A Cobalt-60-based irradiation sterilization and preservation process for fresh food

Abstract

This application relates to the field of food processing technology, specifically disclosing a cobalt-60-based irradiation sterilization and preservation process for fresh food. The process includes the following steps: S1, pre-treating the fresh food raw materials to obtain pre-treated fresh food; S2, sealing and packaging the pre-treated fresh food obtained in S1 to obtain packaged fresh food; S3, irradiating the packaged fresh food obtained in S2 with a cobalt-60 irradiation source to obtain irradiated sterilized and preserved fresh food. This irradiation sterilization and preservation process can be used for various food categories with high requirements for preservation quality, such as fresh vegetables, fresh fruits, fresh-cut foods, and pre-cooked dishes, where traditional heat processing is difficult to apply. It has the advantages of efficient sterilization at low or room temperature, the ability to penetrate packaging and kill microorganisms inside and on the surface of the food without heating, and the ability to preserve the original nutrients, flavor substances, color, and texture of the food while extending its shelf life.

Description

Technical Field

[0001] This application relates to the field of food processing technology, and more specifically, to a cobalt-60-based irradiation sterilization and preservation process for fresh food. Background Technology

[0002] The application of food processing technology in the fresh food sector covers multiple levels, from physical sorting and cutting to biological fermentation and enzyme treatment. Its advantages lie in slowing down the respiration and microbial growth of fresh ingredients through low-temperature preservation, sterilization and bacteriostasis, modified atmosphere packaging, and drying or cooking, thereby extending shelf life while preserving the original color, flavor, texture, and nutritional components of the food. In addition, it can also transform fresh raw materials into standardized, ready-to-use semi-finished products or ready-to-eat products through pre-washing, grading, and cutting operations.

[0003] Food processing methods extend the shelf life of fresh food through heat sterilization, chemical preservation, or conventional packaging techniques. However, high-temperature processing can lead to darkening of the food's color, deterioration of its flavor, and significant loss of heat-sensitive nutrients. Chemical preservation carries the risk of chemical reagent residue. Conventional modified atmosphere or vacuum packaging can only inhibit the growth of surface microorganisms and cannot penetrate to kill pathogens and spores attached to the inside or deep layers of the material, thus leaving the product vulnerable to spoilage in the later stages of storage. Summary of the Invention

[0004] To address the issue that the shelf life of fresh food is extended through heat sterilization, chemical preservation, or conventional packaging techniques, but this still results in the potential for spoilage and deterioration in the later stages of storage, this application provides a cobalt-60-based irradiation sterilization and preservation process for fresh food.

[0005] This application provides a cobalt-60-based irradiation sterilization and preservation process for fresh food, employing the following technical solution: A cobalt-60-based irradiation sterilization and preservation process for fresh food includes the following steps: S1. Pre-process fresh food raw materials to obtain pre-processed fresh food; S2. Seal and package the fresh food obtained from the pretreatment in S1 to obtain packaged fresh food. S3. The packaged fresh food obtained in S2 is irradiated using a cobalt-60 irradiation source to obtain irradiated sterilized and preserved fresh food.

[0006] By adopting the above technical solution, the pretreatment step first removes some contaminants from the surface of the raw materials and adjusts the material morphology, creating a clean and uniform foundation for subsequent packaging and irradiation. Then, the sealing packaging step isolates the pretreated food from the external environment, effectively preventing secondary microbial contamination before irradiation and during storage. Finally, the packaged food is irradiated with highly penetrating cobalt-60 gamma rays. The rays penetrate the packaging material without obstruction, destroying the genetic material of microorganisms inside the packaging and rendering them unable to reproduce, thereby achieving non-thermal physical sterilization. Therefore, the solution effectively kills deep-seated microorganisms, avoids cross-contamination, and can be processed without unpacking, thus extending the shelf life of fresh food.

[0007] Preferably, after step S2, the packaged fresh food is further subjected to a cooling process to reduce the temperature of the packaged fresh food to 0-10°C.

