JP6425506B2 - Retort device and retort sterilization method - Google Patents

Description

  The present invention relates to a retort device for sterilizing packaged food with high temperature and high pressure steam and a retort sterilization method using the same.

  Conventionally, in the manufacturing process of container-packed food filled and sealed in containers such as cans and pouches, the container-packed food is mainly filled with high-temperature and high-pressure steam in a retort pot mainly for the purpose of killing food poisoning bacteria in the container. Sterilization (retort sterilization) has been performed.

  Patent Documents 1 and 2 disclose a retort sterilization method using a retort device. In the technique disclosed in Patent Document 1, in order to replace the air in the retort pot with steam, steam is supplied from the lower part of the retort pot and air is exhausted from the upper part of the retort pot. On the other hand, in the technique disclosed in Patent Document 2, steam is supplied from the upper part of the retort pot and air is exhausted from the lower part of the retort pot.

Japanese Patent Application Laid-Open No. 3-80067 JP-A-8-173115

  However, in the above method, since the steam is always supplied from one side of the retort pot, there is a possibility that air stagnation may occur in the retort pot. When air accumulation occurs, uneven temperature distribution occurs in the retort kettle. Therefore, steam is supplied more than necessary to reach the sterilization temperature in the retort pot.

  Further, in the above method, steam and air may be mixed in the retort kettle, and the steam may be exhausted together with the air from the retort kettle. For this reason, more steam is needed to bring the temperature in the retort pot to the sterilization temperature.

  Providing more steam results in more energy consumption and thus an increase in the cost of retort sterilization.

  Therefore, the present invention has been made in view of the above problems, and the cost for retort sterilization is reduced by reducing the amount of steam required to cause the temperature in the retort pot to reach the sterilization temperature. The purpose is to reduce.

  In a first aspect of the present invention, a retort device is provided, which is connected to a retort pot, a first steam pipe for supplying steam to the retort pot, and is connected to an upper part of the retort pot. The first exhaust pipe for exhausting air from the retort pot, the second steam pipe connected to the lower part of the retort pot and supplying steam to the retort pot, and the lower part of the retort pot from the retort pot First steam valve, first exhaust valve, second steam valve provided on the second exhaust pipe for exhausting air, the first steam pipe, the first exhaust pipe, the second steam pipe, and the second exhaust pipe, And a second exhaust valve, and a control unit that controls the first steam valve, the first exhaust valve, the second steam valve, and the second exhaust valve.

  In the first aspect of the present invention, the control unit is configured to supply the first steam valve and the second exhaust valve such that steam is supplied from the first steam pipe to the retort pot and air is exhausted from the retort pot through the second exhaust pipe. Is opened and the first exhaust valve and the second steam valve are closed, and then, when the predetermined condition is satisfied, steam is supplied from the second steam pipe to the retort pot and air is exhausted from the retort pot through the first exhaust pipe. Preferably, the first steam valve and the second exhaust valve are closed and the first exhaust valve and the second steam valve are opened.

  In the first aspect of the present invention, the retort device further includes a temperature sensor disposed inside the retort pot, and the predetermined condition is that the temperature inside the retort pot detected by the temperature sensor is a predetermined temperature. It is preferred to be reached.

  In the first aspect of the present invention, the predetermined temperature is preferably 100 ° C. or more and 130 ° C. or less.

  In the first aspect of the present invention, the retort device further includes a pressure sensor disposed inside the retort pot, and the predetermined condition is that the pressure inside the retort pot detected by the pressure sensor is a predetermined pressure. It is preferred to be reached.

  In the first aspect of the present invention, the predetermined pressure is preferably 102 kPa or more and 270 kPa or less.

  In the first aspect of the present invention, it is preferable that the first exhaust pipe and the second exhaust pipe have a plurality of pipes, respectively, and the pipes are open at one end to the atmosphere without joining the pipes. .

  In the first aspect of the present invention, the first exhaust pipe preferably comprises an air vent.

  In a second aspect of the present invention, in a retort sterilization method of sterilizing container-packed food with high temperature and high pressure steam in a retort pot, supplying steam from the top of the retort pot and exhausting air from the bottom of the retort pot Supplying steam from the lower part of the retort pot and exhausting air from the upper part of the retort pot when the predetermined conditions are satisfied.

  In the second aspect of the present invention, the predetermined condition is preferably that the temperature inside the retort pot reaches a predetermined temperature.

