Processing method and device for improving freezing damage and reheating fishy smell of fish meat prefabricated dish

Abstract

The invention provides a processing method and device for improving freezing damage and reheating fishy smell of fish meat prefabricated vegetables. The processing method comprises the following steps: carrying out pre-cooling treatment on a pre-treated product by adopting recycled liquid nitrogen cold steam, and carrying out ultralow-temperature liquid nitrogen quick-freezing on the pre-cooled product. Carrying out modified atmosphere packaging and freezing storage on the quick-frozen product to obtain a stored product; and unfreezing and reheating the stored product by adopting a heat pipe microwave coupling technology to obtain a reheated product. The center temperature of the product is reduced to-18 DEG C or below by adopting a liquid nitrogen quick-freezing technology, and the product is sealed and stored by adopting modified atmosphere packaging. And unfreezing and reheating the stored product by adopting a heat pipe microwave coupling technology to obtain a reheated product. In the reheating process, the quality change is monitored through a low-field nuclear magnetic resonance (LF-NMR) technology, the dish is unfrozen at 45 DEG C, the water state of the dish is most stable when the dish is reheated at 800 W, and the quality is better. Through cooperative regulation and control, freezing damage is remarkably inhibited, and deodorization and synergy are achieved in the reheating stage.

Description

Technical Field

[0001] This invention relates to the field of pre-prepared food processing and storage technology, and in particular to a processing method and apparatus for improving frozen damage and reheating fish and meat pre-prepared dishes. Background Technology

[0002] With the rapid development of the ready-to-cook meal industry, fish and meat dishes are favored by consumers for their high-quality protein and unique flavor. However, during the freezing and reheating process, fish and meat products generally suffer from the following problems: First, severe freezing damage occurs. During the freezing process, ice crystals grow slowly, damaging cell structure, leading to increased water migration and juice loss, resulting in poor product texture. Second, the problem of fishy smell re-emerging is obvious. During freezing and reheating, volatile fishy substances (such as trimethylamine and hexanal) accumulated due to oxidation reactions and protein degradation, affecting the quality of consumption. Third, traditional heating and thawing methods have defects. Conventional water baths, steam, or microwave reheating are prone to uneven temperature, over-thawing, or undercooking in the center, further aggravating the release of volatile fishy smells and flavor deterioration.

[0003] Therefore, a new processing technology is needed that can effectively and synergistically regulate the quality and odor release of fish meat throughout the freezing, storage and reheating process, thereby improving the flavor and quality of pre-prepared fish dishes. Summary of the Invention

[0004] To overcome the problems existing in related technologies, the purpose of this invention is to provide a processing method and apparatus for improving the freezing damage and reheating fishy odor of pre-cooked fish dishes. By optimizing the temperature control during the freezing stage, the packaging and storage gas environment, and the coupled heating technology during the reheating stage, the integrity of the fish tissue structure is maintained and the generation and release of fishy odor substances are inhibited, thereby significantly improving the flavor quality of the product after reheating.

[0005] A processing method for improving frozen damage and reheated fishy odor in prepared fish dishes includes: The raw materials are pretreated to obtain pretreated products; The pretreated product is precooled using recycled liquid nitrogen vapor to obtain a precooled product. The pre-cooled product is then subjected to ultra-low temperature liquid nitrogen quick-freezing to obtain a quick-frozen product; The quick-frozen product is subjected to modified atmosphere packaging and frozen storage to obtain the stored product; The stored product was thawed and reheated using heat pipe microwave coupling technology to obtain a reheated product. The reheated product was evaluated using low-field nuclear magnetic resonance technology, and the evaluation results were obtained.

[0006] In a preferred embodiment of the present invention, the pretreatment of the raw materials to obtain a pretreated product includes: The raw materials are descaled, gutted, cut, and washed to obtain the cleaned product; wherein the raw materials are fresh fish meat; The cleaned product is seasoned according to the pre-cooked dish recipe to obtain the pre-treated product.

[0007] In a preferred embodiment of the present invention, the pre-cooling treatment of the pretreated product using recovered liquid nitrogen vapor to obtain a pre-cooled product includes: The pretreated product is placed in the precooling tunnel; The cold vapor recovered from the liquid nitrogen system is introduced into the precooling channel so that the pretreated product is uniformly cooled in a low-temperature airflow environment below -20°C. The pre-cooling time of the pretreated product is controlled to be 3-8 minutes to ensure that the overall temperature of the pretreated product drops to 0-5℃.

[0008] In a preferred embodiment of the present invention, the step of subjecting the pre-cooled product to cryogenic liquid nitrogen quick-freezing to obtain a quick-frozen product includes: The pre-cooled product is placed in a liquid nitrogen quick-freezing device; Start the liquid nitrogen quick-freezing device and freeze the pre-cooled product at a temperature of -120℃±5℃ until the core temperature of the pre-cooled product drops below -20℃. Turn off the liquid nitrogen quick-freezing device and immediately remove the product to obtain the quick-frozen product.

[0009] In a preferred embodiment of the present invention, the step of performing modified atmosphere packaging and frozen storage on the quick-frozen product to obtain the stored product includes: The quick-frozen product is heat-sealed using a high-barrier, multi-layered modified atmosphere film. During the heat-sealing process, N2 is simultaneously introduced to isolate external oxygen, resulting in a packaged product. The packaged product is stored in a frozen storage environment below -18°C to obtain the stored product.

[0010] In a preferred embodiment of the present invention, the step of using heat pipe microwave coupling technology to thaw and reheat the stored product to obtain a reheated product includes: Heat pipes are used to conduct heat to the stored product to thaw the surface of the stored product, thereby achieving temperature gradient equalization. The interior of the stored product is heated by microwave heating to obtain a reheated product.

[0011] In a preferred embodiment of the present invention, after thawing the surface of the stored product, the method further includes: During microwave heating, the core temperature of the stored product is monitored in real time. Microwave heating is stopped when the center temperature is greater than or equal to the reheating temperature threshold.

