Microwave-Steam Combined Sterilization Method for Meat Products and Its Application

Abstract

This invention belongs to the field of food processing, specifically relating to a microwave-steam combined sterilization method for meat products and its application. The sterilization method includes the following steps: S1: Microwave sterilization of the meat products to be processed to obtain pre-sterilized meat products; S2: Steam sterilization of the pre-sterilized meat products to obtain finished meat products; wherein, the initial temperature of the meat products to be processed is 42~55℃. This invention's sterilization method, by combining "microwave sterilization" with "precise steam sterilization," solves the problems of "incomplete sterilization" or "deterioration of meat quality" in traditional sterilization methods. It can efficiently and thoroughly sterilize (total bacterial count <10 CFU / g, no pathogenic bacteria detected) while maximizing the preservation of the original quality of the meat products (elasticity retention rate >85%, key nutrient retention rate >90%). It is simple to operate, biosafe, and has broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of food processing, specifically relating to a microwave-steam combined sterilization method for meat products and its application. Background Technology

[0002] Meat products, rich in protein and water, easily become a breeding ground for microorganisms. Therefore, sterilization is indispensable in meat processing to ensure food safety and extend shelf life. Traditional heat sterilization techniques (such as pasteurization and high-temperature, high-pressure sterilization) can effectively inactivate pathogenic and spoilage bacteria, significantly reduce microbial load, and extend product shelf life. However, high-intensity heat treatment often causes irreversible damage to the product's nutritional content, flavor, color, texture, and other sensory qualities. While microwave sterilization heats up rapidly, it suffers from uneven field distribution leading to "cold spots," resulting in incomplete sterilization (the bacterial count in the central area of ​​meat products often reaches 10). 2 (CFU / g grade) cannot meet the requirements for thorough sterilization in food safety.

[0003] Therefore, there is an urgent need to develop a sterilization method that is efficient, thoroughly sterilizes, and can preserve the original quality of meat products to the greatest extent. Summary of the Invention

[0004] This invention aims to at least partially solve one of the technical problems existing in the prior art. To this end, this invention provides a microwave-steam combined sterilization method for meat products and its application. The sterilization method of this invention, by combining "microwave sterilization" with "precise steam sterilization," solves the problems of "incomplete sterilization" or "deterioration of meat quality" in traditional sterilization methods. It can efficiently and thoroughly sterilize (total bacterial count <10 CFU / g, no pathogenic bacteria detected) while maximizing the preservation of the original quality of meat products (elasticity retention rate >85%, key nutrient retention rate >90%). The method is simple to operate, biosafe, and has broad application prospects.

[0005] In a first aspect, the present invention provides a method for sterilizing meat products. According to an embodiment of the present invention, the sterilization method includes the following steps: S1: subjecting the meat products to be processed to microwave sterilization to obtain pre-sterilized meat products; S2: subjecting the pre-sterilized meat products to steam sterilization to obtain finished meat products; wherein the initial temperature of the meat products to be processed is 42~55℃. According to the sterilization method of the embodiment of the present invention, the meat products to be processed at a suitable initial temperature are first subjected to microwave sterilization, thereby effectively killing most of the microorganisms on the surface and inside of the material, and then immediately followed by steam sterilization, thereby utilizing the excellent penetrability and humidity environment of high temperature and high pressure steam to thoroughly disinfect any heating blind spots or heat-resistant bacteria that may remain in the microwave sterilization process. Thus, while significantly shortening the total sterilization time, thorough sterilization is ensured (total bacterial count <10 CFU / g, no pathogenic bacteria detected), and the original texture, color, and nutritional components of the meat products are preserved to the greatest extent (elasticity retention rate >85%, key nutrient retention rate >90%).

[0006] According to embodiments of the present invention, the above-described sterilization method may further include at least one of the following additional technical features: According to an embodiment of the present invention, the power of the microwave sterilization process is 5~8 kW, the time is 3~4 min, and the final temperature is ≥95℃.

[0007] According to an embodiment of the present invention, the steam sterilization process is performed at a pressure of 0.1~0.15 MPa, a time of 8.5~10 min, and a temperature of 100~121 °C.

[0008] According to an embodiment of the present invention, the sterilization method further includes the following step: preheating the meat product to be processed to reach the initial temperature before performing the microwave sterilization treatment.

[0009] According to an embodiment of the present invention, the preheating time is 8~20 min and the temperature is 35~55 ℃.

[0010] According to an embodiment of the present invention, the sterilization method further includes the following step: before the preheating, the meat product to be treated is mixed with the auxiliary materials.

[0011] According to an embodiment of the present invention, the excipient is a food additive.

[0012] According to embodiments of the present invention, the food additive includes one or more of flavoring agents, water-retaining agents, and preservatives.

