Processing method of long-term stored food

Abstract

The invention provides a processing method of long-term stored food, and belongs to the technical field of food preservation. The invention provides a processing method of long-term storage food, which comprises the following steps: freeze-drying food at low temperature to obtain freeze-dried food; the freeze-dried food is irradiated, and sterilized food is obtained; and carrying out vacuum treatment on the sterilized food to obtain the food capable of being stored for a long time. According to the treatment method provided by the invention, the structure change of the food subjected to low-temperature freeze-drying is more beneficial to irradiation uniform penetrating sterilization, and the irradiated food can better avoid quality deterioration caused by oxidation reaction in a vacuum environment. The result of the embodiment shows that the processing method provided by the invention can efficiently control the number of microorganisms in the food for a long time, maintain the color and luster of the food, maintain the sensory quality of the food and maintain the nutritional ingredients of the food.

Description

Technical Field

[0001] The invention belongs to the technical field of food preservation, and in particular relates to a method for processing long-term stored food. Background Art

[0002] In the process of food storage technology development, how to preserve the nutritional content, taste and flavor of food while extending the shelf life has always been a key problem that needs to be solved. Traditional preservation methods, such as refrigeration, are not only costly, but also have strict requirements on environmental conditions; the method of adding preservatives is likely to cause consumers to worry about health risks. In view of this, exploring novel, safe and efficient food preservation technologies and packaging strategies has become a top priority for the food industry. Summary of the invention

[0003] In view of the defects in the prior art, the purpose of the present invention is to provide a method for processing long-term stored food, which can significantly extend the shelf life of food and ensure the excellent quality of food.

[0004] The objective of the present invention is achieved through the following technical solutions:

[0005] The present invention provides a method for processing long-term stored food, comprising the following steps:

[0006] Freeze-drying the food at low temperature to obtain freeze-dried food;

[0007] irradiating the freeze-dried food to obtain a sterilized food;

[0008] The sterilized food is subjected to vacuum treatment to obtain food that can be stored for a long time.

[0009] Preferably, the low-temperature freeze-drying includes low-temperature drying and analytical drying;

[0010] The temperature of the low-temperature drying is -50°C to -10°C; the low-temperature freeze-drying is performed to a moisture content of the food of ≤10%; the vacuum degree during the low-temperature freeze-drying is ≤50Pa;

[0011] The temperature of the analytical drying is 28-40° C.; the vacuum degree of the analytical drying is 5-15 Pa; and the time of the analytical drying is 3-8 hours.

[0012] Preferably, the irradiation comprises ultraviolet irradiation.

[0013] Preferably, the irradiation dose is 30000-80000 μW·s / cm 2 .

[0014] Preferably, the intensity of the irradiation is 20 to 40 μW / cm 2 .

[0015] Preferably, the vacuum treatment includes placing the sterilized food in a sealed device or a sealed container and then evacuating the container so that the sterilized food is in a vacuum environment; the vacuum degree of the vacuum environment is 1-200Pa.

[0016] Preferably, the food comprises any one or two or more of fruits, meat, vegetables and grains.

[0017] Preferably, the processed food is in the shape of any one or more of slices, blocks, shreds and dices.

[0018] The present invention provides application of the processing method described in the above technical solution in food preservation.

[0019] Preferably, the application includes any one or more of the following (1) to (4):

[0020] (1) Control the number of microorganisms in food;

[0021] (2) Maintain food color;

[0022] (3) Maintaining food sensory quality;

[0023] (4) Maintain the nutritional content of food.

[0024] Beneficial effects of the present invention

[0025] The present invention provides a method for processing long-term storage food, comprising the following steps: freeze-drying the food at low temperature to obtain freeze-dried food; irradiating the freeze-dried food to obtain sterilized food; and vacuum-treating the sterilized food to obtain long-term storage food. The present invention freeze-drys the food at low temperature, and uses the low temperature environment to directly sublimate the water in the food, thereby reducing the possibility of microbial reproduction and chemical reactions caused by water from the source, and retaining the inherent nutrients, taste characteristics and flavor characteristics of the food to the greatest extent. The freeze-dried food is irradiated, and the irradiation treatment mode can deeply penetrate the inside of the food, completely kill the residual bacteria, molds, yeasts, spores and other microorganisms therein, and no chemical substances will remain in the food, providing a solid guarantee for the safety of the food during the long storage period. Finally, the food is vacuum-treated to remove oxygen in the food storage environment, effectively inhibit the oxidation reaction processes such as oil oxidation, pigment fading and vitamin oxidation in the food, further stabilize and extend the shelf life of the food, and ensure that the food always maintains a stable quality state during the storage period. The treatment method provided by the present invention is not a simple superposition, but through reasonable adjustments in process sequence, parameter adaptation, etc., the treatment method is coordinated to optimize the effect of the treatment method on food quality, so that the treatment method forms a unique technical innovation. For example, the change in food structure after low-temperature freeze-drying is more conducive to uniform penetration and sterilization by irradiation, and the irradiated food can better avoid quality deterioration caused by oxidation reaction in a vacuum environment. The results of the examples show that the treatment method provided by the present invention can control the number of microorganisms in food for a long time and efficiently, and maintain the color, sensory quality and nutritional content of the food. DETAILED DESCRIPTION

[0026] The present invention provides a method for processing long-term stored food, comprising the following steps:

[0027] Freeze-drying the food at low temperature to obtain freeze-dried food;

[0028] irradiating the freeze-dried food to obtain a sterilized food;

[0029] The sterilized food is subjected to vacuum treatment to obtain food that can be stored for a long time.