[0012] In a preferred embodiment of the present invention, the evaluation of the reheated product using low-field nuclear magnetic resonance technology to obtain evaluation results includes: The T2 relaxation curve of the reheated product was measured using low-field nuclear magnetic resonance. The T2 relaxation curve is inverted to obtain the signal peak areas of various water types, including the peak areas of bound water, non-flowing water, and free water. The moisture stability parameter is calculated using the following formula: ; Where Q is the water stability parameter, and A 21 To incorporate the water peak area, A 22 For the area of ​​the water peak that is not easily moved, A 23 The area of ​​the free water peak; The moisture stability parameter is used to quantitatively evaluate the reheating quality of the product after reheating, wherein the moisture stability parameter is positively correlated with the reheating quality.

[0013] In a preferred embodiment of the present invention, after pretreating the raw materials to obtain the pretreated product, the method further includes: Choose lunch boxes with high thermal conductivity and low temperature resistance; The pre-treated product is evenly spread in the lunch box to ensure uniform thickness.

[0014] A processing apparatus for improving frozen damage and reheated fishy odor in pre-cooked fish dishes, used to perform the above-described method, the apparatus comprising: The pretreatment module is used to pretreat the raw materials to obtain pretreated products; The pre-cooling module is used to pre-cool the pre-treated product using recovered liquid nitrogen cold vapor to obtain a pre-cooled product. The quick-freezing module is used to quick-freeze the pre-cooled product with ultra-low temperature liquid nitrogen to obtain the quick-frozen product. The packaging module is used to perform modified atmosphere packaging on the quick-frozen product to obtain the packaged product. A freezing and storage module is used to freeze and store the quick-frozen product to obtain the stored product. The defrost and reheat module is used to defrost and reheat the stored product using heat pipe microwave coupling technology to obtain the reheated product. The low-field nuclear magnetic resonance technology module is used to evaluate the reheated product using low-field nuclear magnetic resonance technology and obtain the evaluation results.

[0015] The beneficial effects of this invention are as follows: This invention provides a processing method for improving frozen damage and reheating fishy odor in pre-cooked fish dishes. The method includes pre-treating the raw materials to obtain a pre-treated product; pre-cooling the pre-treated product using recovered liquid nitrogen vapor to obtain a pre-cooled product; flash-freezing the pre-cooled product with ultra-low temperature liquid nitrogen to obtain a flash-frozen product; modifying atmosphere packaging and freezing storage of the flash-frozen product to obtain a stored product; and thawing and reheating the stored product using heat pipe microwave coupling technology to obtain a reheated product. First, the raw material, fresh fish, is pre-treated, including descaling, eviscerating, cutting, and washing the fresh fish, and seasoning it according to the pre-cooked dish recipe to obtain the pre-treated product. Next, the pre-treated product is placed in a pre-cooling channel, and pre-cooled using recovered liquid nitrogen vapor to lower the product temperature to approximately -1°C, thereby reducing the initial temperature shock during freezing and improving energy efficiency, resulting in the pre-cooled product. The pre-cooled product is then placed in a liquid nitrogen quick-freezing device for ultra-low temperature liquid nitrogen quick-freezing, lowering the product temperature to below -18℃. This effectively inhibits the damage of ice crystals to cell structure, preserves the original flavor substances of the fish meat to the greatest extent, and reduces the release of fishy odor precursors. During the ultra-low temperature liquid nitrogen quick-freezing process, by controlling the freezing rate within the range of 0.8-1.2℃ / min, the product is frozen rapidly and uniformly at low temperatures, which significantly reduces the formation of large ice crystals, maintains tissue integrity, and provides a good foundation for flavor and texture stability in the subsequent reheating process. After ultra-low temperature liquid nitrogen quick-freezing, the quick-frozen product is obtained. Finally, the quick-frozen product is heat-sealed and filled with N2 using a high-barrier, multi-layer composite modified atmosphere film, which effectively inhibits lipid oxidation and the accumulation of fishy odor substances. After heat-sealing, the product is placed in a frozen storage environment below -18℃ for long-term preservation, thus obtaining the stored product. Before consumption, a heat pipe and microwave coupled thawing and reheating device is used to thaw and reheat the stored product. This device utilizes the efficient heat conduction of the heat pipe to achieve temperature gradient equalization, and microwave heating to achieve rapid internal heating. Through this rapid and uniform heating process, protein denaturation and the dissolution and accumulation of volatile fishy-smelling substances caused by uneven or slow heating are effectively reduced, significantly decreasing the perceived intensity of the fishy smell after reheating and reshaping and enhancing the product's edible flavor. This invention's processing method for improving frozen damage and reheated fishy smell in pre-prepared fish dishes can significantly reduce ice crystal damage and freezing damage. Modified atmosphere packaging effectively inhibits lipid oxidation and the formation of fishy-smelling precursors. The heat pipe and microwave coupling technology achieves uniform reheating and deodorization. The overall synergistic processing forms a systematic flavor control system from freezing to reheating, ensuring a significant improvement in the quality, texture, and flavor of the fish product. Low-field nuclear magnetic resonance (LF-NMR) technology is used to quantify changes in moisture distribution in real time, establishing a model corresponding to the Q function and the reheating effect, enabling controllable quality production.Compared with samples not treated with this method, the sensory scores of the products increased by 20%-25%, the moisture migration rate decreased by 20%, the fishy smell was significantly reduced after reheating, and the overall flavor acceptance was greatly improved. Attached Figure Description

[0016] Figure 1 This is a flowchart of the processing method for improving frozen damage and reheated fishy odor in pre-cooked fish dishes according to the present invention; Figure 2 This is a flowchart of the pretreatment and uniform spreading of raw materials according to the present invention; Figure 3 This is a finished product image of the pre-cooked fish and meat dishes of the present invention; Figure 4 This is an electronic nose radar image of the pre-cooked fish and meat dishes of the present invention. Figure 5 This is a univariate linear fitting curve of the moisture state and sensory evaluation of the pre-cooked fish and meat dishes of the present invention. Detailed Implementation

[0017] Preferred embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While preferred embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make the invention more thorough and complete, and to fully convey the scope of the invention to those skilled in the art.