[0013] In a second aspect, the present invention provides a finished meat product. According to an embodiment of the present invention, the finished meat product is obtained by processing with the sterilization method described in the first aspect. The finished meat product according to an embodiment of the present invention has tender, not dry, meat with a natural, reddish color, and combines the advantages of high safety (free from pathogens), high quality (elasticity retention rate >85%, retention rate of key nutrients such as water-soluble vitamins exceeding 90%), and long shelf life.

[0014] In a third aspect, the present invention proposes the application of the sterilization method described in the first aspect in food processing.

[0015] Those skilled in the art will understand that the features and advantages described above for the sterilization method also apply to this application, and will not be repeated here.

[0016] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the microwave + steam combined sterilization process in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of a single microwave sterilization process in Comparative Example 1 of the present invention; Figure 3 This is a schematic diagram of the single high-temperature steam sterilization process in Comparative Example 2 of the present invention. Detailed Implementation

[0018] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0019] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0020] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0021] In this document, the terms “comprising” or “including” are open-ended expressions, meaning that they include the contents specified in this invention, but do not exclude other aspects.

[0022] In this document, the terms “optionally,” “optionally,” or “optionally” generally refer to an event or condition that may, but may not, occur, and the description includes both cases in which the event or condition occurs and cases in which the event or condition does not occur.

[0023] Terms and Definitions In this paper, the term "microwave-steam combined sterilization process" refers to a comprehensive physical sterilization method that combines microwave sterilization and steam sterilization in a specific sequence and under specific conditions. Microwave sterilization is responsible for rapidly and uniformly raising the overall temperature of meat products to achieve preliminary and efficient sterilization, while steam sterilization is responsible for deep penetration and uniform heat replenishment to ensure the elimination of any possible microwave "cold spots" and to kill heat-resistant microorganisms, thereby achieving efficient and thorough sterilization.

[0024] In this document, the term "initial temperature" refers to the overall average starting temperature of the meat product to be processed when the microwave sterilization process begins.

[0025] In this document, the terms "preheating" and "preheating" are synonymous, referring to the preheating process performed on meat products before microwave sterilization. The purpose of this process is to slowly and uniformly increase the temperature of the meat products by means of water bath, steam, or hot air, aiming to reduce the initial temperature difference (≤5°C) between the interior and surface, and between the center and the edges of the meat products. This lays the foundation for subsequent microwave sterilization and avoids uneven thermal stress and localized overheating caused by excessive temperature differences.

[0026] In this document, the term "endpoint temperature" refers to the overall average temperature at the end of the microwave sterilization process.

[0027] In this article, the term "cold spot" refers to an area with less heat generation and a relatively low temperature during microwave heating due to uneven electromagnetic field distribution or differences in the dielectric properties of materials. This area is a risk zone for incomplete microwave sterilization.

[0028] In this article, the term "texture" refers to the physical structure and sensory properties of meat products, which can be objectively measured by instruments such as texture analyzers, and typically includes indicators such as elasticity.

[0029] In this article, the term "elasticity retention rate" refers to an indicator (in percentage) used to quantify the impact of sterilization processes on the texture of meat products. The higher the indicator, the less the sterilization process damages the product's elasticity.

[0030] In this article, the term "shear force" refers to an objective indicator (in Newtons) for evaluating the tenderness of meat products, measured by a texture analyzer. The lower the value, the more tender the meat.

[0031] In this article, the term "not detected" means that when the detection method and detection limit specified by the national standard are used, the detection result of the target pathogen (such as Escherichia coli, Staphylococcus aureus, Salmonella, etc.) is lower than the minimum limit that the method can report. This indicates that the product is safe under the relevant food safety standards.

[0032] In this article, the term "food additive" refers to artificial or natural substances added to food in accordance with relevant regulations such as the National Food Safety Standard - Standard for the Use of Food Additives, in order to improve the quality, color, aroma, and taste of food, as well as for the needs of preservation, freshness, and processing.

[0033] Sterilization methods This invention proposes a method for sterilizing meat products. According to an embodiment of the invention, the sterilization method includes the following steps: S1: Microwave sterilization of the meat products to be processed to obtain pre-sterilized meat products; S2: Steam sterilization of the pre-sterilized meat products to obtain finished meat products; wherein, the initial temperature of the meat products to be processed is 42~55℃. According to the sterilization method of this invention, the meat products to be processed at a suitable initial temperature are first microwave sterilized to effectively kill most microorganisms on the surface and inside of the material, and then immediately followed by steam sterilization. This utilizes the excellent penetrability and humidity environment of high-temperature, high-pressure steam to thoroughly eliminate any heating blind spots or heat-resistant bacteria that may remain after microwave sterilization. Therefore, while significantly shortening the total sterilization time, thorough sterilization is ensured (total bacterial count <10 CFU / g, no pathogenic bacteria detected), and the original texture, color, and nutritional components of the meat products are preserved to the greatest extent possible (elasticity retention rate >85%, key nutrient retention rate >90%).

