A method of sterilizing canned food

Abstract

The present application relates to the field of food processing technology, and discloses a sterilization method for canned food, which comprises the following steps: (1) placing canned food to be sterilized into a high-pressure sealed sterilization kettle; (2) opening a steam inlet valve of the sterilization kettle, and automatically opening an exhaust valve of the sterilization kettle to exhaust when the temperature is raised to 95-100 DEG C, and closing the exhaust valve to complete the exhaust process after the temperature is raised to 105-110 DEG C and kept for a period of time; (3) continuing to introduce high-temperature steam after the exhaust is completed, and performing sterilization operation after the temperature in the sterilization kettle is raised to 115-120 DEG C; and (4) automatically closing the steam inlet valve of the sterilization kettle after the sterilization is completed, and cooling, thereby obtaining the canned food. The present application avoids using the traditional water bath sterilization method, and adopts steam sterilization, so that the heat energy loss is small, the sterilization kettle can quickly and effectively sterilize the product under the set temperature, time and pressure, the product quality is ensured, and the product qualified rate is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of food processing, in particular to a sterilization method of canned food. BACKGROUND

[0002] Food sterilization is to take food raw materials and processed products as the object, sterilize and decontaminate the main factors causing food deterioration-microorganisms, to achieve the stabilization of food quality, effectively extend the shelf life of food, and thus reduce the survival number of harmful bacteria in food, avoid the intake of live bacteria causing human (usually intestinal) infection or the bacteria toxin produced in food causing human poisoning.

[0003] In the process of high-temperature sterilization of canned food, the main object of sterilization is Clostridium botulinum, which can produce toxins that cause fatal harm to the human body. It is a heat-resistant anaerobic bacteria that loses biological activity in 121℃ environment for three minutes and loses biological activity in 100℃ environment for about 6 hours. The higher the temperature, the shorter the survival time of the bacteria. Scientific tests show that sterilization at 121℃ is more appropriate, at which the packaging material has good heat resistance, and the food taste is also good. When sterilized at 121℃, the F value of the food center reaches 4, and Clostridium botulinum cannot be detected in the food, meeting the requirements of commercial sterility.

[0004] At present, the sterilization method of canned food mostly adopts water bath sterilization, but for 3kg or even larger tin cans filled with food, if water bath sterilization is used, the following technical problems will exist: first, the sterilization effect of water bath sterilization on 3kg tin cans filled with food is poor, the product unqualified rate is high, and it cannot meet the needs of production, and the water bath sterilization efficiency is low, the energy consumption is high, and it cannot meet the speed of continuous production; second, water bath sterilization has high energy consumption and low efficiency, large steam consumption, long sterilization time of about 2 hours, large water consumption, serious waste and high cost; third, due to uneven heat distribution, water bath sterilization is not thorough, the heat penetration cannot meet the sterilization requirements, the core temperature of the can is difficult to reach the required temperature, resulting in unqualified product quality and many problems of can expansion.

[0005] Therefore, how to provide a canned food sterilization method with good sterilization effect and high efficiency is a problem that those skilled in the art need to solve. SUMMARY

[0006] Therefore, the present application provides a canned food sterilization method to solve the technical problems of poor sterilization effect, long sterilization time, low efficiency and low product qualified rate of the existing water bath sterilization technology.

[0007] In order to solve the above technical problems, the present application adopts the following technical scheme:

[0008] A sterilization method of canned food, comprising the following steps:

[0009] (1) placing canned food to be sterilized into a high-pressure sealed sterilization kettle;

[0010] (2) opening the steam inlet valve of the sterilization kettle, and when the temperature is raised to 95-100℃, the exhaust valve of the sterilization kettle is automatically opened for exhaust, and when the temperature is raised to 105-110℃, the exhaust valve is closed after a period of heat preservation to complete the exhaust process;

[0011] (3) continuing to introduce high-temperature steam after the exhaust is completed, and sterilizing when the temperature in the sterilization kettle is raised to 115-120℃;

[0012] (4) automatically closing the inlet valve of the sterilization kettle after the sterilization is completed, and cooling.