  In the second aspect of the present invention, the predetermined temperature is preferably 100 ° C. or more and 130 ° C. or less.

  In the second aspect of the present invention, the predetermined condition is preferably that the pressure inside the retort pot reaches a predetermined pressure.

  In the second aspect of the present invention, the predetermined pressure is preferably 102 kPa or more and 270 kPa or less.

  According to the present invention, by switching between the supply position of the steam and the exhaust position of the air between the upper part and the lower part of the retort pot based on the predetermined conditions, the generation of air stagnation and the mixing of air and steam are reduced, and the retort The amount of steam needed to bring the temperature in the kettle to the sterilization temperature can be reduced. Therefore, according to the present invention, the cost of retort sterilization can be reduced.

FIG. 1 is a schematic view of a retort device according to an embodiment of the present invention. FIG. 2 is a schematic side view of the retort device of FIG. FIG. 3 is a graph schematically showing the relationship between the time in each step of the retort sterilization method and the temperature inside the retort pot.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that these embodiments do not limit the present invention. Further, constituent elements of the above-described embodiment include those that can be easily replaced by persons skilled in the art and those that are substantially the same.

  First, a retort device according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2.

  FIG. 1 is a schematic view of a retort device 1 according to an embodiment of the present invention. FIG. 2 is a schematic side view of the retort device 1 of FIG. In FIG. 2, piping and control units other than the steam piping and the exhaust piping are omitted for the purpose of simplification.

  The retort device 1 includes a cylindrical retort pot 2. As can be seen from FIG. 2, the retort pot 2 accommodates five baskets 3 and in each basket 3 container-packed food (not shown) is placed. The retort device 1 is a batch type, and the container-packed food is sterilized in a state of being accommodated in the basket 3 in the retort pot 2.

  The upper part of the retort pot 2 is connected to a first steam pipe 4, nine first exhaust pipes 5, a water supply pipe 6 and a pressurized air pipe 7. Further, a second steam pipe 8, three second exhaust pipes 9 and a drainage pipe 10 are connected to the lower part of the retort pot 2. In the present specification, the upper part and the lower part of the retort pot 2 respectively mean a part above the half of the retort pot 2 and a part below the half in the vertical direction when the retort pot 2 is installed. .

  The first steam pipe 4 is provided with a first steam valve 40. The first steam valve 40 is, for example, a two-way solenoid valve that opens and closes a pipe. When the first steam valve 40 is opened, steam for sterilizing the container-packed food can be supplied from the first steam pipe 4 to the retort pot 2. When the first steam valve 40 is closed, steam is not supplied to the retort pot 2 from the first steam pipe 4. The first steam pipe 4 is branched into two on the downstream side of the first steam valve 40 and is connected to the upper portion of the retort pot at two points.

  As shown in FIG. 2, nine first exhaust pipes 5 are continuously arranged at equal intervals in the axial direction (longitudinal direction) of the retort pot 2. A first exhaust valve 50 is provided in each of the first exhaust pipes 5. The first exhaust valve 50 is, for example, a two-way solenoid valve that opens and closes a pipe. When the first exhaust valve 50 is opened, air can be exhausted from the retort pot 2 through the first exhaust pipe 5. When the first exhaust valve 50 is closed, air is not exhausted from the retort pot 2 through the first exhaust pipe 5.

  The first exhaust pipe 5 is a pipe of 40A, and one end of the first exhaust pipe 5 disposed on the opposite side to the retort pot 2 is open to the atmosphere. One end of each of the nine first exhaust pipes 5 is opened to the atmosphere without merging with each other, so the back pressure in each of the first exhaust pipes 5 becomes more uniform, and Back pressure is reduced because pressure loss is eliminated. Therefore, in each of the first exhaust pipes 5, the air is exhausted more uniformly, and the exhaust speed is increased, so that the exhaust efficiency is improved.

  In addition, the first exhaust pipe 5 is provided with an air vent 52. The air vent 52 is disposed between the first exhaust valve 50 and the upper portion of the retort pot 2. With this configuration, even when the first exhaust valve 50 is closed, a small amount of air left in the retort pot 2 can be exhausted from the retort pot 2 through the air vent 52. The air vent 52 may be disposed in a pipe (not shown) branched from between the first exhaust valve 50 and the upper portion of the retort pot 2. Also, the number of first exhaust pipes 5 may be one or more other numbers. Furthermore, as long as the first exhaust pipe 5 is connected to the upper portion of the retort pot 2, the first exhaust pipe 5 may have a configuration different from that in FIG.