[0018] Example 1 This embodiment provides a processing method for improving frozen damage and reheated fishy odor in pre-cooked fish dishes, including: S1: Pre-treat the raw materials to obtain the pre-treated product; S2: The pretreated product is precooled using recycled liquid nitrogen vapor to obtain a precooled product; S3: The pre-cooled product is flash-frozen with ultra-low temperature liquid nitrogen to obtain the flash-frozen product; S4: The quick-frozen product is subjected to modified atmosphere packaging and frozen storage to obtain the stored product; S5: The stored product is thawed and reheated using heat pipe microwave coupling technology to obtain the reheated product; S6: The reheated product is evaluated using low-field nuclear magnetic resonance technology, and the evaluation results are obtained.

[0019] like Figure 2 As shown, the method of the present invention has been modified in terms of freezing, packaging, and thawing and reheating, and includes the following steps: First, pretreatment and flavoring are carried out. The pretreatment of raw materials yields a pretreated product, including: S11: The raw material is descaled, gutted, cut, and washed to obtain a cleaned product; wherein the raw material is fresh fish meat; S12: Season the cleaned product according to the pre-cooked dish recipe to obtain the pre-treated product.

[0020] Systematic pretreatment of fresh fish is a crucial step in ensuring its deliciousness and safety for consumption. First, the fresh fish is descaled, removing all scales, especially the small scales near the dorsal fin, pelvic fin, head, neck, and tail. Next, the fish is gutted, completely removing the internal organs and gills, and clearing the black membrane from the abdominal cavity. Then, the fresh fish is sliced ​​into pieces or chunks of the desired size according to the needs of the prepared dish. Finally, all the sliced ​​fish is rinsed thoroughly under clean, cold water to remove any remaining bone fragments, blood, and mucus. Fresh fish meat is scaled, gutted, cut, and washed to obtain a cleaned product. The cleaned product is then seasoned according to a pre-made recipe. This process serves several purposes: first, to ensure standardized flavor, making the taste of each batch and each piece of fish completely consistent; second, to ensure process adaptability, as the seasoning method must be compatible with subsequent freezing and reheating processes to ensure the original flavor is maintained after reheating; third, to optimize texture, by using functional ingredients in the seasoning formula to improve the texture of the fish meat after freezing and heating, preventing it from becoming dry; and finally, to ensure safety and preservation, by inhibiting microorganisms and extending shelf life.

[0021] After seasoning, a pre-treated product is obtained. Following the pre-treatment of the raw materials to obtain the pre-treated product, the process further includes: S13: Choose a lunchbox with high thermal conductivity and low temperature resistance; S14: Spread the pre-treated product evenly in the lunch box to ensure uniform thickness.

[0022] High thermal conductivity food containers can rapidly and evenly transfer heat from external heat sources (hot air, thermal radiation) to the frozen fish inside, achieving rapid and uniform thawing and heating. Low-temperature resistant containers maintain good mechanical strength and toughness even under extreme low-temperature conditions, ensuring the containers do not crack or deform throughout the entire freezing, storage, and logistics chain, providing continuous and stable physical protection for the contents. Pre-treated products are evenly spread in the food container, ensuring uniform thickness during layering. This allows for two main benefits: first, it enables uniform and efficient quick-freezing, guaranteeing optimal texture, with all fish pieces or fillets freezing almost simultaneously and rapidly, resulting in fine and uniform ice crystals that minimize damage to muscle cells; second, it ensures precise and consistent reheating, allowing all fish pieces to simultaneously reach ideal doneness and safe temperature within the set time and temperature.

[0023] After pretreatment of the raw materials, the pretreated product is then precooled. The precooling process uses recovered liquid nitrogen vapor to obtain the precooled product, which includes: S21: Place the pretreated product into the precooling channel; S22: Introduce the cold vapor recovered from the liquid nitrogen system into the precooling channel so that the pretreated product is uniformly cooled in a low-temperature airflow environment below -20°C; S23: Control the pre-cooling time of the pretreated product to 3-8 minutes to ensure that the overall temperature of the pretreated product drops to 0-5℃.

[0024] First, the pretreated product is placed in a pre-cooling channel. Cold vapor recovered from the liquid nitrogen system is used as the cold source. Ultra-low temperature nitrogen gas generated from evaporation in the main freezing zone is guided to the pre-cooling channel by a fan, forming a controllable low-temperature airflow. The pretreated product is uniformly cooled in a low-temperature airflow environment below -20°C. The pre-cooling stage is controlled for 3-8 minutes to ensure the overall product temperature rapidly drops to 0-5°C. This pre-cooling step significantly reduces the temperature shock when the product is in direct contact with liquid nitrogen, avoiding surface cracks, film warping, or moisture condensation caused by sudden cooling. It also helps mitigate the impact of rapid vaporization on liquid nitrogen consumption, thereby improving liquid nitrogen utilization and energy efficiency. After pre-cooling, the product enters the liquid nitrogen rapid freezing stage, achieving efficient and coordinated cooling of the surface and core temperatures, providing a good temperature foundation for subsequent freezing to form a dense and uniform ice crystal structure.

[0025] The process of quick-freezing the pre-cooled product with ultra-low temperature liquid nitrogen to obtain a quick-frozen product includes: S31: Place the pre-cooled product into a liquid nitrogen quick-freezing device; S32: Start the liquid nitrogen quick-freezing device to freeze the pre-cooled product at a temperature of -120℃±5℃ until the core temperature of the pre-cooled product drops below -20℃. S33: Turn off the liquid nitrogen quick-freezing device and immediately remove the product to obtain the quick-frozen product.

[0026] The process of freezing the pre-cooled product at a temperature of -120℃±5℃ includes: The freezing rate is controlled within the range of 0.8-1.2℃ / min to ensure that the pre-cooled product cools uniformly from the surface to the center, forming a stable temperature gradient from the surface to the center.