[0013] Preferably, in the sterilization method of canned food, the canned food to be sterilized is a food filled in a tin can with a capacity of ≥3 kg.

[0014] The present application is directed to canned food in a tin can with a capacity of ≥3 kg. If the canned food filled in a tin can with a capacity of ≥3 kg is sterilized by using the traditional water bath sterilization mode, the heat penetration cannot meet the sterilization requirement when the water bath sterilization is performed due to the large capacity of the can body, which can easily lead to unqualified product quality and the phenomenon of can expansion. The high-temperature and high-pressure steam sterilization used in the present application can effectively penetrate the tin can, so that the food in the center of the can body can also be effectively sterilized.

[0015] Preferably, in the sterilization method of canned food, the high-pressure condition in step (1) is that the steam pressure of the sterilization kettle steam supply pipeline is not less than 0.4 MPa.

[0016] The present application uses high-temperature and high-pressure environment to make the bacterial protein coagulate and denature to achieve the purpose of sterilization.

[0017] Preferably, in the sterilization method of canned food, step (2) comprises:

[0018] opening the steam inlet valve of the sterilization kettle, and when the temperature is raised to 95-100℃, the exhaust valve of the sterilization kettle is automatically opened for exhaust, and at the same time, heat preservation is performed for 1-3 min under a constant temperature condition;

[0019] continuing to introduce high-temperature steam, and when the temperature is raised to 102-106℃, heat preservation is performed for 5-8 min under a constant temperature condition;

[0020] continuing to introduce high-temperature steam, and when the temperature is raised to 107-110℃, heat preservation is performed for 3-6 min under a constant temperature condition, and the exhaust valve is closed to complete the exhaust process.

[0021] Further preferably, in the sterilization method of canned food as described above, the step (2) comprises:

[0022] The steam inlet valve of the sterilization kettle is opened, and when the temperature is raised to 98 DEG C, the exhaust valve of the sterilization kettle is automatically opened for exhaust, and meanwhile, the temperature is kept constant for 2 minutes;

[0023] The high-temperature steam is continuously introduced, and when the temperature is raised to 105 DEG C, the temperature is kept constant for 6 minutes;

[0024] The high-temperature steam is continuously introduced, and when the temperature is raised to 108 DEG C, the temperature is kept constant for 5 minutes, and the exhaust valve is closed to complete the exhaust process.

[0025] The step (2) of the present application can effectively remove the cold air in the sterilization kettle. Since the expansion pressure of air is greater than that of water vapor, when the water vapor contains air, the temperature of the air-containing steam is lower than that of the saturated steam under the same pressure. Therefore, the present application can make the sterilization kettle contain saturated steam, so that the sterilization effect is more thorough.

[0026] Preferably, in the sterilization method of canned food as described above, in the step (3), the temperature in the sterilization kettle is raised to 115-120 DEG C, and then kept constant for 30-50 minutes.

[0027] Preferably, in the sterilization method of canned food as described above, in the step (3), the temperature in the sterilization kettle is raised to 117 DEG C, and then kept constant for 40 minutes.

[0028] In the high-temperature sterilization process of canned food, the main object of sterilization is Clostridium botulinum, which can produce toxins that can cause fatal harm to the human body. In the traditional water bath sterilization method, the biological activity of Clostridium botulinum will be lost within 3 minutes at 121 DEG C. However, due to the large capacity of the tin can, the heat transfer process is slow, and it takes about two hours to sterilize the food in the center of the can to meet the sterilization requirements. The longer the food is in the high-temperature environment, the worse the taste and the more nutrients are lost. By using the method of the present application, the canned food in the tin can can be effectively sterilized within one hour or so, with high sterilization efficiency, higher qualified rate, and the original taste and nutrients of the food are preserved to the greatest extent.

[0029] Preferably, in the sterilization method of canned food as described above, in the steps (2) and (3), the high-temperature steam is introduced into the sterilization kettle through multiple inlet valves, so that the heat distribution in the sterilization kettle is uniform, and the temperature at any point in the sterilization kettle is not lower than the set temperature value.

