℃. For braised foods, the medium in the hot water tank and cold water tank can be brine; for products such as poached chicken, shrimp, and fish, the medium can be brine.

[0030] (4) Food sterilization and cooling steps: The solid food is placed on the basket conveyor chain and passed through the hot water tank for pasteurization, through the cold water tank for cooling, and through the sterile centrifugal fan for drying and cooling.

[0031] (5) Packaging box forming and sterilization steps: The bottom sheet unwinding mechanism unwinds the bottom sheet, which is first sterilized by the bottom sheet sterilization section and then formed into a packaging box by the vacuum forming machine.

[0032] (6) Cover film sterilization step: The cover film unwinding mechanism unwinds the cover film, and the cover film is sterilized by the cover film sterilization section.

[0033] (7) Filling and sealing steps: In the filling position inside the sealing cover, the sterilized and cooled solid food is filled into the formed packaging box; then the traction unit transports the packaged box filled with food to the sealing unit, and the sterilized cover film is heat-sealed onto the packaging box.

[0034] (8) Cutting output step: The sealed packaging box is transported by the traction unit to the cutting unit for cutting to obtain a single finished product. The finished product is output by the finished product conveyor line, and the packaging material residue is recycled by the waste material winding mechanism.

[0035] In the above steps, steps (4), (5), and (6) can be performed simultaneously, and step (7) is a merging process, thereby achieving continuous production.

[0036] In a preferred embodiment, the pasteurization conditions in step (4) are: maintaining a temperature of 85°C at the center of the thickest part of the solid food for 5 minutes. This condition has been repeatedly verified through experiments and can effectively kill the vegetative cells of bacteria in food at temperatures below 100°C.

[0037] In a preferred embodiment, the slight positive pressure inside the sealed enclosure in step (2) is monitored by a pressure sensor to ensure that external air cannot enter the sealed enclosure from the outlet. Specifically, due to the water seal design at the inlet (the chain and material pass through water), bacteria cannot enter from the inlet; at the material outlet, due to the presence of the slight positive pressure inside, there is always an outward airflow, which also prevents bacteria from entering.

[0038] In the preferred embodiment, the packaged finished product in step (7) is stored under refrigeration conditions of 1-10℃, and the shelf life can reach more than 60 days. The preservation principle is that the vegetative cells of bacteria in the food treated by this method have been completely killed, while the spores, although not killed, are in a dormant state. At the refrigeration temperature of 1-10℃, the spores will not germinate and reproduce, so they will not produce toxins or cause food spoilage. After consumption, the ungerminated spores enter the stomach and are inhibited by gastric acid, so they will not cause harm to health.

[0039] Compared with the prior art, the technical solution provided by the present invention has the following outstanding advantages: (1) Significantly extended shelf life under cold storage: By combining pasteurization with hot water at atmospheric pressure below 100℃ with fully automated aseptic packaging, this invention extends the shelf life of solid cooked food under cold storage from 7 days in the prior art to more than 60 days, an improvement of nearly 8 times. This breakthrough improvement greatly reduces food waste and provides technical support for the large-scale production, long-distance sales and flexible operation management of the product.

[0040] (2) Perfect preservation of the original flavor and texture of food: This invention uses atmospheric pressure hot water below 100℃ for sterilization. The sterilization temperature is comparable to the temperature of regular household cooking and will not cause heat damage to the food. Compared with high-temperature canning technology (>100℃), the product of this invention does not have an unpleasant "canned food taste" and the original flavor is preserved. Compared with freezing technology, the product of this invention will not have the problem of juice loss and soft texture after thawing due to ice crystals piercing cell membranes. The texture and taste of the food are better.

[0041] (3) Significantly reduced energy consumption: Compared with freezing technology, the present invention only requires cooling the product to 8-12°C before refrigeration (1-10°C), without undergoing a freezing process (usually requiring a drop to below -18°C), and does not involve frozen transportation or frozen storage, thus saving a lot of energy. At the same time, the heating temperature of the hot water is only 90-95°C, which is far lower than the temperature of high-temperature sterilization, further reducing energy consumption.