[0008] By adopting the above technical solution, a cooling step is introduced after sealing and before irradiation treatment, pre-lowering the material temperature to a refrigeration temperature range of 0-10°C. This provides a low-temperature environment for subsequent irradiation treatment, as the low temperature inhibits the migration and reactivity of secondary active particles generated during irradiation, thereby slowing down their oxidative damage rate to heat-sensitive nutrients, pigments, and flavor substances in food. On the other hand, the low temperature itself can also inhibit the metabolic activity of residual microorganisms in the packaging, putting them in a physiological dormant or sluggish state, making them more sensitive to irradiation. This helps to achieve better sterilization results with the same absorbed dose, or to appropriately reduce the required irradiation dose to achieve the same sterilization goal, reducing the impact on food quality. Therefore, the gain of synergistically enhancing irradiation sterilization efficiency and ensuring food quality retention through pre-temperature control is obtained, further improving the effectiveness of the preservation process.

[0009] Preferably, the fresh food is at least one of fresh vegetables, fresh fruits, fresh-cut food, or pre-cooked dishes.

[0010] By adopting the above technical solutions, since the fresh vegetables, fruits and other materials targeted are rich in water and nutrients, which are a substrate for microbial growth, and fresh-cut foods and pre-cooked dishes are more prone to spoilage due to processing damage, there is an urgent need for efficient sterilization and preservation technology. Cobalt-60 irradiation, as a cold sterilization technology, generates little heat while its gamma rays inactivate pathogens and spoilage bacteria on the surface and inside of such foods, avoiding thermal damage to heat-sensitive vitamins, pigments, flavor substances and textures. Therefore, it is possible to obtain a solution suitable for processing heat-sensitive fresh foods and achieve long-term preservation without changing their freshness and nutritional quality.

[0011] Preferably, step S1 further includes at least one of the following processing methods for the fresh food raw materials: washing, sorting, shaping, cutting, peeling, draining, or seasoning.

[0012] By adopting the above technical solutions, the cleaning process removes impurities such as mud, sand, some microorganisms, and pesticide residues from the surface of the raw materials, reducing the initial load for sterilization; sorting and shaping remove non-compliant parts of the raw materials, ensuring the uniformity of product specifications; cutting and peeling processes change the physical shape and size of the materials, increasing the specific surface area, which helps the gamma rays to be absorbed more evenly by the materials during subsequent irradiation, reducing sterilization dead zones caused by uneven thickness or density; draining removes surface free water, reducing humidity inside the packaging, which is not conducive to microbial recovery; and flavoring imparts basic flavor to the food before sterilization. These pretreatment steps improve the initial state of the food, thus obtaining materials with higher cleanliness, uniform specifications, and more favorable uniform distribution and absorption of irradiation dose, laying the foundation for efficient sterilization and stable quality.

[0013] Preferably, when cutting fresh food, the particle size of the cut material is controlled to be 0.5-5cm.

[0014] By adopting the above technical solution, the material is cut into particles with a diameter of 0.5-5 cm, which ensures that the material has a suitable specific surface area. When the particle size is too small, the specific surface area is too large, which is conducive to the uniform penetration of the irradiation dose, but excessive cutting damage leads to increased juice loss, softening of texture, and increased oxidative browning. When the particle size is too large, the center of the material forms a weak dose area due to insufficient ray penetration, affecting the thoroughness of sterilization. This preferred range balances the requirements for irradiation uniformity and the requirements for maintaining the material texture, allowing gamma rays to cover all material surfaces and penetrate to the internal center, while avoiding quality deterioration caused by over-cutting. Therefore, while ensuring the consistency of sterilization effect, the sensory quality and marketability of the product are improved.

[0015] Preferably, in step S2, the packaging is at least one of vacuum packaging, modified atmosphere packaging, deoxygenated packaging, or nitrogen-filled packaging.

[0016] By adopting the above technical solutions, vacuum or various modified atmosphere packaging methods are used to further alter the gas composition inside the packaging and maintain a low-oxygen or anaerobic environment, based on the physical isolation of environmental microorganisms. This inhibits the growth and reproduction of aerobic spoilage microorganisms and slows down the oxidation reaction of food components. This step works synergistically with the subsequent irradiation treatment. Irradiation is responsible for killing existing microbial populations, while the low-oxygen packaging environment prevents the growth of residual radiation-resistant microorganisms or subsequent invading trace microorganisms during storage. Therefore, a superimposed preservation effect is achieved, which improves the quality stability of the product after irradiation sterilization during storage and makes the color and flavor last longer.