[0030] The function of the sterilization kettle is to provide an environment for high-temperature sterilization of canned food, and can sterilize the food at a specified temperature, time and pressure. It must have good heat distribution, that is, the temperature of any point in the container during sterilization should be at least the set temperature value. If the temperature of a certain point is lower than the set temperature, the point cannot reach the predetermined sterilization F value, and the food near the point cannot meet the sterilization requirements.

[0031] Preferably, in the sterilization method of canned food, the cooling in step (4) is to cool the canned food to below 40℃ within 5min by controlling the flow and temperature of the circulating cooling water.

[0032] The present application can make the food leave the high-temperature environment in the shortest possible time by controlling the temperature and flow of the circulating cooling water, thereby minimizing the sterilization time and improving the sterilization effect.

[0033] Preferably, in the sterilization method of canned food, the temperature of the circulating cooling water is 10-25℃.

[0034] The present application provides a sterilization method for canned food, which has the following advantages compared with the prior art:

[0035] (1) The high-temperature and high-pressure sterilization of the present application is completed at one time from start to finish, avoiding repeated sterilization treatment, and having better sterilization effect and higher processing efficiency;

[0036] (2) The present application avoids using the traditional water bath sterilization method, but uses steam sterilization, which has less heat loss. The product can be quickly and effectively sterilized at a set temperature, time and pressure by the sterilization kettle, ensuring product quality and high product pass rate;

[0037] (3) The present application can achieve better sterilization effect in a shorter time by controlling the exhaust and sterilization process, and because the sterilization and cooling time are both short, the original taste and nutrition of the food can be preserved to the greatest extent, the stability is higher, and the shelf life of the product can be effectively improved. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0039] Embodiment 1

[0040] The present embodiment provides a sterilization method for canned food, comprising the following steps:

[0041] (1) Put the 3kg tin cans to be sterilized filled with tomato pieces into a high-pressure closed sterilization kettle, and the steam pressure of the steam supply pipeline of the sterilization kettle is not less than 0.4MPa;

[0042] (2) Open the steam inlet valve of the sterilization kettle, and when the temperature is raised to 98℃, the exhaust valve of the sterilization kettle is automatically opened for exhaust, and at the same time, the temperature is kept constant for 2min; continue to input high-temperature steam, set the temperature to 105℃, and keep the temperature constant for 6min; continue to input high-temperature steam, set the temperature to 108℃, and keep the temperature constant for 5min, and close the exhaust valve to complete the exhaust process;

[0043] (3) After the exhaust is completed, continue to input high-temperature steam, and the temperature in the sterilization kettle is raised to 117℃ and kept for 40min for sterilization operation;

[0044] In steps (2) and (3), the high-temperature steam enters the sterilization kettle through multiple inlet valves to make the heat distribution in the sterilization kettle uniform, and the temperature at any point in the sterilization kettle is not less than the set temperature value;

[0045] (4) After the sterilization is completed, the inlet valve of the sterilization kettle is automatically closed, and the canned food is cooled to below 40℃ within 5min by controlling the flow and temperature of the circulating cooling water;

[0046] (5) Open the sterilization kettle, and take out the sterilized tin cans filled with food, and the can body is complete without shrinkage deformation.

[0047] Example 2

[0048] The present embodiment provides a sterilization method for canned food, comprising the following steps:

[0049] (1) Put the 3kg tin cans to be sterilized filled with tomato pieces into a high-pressure closed sterilization kettle, and the steam pressure of the steam supply pipeline of the sterilization kettle is not less than 0.4MPa;

[0050] (2) Open the steam inlet valve of the sterilization kettle, and when the temperature is raised to 95℃, the exhaust valve of the sterilization kettle is automatically opened for exhaust, and at the same time, the temperature is kept constant for 3min; continue to input high-temperature steam, set the temperature to 102℃, and keep the temperature constant for 8min; continue to input high-temperature steam, set the temperature to 107℃, and keep the temperature constant for 6min, and close the exhaust valve to complete the exhaust process;