[0027] The pre-cooled product is placed in a liquid nitrogen quick-freezing device for rapid freezing. The cold source in the liquid nitrogen quick-freezing device mainly consists of directly sprayed liquid nitrogen and vaporized ultra-low temperature nitrogen gas. After starting the liquid nitrogen quick-freezing device, the pre-cooled product is rapidly frozen at a temperature of -120℃±5℃, allowing the product to cool evenly from the outside to the inside, forming a stable temperature gradient from the surface to the center. To ensure freezing uniformity, the freezing rate is preferably controlled within the range of 0.8-1.2℃ / min. When the core temperature of the product drops below -20℃, the quick-freezing process is immediately stopped and the sample is removed to avoid overfreezing and causing the tissue structure to become brittle. By rapidly passing the maximum ice crystal formation zone of -1℃ to -5℃ in a very short time, and forming a large number of extremely small ice crystals inside and outside the cells, mechanical damage to the cell structure is minimized, achieving near-perfect preservation.

[0028] After quick-freezing, the product enters the modified atmosphere packaging stage, where the quick-frozen product undergoes modified atmosphere packaging and frozen storage to obtain the stored product, including: S41: The quick-frozen product is heat-sealed using a high-barrier and multi-layer composite modified atmosphere film. During the heat-sealing process, N2 is simultaneously introduced to isolate external oxygen, resulting in a packaged product. S42: The packaged product is stored in a frozen storage environment below -18°C to obtain the stored product.

[0029] High barrier properties and multi-layered composites simultaneously meet all requirements for high barrier strength, toughness, and easy heat sealing. During the heat-sealing process, nitrogen is simultaneously introduced to replace oxygen. By introducing high-purity nitrogen and simultaneously expelling oxygen from the packaging, oxidation reactions and the growth of aerobic microorganisms are fundamentally inhibited. Modified atmosphere packaging effectively isolates external oxygen, inhibits lipid oxidation and the accumulation of volatile odor compounds, thus delaying the deterioration of vitamins and color components. Figure 3 As shown, Figure 3 The leftmost image shows the finished product of the pre-prepared fish and meat dishes of this invention. Compared to the finished products of the pre-prepared fish and meat dishes made by the other three existing methods, the finished product of the pre-prepared fish and meat dishes of this invention has the brightest color, indicating that the vitamins in tomatoes and beans are best preserved. After packaging, the sealed product is obtained. The sealed product is then stored in a frozen storage environment below -18°C for long-term storage, preferably in a temperature range of -18°C to -35°C. The temperature fluctuation during storage should not exceed ±1°C to ensure cold chain stability and prevent repeated freezing and thawing, thus obtaining the stored product.

[0030] This embodiment describes a processing method for improving frozen damage and reheating fishy odor in pre-cooked fish dishes. The method includes pre-treating the raw materials to obtain a pre-treated product; pre-cooling the pre-treated product using recovered liquid nitrogen vapor to obtain a pre-cooled product; flash-freezing the pre-cooled product with ultra-low temperature liquid nitrogen to obtain a flash-frozen product; modifying atmosphere packaging and freezing storage of the flash-frozen product to obtain a stored product; and thawing and reheating the stored product using heat pipe microwave coupling technology to obtain a reheated product. First, the raw material, fresh fish, is pre-treated, including descaling, eviscerating, cutting, and washing the fresh fish, and seasoning it according to the pre-cooked dish recipe to obtain the pre-treated product. Next, the pre-treated product is placed in a pre-cooling channel, and pre-cooled using recovered liquid nitrogen vapor to lower the product temperature to approximately -1°C, thereby reducing the initial temperature shock during freezing and improving energy efficiency, resulting in the pre-cooled product. The pre-cooled product is then placed in a liquid nitrogen quick-freezing device for ultra-low temperature liquid nitrogen quick-freezing, lowering the product temperature to below -18℃. This effectively inhibits the damage of ice crystals to cell structure, preserves the original flavor substances of the fish meat to the greatest extent, and reduces the release of fishy odor precursors. During the ultra-low temperature liquid nitrogen quick-freezing process, by controlling the freezing rate within the range of 0.8-1.2℃ / min, the product is frozen rapidly and uniformly at low temperatures, which significantly reduces the formation of large ice crystals, maintains tissue integrity, and provides a good foundation for flavor and texture stability in the subsequent reheating process. After ultra-low temperature liquid nitrogen quick-freezing, the quick-frozen product is obtained. Finally, the quick-frozen product is heat-sealed and filled with N2 using a high-barrier, multi-layer composite modified atmosphere film, which effectively inhibits lipid oxidation and the accumulation of fishy odor substances. After heat-sealing, the product is placed in a frozen storage environment below -18℃ for long-term preservation, thus obtaining the stored product. Before consumption, a heat pipe and microwave coupled thawing and reheating device is used to thaw and reheat the stored product. This device utilizes the efficient heat conduction of the heat pipe to achieve temperature gradient equalization, and microwave heating to achieve rapid internal heating. Through this rapid and uniform heating process, protein denaturation and the dissolution and accumulation of volatile fishy-smelling substances caused by uneven or slow heating are effectively reduced, significantly decreasing the perceived intensity of the fishy smell after reheating and reshaping and enhancing the product's edible flavor. This invention's processing method for improving frozen damage and reheated fishy smell in pre-prepared fish dishes can significantly reduce ice crystal damage and freezing damage. Modified atmosphere packaging effectively inhibits lipid oxidation and the formation of fishy-smelling precursors. The heat pipe and microwave coupling technology achieves uniform reheating and deodorization. The overall synergistic processing forms a systematic flavor control system from freezing to reheating, ensuring a significant improvement in the quality, texture, and flavor of the fish product. Compared with samples not treated with this method, the product's sensory score increased by 20%-25%, moisture migration decreased by 20%, the fishy smell was significantly reduced after reheating, and the overall flavor acceptance was greatly improved.By leveraging the synergistic effect of heat pipe microwave coupling reheating and combining it with low-field nuclear magnetic resonance (LF-NMR) technology to evaluate moisture migration during thawing and reheating, and using LF-NMR relaxation signals as a quantitative evaluation method for reheating effect, the moisture state of products under different reheating conditions is characterized, thereby determining the optimal process conditions.