  The air vent 52 is provided with an air vent valve 54. The air vent valve 54 is, for example, a two-way solenoid valve that opens and closes the air vent 52. When the air vent valve 54 is opened, air can be exhausted from the retort pot 2 through the air vent 52. When the air vent valve 54 is closed, air is not exhausted from the retort pot 2 through the air vent 52.

  A water supply valve 60 is provided in the water supply pipe 6. The feed valve 60 is, for example, a two-way solenoid valve that opens and closes a pipe. When the water supply valve 60 is opened, water can be supplied from the water supply pipe 6 to the retort pot 2 in order to lower the temperature inside the retort pot 2. When the water supply valve 60 is closed, water is not supplied from the water supply pipe 6 to the retort pot 2. The water supply pipe 6 is branched into two on the downstream side of the water supply valve 60, and a shower nozzle 62 is provided at the tip of each pipe. Water is supplied from the shower nozzle 62 to the inside of the retort pot 2. In addition, in order to circulate the supplied water, the retort device 1 may further include a circulation pipe (not shown) that connects the upper portion and the lower portion of the retort pot 2. In this case, in order to pump up the water in the lower part of the retort pot 2 to the upper part of the retort pot 2, a pump is provided in the circulation pipe.

  The pressurized air pipe 7 is provided with an air supply valve 70. The air supply valve 70 is, for example, a two-way solenoid valve that opens and closes a pipe. When the air supply valve 70 is opened, pressurized air can be supplied from the pressurized air pipe 7 to the retort pot 2 in order to increase the pressure in the retort pot 2. When the air supply valve 70 is closed, pressurized air is not supplied to the retort pot 2 from the pressurized air pipe 7. When the contents of the container contain alcohol, carbon dioxide gas, etc., the pressure difference between the inside and the outside of the container becomes large, and the container may be deformed or broken. For this reason, pressurized air is supplied to the retort pot 2 as necessary in order to avoid this problem by increasing the pressure outside the container.

  The second steam pipe 8 is provided with a second steam valve 80. The second steam valve 80 is, for example, a two-way solenoid valve that opens and closes a pipe. When the second steam valve 80 is opened, steam for sterilizing container-packed food can be supplied from the second steam pipe 8 to the retort pot 2. When the second steam valve 80 is closed, steam is not supplied from the second steam pipe 8 to the retort pot 2. The second steam pipe 8 is branched into four on the downstream side of the second steam valve 80 and is connected to the lower portion of the retort pot at four points.

  As shown in FIG. 2, the three second exhaust pipes 9 are continuously arranged at equal intervals in the axial direction (longitudinal direction) of the retort pot 2. A second exhaust valve 90 is provided in each of the second exhaust pipes 9. The second exhaust valve 90 is, for example, a two-way solenoid valve that opens and closes a pipe. When the second exhaust valve 90 is opened, air can be exhausted from the retort pot 2 through the second exhaust pipe 9. When the second exhaust valve 90 is closed, air is not exhausted from the retort pot 2 through the second exhaust pipe 9.

  The second exhaust pipe 9 is a pipe of 80A, and one end thereof is open to the atmosphere. One end of each of the three second exhaust pipes 9 is opened to the atmosphere without merging with each other, so the back pressure in each second exhaust pipe 9 becomes more uniform, and Back pressure is reduced because pressure loss is eliminated. Therefore, in each of the second exhaust pipes 9, the air is exhausted more uniformly, and the exhaust speed is increased, so that the exhaust efficiency is improved. The number of second exhaust pipes 9 may be one or more other numbers. Further, as long as the second exhaust pipe 9 is connected to the lower portion of the retort pot 2, the second exhaust pipe 9 may have a configuration different from that in FIG.

  The drainage pipe 10 is provided with a drainage valve 100. The drain valve 100 is, for example, a two-way solenoid valve that opens and closes a pipe. When the drain valve 100 is opened, the water supplied to the retort pot 2 can be drained from the retort pot 2 through the drain pipe 10. When the drain valve 100 is closed, water is not drained from the retort pot 2 through the drain pipe 10.