[0017] Preferably, in step S2, a protective gas is also introduced into the packaging, the protective gas including nitrogen or carbon dioxide, with a gas volume ratio of 50-90% nitrogen and 10-50% carbon dioxide.

[0018] By adopting the above technical solution, a mixture of nitrogen and carbon dioxide is filled into the sealed packaging. Nitrogen acts as an inert filling gas, providing physical support to isolate oxygen and prevent packaging collapse. Carbon dioxide, on the other hand, has antibacterial properties. It dissolves in the moisture and oil of food to form carbonic acid, slightly lowering the pH value and acting on the cell membranes of microorganisms, interfering with their enzyme systems and metabolic processes, thereby inhibiting the growth of various bacteria and molds. By controlling the proportion of carbon dioxide at 10%-50%, it is possible to inhibit specific spoilage bacteria while avoiding physiological damage or sour taste to some fruits and vegetables caused by excessively high concentrations. Therefore, a synergistic preservation atmosphere is obtained by supplementing and enhancing the effect of physical irradiation sterilization through the biochemical regulation of gas components, further extending the microbial safety shelf life of the product.

[0019] Preferably, in step S3, the irradiation treatment is carried out at a temperature not higher than room temperature, with the irradiation temperature being 0–25°C.

[0020] By adopting the above technical solution, the temperature of the irradiation treatment environment is controlled within the normal or low temperature range of 0-25℃. During the irradiation process, gamma rays interact with matter to generate active particles such as secondary electrons and free radicals. Irradiation itself is a cold process. When the ambient temperature is high, the migration and reaction rate of active particles will accelerate, exacerbating their oxidative damage to the nutrients in food. On the other hand, the low temperature environment can inhibit the rate of these irradiation-induced chemical side reactions, reduce nutrient loss and the generation of undesirable flavor substances. Therefore, the treatment conditions are obtained to achieve the predetermined sterilization dose while preserving the inherent nutrients, color and flavor of food, ensuring the effect of irradiation preservation.

[0021] Preferably, in step S3, the absorption dose of the packaged fresh food is controlled to be 1.0 to 10.0 kGy.

[0022] By adopting the above technical solution, the absorbed dose of cobalt-60 gamma rays is precisely controlled within the range of 1.0 to 10.0 kGy. A lower dose of around 1.0 kGy is sufficient to reduce the number of most spoilage bacteria and kill common foodborne pathogens. For cases with high microbial load or strong tolerance, it is necessary to increase the dose to 10.0 kGy to ensure sterility. At the same time, this upper limit dose has been evaluated and its negative impact on the main nutrients, texture, and flavor of fresh food is within an acceptable range. It avoids tissue softening, off-flavor generation, or excessive degradation of nutrients caused by excessive doses. Therefore, a dose window that can balance sterilization thoroughness and food quality maintenance is obtained, achieving a balance between safety and marketability.

[0023] Preferably, after step S3, the total bacterial count of the irradiated sterilized and preserved fresh food is reduced to 10. 3 Products with a CFU / g content below 85% and a vitamin C retention rate of ≥85% and a chlorophyll retention rate of ≥90%.

[0024] By employing the above technical solutions, precise targeting is achieved through the comprehensive application of cooling, appropriate pretreatment, protective atmosphere packaging, low-temperature environmental control, and improved irradiation dose. The high-energy photons of cobalt-60 gamma rays primarily act on the nucleic acid molecules of microorganisms, causing DNA strand breaks through direct ionization or the generation of free radicals, thus efficiently inactivating microorganisms and reducing the total bacterial count to 10. 3 Food safety levels below CFU / g are achieved. Simultaneously, the process utilizes low-temperature conditions, a low-oxygen packaging environment, and appropriate irradiation doses throughout the process to synergistically protect small-molecule functional components and pigments such as vitamin C, gingerol, and chlorophyll, which are relatively sensitive to radiation and oxidation, and inhibit their degradation pathways. Therefore, fresh food with both high microbial safety and high nutritional quality retention is obtained, demonstrating the advantages of this non-thermal sterilization technology in the field of food preservation.