[0030] The present invention freeze-dries food at low temperature to obtain freeze-dried food. In the present invention, the food includes any one or more of fruits, meat, vegetables and grains. In the present invention, the fruits, meat, vegetables and grains can be any one or more of uncooked fruits, meat, vegetables and grains, and can also be any one or more of cooked fruits, meat, vegetables and grains. In the present invention, the cooking includes any one or more of pickling, marsh water and cooked. In the present invention, the shape of the food when processed includes any one or more of slices, blocks, shreds and dices.

[0031] Before the food is treated by the treatment method, the food is preferably pretreated. The method for pretreatment of the food is not particularly limited in the present invention, and any conventional pretreatment method in the art can be used. When the fruit is treated by the treatment method, the fruit is preferably pretreated first; the pretreatment includes any one or more of peeling, core removal, slicing, dicing, and shredding. When the meat is treated by the treatment method, the meat is preferably pretreated first; the pretreatment includes any one or more of pickling, blanching, dicing, slicing, shredding, dicing, and cooking. When the vegetables are treated by the treatment method, the vegetables are preferably pretreated first; the pretreatment includes any one or more of washing, peeling, segmenting, dicing, shredding, dicing, blanching, pickling, and cooking. In the present invention, washing includes removing impurities such as yellow leaves and rotten leaves and washing; peeling includes removing the outer skin. When the present invention adopts the processing method to process grains, it is preferred to pre-process the grains first; the pre-processing includes any one or more of screening, washing, soaking, crushing, grinding, cutting and cooking. In the present invention, the screening includes removing impurities and shrunken grains, etc.; the washing is mainly to clean dust, etc.; the soaking is mainly to make it easier for subsequent processing, etc.; the cutting mainly refers to the cutting of some long-grain grains.

[0032] In the present invention, the length of the fruit slices can be 1-5 cm and the width can be 1-3 cm; the length of the meat slices can be 1-6 cm and the width can be 1-4 cm; the side length of the fruit pieces can be a cube with a side length of 1-3 cm; the side length of the meat pieces can be a cube with a side length of 1-4 cm.

[0033] As an optional embodiment of the present invention, the vegetables include any one or more of cabbage, cucumber, potato, tomato, eggplant, green pepper, beans, celery, spinach, broccoli, onion, carrot, wax gourd and pumpkin; the fruits include any one or more of banana, apple, pear, orange, tangerine, strawberry, blueberry, grape, mango, watermelon, peach, plum, kiwi and pitaya; the meat includes any one or more of beef, pork, donkey meat, mutton, chicken, duck meat, goose meat, fish and shrimp meat; the cereals include any one or more of rice, millet, corn, wheat, oats, buckwheat, sorghum, coix seed, red bean, mung bean and black bean.

[0034] The low-temperature freeze-drying of the present invention includes low-temperature drying and analytical drying; the temperature of the low-temperature drying can be -50°C to -10°C, or -40°C to -20°C, or -35°C to -22°C, or -33°C to -25°C, or -28°C; the low-temperature drying to the moisture content of the food ≤10%, can be 5% to 8%, or 6% to 7%; the vacuum degree during the low-temperature drying is ≤50Pa, can be 25 to 50Pa, or 15 to 28Pa, or 18 to 20Pa. After the low-temperature drying, the present invention also includes analytical drying of the low-temperature dried food to obtain a freeze-dried food. The temperature of the analytical drying of the present invention can be 28 to 40°C, or 30 to 38°C, or 33 to 35°C; the vacuum degree of the analytical drying can be 5 to 15Pa, or 8 to 12Pa, or 10 to 11Pa; the time of the analytical drying can be 3 to 8h, or 4 to 6h, or 5h. After the analytical drying is completed in the present invention, freeze-dried food is obtained. The present invention uses low-temperature freeze-drying to directly sublimate the water in the food, reducing the possibility of microbial reproduction and chemical reactions caused by water from the source, and retaining the inherent nutrients, taste characteristics and flavor characteristics of the food to the greatest extent; at the same time, the change in food structure after low-temperature freeze-drying is more conducive to uniform penetration and sterilization by irradiation.

[0035] After obtaining the freeze-dried food, the present invention irradiates the freeze-dried food to obtain a sterilized food. In the present invention, the irradiation includes ultraviolet irradiation. As an optional embodiment of the present invention, the ultraviolet radiation source can be an ultraviolet lamp with a specific wavelength; the wavelength of the ultraviolet irradiation can be 200-280nm, 220-270nm, or 250-270nm. In the present invention, the irradiation dose can be 30,000-80,000 μW·s / cm 2 , can also be 40000~60000μW·s / cm 2 , and can also be 50000μW·s / cm 2 In the present invention, the intensity of the radiation can be 20 to 40 μW / cm 2 , can also be 22 to 30 μW / cm 2 , and can also be 25 to 26 μW / cm 2 After irradiation, sterilized food is obtained. The irradiation treatment mode of the present invention can deeply penetrate into the food, completely kill the residual bacteria, molds, yeasts and their spores and other microorganisms, and no chemical substances will remain in the food, providing a solid guarantee for the safety of food during a long storage period.

[0036] After obtaining the sterilized food, the present invention performs a vacuum treatment on the sterilized food to obtain food that can be stored for a long time. In the present invention, the vacuum treatment includes placing the sterilized food in a sealing device or a sealed container and then evacuating the container so that the sterilized food is in a vacuum environment; the vacuum degree of the vacuum environment can be 1 to 200Pa, or 10 to 100Pa, or 30 to 80Pa, or 50Pa. The present invention obtains food that can be stored for a long time through vacuum treatment. The present invention can effectively inhibit the oxidation reaction processes such as oil oxidation, pigment fading, and vitamin oxidation inside the food by means of vacuum treatment, further stabilize and extend the shelf life of the food, and ensure that the food always maintains a stable quality state during storage.