[0051] (3) After the exhaust is completed, continue to input high-temperature steam, and the temperature in the sterilization kettle is raised to 115℃ and kept for 50min for sterilization operation;

[0052] The high-temperature steam in steps (2) and (3) enters the sterilization kettle through multiple air inlet valves to make the heat distribution in the sterilization kettle uniform, and the temperature at any point in the sterilization kettle is not lower than the set temperature value;

[0053] (4) After sterilization, the air inlet valve of the sterilization kettle is automatically closed, and the canned food is cooled to below 40°C within 5 minutes by controlling the flow and temperature of the circulating cooling water.

[0054] (5) Open the sterilization kettle, take out the canned food in the tin cans after sterilization, and the can body is complete without shrinkage deformation.

[0055] Example 3

[0056] The present embodiment provides a sterilization method for canned food, comprising the following steps:

[0057] (1) Put the 3 kg tin cans filled with tomato pieces to be sterilized into a high-pressure sealed sterilization kettle, and the steam pressure of the sterilization kettle supply pipeline is not lower than 0.4 MPa.

[0058] (2) Open the steam inlet valve of the sterilization kettle, and when the temperature is raised to 97°C, the exhaust valve of the sterilization kettle is automatically opened for exhaust, and at the same time, the temperature is kept constant for 2 minutes; continue to input high-temperature steam, set the temperature to 104°C, and keep the temperature constant for 7 minutes; continue to input high-temperature steam, set the temperature to 110°C, and keep the temperature constant for 4 minutes, and close the exhaust valve to complete the exhaust process.

[0059] (3) After the exhaust is completed, continue to input high-temperature steam, and the temperature in the sterilization kettle is raised to 118°C and kept for 35 minutes for sterilization operation.

[0060] The high-temperature steam in steps (2) and (3) enters the sterilization kettle through multiple air inlet valves to make the heat distribution in the sterilization kettle uniform, and the temperature at any point in the sterilization kettle is not lower than the set temperature value;

[0061] (4) After sterilization, the air inlet valve of the sterilization kettle is automatically closed, and the canned food is cooled to below 40°C within 5 minutes by controlling the flow and temperature of the circulating cooling water.

[0062] (5) Open the sterilization kettle, take out the canned food in the tin cans after sterilization, and the can body is complete without shrinkage deformation.

[0063] Example 4

[0064] The present embodiment provides a sterilization method for canned food, comprising the following steps:

[0065] (1) The 3kg tin cans to be sterilized are filled with diced tomatoes and put into a high-pressure closed sterilization kettle, and the steam pressure of the steam supply pipeline of the sterilization kettle is not less than 0.4MPa;

[0066] (2) The steam inlet valve of the sterilization kettle is opened, and when the temperature of the sterilization kettle reaches 100℃, the exhaust valve is automatically opened for exhaust, and at the same time, the temperature is kept constant for 1min; high-temperature steam continues to be introduced, and after the temperature is set to 106℃, the temperature is kept constant for 5min; high-temperature steam continues to be introduced, and after the temperature is set to 109℃, the temperature is kept constant for 3min, and the exhaust process is completed by closing the exhaust valve;

[0067] (3) After the exhaust is completed, high-temperature steam continues to be introduced, and after the temperature of the sterilization kettle reaches 120℃, the temperature is kept constant for 30min, and the sterilization operation is performed;

[0068] In steps (2) and (3), the high-temperature steam enters the sterilization kettle through multiple inlet valves to make the heat distribution in the sterilization kettle uniform, and the temperature of any point in the sterilization kettle is not less than the set temperature value;

[0069] (4) After the sterilization is completed, the inlet valve of the sterilization kettle is automatically closed, and the canned food is cooled to below 40℃ within 5min by controlling the flow and temperature of the circulating cooling water;

[0070] (5) The sterilization kettle is opened, and the sterilized tin cans filled with food are taken out, and the can body is complete without shrinkage deformation.