[0034] For example, the initial temperature of the meat product to be processed is 42°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, 51°C, 52°C, 53°C, 54°C, or 55°C, preferably 46°C to 54°C, and more preferably 48°C to 52°C.

[0035] According to an embodiment of the present invention, the microwave sterilization process uses a power of 5-8 kW, a time of 3-4 min, and an endpoint temperature ≥95℃. Thus, by optimizing and controlling the parameters of the microwave sterilization process, it is possible to ensure sufficient microwave energy for rapid and uniform heating of meat products while effectively killing most common microorganisms. This avoids quality deterioration problems such as excessive protein denaturation and juice loss caused by overheating or prolonged heat exposure, laying a good foundation for subsequent steam sterilization with "preliminary sterilization and uniform heating." For example, the microwave sterilization process uses a power of 5 kW, 5.5 kW, 6 kW, 6.5 kW, 7 kW, 7.5 kW, or 8 kW, preferably 5-7 kW; the microwave sterilization process uses a time of 3 min, 3.2 min, 3.5 min, 3.7 min, or 4 min, preferably 3-3.5 min.

[0036] According to an embodiment of the present invention, the steam sterilization treatment is performed at a pressure of 0.1~0.15 MPa, a time of 8.5~10 min, and a temperature of 100~121℃. Thus, by optimizing and controlling the parameters of the steam sterilization treatment, the strong heat penetration and uniform heating characteristics of high-temperature saturated steam can be fully utilized to completely eliminate any "cold spots" that may remain after microwave sterilization and reliably inactivate heat-resistant spores and other stubborn microorganisms, while avoiding excessive heat damage to the already preliminarily formed meat structure. This achieves an optimal balance between thorough sterilization and quality preservation. For example, the steam sterilization treatment pressure is 0.1 MPa, 0.12 MPa, 0.13 MPa, 0.14 MPa, or 0.15 MPa, preferably 0.12~0.14 MPa; the steam sterilization treatment time is 8.5 min, 9 min, 9.5 min, or 10 min, preferably 8.5~9 min. The steam sterilization temperature is 100℃, 101℃, 102℃, 103℃, 104℃, 105℃, 106℃, 107℃, 108℃, 109℃, 110℃, 111℃, 112℃, 113℃, 114℃, 115℃, 116℃, 117℃, 118℃, 119℃, 120℃, or 121℃, preferably 115℃ to 121℃.

[0037] According to an embodiment of the present invention, the sterilization method further includes the following step: preheating the meat product to be treated to reach the initial temperature before performing the microwave sterilization treatment. Thus, the preheating treatment significantly reduces the initial temperature difference inside the meat product (core and surface), thereby effectively avoiding uneven thermal stress caused by a large temperature gradient during the subsequent microwave sterilization process.

[0038] It should be noted that the specific implementation method of the "preheating" is not limited, including but not limited to constant temperature water bath heating, low temperature steam treatment, controllable hot air circulation heating, and mild infrared radiation heating. Any heating method that can make the meat products to be processed reach the required initial temperature uniformly and gently without causing irreversible quality damage to them is within the protection scope of this invention.

[0039] According to an embodiment of the present invention, the preheating time is 8-20 min, and the temperature is 35-55°C. Therefore, by optimizing and controlling the preheating parameters, the overall temperature of the meat product can be gently and gradually increased without causing significant denaturation of the meat protein. For example, the preheating time is 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, or 20 min, preferably 10-13 min; the preheating temperature is 35°C, 37°C, 39°C, 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, or 55°C, preferably 38-45°C.

[0040] It is important to clarify that in the sterilization method described in this invention, microwave sterilization and steam sterilization are not "primary and secondary," but rather "synergistic and complementary, and indispensable" core components. Each plays a crucial role. Specifically, microwave sterilization can rapidly and uniformly raise the temperature of meat products to ≥95°C, killing 85-90% of microorganisms (including most pathogenic and spoilage bacteria), laying a "low bacterial load" foundation for subsequent steam sterilization. At the same time, the rapid heating characteristic of microwaves can reduce the denaturation time of meat proteins, which is a key prerequisite for achieving "quality preservation." Steam sterilization, on the other hand, utilizes the strong penetrability of high-temperature saturated steam to precisely eliminate "cold spots" that may remain after microwave sterilization, killing stubborn microorganisms such as heat-resistant spores (accounting for approximately 10-15% of the total bacteria count), which is a key guarantee for achieving "thorough sterilization." Meanwhile, the high humidity environment of steam can prevent excessive moisture loss from the meat, further assisting in the preservation of meat product quality. Furthermore, without microwave sterilization, relying solely on steam sterilization requires extended processing time (e.g., 15 minutes or more at 121°C for thorough sterilization), which can severely damage the quality. Conversely, without steam sterilization, microwave sterilization alone can leave "cold spot" areas, resulting in incomplete sterilization. The sterilization method described in this invention, which combines microwave sterilization with steam sterilization in sequence and ensures that the final temperature of microwave sterilization is ≥95°C, can simultaneously achieve the technical goals of "thorough sterilization" and "high-quality preservation".