[0037] The processing method described in the above technical solution of the present invention forms a unique technical innovation in terms of process sequence, parameter adaptation and coordinated optimization of the impact on food quality by sequentially subjecting food to low-temperature freeze-drying, irradiation and vacuum treatment. The structural changes of food after low-temperature freeze-drying are more conducive to uniform penetration and sterilization by irradiation, and the irradiated food can better avoid quality deterioration caused by oxidation reaction in a vacuum environment.

[0038] The present invention provides an application of the treatment method described in the above technical solution in food preservation. In the present invention, the application preferably includes any one or more of the following (1) to (4): (1) controlling the number of microorganisms in food; (2) maintaining the color of food; (3) maintaining the sensory quality of food; (4) maintaining the nutritional components of food.

[0039] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0040] Example 1

[0041] A method for processing a dish prepared with beef, broccoli, onions and other ingredients stored for a long time, the steps are as follows:

[0042] The above materials are processed, boiled and processed into dishes, and then put into a mold, which is a 1010 square grid, and each grid is 3 cm long, 4 cm wide and 5 cm high respectively. The mold containing the dishes is placed inside a freeze-drying device for low-temperature freeze-drying. During low-temperature freeze-drying, the vacuum is 25-50 Pa, and the freeze-drying temperature is set at -25°C to -30°C for freeze-drying for 12-18 hours, so that the moisture content of the freeze-dried dishes is reduced to 8% to 10%. After 6-8 hours, the temperature is 35-40°C, and the vacuum degree is 5-10Pa, analytical drying is performed to obtain freeze-dried soup cubes of dishes with a moisture content of 1% to 3%.

[0043] The freeze-dried soup cubes were irradiated with ultraviolet light at a wavelength of 250nm and a dose of 60,000μW·s / cm 2 , irradiation intensity is 25μW / cm 2 The irradiation time is precisely calculated to be 40 minutes. After the irradiation is completed, the freeze-dried soup cubes of the sterilized dishes are obtained.

[0044] The freeze-dried soup cubes of the sterilized dishes are placed in an iron can, and the inside of the iron can is evacuated to a vacuum degree of 50Pa, and then stored at room temperature.

[0045] Example 1-1

[0046] A method for processing a dish prepared with beef, broccoli, onion and other raw materials stored for a long time, the steps are the same as those in Example 1, wherein the vacuum is 25-50Pa during low-temperature freeze-drying, the freeze-drying temperature is set to -25°C and the freeze-drying is performed for 12 hours to reduce the moisture content of the freeze-dried dish to 4%-6%, and then after 6 hours, the temperature is 35°C and the vacuum degree is 5-15Pa, analytical drying is performed to obtain freeze-dried soup cubes of the dish with a moisture content of 1%-3%.

[0047] The freeze-dried soup cubes were irradiated with ultraviolet light at a wavelength of 250nm and a dose of 60,000μW·s / cm 2 , irradiation intensity is 25μW / cm 2 The irradiation time is precisely calculated to be 40 minutes. After the irradiation is completed, the freeze-dried soup cubes of the sterilized dishes are obtained.

[0048] The freeze-dried soup cubes of the sterilized dishes are placed in an iron can, and the inside of the iron can is evacuated to a vacuum degree of 50Pa, and then stored at room temperature.

[0049] Example 1-2

[0050] A method for processing a dish prepared with beef, broccoli, onion and other raw materials stored for a long time, the steps are the same as those in Example 1, wherein the vacuum is 25-50Pa during low-temperature freeze-drying, the freeze-drying temperature is set to -30°C and the freeze-drying is performed for 18 hours, so that the moisture content of the freeze-dried dish is reduced to 8%-10%, and then after 8 hours of analytical drying at a temperature of 40°C and a vacuum degree of 5-15Pa, a freeze-dried soup cube with a moisture content of 1%-3% of the dish is obtained.

[0051] The freeze-dried soup cubes were irradiated with ultraviolet light at a wavelength of 270 nm and a dose of 60,000 μW·s / cm 2 , irradiation intensity is 25μW / cm 2The irradiation time is precisely calculated to be 40 minutes. After the irradiation is completed, the freeze-dried soup cubes of the sterilized dishes are obtained.

[0052] The freeze-dried soup cubes of the sterilized dishes are placed in an iron can, and the inside of the iron can is evacuated to a vacuum degree of 50Pa, and then stored at room temperature.

[0053] Example 2

[0054] A method for processing dried fruits for long-term storage, comprising the following steps:

[0055] Fresh apples were sliced ​​to a thickness of 1 cm to obtain fruit slices; the fruit slices were placed in a mold (the mold was the same as in Example 1) and placed inside a freeze-drying device for low-temperature freeze-drying. During the low-temperature freeze-drying, the vacuum degree was 25-50 Pa. The freeze-drying temperature was set to -30°C. The freeze-drying was performed for 10 hours to reduce the moisture content to 7%. After 5 hours of analytical drying at a temperature of 32.5°C and a vacuum degree of 5-15 Pa, freeze-dried fruit slices with a moisture content of 3% were obtained.

[0056] The freeze-dried fruit slices were irradiated with ultraviolet light at a wavelength of 250nm and a dose of 40,000μW·s / cm 2 , irradiation intensity is 20μW / cm 2 The irradiation treatment time is accurately calculated to be 33.3 minutes. After the irradiation treatment is completed, sterilized fruit slices are obtained.