[0071] Comparative Example 1

[0072] The present comparative example provides a sterilization method for canned food, comprising the following steps:

[0073] (1) The water in the hot water tank is heated to 100℃, and the 3kg tin cans to be sterilized are filled with diced tomatoes and put into a closed sterilization kettle, and the pressure of the sterilization kettle is not less than 0.4MPa;

[0074] (2) The water pump is opened, the hot water inlet valve and the circulating valve are opened, and after the canned food is immersed in the hot water in the sterilization kettle, the hot water inlet valve is closed;

[0075] (3) The sterilization switch is turned on, and the temperature in the sterilization kettle rises to 121℃, and after keeping constant temperature and pressure for two hours, the sterilization is completed, and the sterilization switch is turned off;

[0076] (4) After the sterilization is completed, the inlet valve of the sterilization kettle is automatically closed, and the canned food is cooled to below 40℃ within 5min by controlling the flow and temperature of the circulating cooling water;

[0077] (5) The sterilization kettle is opened, and the sterilized tin cans filled with food are taken out, and the can body is complete without shrinkage deformation.

[0078] The same batch of tomato dices was used in Examples 1-4 and Comparative Example 1, and the changes of the substance content indexes of the tomato dices after sterilization in Examples 1-4 and Comparative Example 1 were detected, and the stability of the treated tomato dices was detected, and the detection results are shown in Table 1.

[0079] Table 1: Performance detection results of Examples 1-4 and Comparative Example 1

[0080]

[0081] As can be seen from Table 1, compared with the water bath sterilization method, the present application not only shortens the sterilization time, but also effectively retains the original nutrition, taste and appearance color of the food while ensuring the sterilization effect, and has more excellent stability and higher qualified rate.

[0082] Comparative Example 2

[0083] The present comparative example provides a sterilization method for canned food, comprising the following steps:

[0084] (1) Put the 3 kg tin cans filled with tomato dices to be sterilized into a high-pressure sealed sterilization kettle, and the steam pressure of the sterilization kettle supply pipeline is not less than 0.4 MPa;

[0085] (2) Open the steam inlet valve of the sterilization kettle, and when the temperature is raised to 98℃, the exhaust valve of the sterilization kettle is automatically opened for exhaust, and high-temperature steam is continuously introduced, and after setting the temperature to 108℃, the temperature is kept constant for 13 min, and the exhaust valve is closed to complete the exhaust process;

[0086] (3) After the exhaust is completed, high-temperature steam is continuously introduced, and the temperature in the sterilization kettle is raised to 117℃ and kept for 40 min for sterilization operation;

[0087] In steps (2) and (3), the high-temperature steam enters the sterilization kettle through multiple inlet valves to make the heat distribution in the sterilization kettle uniform, and the temperature at any point in the sterilization kettle is not less than the set temperature value;

[0088] (4) After sterilization, the inlet valve of the sterilization kettle is automatically closed, and the canned food is cooled to below 40℃ within 5 min by controlling the flow and temperature of the circulating cooling water;

[0089] (5) Open the sterilization kettle, and take out the canned food in the tin cans after sterilization, and the tin body is complete without shrinkage deformation.

[0090] Comparative Example 3

[0091] The present comparative example provides a sterilization method for canned food, comprising the following steps:

[0092] (1) Put the 3kg tin cans to be sterilized filled with tomato pieces into a high-pressure closed sterilization kettle, and the steam pressure of the steam supply pipeline of the sterilization kettle is not less than 0.4MPa;

[0093] (2) Open the steam inlet valve of the sterilization kettle, and when the temperature is raised to 98℃, the exhaust valve of the sterilization kettle is automatically opened for exhaust, and high-temperature steam is continuously introduced, and after setting the temperature to 108℃, the temperature is kept constant for 5min, and the exhaust valve is closed to complete the exhaust process;

[0094] (3) After the exhaust is completed, high-temperature steam is continuously introduced, and after the temperature in the sterilization kettle is raised to 117℃, the temperature is kept constant for 40min to perform sterilization operation;

[0095] In steps (2) and (3), the high-temperature steam enters the sterilization kettle through multiple inlet valves to make the heat distribution in the sterilization kettle uniform, and the temperature at any point in the sterilization kettle is not less than the set temperature value;

[0096] (4) After the sterilization is completed, the inlet valve of the sterilization kettle is automatically closed, and the canned food is cooled to below 40℃ within 5min by controlling the flow and temperature of the circulating cooling water;

[0097] (5) Open the sterilization kettle, and take out the sterilized tin cans filled with food, and the can body is complete without shrinkage deformation.