[0025] In summary, this application has the following beneficial effects: 1. Since this application adopts a process based on cobalt-60 irradiation, combined with pretreatment and sealed packaging, the pretreatment step cleans and organizes the materials, laying the foundation for subsequent operations; while the sealed packaging step maintains a physically isolated environment; finally, the cobalt-60 gamma rays penetrate the packaging to inactivate the internal microorganisms, thereby obtaining a non-thermal sterilization and preservation effect that can kill deep-seated microorganisms and extend the product shelf life without unpacking.

[0026] 2. In this application, pre-cooling is preferred to reduce the physiological metabolism and microbial activity of food from the source; on this basis, nitrogen-filled or carbon dioxide modified atmosphere packaging further creates a low-oxygen and antibacterial environment inside the packaging; and subsequent irradiation under low-temperature conditions inhibits irradiation-induced oxidation and other side reactions; at the same time, cooling provides the initial conditions for low-temperature irradiation, modified atmosphere packaging provides a continuous freshness atmosphere for the irradiated product, and the low-temperature environment ensures the stability of the irradiation process itself and the gas inside the packaging, thereby achieving the effect of sterilization while maintaining the color, flavor and heat-sensitive nutrients of fresh food.

[0027] 3. The method of this application achieves precise process control by improving and optimizing the cutting particle size range, irradiation absorbed dose, and protective gas ratio. A suitable cutting particle size ensures uniform distribution of the irradiation dose in the material. Based on this, an irradiation dose window of 1.0 to 10.0 kGy can achieve sterilization for different initial bacterial conditions while minimizing damage to texture and flavor. The optimal ratio of nitrogen and carbon dioxide creates a protective atmosphere within the packaging that effectively inhibits bacteria without negatively impacting the product. Particle size uniformity affects dose effectiveness, and the dose size must consider the product's tolerance under the gas atmosphere. The gas composition helps consolidate the antibacterial state after low-dose irradiation. Therefore, the final result is high-quality fresh food with a total bacterial count reduced to a safe level and high retention rates of functional components such as vitamin C, gingerol, and chlorophyll. Attached Figure Description

[0028] Figure 1 This is a flowchart of a cobalt-60-based irradiation sterilization and preservation process for fresh food proposed in this application. Detailed Implementation

[0029] The present application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0030] Technical concept: Food processing methods extend the shelf life of fresh food through heat sterilization, chemical preservation, or conventional packaging techniques. However, high-temperature processing can lead to darkening of the food's color, deterioration of its flavor, and significant loss of heat-sensitive nutrients. Chemical preservation carries the risk of chemical reagent residue. Conventional modified atmosphere or vacuum packaging can only inhibit the growth of surface microorganisms and cannot penetrate to kill pathogens and spores attached to the inside or deep layers of the material, thus leaving the product vulnerable to spoilage in the later stages of storage.

[0031] See appendix Figure 1 This application discloses a cobalt-60-based irradiation sterilization and preservation process for fresh food. It includes the following steps: S1, pre-treating the fresh food raw materials to obtain pre-treated fresh food; S2, sealing and packaging the pre-treated fresh food obtained in S1 to obtain packaged fresh food; S3, irradiating the packaged fresh food obtained in S2 using a cobalt-60 irradiation source to obtain irradiated sterilized and preserved fresh food.

[0032] This application employs a process based on cobalt-60 irradiation, combined with pretreatment and sealed packaging. The pretreatment step cleans and organizes the materials, laying the foundation for subsequent operations; while the sealed packaging step maintains a physically isolated environment; finally, cobalt-60 gamma rays penetrate the packaging to inactivate internal microorganisms, achieving a non-thermal sterilization and preservation effect that can kill deep-seated microorganisms and extend the product's shelf life without requiring unpacking.