  The ends of the first steam piping 4 and the second steam piping 8 opposite to the retort pot 2 are connected to a common boiler 11 which is a steam supply source. Further, the retort device 1 further includes a control unit 12 and a temperature sensor 13 and a pressure sensor 14 which are disposed inside the retort pot 2. The temperature sensor 13 is configured to detect the temperature inside the retort pot 2, and the pressure sensor 14 is configured to detect the pressure inside the retort pot 2.

  The control unit 12 includes a memory such as a ROM, a CPU, a RAM, and an input / output device. The control unit 12 receives temperature data detected by the temperature sensor 13 and pressure data detected by the pressure sensor 14. Further, the control unit 12 controls the first steam valve 40, the first exhaust valve 50, the water supply valve 60, the air supply valve 70, the second steam valve 80, and the like based on temperature data, pressure data, input from the user, and the like. 2 Control the exhaust valve 90, the drainage valve 100, the boiler 11, and the like. The number of temperature sensors 13 may be two or more. In this case, the control unit 12 controls the average value or any one value of the temperatures detected from the plurality of temperature sensors 13 as the temperature inside the retort pot 2. Further, the number of pressure sensors 14 may be two or more. In this case, the control unit 12 controls the average value or any one value of the pressures detected from the plurality of pressure sensors 14 as the pressure inside the retort pot 2.

  Next, with reference to FIG. 3, a retort sterilization method using the retort device 1 will be described.

  In the retort sterilization method, container-packed food is accommodated in the basket 3 in the retort pot 2, and the container-packed food is sterilized by supplying high temperature and high pressure steam to the retort pot 2. The container-packed food is, for example, a beverage can, canned food, a bottled food, curry sealed in a pouch, soup, hamburger and the like. The container-packed food is not limited to human food but may be animal food.

Among the food poisoning bacteria, botulinum, which is the most heat resistant, is known to die at 120 ° C. for 4 minutes. Therefore, in the Food Sanitation Law, the minimum condition for sterilization is 121.1 ° C., 4 minutes (F ₀ value = 4). In fact, in consideration of safety, sterilization is often performed with an F value of 5 to 10 depending on the contents of the container-packed food.

  FIG. 3 is a graph schematically showing the relationship between the time in each step of the retort sterilization method and the temperature inside the retort pot 2. The horizontal axis of the graph indicates time, and the vertical axis indicates temperature. As shown in FIG. 1, the retort sterilization method includes five steps of a preheating step, a holding step, a heating step, a sterilization step and a cooling step.

  In the preheating step, the retort pot 2 is supplied with steam and the air is exhausted from the retort pot 2 in order to replace the air in the retort pot 2 with steam. In the preheating step, the temperature in the retort pot 2 is raised to 110 ° C.

  In the preheating step, first, steam is supplied from the upper portion of the retort pot 2 and air is exhausted from the lower part of the retort pot 2. Therefore, the control unit 12 controls the first steam valve 40 and the second exhaust valve so that steam is supplied from the first steam pipe 4 to the retort pot 2 and air is exhausted from the retort pot 2 through the second exhaust pipe 9. Open 90 and close the first exhaust valve 50 and the second steam valve 80. Also, the controller 12 opens the air vent valve 54.

  Thereafter, when the temperature inside the retort pot 2 reaches 104 ° C., steam is supplied from the lower part of the retort pot 2 and air is exhausted from the upper part of the retort pot 2. Therefore, when the control unit 12 receives from the temperature sensor 13 a signal indicating that the temperature inside the retort pot 2 is 104 ° C., steam is supplied from the second steam pipe 8 to the retort pot 2 and the first exhaust pipe The first steam valve 40 and the second exhaust valve 90 are closed and the first exhaust valve 50 and the second steam valve 80 are opened so that air is exhausted from the retort pot 2 through 5. The timing at which the first steam valve 40 and the second exhaust valve 90 are closed and the first exhaust valve 50 and the second steam valve 80 are opened is not when the temperature inside the retort pot 2 reaches 104 ° C. It may be when a predetermined time has elapsed since the internal temperature of the kettle 2 has reached 104 ° C.

  At a pressure of 0.1 MPa (gauge pressure), steam is lighter than air at temperatures lower than 105 ° C. and heavier at temperatures higher than 105 ° C. than air. Therefore, at a temperature lower than 105 ° C., supply the steam from the upper part of the retort pot 2 and exhaust the air from the lower part of the retort pot 2 in order to reduce the generation of air accumulation and the mixing of air and steam. Is desirable. On the other hand, at a temperature higher than 105 ° C., it is desirable to supply steam from the lower part of the retort pot 2 and exhaust air from the upper part of the retort pot 2.