[0042] (4) Achieving fully automated continuous production: The entire process of food conveying, sterilization, cooling, filling, packaging, sealing to shearing output is automatically completed in a closed sterile chamber without human intervention. Through PLC central control, the process parameters of different foods can be preset and called with one click, ensuring the stability and repeatability of the process, and facilitating large-scale industrial production.

[0043] (5) Multi-level aseptic protection system: The present invention constructs a strict aseptic protection system through multiple measures such as initial steam sterilization, online sterilization of packaging materials, water seal at the feed inlet, and micro-positive pressure protection of sterile gas, ensuring that no secondary pollution is introduced during the packaging process and providing a reliable technical basis for long shelf life.

[0044] (6) Wide applicability: The system and method of this invention are applicable to a variety of solid foods, including but not limited to braised foods (braised goose, braised duck, braised beef, braised pork), poached chicken, salted duck, and seafood (shrimp, fish, shellfish), etc. For different foods, only parameters such as the temperature of the hot water tank and the sterilization time need to be adjusted, which has strong versatility and promotional value. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the overall structure of the atmospheric pressure water sterilization and aseptic packaging system for solid food according to the present invention.

[0046] The meanings of the labels in the figures are as follows: 1-Basket conveyor chain; 2-Hot water tank; 3-Cold water tank; 4-Aseptic centrifugal fan; 5-Sealed cover (pot body); 6-Cover film sterilization section; 7-Cover film unwinding mechanism; 8-Waste material winding mechanism; 9-Finished product conveyor line; 10-Shearing section; 11-Traction section; 12-Sealing section; 13-Steam pipe; 14-Filling position; 15-Blister forming machine; 16-Bottom film sterilization section; 17-Bottom film unwinding mechanism; 18-Chiller; 19-Drain valve; 20-Heat exchanger; 21-Diaphragm pump; 22-Filter. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and accompanying drawings. These embodiments are only used to explain and illustrate this invention and should not be construed as limiting this invention in any way.

[0048] Example 1: System Structure Reference Figure 1 This embodiment provides a system for sterilizing and aseptically packaging solid food with atmospheric pressure water.

[0049] The system includes: Basket Conveyor Chain 1: Used to carry and transport solid food. The conveyor chain is made of high-temperature and corrosion-resistant food-grade stainless steel and can operate continuously in a cycle.

[0050] Hot water tank 2: Located on the conveyor path of basket conveyor chain 1, the tank contains hot water (or brine or salt water depending on the type of food). The tank is equipped with a temperature sensor and heating device to control the water temperature at 90-95℃. The length of hot water tank 2 is designed according to the preset sterilization time to ensure that the food remains in the tank for a sufficient period to achieve pasteurization.

[0051] Cold water tank 3: Located on the conveying path of basket conveyor chain 1 and downstream of hot water tank 2, the tank contains cold water (or brine, salt water). The tank is equipped with a temperature sensor and cooling coils to control the water temperature at 8-12℃.

[0052] Sealed enclosure 5: This is a sealed cavity structure (often called a "pot" in the food processing industry), covering the rear half of the basket conveyor chain 1 (starting from the outlet of the cold water tank 3, passing through loading, sealing, shearing, and finally to the finished product outlet), forming a sterile cavity. The inlet side of the sealed enclosure 5 connects to the cold water tank 3. Because the inlet is designed with a water seal structure—the chain and material pass through water—bacteria cannot enter the sterile cavity through this inlet. The finished product outlet of the sealed enclosure 5 is equipped with an air curtain or similar structure, which, combined with internal slight positive pressure, prevents external air from flowing back in.

[0053] Aseptic centrifugal fan 4: Located inside the sealed enclosure 5, above the outlet of the cold water tank 3, it is used to blow air to dry and further cool the solid food coming out of the cold water tank 3.