[0057] Put the sterilized fruit slices into an iron can, evacuate the inside of the can to a vacuum degree of 50Pa, and store it at room temperature.

[0058] Example 3

[0059] A method for processing rice for long-term storage, comprising the following steps:

[0060] The cooked rice is put into a mold (the mold is the same as in Example 1), placed inside a freeze-drying device, and subjected to low-temperature freeze-drying. The vacuum degree during low-temperature freeze-drying is 25 to 50 Pa, and the freeze-drying temperature is set to -22 to -28°C. The freeze-drying is performed for 6 to 10 hours to reduce the moisture content to 5% to 7%. The freeze-dried rice is then subjected to analytical drying for 3 to 5 hours at a temperature of 28 to 33°C and a vacuum degree of 10 to 15 Pa to obtain the freeze-dried rice.

[0061] The freeze-dried rice was irradiated with ultraviolet light, with a wavelength of 270nm and a dose of 50,000μW·s / cm 2 , irradiation intensity is 22μW / cm 2 The irradiation treatment time is accurately calculated to be 37 minutes. After the irradiation treatment is completed, sterilized rice is obtained.

[0062] Put the sterilized rice into an iron can, evacuate the inside of the can to a vacuum degree of 50Pa, and store it at room temperature.

[0063] Example 3-1

[0064] A method for processing rice for long-term storage, step embodiment 3, wherein the vacuum degree is 25-50Pa during low-temperature freeze-drying, the freeze-drying temperature is set to -22°C, and the moisture content is reduced to 5%-7% by freeze-drying for 6 hours, and then the freeze-dried rice is obtained by analytical drying at a temperature of 28°C and a vacuum degree of 10Pa for 3 hours.

[0065] The freeze-dried rice was irradiated with ultraviolet light, with a wavelength of 250nm and a dose of 50,000μW·s / cm 2 , irradiation intensity is 22μW / cm 2 The irradiation treatment time is accurately calculated to be 37 minutes. After the irradiation treatment is completed, sterilized rice is obtained.

[0066] Put the sterilized rice into an iron can, evacuate the inside of the can to a vacuum degree of 50Pa, and store it at room temperature.

[0067] Example 3-2

[0068] A method for processing rice for long-term storage, step embodiment 3, wherein the vacuum degree is 25-50Pa during low-temperature freeze-drying, the freeze-drying temperature is set to -28°C, and the moisture content is reduced to 4-6% by freeze-drying for 10 hours, and then the freeze-dried rice is obtained by analytical drying at a temperature of 33°C and a vacuum degree of 10-15Pa for 5 hours.

[0069] The freeze-dried rice was irradiated with ultraviolet light, with a wavelength of 270nm and a dose of 50,000μW·s / cm 2 , irradiation intensity is 22μW / cm 2 The irradiation treatment time is accurately calculated to be 37 minutes. After the irradiation treatment is completed, sterilized rice is obtained.

[0070] Put the sterilized rice into an iron can, evacuate the inside of the can to a vacuum degree of 50Pa, and store it at room temperature.

[0071] Example 4

[0072] A method for processing beef jerky for long-term storage, comprising the following steps:

[0073] The beef is pre-processed to obtain processed beef; the pre-processing method is to cut the beef into pieces, and the size of the pieces is: beef pieces with a side length of 1 cm cube.

[0074] The treated beef is placed in a mold (the mold is the same as in Example 1), placed inside a freeze-drying device, and subjected to low-temperature freeze-drying. The vacuum degree during low-temperature freeze-drying is 25 to 50 Pa, and the freeze-drying temperature is set to -28 to -33°C. The freeze-drying is performed for 10 to 15 hours to reduce the moisture content to 7% to 8%. After 5 to 7 hours of analytical drying at a temperature of 32 to 38°C and a vacuum degree of 10 to 15 Pa, freeze-dried beef is obtained.

[0075] The freeze-dried beef was irradiated with ultraviolet light, with a wavelength of 250nm and an irradiation dose of 80,000μW·s / cm 2 , irradiation intensity is 30μW / cm 2 The irradiation treatment time is precisely calculated to be 44.4 minutes. After the irradiation treatment is completed, sterilized beef is obtained.

[0076] Put the sterilized beef into an iron can, evacuate the inside of the can to a vacuum degree of 150Pa, and store it at room temperature.

[0077] Example 4-1

[0078] A method for processing beef jerky for long-term storage, the steps are the same as those of Example 4, wherein the vacuum degree is 25-50Pa during low-temperature freeze-drying, the freeze-drying temperature is set to -28°C, and the freeze-drying is performed for 10 hours to reduce the moisture content to 5%-8%, and then analytical drying is performed for 5 hours at a temperature of 32°C and a vacuum degree of 5-15Pa to obtain freeze-dried beef.

[0079] The freeze-dried beef was irradiated with ultraviolet light, with a wavelength of 250nm and an irradiation dose of 80,000μW·s / cm 2 , irradiation intensity is 30μW / cm 2 The irradiation time is precisely calculated to be 44.4 minutes. After the irradiation is completed, sterilized beef is obtained.

[0080] Put the sterilized beef into an iron can, evacuate the inside of the can to a vacuum degree of 10Pa, and store it at room temperature.

[0081] Example 4-2

[0082] A method for processing beef jerky for long-term storage, the steps are the same as those of Example 4, wherein the vacuum degree is 25-50Pa during low-temperature freeze-drying, the freeze-drying temperature is set to -30°C, and the freeze-drying is performed for 12 hours to reduce the moisture content to 7%-8%, and then analytical drying is performed for 6 hours at a temperature of 35°C and a vacuum degree of 5-15Pa to obtain freeze-dried beef.