[0041] According to an embodiment of the present invention, the sterilization method further includes the following step: before performing the preheating treatment, mixing the meat product to be treated with the auxiliary materials.

[0042] According to an embodiment of the present invention, the excipient is a food additive.

[0043] According to embodiments of the present invention, the food additive includes one or more of flavoring agents, water-retaining agents, and preservatives.

[0044] For example, the food additive can be of various specific types such as salt (seasoning), sodium pyrophosphate (water-retaining agent), and potassium sorbate (preservative). The addition range of food additives is usually 0.05~2.0 wt% of the total weight of meat products. The specific types and proportions of food additives can be adapted and optimized according to the product flavor design, texture requirements, preservation needs, and the provisions of the "National Food Safety Standard - Standard for the Use of Food Additives".

[0045] Meat products This invention provides a finished meat product. According to an embodiment of the invention, the finished meat product is obtained after treatment using the aforementioned sterilization method. The finished meat product according to an embodiment of the invention has tender, not dry, meat with a natural, reddish color, and combines the advantages of high safety (free from pathogens), high quality (elasticity retention rate >85%, retention rate of key nutrients such as water-soluble vitamins exceeding 90%), and long shelf life.

[0046] application This invention proposes the application of the aforementioned sterilization method in food processing.

[0047] Those skilled in the art will understand that the features and advantages described above for the sterilization method also apply to this application, and will not be repeated here.

[0048] It should be noted that the application is specifically reflected in the following aspects: (1) The total bacterial count of meat products treated by the above method can be reduced to below 10 CFU / g. Common pathogenic bacteria such as Escherichia coli and Staphylococcus aureus were not detected. It fully meets and exceeds the national food safety standards for the microbial limit requirements of cooked meat products. It can be applied to the production of ready-to-eat meat products and snack meat products with strict hygiene and safety requirements. (2) It can maintain the elasticity retention rate of meat products at more than 85% while ensuring thorough sterilization and effectively maintain the red color of the products. This makes the method particularly suitable for processing high-quality ham, sausage, braised meat and other meat products that have high requirements for taste, texture and appearance. (3) The retention rate of heat-sensitive nutrients such as vitamin B1 in meat products reaches more than 90%, which is significantly higher than that of traditional high temperature and high pressure sterilization process.

[0049] The present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0050] Example 1: Parameter optimization of microwave + steam combined sterilization process 1. Optimization of preheating parameters (1) Raw material pretreatment 1 kg of fresh pork hind leg meat (quarantined, pH 5.8-6.2, moisture content 70%-75%) was minced after removing the fascia using a meat grinder (2 mm pore size). 1 wt% salt and 0.3 wt% sodium pyrophosphate were added by weight of the meat, and the mixture was placed in an ice bath and stirred at 1200 r / min for 2 min until homogeneous. Then, a mixed bacterial suspension of *E. coli* (purchased from an authorized domestic agent of the American Type Culture Collection (ATCC), strain accession number ATCC 25922) and *Staphylococcus aureus* (purchased from an authorized domestic agent of the American Type Culture Collection (ATCC), strain accession number ATCC 6538) was inoculated (total concentration 10). 8 CFU / mL, Escherichia coli: Staphylococcus aureus = 1:1), the inoculation method was to add the bacterial solution dropwise and stir for a short time (stirring at 800 r / min for 1 min), and let it stand for 30 min to obtain a pork hind leg meat sample (initial bacterial count of 10). 5 CFU / g).

[0051] (2) Tumbling and filling The pork hind leg mince sample obtained in step (1) was placed in a vacuum tumbler (vacuum degree 0.08 MPa, speed 1200 r / min, temperature ≤12℃) and tumbled for 20 min. Then, it was quantitatively filled using a filling machine, with a filling amount of 10 g / segment. The casing was made of food-grade PVDC casing (the product meets the requirements of the National Food Safety Standard for Plastic Materials and Products for Food Contact (GB4806.7), the product number is PVDC-002, the casing thickness is 0.08 mm and the width is 28 mm). The casing was sealed using a heat sealing machine to obtain the filled pork sausage sample.

[0052] (3) Preheating The pork sausage samples obtained in step (2) were kept in a constant temperature water bath at 30℃ for 5 min to obtain pork sausage sample 1 (preheating).

[0053] (4) Microwave sterilization The preheated pork sausage sample 1 obtained in step (3) is placed in a microwave device and processed at 7 kW power for 3 minutes to obtain the preheated pork sausage sample 1 (microwave sterilization). At this time, the temperature of the sample is ≥95℃.