[0054] Sterile gas supply system: This includes a sterile gas generator and piping, through which sterile air or sterile nitrogen is introduced into the interior via a sterile gas inlet on the sealed enclosure 5. A pressure sensor is also installed on the sealed enclosure 5 to monitor the pressure inside the cavity and ensure that a slightly positive pressure is maintained (e.g., 5-20 Pa higher than atmospheric pressure).

[0055] Film supply unit: includes film unwinding mechanism 17, film sterilization section 16, and vacuum forming machine 15. Film unwinding mechanism 17 is used to unwind packaging box films (usually multi-layer composite plastic sheets). The film is drawn by traction section 11 and first enters film sterilization section 16, which can sterilize both sides of the film using steam or hydrogen peroxide. After sterilization, the film enters vacuum forming machine 15, where it is formed into a packaging box of a specific shape under heating and vacuum / compressed air.

[0056] The cap film supply unit includes a cap film unwinding mechanism 7 and a cap film sterilization section 6. The cap film unwinding mechanism 7 is used to unwind the packaging cap film (usually a composite film or aluminum foil film). The cap film is pulled by the traction section 11, first enters the cap film sterilization section 6 for sterilization, and then enters the sealing section 12.

[0057] Loading position 14: Located inside the sealed enclosure 5, downstream of the thermoforming machine 15. The formed packaging box is transported to the loading position 14 by the traction unit 11 or another clamping conveyor. At this time, the basket conveyor chain 1 also transports the sterilized and dried solid food to directly above the loading position 14. A pressing mechanism is provided at the loading position 14. Figure 1 (Not shown in the image), the food on the basket conveyor chain 1 can be pushed down into the packaging box below.

[0058] Sealing section 12: Located downstream of the filling position 14. The food-filled packaging box is conveyed to the sealing section 12 by the traction section 11, and the sterilized lid film is also pulled to the top of the sealing section 12. The sealing section 12 heat-seals the lid film onto the edge of the packaging box by heating and pressurizing, forming a sealed package.

[0059] Shearing section 10: Located downstream of sealing section 12. Sealed continuous packaging boxes (multiple packaging boxes connected together) are conveyed to shearing section 10 by traction section 11. Shearing section 10 cuts the connected packaging boxes into individual finished products by mold and punching mechanism.

[0060] Finished product conveyor line 9: Located downstream of the shearing section 10, it is used to convey the sheared individual finished products out of the sealed cover 5 and into subsequent packaging or direct storage for cold storage.

[0061] Waste winding mechanism 8: Used to recycle the remaining packaging material edge scraps after shearing by shearing section 10, keeping the production environment clean.

[0062] Steam pipe 13: Connected to the sealing cover 5, hot water tank 2, and cold water tank 3, it is used for comprehensive steam sterilization of the system interior before system startup. Steam pipe 13 is equipped with a steam trap 19 for draining condensate.

[0063] The temperature-controlled circulation unit includes a heat exchanger 20, a chiller 18, a diaphragm pump 21, and a filter 22. The heat exchanger 20 is connected to the hot water tank 2 and the cold water tank 3 via piping, and can provide heating or cooling to the medium in the tanks as needed. The chiller 18 is connected to the heat exchanger 20 and provides a low-temperature refrigerant to cool the medium in the cold water tank 3 to 5-8°C. The diaphragm pump 21 drives the medium to circulate between the heat exchanger 20 and the tanks. The filter 22 is installed on the circulation pipeline to filter impurities in the medium and maintain its cleanliness.

[0064] PLC central control system ( Figure 1 (Not shown in the image): Electrically connected to all the controllable components mentioned above (such as heating devices, cooling devices, pumps, fans, various drive motors, sensors, etc.). The PLC has pre-stored process parameters corresponding to various foods (such as hot water temperature, sterilization time, cooling temperature, packaging speed, etc.). During operation, simply select the food type number, and the system will run automatically.