[0031] Example 2 This embodiment provides a processing method for improving frozen damage and reheated fishy odor in prepared fish dishes. This embodiment describes the differences from Embodiment 1, based on Embodiment 1. The method includes: S1: Pre-treat the raw materials to obtain the pre-treated product; S2: The pretreated product is precooled using recycled liquid nitrogen vapor to obtain a precooled product; S3: The pre-cooled product is flash-frozen with ultra-low temperature liquid nitrogen to obtain the flash-frozen product; S4: The quick-frozen product is subjected to modified atmosphere packaging and frozen storage to obtain the stored product; S5: The stored product is thawed and reheated using heat pipe microwave coupling technology to obtain the reheated product; S6: The reheated product is evaluated using low-field nuclear magnetic resonance technology, and the evaluation results are obtained.

[0032] The process of thawing and reheating the stored product using heat pipe microwave coupling technology to obtain a reheated product includes: S51: Heat pipes are used to conduct heat to the stored product to thaw the surface of the stored product in order to achieve temperature gradient equalization; S52: The interior of the stored product is heated by microwave heating to obtain a reheated product.

[0033] Heat pipe microwave coupling technology is a deep integration of high-efficiency heat transfer technology (heat pipe) and high-efficiency heating technology (microwave). A heat pipe is a superconducting device that uses phase change (evaporation-condensation) to transfer a large amount of heat. It not only has extremely high equivalent thermal conductivity, hundreds to thousands of times that of copper and aluminum, but also excellent isothermal properties, with minimal temperature difference between the evaporation and condensation sections. Introducing a heat pipe into a microwave system offers several advantages: First, it rapidly transfers heat from localized hot spots generated during microwave heating to lower-temperature regions, achieving temperature homogenization in the product or microwave reactor. Second, by adjusting the cooling intensity of the external cooling system connected to the condensation section of the heat pipe, the temperature of the evaporation section (microwave heating zone) can be precisely controlled, achieving constant temperature or programmed heating. Third, excess heat generated during microwave heating can be efficiently transferred through the heat pipe to products requiring thawing and reheating, achieving cascaded energy utilization and improving overall energy efficiency. Furthermore, the passive and efficient heat transfer of the heat pipe itself reduces the need for excessive microwave energy input to maintain temperature uniformity. By employing heat pipe microwave coupling technology, key challenges such as uniform heating of materials in a microwave field, precise temperature control, and energy efficiency have been solved, thus achieving uniform reheating of stored products. Before consumption, the stored product is placed in a heat pipe and microwave coupled thawing and reheating device. The product is thawed and reheated using heat pipe microwave coupling technology, with the final reheating temperature set at 80±2℃. The total thawing and heating time is controlled to not exceed 10 minutes. A synchronous temperature control feedback system prevents local overheating and secondary protein denaturation.

[0034] After thawing the surface of the stored product, the process further includes: S513: During microwave heating, the core temperature of the stored product is monitored in real time; S514: When the center temperature is greater than or equal to the reheating temperature threshold, microwave heating shall be stopped.

[0035] Before step S513, the system includes step S511: using a heat pipe to conduct heat to the stored product, and step S512: thawing the surface of the stored product. Before starting the thawing and reheating device, a reheating temperature threshold for the stored product needs to be set, for example, setting the reheating temperature threshold to 80℃. After starting the thawing and reheating device, the temperature control feedback system monitors the center temperature of the stored product in real time. When the center temperature is much lower than the reheating temperature threshold of 80℃, the controller automatically uses high-power microwaves to rapidly heat the stored product. When the center temperature approaches the reheating temperature threshold (e.g., reaching 90% of the reheating temperature threshold), the controller automatically reduces the microwave power (e.g., switching to 50% power) to slow down the heating rate of the stored product and avoid temperature overshoot due to thermal inertia. When the center temperature is greater than or equal to the reheating temperature threshold of 80℃, the system immediately stops microwave heating and indicates that reheating is complete. After the microwave heating stops, the user can take out the reheated product and consume it.

[0036] The reheated product was evaluated using low-field nuclear magnetic resonance (NMR) technology, and the evaluation results included: The T2 relaxation curve of the reheated product was measured using low-field nuclear magnetic resonance. The T2 relaxation curve is inverted to obtain the signal peak areas of various water types, including the peak areas of bound water, non-flowing water, and free water. The moisture stability parameter is calculated using the following formula: ; Where Q is the water stability parameter, and A 21 To incorporate the water peak area, A 22 For the area of ​​the water peak that is not easily moved, A 23 The area of ​​the free water peak; The moisture stability parameter is used to quantitatively evaluate the reheating quality of the product after reheating, wherein the moisture stability parameter is positively correlated with the reheating quality.

[0037] The reheated product quality was evaluated using low-field nuclear magnetic resonance (LF-NMR) technology. For each reheated product, several samples were selected, and their T2 relaxation curves were measured using LF-NMR. The LF-NMR spectrometer was a Bruker Minispec mq20, with FID parameters set as follows: gain 61 dB, 8 scans, and a scan interval of 2 s. T2 parameters were set as follows: a CPMG pulse sequence with 1200 echoes and a half-echo time of 0.5 s.

[0038] The peak areas of different moisture components, including the bound water peak area A, were obtained through inversion. 21 Area A of the water peak that is not easily moved 22 and free water peak area A 23 .

[0039] Calculate their respective proportions and define the moisture stability parameter function: ; Where Q is the water stability parameter, and A 21 To incorporate the water peak area, A 22 For the area of ​​the water peak that is not easily moved, A 23 The area of ​​the free water peak.

[0040] Based on the Q-value changes measured under different thawing temperatures, thawing center temperatures, and reheating power conditions, a Q-process curve was established, using LF-NMR data as feedback signals to achieve dynamic optimization of the reheating process. This function comprehensively reflects the ratio of bound water to free water in the fish sample; a larger Q-value indicates a tighter water binding and a more complete structure. By quantifying the changes in water distribution in real time using LF-NMR, a correspondence model between the Q-function and the reheating effect was established, enabling quality-controlled production.