[0083] The freeze-dried beef was irradiated with ultraviolet light, with a wavelength of 260nm and a dose of 80,000μW·s / cm 2 , irradiation intensity is 30μW / cm 2 The irradiation treatment time is precisely calculated to be 44.4 minutes. After the irradiation treatment is completed, sterilized beef is obtained.

[0084] Put the sterilized beef into an iron can, evacuate the inside of the can to a vacuum degree of 50Pa, and store it at room temperature.

[0085] Example 4-3

[0086] A method for processing beef jerky for long-term storage, the steps are the same as those of Example 4, wherein the vacuum degree is 25-50Pa during low-temperature freeze-drying, the freeze-drying temperature is set to -33°C, and the freeze-drying is performed for 15 hours to reduce the moisture content to 7%-8%, and then analytical drying is performed for 7 hours at a temperature of 38°C and a vacuum degree of 5-15Pa to obtain freeze-dried beef.

[0087] The freeze-dried beef was irradiated with ultraviolet light, with a wavelength of 250nm and an irradiation dose of 80,000μW·s / cm 2 , irradiation intensity is 30μW / cm 2 The irradiation treatment time is precisely calculated to be 44.4 minutes. After the irradiation treatment is completed, sterilized beef is obtained.

[0088] Put the sterilized beef into an iron can, evacuate the inside of the can to a vacuum degree of 50Pa, and store it at room temperature.

[0089] Comparative Example 1

[0090] A method for processing stored dried fruits, comprising the following steps:

[0091] Fresh apples were sliced ​​(the size of the slices was the same as in Example 2) to obtain fruit slices. The fruit slices were low-temperature dried at 50° C. to reduce the moisture content to 5%, thereby obtaining dried fruit slices.

[0092] The dried fruit slices were irradiated with ultraviolet light at a wavelength of 250nm and a dose of 40,000μW·s / cm 2 , irradiation intensity is 20μW / cm 2 The irradiation treatment time is accurately calculated to be 33.3 minutes. After the irradiation treatment is completed, sterilized fruit slices are obtained.

[0093] Put the sterilized fruit slices into an iron can, evacuate the inside of the can to a vacuum degree of 50Pa, and then store them at room temperature.

[0094] Comparative Example 2

[0095] A method for processing stored dried fruits, comprising the following steps:

[0096] Fresh apples are sliced ​​(the size of the slices is the same as in Example 2) to obtain fruit slices. The fruit slices are placed in a mold (the mold is the same as in Example 1) and placed inside a freeze-drying device for low-temperature freeze-drying. During low-temperature freeze-drying, the vacuum degree is 25-50 Pa. The freeze-drying temperature is set to -30°C. The freeze-drying is performed for 10 hours to reduce the moisture content to 6%-8%. After 5 hours of analytical drying at a temperature of 32.5°C and a vacuum degree of 5-15 Pa, freeze-dried fruit slices with a moisture content of 2%-4% are obtained.

[0097] The freeze-dried fruit slices were irradiated with ultraviolet light at a wavelength of 250nm and the irradiation dose was precisely set to 40,000μW·s / cm 2 , irradiation intensity is 20μW / cm 2 The irradiation time is calculated to be 33.3 minutes. After the irradiation is completed. After the irradiation is completed, the sterilized fruit slices are obtained.

[0098] After the irradiation treatment is completed, the sterilized fruit slices are placed in iron cans, and nitrogen is filled into the iron cans to a pressure of 80 kPa.

[0099] Store at room temperature.

[0100] Comparative Example 3

[0101] A method for processing stored beef jerky, comprising the following steps:

[0102] The processed beef (processing method is the same as that in Example 4) is subjected to low-temperature drying at a temperature of 65° C. to reduce its moisture content to 10%, thereby obtaining dried beef slices.

[0103] The dried beef slices were irradiated with ultraviolet light, with a wavelength of 250nm and a dose of 80,000μW·s / cm 2 , irradiation intensity is 30μW / cm 2 The irradiation treatment time is precisely calculated to be 44.4 minutes. After the irradiation treatment is completed, sterilized beef slices are obtained.

[0104] Put the sterilized beef slices into an iron can, evacuate the inside of the can to a vacuum degree of 50Pa, and store it at room temperature.

[0105] Comparative Example 4

[0106] A method for processing stored beef jerky, comprising the following steps:

[0107] The treated beef (the treatment method is the same as that in Example 4) is placed in a mold (the mold is the same as that in Example 1), and then the mold is placed inside a freeze-drying device for low-temperature freeze-drying. The vacuum degree during low-temperature freeze-drying is 25 to 50 Pa, and the freeze-drying temperature is set to -28°C. Freeze-drying is performed for 10 hours to reduce its moisture content to 5% to 8%. After 5 hours of analytical drying at a temperature of 32°C and a vacuum degree of 5 to 15 Pa, freeze-dried beef is obtained.

[0108] The freeze-dried beef was irradiated with ultraviolet light, with a wavelength of 250nm and an irradiation dose of 80,000μW·s / cm 2 , irradiation intensity is 30μW / cm 2 The irradiation treatment time is precisely calculated to be 44.4 minutes. After the irradiation treatment is completed, sterilized beef is obtained.

[0109] The sterilized beef was placed in an iron can and nitrogen was filled into the iron can to a pressure of 80 kPa.

[0110] Store at room temperature.

[0111] Comparative Example 5

[0112] A method for processing stored beef jerky, comprising the following steps:

[0113] The processed beef (processing method is the same as in Example 4) is irradiated by ultraviolet technology, and the irradiation dose is precisely set to 80000 μW·s / cm 2 , irradiation intensity is 30μW / cm 2 The irradiation treatment time is precisely calculated to be 44.4 minutes. After the irradiation treatment is completed, sterilized beef is obtained.