[0098] Comparative Example 4

[0099] The present comparative example provides a sterilization method of canned food, comprising the following steps:

[0100] (1) Put the 3kg tin cans to be sterilized filled with tomato pieces into a high-pressure closed sterilization kettle, and the steam pressure of the steam supply pipeline of the sterilization kettle is not less than 0.4MPa;

[0101] (2) Open the steam inlet valve of the sterilization kettle, and when the temperature is raised to 102℃, the exhaust valve of the sterilization kettle is automatically opened for exhaust, and at the same time, the temperature is kept constant for 5min; continue to introduce high-temperature steam, and after setting the temperature to 105℃, the temperature is kept constant for 3min; continue to introduce high-temperature steam, and after setting the temperature to 112℃, the temperature is kept constant for 3min, and the exhaust valve is closed to complete the exhaust process;

[0102] (3) After the exhaust is completed, high-temperature steam is continuously introduced, and after the temperature in the sterilization kettle is raised to 117℃, the temperature is kept constant for 40min to perform sterilization operation;

[0103] In steps (2) and (3), the high-temperature steam enters the sterilization kettle through multiple inlet valves to make the heat distribution in the sterilization kettle uniform, and the temperature at any point in the sterilization kettle is not less than the set temperature value;

[0104] (4) After the sterilization is completed, the inlet valve of the sterilization kettle is automatically closed, the circulation cooling water is controlled in terms of flow and temperature, and the canned food is cooled to below 40℃ within 5 minutes, and then the canned food is taken out from the sterilization kettle, and the can body is complete and has no shrinkage deformation sign

[0105] (5) The sterilization kettle is opened, and the canned food in the tin cans after sterilization is taken out, and the can body is complete and has no shrinkage deformation sign

[0106] The difference between Comparative Examples 2-4 and Example 1 is only that the exhaust process in step (2) is changed, the material content index of the diced tomatoes after sterilization of Comparative Examples 2-4 is detected, and the stability of the diced tomatoes after treatment is detected, and the detection results are shown in Table 2.

[0107] Table 2: Performance detection results of Comparative Examples 2-4

[0108]

[0109]

[0110] The above results show that the staged temperature rising and holding exhaust process has a relatively important influence on various nutrients, taste, morphology, stability, and qualified rate of the diced tomatoes, and only under the conditions defined in the present application, the nutrients and appearance color of the diced tomatoes after sterilization can be maintained at a high level.

[0111] Comparative Example 5

[0112] Comparative Example 5 is basically the same as Example 1, and the difference is only that the influence of the sterilization process on the quality change of the diced tomatoes is studied by changing the sterilization temperature.

[0113] Specifically, the temperature in the sterilization kettle in step (3) is sequentially limited to be raised to 112℃ and held for 40 minutes, raised to 113℃ and held for 40 minutes, raised to 115℃ and held for 40 minutes, raised to 117℃ and held for 40 minutes, raised to 120℃ and held for 40 minutes, and raised to 121℃ and held for 40 minutes, and the performance of the diced tomatoes after sterilization is detected, and the detection results are shown in Table 3.

[0114] Table 3: Performance detection results of Comparative Example 5

[0115]

[0116]

[0117] Comparative Example 6

[0118] Comparative Example 6 is basically the same as Example 1, and the difference is only that the influence of the sterilization process on the quality change of the diced tomatoes is studied by changing the sterilization time.