[0033] Example 1: This example provides a method for sterilizing fresh ginger by irradiation at room temperature, including the following steps: S1. Pretreatment: Select fresh ginger and rinse it with clean water; use a mechanical peeler to remove the outer skin to a thickness of about 0.7mm; cut the peeled ginger into strips about 0.3cm wide and 4.5cm long; place the cut ginger strips in a draining device to drain the surface water for about 15 minutes until the surface moisture content drops to about 3%. S2. Packaging: Pack the drained ginger shreds into vacuum packaging bags made of 80μm thick PET / PE composite film, with each bag containing 100g; vacuum to an absolute pressure of 0.09MPa, and then heat seal; S3. Irradiation treatment: The packaged ginger products are placed at room temperature (approximately 20-25°C) and then sent into the irradiation channel of a cobalt-60 gamma ray irradiation device. The product absorbs an irradiation dose of 5.5 kGy. The entire irradiation process does not require heating. The product temperature increases slightly due to the conversion of irradiation energy, but it is still far below the temperature for high-temperature sterilization.

[0034] Example 2: This example provides irradiation sterilization of fresh-cut lettuce under refrigeration, including the following steps: S1. Pre-treatment: Select fresh lettuce and remove the outer old leaves and roots. Wash three times with cold water at 2-5℃ to remove dirt and impurities; cut the lettuce into pieces about 3-5cm in size; use a centrifugal dehydrator to drain the surface water, controlling the speed at 800rpm for 2 minutes, until the surface moisture content is reduced to below 5%.

[0035] S2. Packaging: Freshly cut lettuce is packed into modified atmosphere packaging boxes made of PP material with transparent lids, each box containing 150g; then a protective gas consisting of 65% nitrogen, 5% carbon dioxide, and 30% oxygen is introduced and sealed; a certain oxygen concentration is maintained to preserve the respiration and freshness of the lettuce.

[0036] S3. Irradiation treatment: The packaged fresh-cut lettuce is directly sent into the cobalt-60 gamma ray irradiation device while refrigerated at a temperature of 2-4℃; and the irradiation dose is controlled at 1.8kGy; no heating is required during the irradiation process, and the product is kept at the refrigerated temperature.

[0037] Example 3: This example provides room temperature irradiation sterilization of fresh-cut pineapples, including the following steps: S1. Pre-treatment: Select a fresh pineapple with moderate ripeness, peel and core it, and cut it into pieces of about 2cm×2cm×2cm; rinse it quickly with 5℃ cold water and drain the surface water.

[0038] S2. Packaging: Pack the fresh-cut pineapple into PET deoxygenated packaging boxes, 300g per box. Add 50ml of oxygen absorber and seal.

[0039] S3. Irradiation treatment: The packaged fresh-cut pineapple is placed in a cobalt-60 gamma ray irradiation device at room temperature with an irradiation dose of 2.5 kGy; after irradiation, it is transferred to cold storage.

[0040] Example 4: This example provides a method for sterilizing Kung Pao Chicken (a pre-cooked dish) at room temperature by irradiation, including the following steps: S1. Pre-treatment: According to the Kung Pao Chicken recipe, cut the chicken into cubes and marinate it, and cut the vegetables. Pre-fry the chicken in a clean room until it is 70-80% cooked, and add the seasonings. Quickly cool it to about 20-25℃.

[0041] S2. Packaging: Pack the pre-cooked food into modified atmosphere packaging boxes made of PP / EVOH / PP composite material, with each box containing 300g; fill the boxes with a protective gas consisting of 70% nitrogen and 30% carbon dioxide, and seal them.

[0042] S3. Irradiation Treatment: The packaged pre-prepared food is directly placed into a cobalt-60 gamma ray irradiation device at room temperature, with an irradiation dose of 6.5 kGy. No heating is required during the irradiation process, and the product remains at room temperature.

[0043] Comparative Example 1: This comparative example provides high-temperature sterilization treatment, i.e., pasteurization, using the same pretreatment and packaging method as Example 1, but pasteurization is used: the packaged ginger is treated in hot water at 85°C for 15 minutes, and then rapidly cooled.

[0044] Comparative Example 2: This comparative example provides high-temperature sterilization treatment, i.e., blanching, using the same pretreatment and packaging method as Example 2, but using blanching treatment: fresh-cut lettuce is treated in 80°C hot water for 3 minutes, then quickly cooled, drained and packaged.