[0065] Example 2: System Workflow This embodiment describes a method for sterilizing and aseptically packaging solid food using atmospheric pressure water with the system of Example 1. Taking braised goose meat as an example, the specific process is as follows: (a) Pre-production preparation and system sterilization Before starting the system, open the steam pipe 13 to introduce high-temperature steam into the sealed enclosure 5, hot water tank 2, and cold water tank 3 to thoroughly sterilize the entire system and kill any microorganisms that may be attached to the system's internal surfaces. After maintaining the steam sterilization for a certain period of time (e.g., 15-30 minutes), close the steam valve.

[0066] The condensate in the pipes and tank is drained through the steam trap 19.

[0067] (II) Establishment of a sterile environment and preparation of media Turn on the sterile gas supply system to continuously introduce sterile air into the sealed enclosure 5. Monitor and adjust the air intake using a pressure sensor to maintain a slight positive pressure inside the sealed enclosure 5 (e.g., 10 Pa higher than the external atmospheric pressure). At this time, because the internal pressure is slightly higher than the external pressure, external air cannot enter the cavity from gaps such as the finished product outlet.

[0068] Start the temperature control circulation unit: For braised foods, pre-prepared brine is added to both the hot water tank 2 and the cold water tank 3. The brine in the hot water tank 2 is heated to 92-95℃ via heat exchanger 20, and the temperature is maintained uniformly through circulation by diaphragm pump 21. The brine in the cold water tank 3 is cooled to 8-12℃ via heat exchanger 20 and chiller 18. The filtration system runs continuously to keep the brine clean.

[0069] (III) Food sterilization and cooling The pre-braised goose meat (cooled to room temperature) is neatly arranged on the basket conveyor chain 1. The residence time in the hot water tank 2 is initially set according to the size and thickness of the goose meat pieces to ensure that the center temperature of the thickest part of the goose meat can reach above 85℃.

[0070] The basket conveyor chain 1 carries the goose meat into the hot water tank 2, where the meat is completely submerged in hot brine at 92-95℃. As the meat moves forward in the hot water, the core temperature of the goose meat gradually rises. Preliminary experiments have determined that when the core temperature of the thickest part of the goose meat reaches 85℃, maintaining this temperature for 5 minutes is optimal. At this point, the vegetative cells of all bacteria inside the goose meat (including common bacteria such as Salmonella, Listeria, and E. coli) are effectively killed. Because the sterilization temperature remains below 100℃, the muscle fiber structure of the goose meat is not damaged, resulting in a rich, savory flavor and a tender texture.

[0071] After sterilization, the basket conveyor chain 1 carries the goose meat away from the hot water tank 2 and immediately into the cold water tank 3. The goose meat is immersed in cold brine at 8-12℃ for rapid cooling. The purpose of cooling is to quickly lower the temperature of the goose meat to prevent any remaining spores from germinating at a suitable temperature. The goose meat remains in the cold water tank 3 for a sufficient time to lower its core temperature to below 15℃.

[0072] After cooling, the goose meat leaves the cold water tank 3 and enters the sealed enclosure 5. At this time, a sterile centrifugal fan 4 blows sterile cold air from above onto the goose meat, further cooling it and drying any remaining moisture on its surface. A dry surface is beneficial for the sealing quality of subsequent heat-sealing packaging.

[0073] (iv) Packaging box forming and sterilization Simultaneously with the above steps, the film unwinding mechanism 17 unwinds the packaging box film. The film is pulled by the traction unit 11 and first enters the film sterilization unit 16. In the sterilization unit, sterilization can be performed by steam, ultraviolet light, or hydrogen peroxide, effectively killing any microorganisms attached to the surface.

[0074] The sterilized clean sheet enters the vacuum forming machine 15. The vacuum forming machine 15 heats the sheet to a softening temperature, and then uses vacuum suction or compressed air to adhere the softened sheet to the mold surface, forming a packaging box of a specific shape (such as a rectangular or oval tray). The formed packaging box is then conveyed by a clamping and conveying device (…). Figure 1 (Not shown in the image) Continue forward to loading position 14.