[0114] The sterilized beef slices were frozen and stored at -18°C.

[0115] Comparative Example 6

[0116] A method for processing stored dried fruits, the steps are the same as those of Example 2, the only difference being that low-temperature freeze-drying is not performed.

[0117] Comparative Example 7

[0118] A method for processing stored dried fruits, the steps are the same as those of Example 2, the only difference being that no irradiation treatment is performed.

[0119] Comparative Example 8

[0120] A method for processing stored dried fruits, the steps are the same as those of Example 2, the only difference being that no vacuum treatment is performed.

[0121] Comparative Example 9

[0122] A method for processing stored dried fruits, comprising the following steps:

[0123] Slice fresh apples into slices of 1 cm thick.

[0124] The apple slices were irradiated with ultraviolet light at a wavelength of 250 nm and a dose of 40,000 μW·s / cm 2 , irradiation intensity is 20μW / cm 2 , the irradiation treatment time is 33.3min.

[0125] The irradiated fruit slices are placed in a mold and placed inside a freeze-drying device for low-temperature freeze-drying. The temperature of the low-temperature freeze-drying is -30°C, the vacuum degree is set to 25-50Pa, the freeze-drying time is 10 hours to reduce the moisture content to 7%, and then after 5 hours, the temperature is 32.5°C, the vacuum degree is 5-15Pa, and the dried fruit with a moisture content of 3% is obtained.

[0126] Put the dried fruits into an iron can, evacuate the inside of the can to a vacuum degree of 50Pa, and store it at room temperature.

[0127] Application Example 1

[0128] 1. The microbial content of the reserve foods prepared in Example 2, Example 4-1 and Comparative Examples 1 to 9 was tested after storage for 1 month and 12 months. The frozen food in Comparative Example 5 was tested after thawing. The total colony count of the food was determined according to the plate count method of the National Food Safety Standard for Food Microbiological Examination (GB 4789.2).

[0129] The results of the determination of microbial content in the reserve foods prepared in Example 2, Example 4-1 and Comparative Examples 1 to 9 are shown in Table 1.

[0130] Table 1 Results of determination of microbial content in the stored foods prepared in Example 2, Example 4-1 and Comparative Examples 1 to 9

[0131]

[0132]

[0133] In this experiment, the effects of different treatment methods on the total colony count of various foods were studied. From the total colony count data in Table 1: Example 2 (canned fruit) and Example 4-1 (canned beef): the total colony count remained at a low level (≤10 CFU / g and ≤20 CFU / g) during the storage time of 1 month and 12 months. This shows that freeze-drying-irradiation-vacuum treatment can effectively inhibit the growth of microorganisms in the preservation of fruits and beef, maintain a low total colony count for a long time, and ensure the quality and safety of food.

[0134] Comparative Example 1 (canned fruit treated with low-temperature drying-irradiation-vacuum treatment): The total colony counts in January and December were similar to those in Example 2 (≤10 CFU / g in January and ≤10 CFU / g in December), which indicated that the effects of low-temperature drying and freeze-drying on inhibiting microbial growth in the early stage of treatment were not much different in the short term, but in the long run, freeze-drying treatment may have a more stable antibacterial effect.

[0135] Comparative Example 2 (freeze-dried-irradiated-nitrogen-filled canned fruit): The total colony count in December was 40 CFU / g, which was higher than that in Example 2 in December. This indicates that in the treatment of canned fruit, vacuum treatment is more conducive to inhibiting the growth of microorganisms than nitrogen filling treatment.

[0136] Comparative Example 3 (canned beef dried at low temperature, irradiated and vacuum treated): the total colony count in December reached 400 CFU / g, which was much higher than that in Example 4 in December (≤10 CFU / g), indicating the importance of freeze-drying for controlling microbial growth during beef processing, and that drying could not achieve the antibacterial effect of freeze-drying.

[0137] Comparative Example 4 (freeze-dried-irradiated-nitrogen-filled canned beef): The total colony count in December was 50 CFU / g, which was higher than the total colony count in December of Example 4, further verifying the advantage of vacuum treatment in beef preservation.

[0138] Comparative Example 5 (beef treated with irradiation-freezing): The total colony count in December was as high as 100,000 CFU / g. Compared with Example 4, it fully demonstrates that the traditional freezing treatment is far inferior to the freeze-drying-irradiation-vacuum treatment in inhibiting microbial growth.

[0139] Comparative Example 6 (irradiation-vacuum treated canned fruit): The total colony count in December was 9300 CFU / g. Due to the lack of a freeze-drying step, the colony count increased significantly, indicating that freeze-drying is an indispensable part of the patented process.

[0140] Comparative Example 7 (freeze-dried and vacuum-treated canned fruit): The total colony count in December was 163,000 CFU / g, indicating that without irradiation treatment, microbial growth is difficult to be effectively controlled and irradiation treatment is essential for inhibiting microbial growth.

[0141] Comparative Example 8 (freeze-dried-irradiated canned fruit): The total colony count in December was estimated to be 3,970,000 CFU / g. This data highlights the critical role of vacuum treatment in the food storage process. The lack of vacuum treatment will lead to the massive reproduction of microorganisms.

[0142] Comparative Example 9 (irradiation-freeze-drying-vacuum treated canned fruit): The total number of colonies at 1 month and 12 months was higher than that in the example, indicating that changing the order of irradiation and freeze-drying would affect the preservation effect of food.