[0045] Comparative Example 3: This comparative example provides chemical disinfection treatment, using the same pretreatment method as Example 3, but using chemical disinfection: the strawberries were soaked in a sodium hypochlorite solution with an effective chlorine concentration of 50 ppm for 3 minutes, then rinsed with clean water, drained and packaged.

[0046] Comparative Example 4: This comparative example provides only refrigeration preservation without sterilization treatment, using the same pretreatment and packaging methods as Example 4, but without any sterilization treatment, relying solely on refrigeration preservation.

[0047] Comparative Example 5: This comparative example provides dried food products that have undergone irradiation treatment.

[0048] Performance testing Sample preparation: Food samples were prepared according to Examples 1-4 and Comparative Examples 1-5 for subsequent performance testing.

[0049] Microbiological index detection: The test should be carried out under a sterile operating table. Take 25g of representative sample and place it in a sterile homogenizing bag. Add 225mL of sterile physiological saline or phosphate buffer and homogenize with a tapping homogenizer for 2min to prepare a 1:10 sample homogenate. Then perform a 10-fold serial dilution. According to the target microorganism, take an appropriate amount of dilution and inoculate it on the corresponding selective or non-selective culture medium plate. The total bacterial count was determined according to GB 4789.2 using plate counting agar and incubated at 36±1℃ for 48±2h. The coliform count was determined according to GB 4789.3 using crystal violet neutral red bile agar or lauryl sulfate tryptone broth for confirmation. The mold and yeast counts were determined according to GB 4789.15 using Bengal red agar or potato dextrose agar and incubated at 28℃ for 5 to 7 days. After incubation, typical and suspected colonies on the plates were counted, and the number of colony-forming units per gram of sample was calculated based on the dilution factor. Simultaneously, the sample was inoculated and cultured according to GB 4789.26, the standard for commercial sterility testing, to observe for microbial growth.

[0050] Sensory quality testing: A team of at least 8 trained sensory evaluators shall be formed. The selection and training of evaluators shall refer to GB / T16291. The evaluation shall be conducted under standard conditions in a sensory laboratory. Samples shall be randomly numbered and presented in a blind sample format. The general methodology shall refer to GB / T10220. Before evaluation, evaluators shall rinse their mouths with water. During evaluation, the color, gloss, and morphology of the sample shall be observed under a standard light source, and the presence of browning, fading, or juice loss shall be recorded. Subsequently, the texture of the sample shall be evaluated by touch or chewing, such as crispness, hardness, and juiciness, and the degree of softening or dehydration shall be recorded. Finally, the aroma and taste of the sample shall be evaluated by smell and taste, and the retention of the original characteristic flavor and the presence of any cooked taste, off-flavor, or flavor reduction due to processing shall be recorded and analyzed using quantitative descriptive analysis or preference rating methods.

[0051] Nutritional component analysis: The purpose of nutritional component analysis is to quantify the heat sensitivity of the process and the retention rate of nutrients. For different samples, representative nutrients are selected for analysis according to the corresponding standard methods. For ginger samples, the contents of gingerol and vitamin C are determined; for lettuce samples, the contents of vitamin C and chlorophyll are determined; for pineapple samples, the contents of vitamin C and bromelain activity are determined. The determination of vitamin C content is usually in accordance with GB5009.86, using the dichlorophenolindophenol titration method or high performance liquid chromatography (HPLC). The determination of gingerol content is performed using HPLC. The determination of chlorophyll content is performed using spectrophotometry, after extraction with acetone, and the absorbance is measured at a specific wavelength. The determination of bromelain activity is performed using the Folin-Ciocalteu method, with casein as the substrate to determine its protease activity. The treated samples are compared with the raw materials or control group before treatment to calculate the retention rate of specific nutrients.

[0052] Accelerated Shelf Life and Actual Storage Testing: Shelf life testing aims to determine the shelf life of products after processing, with evaluation based on guidelines such as GB / T31268. The tests are divided into accelerated storage tests and actual storage tests. Accelerated storage tests typically place samples at a high, constant temperature, with periodic sampling to test microbiological indicators, sensory quality, and key physicochemical indicators. Actual storage tests place samples under the recommended storage conditions indicated on the product label, with periodic sampling; the sampling frequency is higher in the early stages of storage and can be appropriately extended later. Each sampling must be conducted according to the above procedure to fully test microbiological indicators, sensory quality, and nutritional components. The point at which unacceptable deterioration begins for each indicator is recorded, with the decline in sensory quality or the microbiological indicators exceeding safety limits serving as the shelf life endpoint. By comparing the shelf life of the treated group with that of the untreated control group, the shelf life extension factor is calculated.