[0041] A processing apparatus for improving frozen damage and reheated fishy odor in pre-cooked fish dishes, used to perform the above-described method, the apparatus comprising: The pretreatment module is used to pretreat the raw materials to obtain pretreated products; The pre-cooling module is used to pre-cool the pre-treated product using recovered liquid nitrogen cold vapor to obtain a pre-cooled product. The quick-freezing module is used to quick-freeze the pre-cooled product with ultra-low temperature liquid nitrogen to obtain the quick-frozen product. The packaging module is used to perform modified atmosphere packaging on the quick-frozen product to obtain the packaged product. A freezing and storage module is used to freeze and store the quick-frozen product to obtain the stored product. The defrost and reheat module is used to defrost and reheat the stored product using heat pipe microwave coupling technology to obtain the reheated product. The low-field nuclear magnetic resonance technology module is used to evaluate the reheated product using low-field nuclear magnetic resonance technology and obtain the evaluation results.

[0042] The pre-processing module is mainly used to pre-process the raw material, namely fresh fish meat. This includes descaling, eviscerating, cutting, washing, and seasoning the fresh fish meat. Descaling and eviscerating are to remove inedible parts to ensure food safety and flavor. Cutting is to divide the fish into specific shapes and sizes according to cooking or sales needs, so as to facilitate even heating, flavoring, packaging, and consumption. Washing removes residual blood, mucus, scales, and internal organ fragments to further clean the fish and remove fishy smell, providing clean raw materials for subsequent processing. Seasoning is to season according to the pre-made recipe. Through standardized and scientific flavor blending, the consistency, stability, and industrial reproducibility of the product's taste are achieved, while meeting the preferences of target consumers, reducing costs, and extending shelf life.

[0043] The pre-cooling module is used to pre-cool the pre-treated products. By introducing the cold vapor recovered from the liquid nitrogen system into the pre-cooling channel, the pre-treated products are uniformly cooled in a low-temperature airflow environment below -20°C. After pre-cooling, the temperature difference impact when the products come into direct contact with liquid nitrogen can be significantly reduced, avoiding surface cracks, film warping, or moisture condensation caused by sudden cooling. At the same time, it helps to reduce the impact of rapid vaporization on liquid nitrogen consumption, thereby improving liquid nitrogen utilization and energy efficiency.

[0044] The quick-freezing module is used for ultra-low temperature liquid nitrogen quick-freezing of pre-cooled products. The pre-cooled products are then rapidly frozen at -120℃±5℃, resulting in uniform cooling from the surface to the center, creating a stable temperature gradient. This rapid and uniform freezing method significantly reduces the formation of large ice crystals, maintains tissue integrity, and provides a good foundation for flavor and texture stability during subsequent reheating.

[0045] The packaging module is used for modified atmosphere packaging of quick-frozen products. It uses a high-barrier and multi-layered composite modified atmosphere film to heat-seal the quick-frozen products. Nitrogen gas is introduced during the heat-sealing process. The modified atmosphere packaging can effectively isolate external oxygen, inhibit lipid oxidation and the accumulation of volatile odor compounds, and delay the deterioration of vitamins and color components.

[0046] The frozen storage module is used to freeze and store quick-frozen products. After the quick-frozen products are packaged with modified atmosphere packaging, they are sealed and then placed in a frozen storage environment below -18°C for long-term preservation, thus obtaining the stored products.

[0047] The defrosting and reheating module uses heat pipe microwave coupling technology to defrost and reheat the stored product. On the one hand, it utilizes the efficient heat conduction of the heat pipe to achieve temperature gradient equalization, and on the other hand, it uses microwave heating to achieve rapid internal heating, thereby achieving uniform reheating and deodorization of the stored product.

[0048] The low-field nuclear magnetic resonance (LF-NMR) technology module evaluates moisture migration during thawing and reheating by using LF-NMR technology. It utilizes LF-NMR relaxation signals as a quantitative evaluation method for reheating effect, characterizes the moisture state of products under different reheating conditions, and thus determines the optimal process conditions.

[0049] Through the overall synergistic processing of the above modules, a systematic flavor control system from freezing to reheating is formed, ensuring a significant improvement in the quality, taste, and flavor of fish products.

[0050] Example 3 This embodiment provides a processing method for improving frozen damage and reheated fishy odor in prepared fish dishes. This embodiment describes the differences from Embodiment 1, based on Embodiment 1. The method includes: S1: Pre-treat the raw materials to obtain the pre-treated product; S2: The pretreated product is precooled using recycled liquid nitrogen vapor to obtain a precooled product; S3: The pre-cooled product is flash-frozen with ultra-low temperature liquid nitrogen to obtain the flash-frozen product; S4: The quick-frozen product is subjected to modified atmosphere packaging and frozen storage to obtain the stored product; S5: The stored product is thawed and reheated using heat pipe microwave coupling technology to obtain the reheated product; S6: The reheated product is evaluated using low-field nuclear magnetic resonance technology, and the evaluation results are obtained.

[0051] This embodiment uses fresh sea bass as the raw material.

[0052] (1) Pre-treatment of fresh sea bass.

[0053] Table 1 Raw Materials and Formulation ; First, the raw material, fresh sea bass, is processed by scaling, gutting, cutting, and washing the fish to obtain sea bass fillets. The fillets are then blanched in hot water at approximately 80 degrees Celsius for ten seconds to remove surface slime, blood, and some lipid impurities. The blanched fillets are immediately removed and patted dry with clean filter paper for later use.

[0054] Next, prepare the tomato sauce. Select ripe tomatoes, peel and chop them, then add a suitable amount of oil, chopped green onions, salt, sugar, and a small amount of black pepper. Heat for three to four minutes to soften the tomatoes and form a thick sauce. Stir gently during heating to prevent burning and to promote a balance of sweet and sour flavors. Set aside after preparation.

[0055] Table 1 shows the ingredients and recipe for pre-treating fresh sea bass. The blanched fish fillets are evenly placed in a lunchbox, approximately 80 grams per box. While still hot, tomatoes are evenly poured over the fish fillets, creating a sauce layer about two millimeters thick, ensuring the fish fillets are fully coated. No further cooking or heating is performed at this point; the residual heat of the sauce is used to lightly cook the surface of the fish fillets, providing a suitable temperature for subsequent cooling and quick-freezing. Basil leaves, corn kernels, or diced carrots are then added.