[0054] (5) Steam sterilization The pork sausage sample 1 (microwave sterilization) obtained in step (4) was transferred to a pressure cooking device and treated at 121°C and 0.12 MPa for 5 min to obtain the pork sausage sample 1 (steam sterilization).

[0055] (6) Post-processing The pork sausage sample 1 (steam sterilization) obtained in step (5) was placed in an ice water bath and cooled to a core temperature of <38℃. Then it was dried with hot air at 40℃ for 15 min to obtain the finished pork sausage 1.

[0056] Microwave + Steam Combined Sterilization Process Flowchart Figure 1 .

[0057] The preparation steps for finished pork sausages 2-10 are the same as steps (1)-(6), with the only difference being: When performing step (3), the constant temperature water bath parameters are different. The preheating parameters for filling pork sausage products 1 to 10 are shown in Table 1.

[0058] Table 1. Preheating parameter settings for finished pork sausage products 1-10

[0059] 2. Parameter optimization for microwave sterilization The preparation steps for the finished pork sausages 11-25 are the same as those in steps 1 (1)-(6), with the only difference being: When performing step (3), the constant temperature water bath parameters are all adjusted to be kept in a constant temperature water bath at 40℃ for 12 min; at the same time, when performing step (4), the microwave equipment parameters are set differently, and the microwave sterilization parameters for filling pork sausage products 11~25 are shown in Table 2.

[0060] Table 2 Microwave sterilization parameter settings for finished pork sausage products (11-25%)

[0061] 3. Parameter optimization for steam sterilization The preparation steps for the finished pork sausages 26-38 are the same as those in steps 1 (1) to (6), with the only difference being: In step (3), the constant temperature water bath parameters were all adjusted to be kept in a constant temperature water bath at 40℃ for 12 min; and in step (4), the microwave equipment parameters were all adjusted to be processed with 6 kW power for 3 min; at the same time, in step (5), the steam sterilization parameters were set differently, and the steam sterilization parameters for the finished pork sausages 26~38 are shown in Table 3.

[0062] Table 3. Steam sterilization parameter settings for finished pork sausages (26-38g).

[0063] 4. Comparative Test Samples of finished packaged pork sausages (1-10, 11-25, and 26-38) were taken respectively for multi-dimensional quality comparison tests, including physicochemical indicators, textural properties, microstructure, and comprehensive sensory evaluation, as detailed below: (1) Microbial content Samples were taken for microbial content testing. The testing standards and methods referred to the following standards and methods: "National Food Safety Standard for Microbiological Examination of Food - Determination of Total Colony Count" (GB 4789.2-2022), "National Food Safety Standard for Microbiological Examination of Food - Coliform Count" (GB 4789.3-2025), "National Food Safety Standard for Microbiological Examination of Food - Staphylococcus aureus Test" (GB 4789.10-2016), and "National Food Safety Standard for Limits of Pathogenic Bacteria in Food" (GB 29921-2021). Specific indicators included total colony count (CFU / g), Escherichia coli content (MPN / 100 g), Staphylococcus aureus content (CFU / g), and total pathogenic bacteria content (total pathogenic bacteria include Escherichia coli and Staphylococcus aureus, in CFU / g).

[0064] (2) Texture quality The elasticity and shear force (in Newtons, N) of each sample were measured using a texture analyzer, and the elasticity retention rate was calculated. The formula for calculating the elasticity retention rate is shown in Equation 1.

[0065] Elasticity retention rate (%) = (Elasticity value of the finished product after complete sterilization process / Elasticity value of the sample without sterilization process) * 100% Formula 1 In Formula 1, "the finished product after complete sterilization process" refers to the finished product obtained in step (6), and "the sample without sterilization process" refers to the sample obtained in step (2).

[0066] (3) Nutrient content Samples were taken for nutrient content testing, with the vitamin B1 content level (in μg / g) as the test indicator. The test method was high performance liquid chromatography, and the vitamin B1 retention rate was calculated. The formula for calculating the vitamin B1 retention rate is shown in Equation 2.

[0067] Vitamin B1 retention rate (%) = (Vitamin B1 content of the finished product after complete sterilization process / Vitamin B1 content of the sample without sterilization process) * 100% Formula 2 In Formula 2, "the finished product after complete sterilization process" refers to the finished product obtained in step (6), and "the sample without sterilization process" refers to the sample obtained in step (2).

[0068] The comparative test results of different preheating parameter settings on the quality indicators of pork sausages are shown in Table 4.