[0075] (v) Sterilization by covering with film Simultaneously with the above steps, the cover film unwinding mechanism 7 unwinds the cover film. The cover film, pulled by the traction unit 11, first enters the cover film sterilization unit 6. In the sterilization unit, the cover film can be sterilized by steam, ultraviolet light, or hydrogen peroxide. After sterilization, the cover film continues to be conveyed forward to the sealing unit 12 to await further processing.

[0076] (vi) Filling and sealing When the packaging box reaches the loading position 14, the position sensor sends a signal. At this time, the basket conveyor chain 1 carrying the sterilized and cooled goose meat is also directly above the loading position 14. The pressing mechanism of the loading position 14 moves downward, pushing the goose meat on the basket conveyor chain 1 into the packaging box below. This process is completed in the sterile environment of the sealed enclosure 5, ensuring that the food does not come into contact with external contaminants.

[0077] The packaging box containing the goose meat is conveyed forward by the traction unit 11 to the sealing unit 12. At the same time, the sterilized lid film also arrives above the sealing unit 12, covering the opening of the packaging box. The sealing unit 12 descends, and the lid film and the edges of the packaging box are heated and pressurized by the heating plate to achieve heat sealing. The heat sealing parameters (temperature, time, pressure) are preset according to the packaging material to ensure a firm seal and no leakage.

[0078] (vii) Cutting and Output After sealing, the continuous packaging (multiple boxes connected in one strip) is conveyed forward by the traction unit 11 to the shearing unit 10. The shearing unit 10 cuts the continuous packaging into individual packages using a punching die according to the preset spacing between the boxes.

[0079] The cut-off individual finished products fall onto the finished product conveyor line 9 and are conveyed out of the sealed cover 5. At the same time, the remaining packaging material edge scraps are automatically wound up and recycled by the waste material winding mechanism 8.

[0080] After being collected by the conveyor line, the finished products are immediately transferred to a cold storage room at 1-5℃ for cold storage. The time from sealing to entering the cold storage is controlled within 30 minutes to ensure that the products are always kept in a low-temperature environment.

[0081] (viii) Continuous production and parameter control The above steps (3) to (16) are performed simultaneously to achieve continuous production. The PLC central control system monitors key parameters such as the temperature of the hot water tank 2, the temperature of the cold water tank 3, the pressure inside the sealed cover 5, and the conveying speed in real time. If a parameter exceeds the set range, the system will automatically alarm or adjust. For different types of food (such as braised duck, braised beef, and poached chicken), the corresponding process parameters (hot water temperature 92-95℃, center temperature 85℃ for 5 minutes) are basically the same. The main difference is the residence time in the hot water tank (depending on the size and thickness of the food). These parameters are stored in the PLC after being verified by experiments. Each time production is carried out, only the corresponding food number needs to be retrieved and the system can run automatically.

[0082] Example 3: Product Testing and Effect Verification The inventors used the system and method of Example 1 to conduct batch production tests on various solid foods and carried out a series of tests and evaluations on the products.

[0083] Tested products: braised goose, braised beef, poached chicken, and cooked shrimp.

[0084] Process parameters: Hot water bath temperature: 92-95℃ Target temperature for food processing: 85℃ Core temperature holding time: 5 minutes Cold water bath temperature: 8-12℃ Finished product refrigeration temperature: 1-5℃ Test items and results: Microbiological testing: The total bacterial count was determined according to the national food safety standard GB 4789.2-2022. The results showed that the total bacterial count of all products was <10 CFU / g (below the detection limit) when samples were taken on the 1st, 30th and 60th day after sealing. This indicates that the vegetative cells of bacteria in the product were completely killed and no obvious spore germination and reproduction occurred during the 60-day refrigeration process.

[0085] Sensory evaluation: Ten trained sensory evaluators conducted blind tests on the product, evaluating aspects including color, aroma, taste, and texture. There were no significant differences in sensory indicators between the product after 60 days of refrigeration and the product on day 1 after production (P>0.05). Compared to commercially available frozen braised goose meat, the meat of this invention is firmer and juicier, without the "sponge-like" texture and juice loss issues commonly found in frozen products. Compared to high-temperature canned products, this invention's product has no "canned taste" and a more natural flavor.