[0056] After the above pretreatment process, fresh sea bass are processed to obtain a pretreated product.

[0057] (2) Ultra-low temperature liquid nitrogen quick-freezing The pre-treated product is placed in a liquid nitrogen quick-freezing device for quick-freezing. First, it is pre-cooled using recycled liquid nitrogen vapor to rapidly lower the temperature of the fish meat to 0-5℃. Then, it is placed in the liquid nitrogen quick-freezing device and rapidly frozen at -120℃±5℃. The quick-freezing process ends when the core temperature of the product drops below -20℃.

[0058] The pre-treated product undergoes pre-cooling and liquid nitrogen quick-freezing to obtain the quick-frozen product.

[0059] (3) Modified atmosphere packaging and storage The quick-frozen product, i.e., the quick-frozen food container, is sealed with a high-barrier composite film and filled with a mixed preservative gas, N2. The sealing temperature is 135℃, and the sealing edge width is 10mm to ensure airtightness. The finished product can be stably stored for more than 8 months in a cold storage below -18℃, and the content of volatile odorous substances does not increase significantly during the process.

[0060] After quick-freezing, the product undergoes modified atmosphere packaging and storage to obtain the stored product.

[0061] (4) Heat pipe microwave coupling defrosting and reheating Before consumption, the stored product is taken out of the cold storage and placed directly in the heat pipe-microwave reheating device without pre-thawing.

[0062] The reheating parameters are as follows: microwave power: 800W; heat pipe temperature: 45℃; total reheating time: 15min; temperature control mode: real-time monitoring of the center temperature of the fish fillet, and automatic stopping of heating when the center temperature reaches 90±2℃.

[0063] Maintain a uniform temperature field throughout the heating process to avoid overheating of the surface and undercooling of the center.

[0064] After reheating, the sauce on the surface of the product remains bright red, with a distinct basil aroma, and the fish meat is tender and shows no signs of aging.

[0065] Example 4 This embodiment describes the differences from Embodiment 3, based on Embodiment 3. The following are three comparative examples: Comparative Example 1: The difference from Example 3 is that in step (2), conventional freezer freezing was used instead of ultra-low temperature liquid nitrogen quick-freezing.

[0066] Comparative Example 2: The difference from Example 3 is that in step (3), direct packaging was used instead of modified atmosphere packaging and storage.

[0067] Comparative Example 3: The difference from Example 3 is that in step (4), conventional microwave reheating is used instead of heat pipe microwave coupling for defrosting and reheating.

[0068] Figure 3The images show the finished products of Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 3. In Example 3, the surface is smooth and free of ice crystals, resulting in the best appearance.

[0069] Table 2 Color of Pre-cooked Fish and Meat Dishes ; Table 2 shows the color of Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 3. The color of the fish meat is represented by L*, a*, and b* values, where L* represents the brightness value, a* represents the redness value, and b* represents the yellowness value. In Example 3, b* is the smallest, indicating the lowest degree of lipid oxidation on the surface.

[0070] Table 3 Textural characteristics of pre-cooked fish and meat dishes ; Table 3 shows the textural characteristics of Example 3, Comparative Example 1, Comparative Example 2 and Comparative Example 3. As can be seen from Table 3, Example 3 has greater hardness, chewiness and cohesiveness. The smaller the shear force, the better the tenderness of the fish meat. Example 3 has a small shear force and better tenderness, indicating that this treatment method can improve the quality of pre-cooked fish dishes.

[0071] Table 4. Moisture content of prepared fish and meat dishes ; Table 4 shows the moisture state of Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 3. Moisture has a significant impact on the mechanism of fish quality deterioration and tissue structure stability. Table 4 shows the moisture state content under different treatment conditions, T 21 (1-10ms) represents bound water, T 22 (10-100ms) represents still water, T 23 (100-1000ms) represents free water, with the majority of the water in the fish fillet being stagnant water. Bound water does not easily migrate to other areas, indicating that bound water is not affected by small mechanical stresses and microstructural changes in muscle tissue. Example 3 has the least amount of free water, suggesting that this method promotes a more stable water binding state within the fish meat.

[0072] Table 5 Sensory Evaluation Table for Prepared Fish and Meat Dishes ; Table 6 Sensory evaluation results of prepared fish and meat dishes ; Table 5 shows the sensory evaluation tables for Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 3. The scores for different items in Table 5 are summed to obtain the total score, which is less than or equal to 100. Table 6 shows the sensory scoring results. As can be seen from Table 6, Example 3 has the highest sensory score, indicating that this method has a certain advantage in maintaining the sensory quality of fish fillets.

[0073] like Figure 4 The image shown is an electronic nose radar image of pre-cooked fish and meat dishes. The results indicate that the process of this invention can further enhance the deodorizing effect under the acidic environment of tomatoes and the aroma of volatile oils from basil. Simultaneously, through liquid nitrogen quick-freezing and coupled reheating technology, the fish meat tissue remains delicate and juicy, with a stable overall flavor.

[0074] Example 5 This embodiment provides a processing method to improve the freezing damage and reheating fishy smell of pre-cooked fish dishes. This embodiment describes the differences from Embodiments 3 and 4 based on Embodiments 3 and 4. Steps (1), (2), and (3) are the same as in Embodiment 3, and step (4) is as follows: (4) Before consumption, remove the stored product from the cold storage and place it directly in the heat pipe-microwave reheating device without pre-thawing. The reheating parameters are as follows: Table 7. Available parameters for reheating ; The reheating process for dishes should be calculated using the following formula: ; Where Q is the water stability parameter, and A 21 To incorporate the water peak area, A 22 For the area of ​​the water peak that is not easily moved, A 23 The area of ​​the free water peak.

[0075] Table 5 in Example 4 is a sensory evaluation table of pre-cooked fish and meat dishes measured under different reheating power, temperature and time conditions. Table 5 is used to analyze the influence of moisture state on the quality of the product after reheating. Table 8 is a comparison table of Q value changes and sensory evaluation measured under different reheating power, temperature and time conditions.