[0143] Conclusion: Through the analysis of the data in Table 1, it can be concluded that freeze-drying-irradiation-vacuum treatment can significantly inhibit the growth of microorganisms and maintain a low total colony count during the storage of canned dishes, fruits, rice and beef. Changing any of the processing steps, such as replacing freeze-drying with low-temperature drying or drying, replacing vacuum treatment with nitrogen filling treatment, or lack of irradiation treatment, will affect the inhibitory effect on microbial growth to varying degrees, resulting in an increase in the total colony count, thereby affecting the preservation quality and safety of food. Among them, the total number of microbial colonies in the treatment methods of Example 2 and Example 4-1 was reduced to less than 10 CFU / g after one month of storage, which is far below the usual safety standard, and the growth of microorganisms is effectively inhibited throughout the storage period. The above results show that the low-temperature freeze-drying-irradiation-vacuum treatment storage method provided by the present invention, low-temperature freeze-drying, irradiation and vacuum treatment can synergistically exert the antibacterial and antimicrobial effects of food.

[0144] 2. An accelerated aging test was performed on the stored foods prepared in Example 2, Example 4-1 and Comparative Examples 1 to 8.

[0145] Accelerated aging test method:

[0146] Accelerated aging experiments are based on the Arrhenius equation. They accelerate the reaction rate by increasing the temperature, thereby simulating the effects of long-term aging in a shorter time. In order to simulate 15 years of aging, the temperature can be set to 55°C, which is relatively high but does not affect the essential properties of the food, and the relative humidity is maintained at 75%. The food is tested at regular intervals of 1 month, 3 months, 5 months, and 7 months. By comparing the aging rate with that at room temperature, the room temperature aging results of 2.2 years, 6.7 years, 11.1 years, and 15.5 years under the high temperature conditions are calculated.

[0147] The food was subjected to an accelerated aging experiment at a temperature of 55°C and a relative humidity of 75%. The total number of bacterial colonies in the food was measured at 1 month, 3 months, 5 months and 7 months of the experiment. At the same time, professionals evaluated the color and taste of the food. The results of the accelerated aging experiment on the total number of bacterial colonies in the reserve food are shown in Table 2; the evaluation of the color and taste of the reserve food is shown in Table 3.

[0148] Table 2 Determination of microbial content of the reserve foods prepared in Example 2, Example 4-1 and Comparative Examples 1 to 8

[0149]

[0150]

[0151] Table 3 Color and taste of the reserve foods prepared in Example 2, Example 4-1 and Comparative Examples 1 to 8

[0152]

[0153]

[0154]

[0155]

[0156]

[0157] As shown in Tables 2 to 3, the long-term storage food processing method provided by the present invention can significantly control the number of microorganisms in the storage food during the accelerated aging process, while maintaining a high edible value of the storage food, so that its color and taste are more efficiently preserved compared to other storage methods. It can be analyzed from the accelerated aging test and actual storage observation that the dried fruit and beef jerky after comprehensive treatment in Example 2 and Example 4-1 are predicted to maintain high quality within 180 months under normal temperature, significantly extending their market circulation period. The dried fruit or beef jerky treated in Comparative Examples 1 to 8 may be obviously corrupted in 24 months, and the shelf life is greatly shortened.

[0158] 5. The nutritional components of the reserve foods prepared in Example 2, Example 4-1 and Comparative Examples 1 to 8 were analyzed.

[0159] Vitamin C was measured in fruit samples; protein and fat were measured in beef samples.

[0160] Vitamin C determination: High performance liquid chromatography (HPLC) was used to quantify the vitamin C content in the fruit samples.

[0161] Protein determination: The protein content of meat samples was determined using the Kjeldahl method. This method calculates the total amount of protein by measuring the nitrogen content after digestion of the sample.

[0162] Fat determination: The fat content of the samples was analyzed using the Soxhlet extraction method. This method extracts the fat in the sample using an organic solvent and quantifies it by weight.

[0163] The results of the nutritional analysis of the reserve foods prepared in Example 2, Example 4-1 and Comparative Examples 1 to 8 are shown in Table 4.

[0164] Table 4 Nutritional analysis results of the reserve foods prepared in Example 2, Example 4-1 and Comparative Examples 1 to 8

[0165]

[0166]

[0167] The “-” in Table 4 indicates that the relevant components were not detected.

[0168] The following is an analysis summary of the above experimental data:

[0169] (1) Vitamin C content analysis (for fruit samples)

[0170] Example 2 (Freeze-dried-irradiated-vacuum treated canned fruit)

[0171] The vitamin C content was 120 mg / 100 g, the highest among all fruit processing samples. This shows that the freeze-drying-irradiation-vacuum processing process has a good protective effect on the vitamin C in the fruit and can effectively reduce the loss of vitamin C during processing and storage.

[0172] Comparative Example 1 (low temperature drying-irradiation-vacuum treated canned fruit)

[0173] The vitamin C content is 90 mg / 100 g, which is lower than that in Example 2. This indicates that low-temperature drying has a poorer retention effect on vitamin C than freeze-drying, which may be because the temperature and time during the drying process cause partial decomposition of vitamin C.

[0174] Comparative Example 2 (Freeze-dried-irradiated-nitrogen-filled canned fruit)

[0175] The vitamin C content is 100 mg / 100 g, slightly lower than that in Example 2. This indicates that although the nitrogen treatment can protect vitamin C to a certain extent, it is not as good as the vacuum treatment, and a small amount of oxygen may cause vitamin C oxidation.

[0176] Comparative Example 6 (Irradiation-vacuum treated canned fruit)

[0177] The vitamin C content is 170mg / 100g.