[0053] Table 1: Summary of Performance Test Data for Examples and Comparative Examples

[0054] Table 2: Summary of Shelf Life Test Results for Examples and Comparative Examples

[0055] Example Conclusion: As can be seen from Example 1 and Comparative Example 1, and from Tables 1 and 2, room temperature irradiation sterilization can more effectively maintain the sensory quality and nutritional components of fresh food and extend the shelf life of the product compared with traditional high temperature sterilization.

[0056] As can be seen from Example 2 and Comparative Example 2, and from Tables 1 and 2, cold irradiation sterilization can better maintain the freshness and nutrition of fresh-cut vegetables and extend their shelf life compared to blanching.

[0057] As can be seen from Example 3 and Comparative Example 3, and from Tables 1 and 2, irradiation sterilization, compared with chemical disinfection, can better preserve the original flavor and bioactive components of fruits while controlling microorganisms.

[0058] As can be seen from Example 4 and Comparative Example 4, and from Tables 1 and 2, the application of irradiation sterilization technology to pre-cooked dishes can improve food safety and shelf life, while maintaining the sensory quality of the dishes.

[0059] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A cobalt-60-based irradiation sterilization and preservation process for fresh food, characterized in that, Includes the following steps: S1. Pre-process fresh food raw materials to obtain pre-processed fresh food; S2. Seal and package the fresh food obtained from the pretreatment in S1 to obtain packaged fresh food. S3. The packaged fresh food obtained in S2 is irradiated using a cobalt-60 irradiation source to obtain irradiated sterilized and preserved fresh food.

2. The cobalt-60-based irradiation sterilization and preservation process for fresh food according to claim 1, characterized in that, Following step S2, the packaged fresh food is cooled to reduce its temperature to 0–10°C.

3. The cobalt-60-based irradiation sterilization and preservation process for fresh food according to claim 1, characterized in that, The fresh food is at least one of fresh vegetables, fresh fruits, fresh-cut food, or pre-cooked dishes.

4. The cobalt-60-based irradiation sterilization and preservation process for fresh food according to claim 1, characterized in that, Step S1 also includes at least one of the following processing methods for fresh food ingredients: washing, sorting, shaping, cutting, peeling, draining, or seasoning.

5. The cobalt-60-based irradiation sterilization and preservation process for fresh food according to claim 4, characterized in that, When cutting fresh food, the particle size of the cut material should be controlled to be 0.5-5cm.

6. The cobalt-60-based irradiation sterilization and preservation process for fresh food according to claim 1, characterized in that, In step S2, the packaging is at least one of vacuum packaging, modified atmosphere packaging, deoxygenated packaging, or nitrogen-filled packaging.

7. The cobalt-60-based irradiation sterilization and preservation process for fresh food according to claim 1, characterized in that, In step S2, a protective gas is also introduced into the packaging, which includes nitrogen or carbon dioxide, with a gas volume ratio of 50-90% nitrogen and 10-50% carbon dioxide.

8. The cobalt-60-based irradiation sterilization and preservation process for fresh food according to claim 1, characterized in that, In step S3, the irradiation treatment is carried out at a temperature not higher than room temperature, with the irradiation temperature being 0–25°C.

9. The cobalt-60-based irradiation sterilization and preservation process for fresh food according to claim 1, characterized in that, In step S3, the absorption dose of the packaged fresh food is controlled to be 1.0 to 10.0 kGy.

10. The cobalt-60-based irradiation sterilization and preservation process for fresh food according to claim 1, characterized in that, After step S3, the total bacterial count of the irradiated sterilized and preserved fresh food is reduced to 10. 3 Products with a CFU / g content below 85% and a vitamin C retention rate of ≥85% and a chlorophyll retention rate of ≥90%.

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