[0086] Shelf life assessment: Based on the comprehensive microbial testing and sensory evaluation results, the shelf life of the product of this invention under refrigeration conditions of 1-10℃ can reach more than 60 days, which is more than 8 times that of the cleanroom packaged products in the prior art (7 days).

[0087] Energy consumption comparison: Taking the processing energy consumption per ton of braised goose meat as an example, the energy consumption of the method of this invention (atmospheric pressure hot water pasteurization + refrigeration) is approximately 120 kWh / ton, while the energy consumption of the traditional freezing method (-35℃ quick-freezing + -18℃ frozen storage) is approximately 350 kWh / ton. The method of this invention saves approximately 65% ​​of energy. Furthermore, this invention eliminates the need for refrigerated transportation, further reducing carbon emissions throughout the supply chain.

[0088] Typical example: Production of braised goose meat Taking approximately 200g pieces of braised goose leg meat as an example, the goose leg meat is placed on a conveyor belt in a basket, which runs at a speed of 0.5 meters per minute. The hot water tank is 6 meters long, and the goose leg meat stays in the hot water tank for 12 minutes. Temperature probe verification shows that the center temperature of the thickest part of the goose leg meat (approximately 4cm) reaches 85℃ about 7 minutes after entering the hot water tank and remains at this temperature for the next 5 minutes. Then it enters a cold water tank, which is 4 meters long, and the cooling time is 8 minutes, reducing the center temperature of the goose leg meat to 12℃. After exiting the cold water tank, the surface of the goose meat is dried by a sterile centrifugal fan, and the surface temperature is approximately 7℃. Then, it is automatically boxed, sealed, and cut within a sealed enclosure. The finished product is stored in a 4℃ cold storage. After 60 days, it is taken out for testing, and the total bacterial count is <10 CFU / g, indicating good sensory quality.

[0089] This invention provides a system and method for sterilizing and packaging solid food with atmospheric pressure water and preserving it using aseptic packaging. By organically combining atmospheric pressure hot water pasteurization at below 100℃ with fully automated aseptic packaging technology, it successfully solves the technical problems of short shelf life for refrigerated cooked food, poor taste of frozen food, and flavor deterioration of canned food at high temperatures in existing technologies. This invention extends the refrigerated shelf life of solid cooked food from 7 days to over 60-180 days, while perfectly preserving the original flavor and taste of the food, significantly reducing energy consumption, and achieving fully automated continuous production. It has significant industrial application value and market potential.

[0090] The embodiments described above are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they are not intended to limit the present invention. It should be noted that various changes and modifications can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the concept and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A system for sterilizing and aseptically packaging solid food with atmospheric pressure water, characterized in that, include: Basket conveyor chains are used to carry and transport solid food. A hot water tank is installed on the conveying path of the basket conveyor chain to hold hot water for pasteurizing the solid food. A cold water tank is located on the conveying path of the basket conveyor chain and downstream of the hot water tank, and is used to contain cold water to cool the sterilized solid food. A sealed enclosure is placed over at least a portion of the basket conveyor chain to form a sterile cavity; A sterile centrifugal fan is installed inside the sealed enclosure to dry and cool the cooled solid food. The loading position is located inside the sealed cover and is used to load the dried and cooled solid food into the packaging box; A film supply unit for supplying film for packaging boxes, the film supply unit comprising a film unwinding mechanism, a film sterilization section and a vacuum forming machine connected in sequence; A capping film supply unit for supplying packaging capping film, the capping film supply unit comprising a capping film unwinding mechanism and a capping film sterilization section connected in sequence; A sealing section is provided inside the sealing cover and downstream of the filling position, for heat-sealing the cover film onto the packaging box containing the solid food. A shearing section, located inside the sealing cover and downstream of the sealing section, is used to cut the sealed packaging box into individual finished products. And a finished product conveyor line for conveying the cut finished product out of the sealed cover.