[0069] Table 4 Comparative test results of different preheating parameter settings on the quality indicators of pork sausages

[0070] The results showed that the preheating parameters had a significant regulatory effect on the sterilization thoroughness, textural quality, and nutrient retention of packaged pork sausages. Specifically, regarding the microbial sterilization effect, when the preheating parameters were "35~55℃ constant temperature water bath incubation for 8~20 min" (corresponding to a sample temperature of 42~55℃ after preheating), the total bacterial count of the pork sausages after subsequent microwave-steam combined sterilization was consistently <10 CFU / g, and pathogenic bacteria such as Escherichia coli and Staphylococcus aureus were not detected, significantly reducing the microbial load. However, when the sample temperature after preheating was <42℃ (e.g., 30℃ water bath incubation ≤8 min), the total bacterial count still reached 10³~10⁻⁶ CFU / g. 4 The CFU / g of pathogenic bacteria residue was significantly high. In terms of texture quality, when the preheating parameters were "45~55℃ constant temperature water bath for 15~20 min" (corresponding to a sample temperature of 45~55℃ after preheating), the elasticity retention rate of pork sausage was >90% and the shear force was <36N, which was close to the tenderness and elasticity of the unsterilized sample. Among them, when the sample temperature after preheating was 45℃ (corresponding to a constant temperature water bath at 45℃ for 15 min), the elasticity retention rate was as high as 95.1% (Table 4 - Finished 7 of packaged pork sausage), which was the best level in the group. In terms of nutrient retention, when the preheating parameters were "35~55℃ constant temperature water bath for 8~20 min", the vitamin B1 retention rate was >86.8%. When "45℃ constant temperature water bath for 15 min" was used, the vitamin B1 retention rate reached 93.4% (Table 4 - Finished 7 of packaged pork sausage), and the loss of heat-sensitive nutrients was minimal.

[0071] The above results indicate that the optimal preheating parameters are "35~55℃ constant temperature water bath for 8~20 min" (corresponding to a sample temperature of 42~55℃ after preheating), and the preferred parameters are "45℃ constant temperature water bath for 15 min" (corresponding to a sample temperature of 45℃ after preheating). Pork sausages under these parameters can achieve the comprehensive optimal effect of "significantly reducing microbial load + high elasticity retention + high nutrient retention", which not only provides a basis for uniform heating for subsequent microwave-steam combined sterilization, but also effectively balances the thoroughness of sterilization and product quality.

[0072] Table 5 shows the comparative test results of the effects of different microwave sterilization parameter settings on the quality indicators of pork sausages.

[0073] Table 5 Comparative test results of different microwave sterilization parameter settings on the quality indicators of pork sausages

[0074] The results showed that microwave sterilization parameters significantly affected the sterilization thoroughness, textural quality, and nutrient retention of packaged pork sausages. Specifically, in terms of microbial sterilization effect, when the microwave sterilization parameters were "power 3~8 kW, time 2~5 min", subsequent steam sterilization could achieve different degrees of sterilization effect. Among them, when the power was ≥5 kW and the time was ≥3 min, the total bacterial count of pork sausages could be stably <10 CFU / g, and pathogenic bacteria such as Escherichia coli and Staphylococcus aureus were not detected (e.g., finished packaged pork sausage 18 was treated with 5 kW power for 3 min, and finished packaged pork sausage 21 was treated with 8 kW power for 3 min), significantly reducing the microbial load. However, when the power was <3 kW (e.g., finished packaged pork sausages 11~13 were treated with 1 kW power) or the time was <3 min (e.g., finished packaged pork sausages 11 and 14 were treated with 2 min), the total bacterial count still reached 10 CFU / g. 3 ~10 4The CFU / g level indicates a high level of pathogenic bacteria residue, failing to significantly reduce the microbial load. Regarding texture quality, when microwave sterilization parameters are "power 5-8 kW, time 3-4 min," the elasticity retention rate of pork sausages is >92.7%, and the shear force is <35.8 N, approaching the tenderness and elasticity of unsterilized samples. Specifically, when treated with 5 kW power for 3 min (finished pork sausage product 18), the elasticity retention rate reaches as high as 96.3%, and the shear force is only 35.0 N, representing the best texture performance across the entire group. In terms of nutrient retention, when microwave sterilization parameters are "power 5-8 kW, time 3-4 min," the vitamin B1 retention rate is >90.0%. Specifically, when treated with 5 kW power for 3 min (finished pork sausage product 18), the vitamin B1 retention rate reaches 94.2%, with the least loss of heat-sensitive nutrients. However, when the power is >8 kW (e.g., when treated with 10 kW for finished pork sausage products 23-25), the retention rate is significantly lower. At a power of kW, although the microbial load can be significantly reduced, the vitamin B1 retention rate drops to below 90.2%, while the elasticity retention rate decreases slightly.

[0075] The above results indicate that the optimal parameter range for microwave sterilization is "power 5-8 kW, time 3-4 min", with a more preferred parameter being "power 5 kW, time 3 min". Pork sausages with these parameters can simultaneously achieve the optimal combined effect of "significantly reduced microbial load + high elasticity retention + high nutrient retention", effectively killing most microorganisms in meat products while avoiding quality deterioration caused by excessive concentration of microwave energy, thus laying a good foundation for subsequent steam sterilization.