[0178] Comparative Example 7 (Freeze-dried-vacuum treated canned fruit)

[0179] The vitamin C content is 190mg / 100g.

[0180] Comparative Example 8 (Freeze-dried-irradiated canned fruit)

[0181] The vitamin C content is 120mg / 100g.

[0182] The data of comparative examples 6 to 8 show that the vitamin C content varies with irradiation or freeze-drying and vacuum treatment alone. The freeze-drying-irradiation process can preserve nutrients to a greater extent during long-term storage. Although it does not have the highest vitamin C content, it has obvious advantages considering the storage time, nutrition and taste.

[0183] (2) Protein content analysis (for beef samples)

[0184] Example 4-1 (Freeze-dried-irradiated-vacuum treated canned beef)

[0185] The protein content was 25g / 100g, which was higher in the processed beef samples. This indicated that the processing flow could better retain the protein in beef, and freeze-drying, irradiation and vacuum treatment cooperated with each other to reduce the denaturation and loss of protein.

[0186] Comparative Example 3 (Drying-Irradiation-Vacuum Treated Canned Beef)

[0187] The protein content is 22 g / 100 g, which is lower than that of Example 4-1. The drying process may cause partial protein denaturation or loss, which is not as good as the freeze-drying treatment in protecting the protein.

[0188] Comparative Example 4 (Freeze-dried-irradiated-nitrogen-filled canned beef)

[0189] The protein content is 23g / 100g, slightly lower than that of Example 4-1. Nitrogen filling treatment is not as effective as vacuum treatment in protecting protein, and a small amount of oxygen may cause oxidation and other reactions of protein.

[0190] Comparative Example 5 (frozen beef)

[0191] The protein content was 21 g / 100 g, which was lower than that of Example 4-1. Traditional freezing treatment may damage the beef cell structure due to ice crystal formation, resulting in protein loss or denaturation.

[0192] (3) Fat content analysis (for beef samples)

[0193] Example 4-1 (Freeze-dried-irradiated-vacuum treated canned beef)

[0194] The fat content is 15g / 100g, which is at a relatively high level among the processed beef samples. This processing process can better protect the fat in the beef and prevent fat oxidation and loss.

[0195] Comparative Example 3 (Drying-Irradiation-Vacuum Treated Canned Beef)

[0196] - The fat content is 12 g / 100 g, which is lower than that of Example 4-1. The drying process may cause part of the fat to melt and flow out or undergo oxidative decomposition, resulting in a decrease in the fat content.

[0197] Comparative Example 4 (Freeze-dried-irradiated-nitrogen-filled canned beef)

[0198] The fat content is 13 g / 100 g, slightly lower than that of Example 4-1. The protective effect of nitrogen treatment on fat is slightly inferior to that of vacuum treatment, and a small amount of oxygen may enter to cause fat oxidation.

[0199] Comparative Example 5 (frozen beef)

[0200] The fat content was 13 g / 100 g, slightly lower than that of Example 4-1. The freezing process may damage the cell structure of the beef, resulting in partial fat loss or oxidation.

[0201] (4) Summary

[0202] Through the analysis of the nutritional components of the embodiments and comparative examples, it can be concluded that the freeze-drying-irradiation-vacuum treatment process can better retain the nutritional components in the food, such as vitamin C, protein and fat, in the processing of foods such as dishes, fruits, rice and beef. Changing any of the processing steps, such as replacing freeze-drying with low-temperature drying or drying, replacing vacuum treatment with nitrogen filling treatment, or lack of irradiation treatment, will affect the retention effect of nutrients to varying degrees, resulting in a decrease in the content of nutrients such as vitamin C, protein or fat. The processing method for long-term storage food provided by the present invention has obvious advantages in protecting the nutritional components of food.

[0203] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for processing long-term stored food, characterized in that: The following steps are involved: Freeze-drying the food at low temperature to obtain freeze-dried food; irradiating the freeze-dried food to obtain a sterilized food; The sterilized food is subjected to vacuum treatment to obtain food that can be stored for a long time.

2. The processing method according to claim 1, characterized in that: The low-temperature freeze-drying includes low-temperature drying and analytical drying; The temperature of the low-temperature drying is -50°C to -10°C; the low-temperature freeze-drying is performed to a moisture content of the food of ≤10%; the vacuum degree during the low-temperature freeze-drying is ≤50Pa; The temperature of the analytical drying is 28-40° C.; the vacuum degree of the analytical drying is 5-15 Pa; and the time of the analytical drying is 3-8 hours.

3. The processing method according to claim 1, characterized in that: The irradiation includes ultraviolet irradiation.

4. The processing method according to claim 3, characterized in that: The irradiation dose is 30000-80000 μW·s / cm 2 .

5. The processing method according to claim 4, characterized in that: The intensity of the irradiation is 20 to 40 μW / cm 2 .

6. The processing method according to claim 1, characterized in that: The vacuum treatment includes placing the sterilized food in a sealed device or a sealed container and then evacuating the container so that the sterilized food is in a vacuum environment; the vacuum degree of the vacuum environment is 1-200Pa.

7. The processing method according to claim 1, characterized in that: The food comprises any one or two or more of fruits, meat, vegetables and grains.

8. The processing method according to claim 7, characterized in that: The processed food may be in the form of any one or more of slices, blocks, shreds and dices.

9. Use of the treatment method according to any one of claims 1 to 8 in food preservation.

10. The use according to claim 9, characterized in that: The application includes any one or more of the following (1) to (4): (1) Control the number of microorganisms in food; (2) Maintain food color; (3) Maintaining food sensory quality; (4) Maintain the nutritional content of food.

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