  In the present embodiment, the valve is controlled at 104 ° C. just before the change point (105 ° C.) to change the vapor supply position from the top to the bottom and the air exhaust position from the bottom to the top. It is possible to reduce the occurrence of puddles and the mixing of air and steam. Therefore, in the present embodiment, it is possible to reduce the amount of steam required to bring the temperature in the retort pot 2 to the sterilization temperature. In addition, the temperature which controls a valve may be another temperature within the range of 100 degreeC-130 degreeC instead of 104 degreeC. In addition, the time taken to reach a predetermined temperature (for example, 104 ° C.) after supplying the steam may be checked in advance, and the control unit 12 may be configured to control the valve when the time has elapsed. That is, the control unit 12 may control the valve based on the elapsed time instead of the temperature inside the retort pot 2.

When the internal temperature of the retort 2 reaches a predetermined temperature (110 ° C. in this example) at time t _1, the holding step is started. In the holding step, the temperature in the retort pot 2 is kept constant for a predetermined time in order to make the temperature of the contents of the container-packed food contained in the basket 3 uniform.

Thereafter, a heating process at time t ₂ is started. In the heating step, the temperature in the retort pot 2 is raised to the sterilization temperature (125 ° C. in this example). At this time, steam is supplied to the retort pot 2 from the first steam pipe 4 or the second steam pipe 8. In addition, the first exhaust valve 50 and the second exhaust valve 90 remain closed. The steam may be alternately supplied to the retort pot 2 from the first steam pipe 4 and the second steam pipe 8. In this case, the controller 12 alternately opens the first steam valve 40 and closes the second steam valve 80, and alternately closes the first steam valve 40 and opens the second steam valve 80 at predetermined time intervals. To do. By this, steam can be more uniformly supplied into the retort pot 2.

The end time t ₂ of the holding step, since most of the air is already exhausted from the retort 2, the control unit 12 closes the first exhaust valve 50 was open. This reduces steam being exhausted from the retort pot 2 along with the air. Meanwhile, the remaining small amount of air in the retort pot 2 is exhausted from the retort pot 2 through the air vent 52 disposed between the first exhaust valve 50 and the upper part of the retort pot 2.

The temperature in the retort 2 reaches the sterilization temperature, sterilization step is started at time t _3. In the sterilization step, sterilization of a predetermined F value is performed according to the contents of the container-packed food.

Then, when the sterilization process is completed, the cooling step is started at time t _4. In the cooling step, water is supplied to the retort pot 2 to reduce the temperature inside the retort pot 2 to 40 ° C. or less. Therefore, the control unit 12 closes the air vent valve 54, closes the first steam valve 40 and the second steam valve 80 to end the supply of steam, and opens the feed valve 60 to supply water to the retort pot 2 . When the internal temperature of the retort 2 lowers to a predetermined temperature at time t _5, the control unit 12 closes the water supply valve 60.

  When all the processes are completed, the water supplied to the retort pot 2 is drained from the retort pot 2 through the drainage pipe 10. Accordingly, the control unit 12 opens the drain valve 100. Thereafter, the door of the retort pot 2 is opened, and the container-packed food in the basket 3 is recovered.

  The control unit 12 may control the valve based on the pressure in the retort pot 2 instead of the temperature in the retort pot 2 in all or part of the retort sterilization method. For example, when the control unit 12 receives from the pressure sensor 14 a signal indicating that the pressure inside the retort pot 2 is 118 kPa (saturated vapor pressure at 104 ° C.) in the preheating step, the control unit 12 retorts from the second steam pipe 8 The first steam valve 40 and the second exhaust valve 90 are closed and the first exhaust valve 50 and the second steam valve so that steam is supplied to the kettle 2 and air is exhausted from the retort kettle 2 through the first exhaust pipe 5. You may open 80. The pressure for controlling the valve may be another pressure within the range of 102 kPa (saturated vapor pressure at 100 ° C.) to 270 kPa (saturated vapor pressure at 130 ° C.) instead of 118 kPa.