[0076] The comparative test results of the effects of different steam sterilization parameter settings on the quality indicators of pork sausages are shown in Table 6.

[0077] Table 6 Comparative test results of different steam sterilization parameters on the quality indicators of pork sausages

[0078] The results showed that the steam sterilization parameters played a key regulatory role in the sterilization thoroughness, textural quality, and nutrient retention of the packaged pork sausages. Specifically, in terms of microbial sterilization effect, when the steam sterilization parameters were "pressure 0.1~0.15MPa, temperature 100~121℃, time 8.5~10 min", the total bacterial count of the subsequent pork sausage samples could be stably <10 CFU / g, and pathogenic bacteria such as Escherichia coli and Staphylococcus aureus were not detected (e.g., packaged pork sausage product 28 was treated with 0.125 MPa, 110.5℃, 8.5 min, and packaged pork sausage product 33 was treated with the same parameters), significantly reducing the microbial load. However, when the pressure was <0.1 MPa (e.g., packaged pork sausage product 26 was treated with 0.05 MPa), the temperature was <100℃ (e.g., packaged pork sausage product 31 was treated with 90℃), and the time was <8.5 min (e.g., packaged pork sausage product 36 was treated with 5 min), the total bacterial count still reached 10². At the CFU / g level, some pathogenic bacteria remain, failing to significantly reduce the microbial load. Regarding texture quality, when the steam sterilization parameters are "pressure 0.12~0.14 MPa, temperature 110.5~121℃, time 8.5~10 min," the elasticity retention rate of pork sausages is >95%, and the shear force is <35.2N, approaching the tenderness and elasticity of unsterilized samples. Among them, the finished product 33, treated with 0.125 MPa, 110.5℃, and 8.5 min, achieved an elasticity retention rate of 96.3% and a shear force of only 35.0N, representing the best texture performance across the entire group. However, excessively high temperatures (e.g., 130℃ for finished product 35) and excessively high pressures (e.g., 0.20 MPa for finished product 30) lead to excessive protein denaturation, reducing the elasticity retention rate to below 91.5%. Regarding nutrient retention, when the steam sterilization parameters are "pressure 0.1~0.14 MPa,"... When the temperature is within the range of MPa, temperature is 100~121℃, and time is 8.5~10 min, the vitamin B1 retention rate is >90.8%, and the vitamin B1 retention rate of the finished pork sausage product 33 reaches 94.2%, with the least loss of heat-sensitive nutrients. The vitamin B1 retention rate of the over-temperature and over-time groups will decrease by 3~5%.

[0079] The above results indicate that the optimal parameter range for steam sterilization is "pressure 0.1~0.15 MPa, temperature 100~121℃, time 8.5~10 min", and the more preferred parameters are "pressure 0.125 MPa, temperature 110.5℃, time 8.5 min". Pork sausages under these parameters can achieve the comprehensive optimal effect of "significantly reducing microbial load + high elasticity retention + high nutrient retention", which not only completely eliminates residual microorganisms after microwave sterilization, but also avoids quality deterioration caused by excessive heat damage. These are key matching parameters in the entire process.

[0080] Example 2: Practice of Microwave + Steam Combined Sterilization Process The preparation steps for the finished packaged pork sausage (microwave + steam) are the same as those in steps (1) to (6) of Example 1, with the only difference being: When performing step (3), the parameters of the constant temperature water bath are all adjusted to be kept at 40℃ for 12 min.

[0081] Thus, the finished product of canned pork sausage (microwave + steam) is obtained.

[0082] Comparative Example 1: Single Microwave Sterilization Process The preparation steps for the finished packaged pork sausage (microwave only) are the same as in Example 2, except that: Step (5) steam sterilization is not performed.

[0083] Opinions on a single microwave sterilization process Figure 2 .

[0084] Thus, the finished product of canned pork sausage (single microwave) is obtained.

[0085] Comparative Example 2: Single High-Temperature Steam Sterilization Process The preparation steps for the finished pork sausage (single steam) are the same as in Example 2, except that: Step (3) preheating and step (4) microwave sterilization are not performed.

[0086] Flowchart of a single high-temperature steam sterilization process Figure 3 .

[0087] Thus, the finished product of canned pork sausage (single steam) is obtained.

[0088] Comparative Example 3: Practice of Steam + Microwave Combined Sterilization Process The preparation steps for the finished packaged pork sausage (microwave + steam) are the same as in Example 2, except that: Swap the processing order of steps (4) and (5).

[0089] Thus, the finished product of canned pork sausage (steam + microwave) is obtained.

[0090] Example 3: Comparative Test of Quality Indicators of Pork Sausages by Different Sterilization Processes Pork sausage samples prepared using different sterilization processes were subjected to multi-dimensional quality comparison tests. The test samples included the finished packaged pork sausage prepared in Example 2 (microwave + steam), the finished packaged pork sausage prepared in Comparative Example 1 (microwave only), the finished packaged pork sausage prepared in Comparative Example 2 (steam only), and the finished packaged pork sausage prepared in Comparative Example 3 (steam + microwave). The test indicators included physicochemical indicators, textural properties, microstructure, and comprehensive sensory evaluation. The test standards and methods were the same as those in Example 1.