[0119] Specifically, the temperature in the sterilization kettle in step (3) is sequentially limited to be increased to 117 DEG C and then kept for 30 min, 40 min, 50 min, 60 min and 70 min, and the performance of the sterilized tomato dices is detected, and the detection results are shown in Table 4.

[0120] Table 4 performance detection results of comparative example 6

[0121]

[0122]

[0123] From Table 3 and Table 4, it can be seen that the sterilization temperature and sterilization time of step (3) have important influences on the nutritional quality, taste, fruit block morphology and stability of the tomato dices, and if the sterilization temperature is too high or the sterilization time is too long, the degree of the tank swelling phenomenon will appear, compared with water bath sterilization, the sterilization process of the tomato dices can be realized in a shorter time, and the qualified rate is higher, and the tank swelling phenomenon will not appear.

[0124] The embodiments in the specification are described in a progressive manner, and each embodiment focuses on the difference from other embodiments, and the same or similar parts of each embodiment can be referred to each other. For the scheme disclosed by the embodiments, since it corresponds to the method disclosed by the embodiments, the description is relatively simple, and the related parts can be referred to the method part.

[0125] The above description of the disclosed embodiments enables a person skilled in the art to implement or use the present application. Various modifications to the embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method of sterilizing a canned food, characterized by, The method comprises the following steps: (1) placing canned food to be sterilized in a high-pressure sealed sterilization kettle; (2) opening the steam inlet valve of the sterilization kettle, and when the temperature is raised to 95-100 DEG C, the exhaust valve of the sterilization kettle is automatically opened for exhaust, and meanwhile, the temperature is kept constant for 1-3 min; high-temperature steam is continuously introduced, and when the temperature is raised to 102-106 DEG C, the temperature is kept constant for 5-8 min; high-temperature steam is continuously introduced, and when the temperature is raised to 107-110 DEG C, the temperature is kept constant for 3-6 min, and the exhaust valve is closed to complete the exhaust process; (3) after the exhaust is completed, high-temperature steam is continuously introduced, and when the temperature in the sterilization kettle is raised to 115-120 DEG C, sterilization is performed; (4) after the sterilization is completed, the inlet valve of the sterilization kettle is automatically closed, and cooling is performed, and then the process is completed; in step (3), the temperature in the sterilization kettle is raised to 115-120 DEG C and kept constant for 30-50 min.

2. The retort food sterilization method according to claim 1, characterized by, The canned food to be sterilized is a food filled in a tin can with a weight of 3 kg or more.

3. The retort food sterilization method according to claim 1, characterized by, In step (1), the high-pressure condition is that the steam pressure in the steam supply pipeline of the sterilization kettle is not less than 0.4 MPa.

4. The retort food sterilization method according to claim 1, characterized by, Step (2) comprises: opening the steam inlet valve of the sterilization kettle, and when the temperature is raised to 98 DEG C, the exhaust valve of the sterilization kettle is automatically opened for exhaust, and meanwhile, the temperature is kept constant for 2 min; high-temperature steam is continuously introduced, and when the temperature is raised to 105 DEG C, the temperature is kept constant for 6 min; high-temperature steam is continuously introduced, and when the temperature is raised to 108 DEG C, the temperature is kept constant for 5 min, and the exhaust valve is closed to complete the exhaust process.

5. The method of sterilizing canned food according to claim 1, characterized by, In step (3), the temperature in the sterilization kettle is raised to 117 DEG C and kept constant for 40 min.

6. The method of sterilizing canned food according to claim 1, characterized by, In steps (2) and (3), high-temperature steam is introduced into the sterilization kettle through multiple inlet valves, so that the heat distribution in the sterilization kettle is uniform, and the temperature at any point in the sterilization kettle is not less than the set temperature value.

7. The method of sterilizing canned food according to claim 1, characterized by, In step (4), the cooling is performed by controlling the flow rate and temperature of the circulating cooling water, so that the canned food is cooled to below 40 DEG C within 5 min.

8. The method of sterilizing canned food according to claim 7, characterized by, The temperature of the circulating cooling water is 10-25 DEG C.

Images