Reference Signs List 1 retort device 2 retort pot 3 basket 4 first steam piping 5 first exhaust piping 6 water supply piping 7 pressurized air piping 8 second steam piping 9 second exhaust piping 10 drainage piping 11 boiler 12 control section 13 temperature sensor 40 first Steam valve 50 First exhaust valve 52 Air vent 54 Air vent valve 60 Water supply valve 62 Shower nozzle 70 Air supply valve 80 Second steam valve 90 Second exhaust valve 100 Drain valve

Claims (6)

A retort device,
With a retort kettle,
A first steam pipe connected to an upper portion of the retort pot for supplying steam to the retort pot;
A first exhaust pipe connected to an upper portion of the retort pot for discharging air from the retort pot;
A second steam pipe connected to a lower portion of the retort pot for supplying steam to the retort pot;
A second exhaust pipe connected to a lower portion of the retort pot for exhausting air from the retort pot;
A first steam valve, a first exhaust valve, a second steam valve, and a second exhaust valve respectively provided to the first steam pipe, the first exhaust pipe, the second steam pipe, and the second exhaust pipe;
A control unit that controls the first steam valve, the first exhaust valve, the second steam valve, and the second exhaust valve ;
A temperature sensor disposed inside the retort kettle ;
The control unit opens the first steam valve and the second exhaust valve so that steam is supplied from the first steam pipe to the retort pot and air is exhausted from the retort pot through the second exhaust pipe. And when the temperature inside the retort kettle detected by the temperature sensor reaches a predetermined temperature after closing the first exhaust valve and the second steam valve, steam from the second steam pipe to the retort kettle To close the first steam valve and the second exhaust valve and open the first exhaust valve and the second steam valve so that the air is exhausted from the retort pot through the first exhaust pipe.
Wherein the predetermined temperature is Ru der 100 ° C. or higher 130 ° C. or less, retort apparatus. A retort device,
  With a retort kettle,
  A first steam pipe connected to an upper portion of the retort pot for supplying steam to the retort pot;
  A first exhaust pipe connected to an upper portion of the retort pot for discharging air from the retort pot;
  A second steam pipe connected to a lower portion of the retort pot for supplying steam to the retort pot;
  A second exhaust pipe connected to a lower portion of the retort pot for exhausting air from the retort pot;
  A first steam valve, a first exhaust valve, a second steam valve, and a second exhaust valve respectively provided to the first steam pipe, the first exhaust pipe, the second steam pipe, and the second exhaust pipe;
  A control unit that controls the first steam valve, the first exhaust valve, the second steam valve, and the second exhaust valve;
  A pressure sensor disposed inside the retort pot and
Equipped with
  The control unit opens the first steam valve and the second exhaust valve so that steam is supplied from the first steam pipe to the retort pot and air is exhausted from the retort pot through the second exhaust pipe. And closing the first exhaust valve and the second steam valve, and then, when the pressure inside the retort kettle detected by the pressure sensor reaches a predetermined pressure, steam from the second steam pipe to the retort kettle To close the first steam valve and the second exhaust valve and open the first exhaust valve and the second steam valve so that the air is exhausted from the retort pot through the first exhaust pipe.
  The retort device whose said predetermined pressure is 102 kPa or more and 270 kPa or less. The retort according to claim 1 or 2, wherein the first exhaust pipe and the second exhaust pipe each have a plurality of pipes, and the pipes are open to the atmosphere at one end without merging with each other. apparatus. The retort device according to any one of claims 1 to 3, wherein the first exhaust pipe comprises an air vent. In a retort sterilization method for sterilizing packaged food with high temperature and high pressure steam in a retort pot,
  Supplying steam from the top of the retort kettle and exhausting air from the bottom of the retort kettle;
  When the temperature inside the retort pot reaches a predetermined temperature, supplying steam from the lower part of the retort pot and exhausting air from the upper part of the retort pot;
Including
  The retort sterilization method, wherein the predetermined temperature is 100 ° C. or more and 130 ° C. or less. In a retort sterilization method for sterilizing packaged food with high temperature and high pressure steam in a retort pot,
  Supplying steam from the top of the retort kettle and exhausting air from the bottom of the retort kettle;
  When the pressure inside the retort pot reaches a predetermined pressure, supplying steam from the lower part of the retort pot and exhausting air from the upper part of the retort pot
Including
  The retort sterilization method, wherein the predetermined pressure is 102 kPa or more and 270 kPa or less.

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