[0091] The results of comparative tests on the quality indicators of pork sausages by different sterilization processes are shown in Table 7.

[0092] Table 7 Comparative test results of different sterilization processes on the quality indicators of pork sausages

[0093] The results show: (1) Regarding microbial content: The total bacterial count of the packaged pork sausage product (microwave + steam) prepared in Example 2 was <10 CFU / g, and Escherichia coli, Staphylococcus aureus and total pathogens were not detected, significantly reducing the microbial load; while the total bacterial count of the packaged pork sausage product (microwave only) prepared in Comparative Example 1 reached 320 CFU / g, and pathogens such as Escherichia coli (18 MPN / 100g) and Staphylococcus aureus (290 CFU / g) were present; the total bacterial count of the packaged pork sausage product (steam only) prepared in Comparative Example 2 was <10 CFU / g and pathogens were not detected; the total bacterial count of the packaged pork sausage product (steam + microwave) prepared in Comparative Example 3 was 150 CFU / g, and Escherichia coli (10 MPN / 100g) and Staphylococcus aureus (120 CFU / g) were present. (2) In terms of texture quality: the elasticity (0.72) and elasticity retention rate (87.8%) of the finished packaged pork sausage (microwave + steam) prepared in Example 2 are closer to those of the unsterilized packaged pork sausage sample (obtained in step (2)); the elasticity of the finished packaged pork sausage (single microwave) prepared in Comparative Example 1 decreased to 0.65, the elasticity retention rate was 79.3%, and the shear force increased to 38.7 N; the elasticity of the finished packaged pork sausage (single steam) prepared in Comparative Example 2 was only 0.58, the elasticity retention rate was 70.7%, and the shear force reached 42.1 N; the texture of the finished packaged pork sausage (steam + microwave) prepared in Comparative Example 3 deteriorated more significantly, with an elasticity of 0.55, an elasticity retention rate of 68.3%, and a shear force increased to 45.0 N; (3) Regarding the nutrient content: The vitamin B1 content of the finished packaged pork sausage (microwave + steam) prepared in Example 2 was 0.35 μg / g with a retention rate of 92.1%, which is closer to that of the unsterilized packaged pork sausage sample (obtained in step (2)); the vitamin B1 content of the finished packaged pork sausage (microwave only) prepared in Comparative Example 1 decreased to 0.31 μg / g with a retention rate of 81.6%; the vitamin B1 content of the finished packaged pork sausage (steam only) prepared in Comparative Example 2 was only 0.27 μg / g with a retention rate of 71.1%; the finished packaged pork sausage (steam + microwave) prepared in Comparative Example 3 had the most severe nutrient loss, with a vitamin B1 content of 0.25 μg / g and a retention rate of 65.8%.

[0094] The above results demonstrate that the packaged pork sausage product (microwave + steam) prepared using the "microwave-steam combined sterilization process" of this invention exhibits significant advantages in three key dimensions: microbial safety, textural quality, and nutrient retention. This provides a more efficient, higher-quality, and more controllable sterilization technology solution for industrial production.

[0095] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0096] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for sterilizing meat products, characterized in that, The sterilization method includes the following steps: S1: Microwave sterilize the meat products to be processed to obtain pre-sterilized meat products; S2: The pre-sterilized meat products are subjected to steam sterilization to obtain the finished meat products; The initial temperature of the meat products to be processed is 42~55℃.

2. The sterilization method according to claim 1, characterized in that, The microwave sterilization process has a power of 5-8 kW, a time of 3-4 min, and an endpoint temperature of ≥95℃.

3. The sterilization method according to claim 1, characterized in that, The steam sterilization process is performed at a pressure of 0.10~0.15 MPa, a time of 8.5~10 min, and a temperature of 100~121℃.

4. The sterilization method according to claim 1, characterized in that, The sterilization method further includes the following steps: Before performing the microwave sterilization process, the meat products to be processed are preheated to reach the initial temperature.

5. The sterilization method according to claim 4, characterized in that, The preheating time is 8~20 min, and the temperature is 35~55℃.

6. The sterilization method according to claim 4, characterized in that, The sterilization method further includes the following steps: Before the preheating process, the meat products to be processed are mixed with the auxiliary materials.

7. The sterilization method according to claim 6, characterized in that, The excipients are food additives; Optionally, the food additive includes one or more of flavoring agents, water-retaining agents, and preservatives.

8. A finished meat product, characterized in that, The finished meat product is obtained by sterilization according to any one of claims 1 to 7.

9. The application of the sterilization method according to any one of claims 1 to 7 in food processing.

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