[0076] Table 8 Comparison of Q-value changes and sensory evaluation ; Using Q as the independent variable and sensory evaluation Y as the dependent variable, a univariate linear fit was performed, yielding Y = 8.3289Q + 53.064, where the fitted curve is shown in the figure. Figure 5 As shown, the moisture state is positively correlated with sensory evaluation, indicating that the Q value can be used as a quantitative indicator of reheat quality.

[0077] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, apparatus, article, or method that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, apparatus, article, or method. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, apparatus, article, or method that includes that element. The above descriptions are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural modifications made based on the description and drawings of this invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of this invention.

Claims

1. A processing method for improving frozen damage and reheated fishy odor in pre-cooked fish dishes, characterized in that, include: The raw materials are pretreated to obtain pretreated products; The pretreated product is precooled using recycled liquid nitrogen vapor to obtain a precooled product. The pre-cooled product is then subjected to ultra-low temperature liquid nitrogen quick-freezing to obtain a quick-frozen product; The quick-frozen product is subjected to modified atmosphere packaging and frozen storage to obtain the stored product; The stored product was thawed and reheated using heat pipe microwave coupling technology to obtain a reheated product. The reheated product was evaluated using low-field nuclear magnetic resonance technology, and the evaluation results were obtained.

2. The processing method for improving frozen damage and reheated fishy odor in pre-cooked fish dishes according to claim 1, characterized in that, The process of pretreating raw materials to obtain pretreated products includes: The raw materials are descaled, gutted, cut, and washed to obtain the cleaned product; wherein the raw materials are fresh fish meat; The cleaned product is seasoned according to the pre-cooked dish recipe to obtain the pre-treated product.

3. The processing method for improving frozen damage and reheated fishy odor in pre-cooked fish dishes according to claim 1, characterized in that, The pre-cooling treatment of the pretreated product using recycled liquid nitrogen vapor yields a pre-cooled product, comprising: The pretreated product is placed in the precooling tunnel; The cold vapor recovered from the liquid nitrogen system is introduced into the precooling channel so that the pretreated product is uniformly cooled in a low-temperature airflow environment below -20°C. The pre-cooling time of the pretreated product is controlled to be 3-8 minutes to ensure that the overall temperature of the pretreated product drops to 0-5℃.

4. The processing method for improving frozen damage and reheated fishy odor in pre-cooked fish dishes according to claim 1, characterized in that, The process of quick-freezing the pre-cooled product with ultra-low temperature liquid nitrogen to obtain a quick-frozen product includes: The pre-cooled product is placed in a liquid nitrogen quick-freezing device; Start the liquid nitrogen quick-freezing device and freeze the pre-cooled product at a temperature of -120℃±5℃ until the core temperature of the pre-cooled product drops below -20℃. Turn off the liquid nitrogen quick-freezing device and immediately remove the product to obtain the quick-frozen product.

5. The processing method for improving frozen damage and reheated fishy odor in pre-cooked fish dishes according to claim 1, characterized in that, The modified atmosphere packaging and frozen storage of the quick-frozen product yields a stored product, including: The quick-frozen product is heat-sealed using a high-barrier, multi-layered modified atmosphere film. During the heat-sealing process, N2 is simultaneously introduced to isolate external oxygen, resulting in a packaged product. The packaged product is stored in a frozen storage environment below -18°C to obtain the stored product.

6. The processing method for improving frozen damage and reheated fishy odor in pre-cooked fish dishes according to claim 1, characterized in that, The process of thawing and reheating the stored product using heat pipe microwave coupling technology to obtain a reheated product includes: Heat pipes are used to conduct heat to the stored product to thaw the surface of the stored product, thereby achieving temperature gradient equalization. The interior of the stored product is heated by microwave heating to obtain a reheated product.

7. The processing method for improving frozen damage and reheated fishy odor in pre-cooked fish dishes according to claim 6, characterized in that, After thawing the surface of the stored product, the process further includes: During microwave heating, the core temperature of the stored product is monitored in real time. Microwave heating is stopped when the center temperature is greater than or equal to the reheating temperature threshold.

8. The processing method for improving frozen damage and reheated fishy odor in pre-cooked fish dishes according to claim 1, characterized in that, The reheated product was evaluated using low-field nuclear magnetic resonance (NMR) technology, and the evaluation results included: The T2 relaxation curve of the reheated product was measured using low-field nuclear magnetic resonance. The T2 relaxation curve is inverted to obtain the signal peak areas of various water types, including the peak areas of bound water, non-flowing water, and free water. The moisture stability parameter is calculated using the following formula: ； Where Q is the water stability parameter, and A 21 To incorporate the water peak area, A 22 For the area of ​​the water peak that is not easily moved, A 23 The area of ​​the free water peak; The moisture stability parameter is used to quantitatively evaluate the reheating quality of the product after reheating, wherein the moisture stability parameter is positively correlated with the reheating quality.

9. The processing method for improving frozen damage and reheated fishy odor in pre-cooked fish dishes according to claim 1, characterized in that, After pretreating the raw materials to obtain the pretreated product, the process further includes: Choose lunch boxes with high thermal conductivity and low temperature resistance; The pre-treated product is evenly spread in the lunch box to ensure uniform thickness.

10. A processing apparatus for improving frozen damage and reheated fishy odor in pre-cooked fish dishes, characterized in that, The apparatus for performing the method of claim 1, comprising: The pretreatment module is used to pretreat the raw materials to obtain pretreated products; The pre-cooling module is used to pre-cool the pre-treated product using recovered liquid nitrogen cold vapor to obtain a pre-cooled product. The quick-freezing module is used to quick-freeze the pre-cooled product with ultra-low temperature liquid nitrogen to obtain the quick-frozen product. The packaging module is used to perform modified atmosphere packaging on the quick-frozen product to obtain the packaged product. A freezing and storage module is used to freeze and store the quick-frozen product to obtain the stored product. The defrost and reheat module is used to defrost and reheat the stored product using heat pipe microwave coupling technology to obtain the reheated product. The low-field nuclear magnetic resonance technology module is used to evaluate the reheated product using low-field nuclear magnetic resonance technology and obtain the evaluation results.

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