2. The atmospheric pressure water sterilization and aseptic packaging system for solid food according to claim 1, characterized in that, It also includes a steam pipe, which is connected to the sealing cover, the hot water tank and the cold water tank, for steam sterilization of the system interior before system startup.

3. The atmospheric pressure water sterilization and aseptic packaging system for solid food according to claim 1, characterized in that, Also includes: A heat exchanger, connected to the hot water tank and the cold water tank, is used to heat or cool the medium; A chiller, connected to the heat exchanger, is used to cool the medium in the chilled water tank to 5-8°C; A diaphragm pump is used to drive the medium to circulate between the heat exchanger and the hot water tank or the cold water tank. And filters, installed on the media circulation pipeline, are used to filter the media.

4. The atmospheric pressure water sterilization and aseptic packaging system for solid food according to claim 1, characterized in that, The sealing cover is provided with a sterile gas inlet for introducing sterile gas into the sealing cover to maintain a slight positive pressure; the sealing cover is also provided with a pressure sensor for monitoring the pressure inside the sealing cover.

5. The atmospheric pressure water sterilization and aseptic packaging system for solid food according to claim 1, characterized in that, It also includes a traction unit, which is disposed inside the sealing cover and is used to traction the substrate and / or the cover film to move along the conveying direction.

6. The atmospheric pressure water sterilization and aseptic packaging system for solid food according to claim 1, characterized in that, It also includes a waste reeling mechanism for recycling the remaining packaging material scraps after being cut by the shearing section.

7. A method for sterilizing and aseptically packaging solid food with atmospheric pressure water using the system described in any one of claims 1 to 6, characterized in that, Includes the following steps: (1) System sterilization steps: Steam is introduced into the sealed cover, hot water tank and cold water tank through steam pipes to sterilize the entire system; (2) Steps for establishing a sterile environment: After the system is sterilized, sterile gas is introduced into the sealed enclosure to maintain a slightly positive pressure sterile environment inside the sealed enclosure; (3) Medium preparation steps: Heat the hot water in the hot water tank to 90-95℃ and cool the cold water in the cold water tank to 5-12℃; (4) Food sterilization and cooling steps: The solid food is placed on the basket conveyor chain and passes through the hot water tank for pasteurization, through the cold water tank for cooling, and through the sterile centrifugal fan for drying and cooling. (5) Packaging box forming and sterilization steps: The bottom sheet unwinding mechanism unwinds the bottom sheet, the bottom sheet is sterilized by the bottom sheet sterilization section, and then formed into a packaging box by the vacuum forming machine; (6) Cover film sterilization step: The cover film unwinding mechanism unwinds the cover film, and the cover film is sterilized by the cover film sterilization section; (7) Filling and sealing steps: In the filling position inside the sealing cover, the sterilized and cooled solid food is filled into the formed packaging box; then the traction unit transports the packaged box filled with food to the sealing unit, and the sterilized cover film is heat-sealed onto the packaging box. (8) Cutting output step: The sealed packaging box is transported by the traction unit to the cutting unit for cutting to obtain a single finished product. The finished product is output by the finished product conveyor line, and the packaging material residue is recycled by the waste material winding mechanism.

8. The method for sterilizing and aseptically packaging solid food with atmospheric pressure water according to claim 7, characterized in that, In step (4), the pasteurization conditions are: the center temperature of the thickest part of the solid food reaches 85°C and is maintained for 5 minutes.

9. The method for sterilizing and aseptically packaging solid food with atmospheric pressure water according to claim 7, characterized in that, In step (2), the slight positive pressure inside the sealed cover is monitored by a pressure sensor to ensure that external air cannot enter the inside of the sealed cover from the outlet.

10. The method for sterilizing and aseptically packaging solid food with atmospheric pressure water according to claim 7, characterized in that, The packaged finished product in step (7) can be stored under refrigeration conditions of 1-10℃ for more than 60 days.

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