JP5258110B2 - Heat sterilizer for aerated containers - Google Patents

Description

  The present invention relates to a heat sterilization apparatus for an air-containing container for heat-sterilizing an air-sealed sealed storage container.

  Canned and retort foods can be stored at room temperature for a long period of time by heating them from the outside of the container after hermetically sealed and sterilizing the food inside the container. When heat sterilization is performed, an object to be sterilized is stored in a sterilization tank, and the object to be sterilized is heated by spraying high-temperature water onto the object to be sterilized in a state where the inside of the sterilization tank is pressurized. The object to be sterilized is sterilized by maintaining the object to be sterilized to a sterilization temperature for a predetermined time, and after cooling, the object to be sterilized is taken out from the sterilization tank, and the process ends.

  As described in Japanese Patent No. 3078545, when a food containing an aerated container having a gas phase portion in a container is heat sterilized, a difference occurs between the pressure in the container and the pressure in the sterilization tank. May be deformed or damaged. Therefore, it is necessary to adjust the pressure in the tank so that there is no difference between the pressure in the aerated container and the pressure in the sterilization tank. In Japanese Patent No. 3078545, the temperature of the aerated container is calculated from the temperature in the tank using a heat transfer calculation formula. The moisture temperature inside is obtained, the pressure in the aerated container is calculated, and the pressure in the sterilization tank is controlled so that the pressure difference between the inside and outside of the aerated container does not increase. However, with this method, specialized knowledge is required to calculate the set value of the heat transfer calculation formula, or when the set value is a general value, it differs from the actual pressure in the aerated container. There was a possibility of deformation and breakage of the aerated container due to pressure.

Japanese Patent No. 3078545

  The problem to be solved by the present invention is to enable pressure control to prevent deformation and breakage of an air-containing container without specialized knowledge.

The invention according to claim 1 is a heat sterilization in which an aerated container in which a food containing a gas phase is sealed is contained in a sterilization tank, and hot sterilization is performed by injecting high-temperature water into the aerated container. A sterilization tank having a temperature detector for detecting the temperature in the sterilization tank, a pressure detector for detecting the pressure in the sterilization tank, and a pressure adjusting device for adjusting the pressure in the sterilization tank. In a heat sterilization apparatus that performs heat sterilization of an object to be sterilized while adjusting the pressure in the tank, the current temperature in the tank detected by the tank temperature detector is the temperature in the aerated container after a predetermined delay time has elapsed. expected product temperature calculating program may be provided the operation control apparatus having, der performs pressure regulation of the sterilizing chamber based on the calculated predicted product temperature to calculate the predicted product temperature as is, delay time, a plurality sets The delay time is set according to the temperature inside the tank. Cormorant chamber temperature is set at relatively wide intervals in a low temperature region, and wherein the set at a relatively small distance in the high temperature range.

  The invention according to claim 2 is the above-described heat sterilization apparatus, wherein the delay time is set corresponding to each of the plurality of tank temperatures set, and the tank temperature for setting the delay time is set in a low temperature range. The temperature is set at a relatively wide interval, is set at a relatively narrow interval in a high temperature region, and the temperature in the tank and the delay time are proportionally calculated at a temperature intermediate between the set temperatures.

  By carrying out the invention, it is possible to perform pressure control without deforming or damaging the aerated container without specialized knowledge.

Explanatory drawing of temperature change in tank and expected product temperature calculation in one embodiment of the present invention Flow diagram of heat sterilization apparatus for carrying out the present invention Table of delay time set according to the bath temperature

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram of the temperature change in the tank and the expected product temperature in one embodiment of the present invention, where the horizontal axis represents time, the vertical axis represents temperature on the left, and pressure on the right. The process of heat sterilization in this example is performed by performing primary heating for heating the object to be sterilized to 80 ° C., secondary heating for heating to 100 ° C., and tertiary heating for heating to 120 ° C., and then maintaining the sterilization temperature for a predetermined time. Then, sterilization is performed, and then cooling is performed.

FIG. 2 is a flowchart of a heat sterilization apparatus for carrying out the present invention. The heat sterilization apparatus accommodates an object 2 to be sterilized in a cylindrical sterilization tank 1. The object to be sterilized 2 is an aerated container having a gas phase portion, and sterilization is performed by heating the object to be sterilized 2 in the sterilization tank 1. A steam introduction pipe 3 for introducing steam and a feed water introduction pipe 5 for introducing feed water are connected to the lower part of the sterilization tank 1. The steam introduction pipe 3 is provided with a steam introduction control valve 6, and the water supply introduction pipe 5 is provided with a water supply control valve 7, and the introduction of steam and water supply into the sterilization tank 1 is controlled by controlling the opening and closing of each control valve. Like to do. A circulation pipe 8 is connected to the bottom of the sterilization tank 1, and the other end of the circulation pipe 8 is connected to an injection nozzle 9 provided in the sterilization tank. A circulation pump 4 is provided in the middle of the circulation pipe 8. When the circulation pump 4 is operated, water at the bottom of the sterilization tank 1 is sent to the injection nozzle 9 through the circulation pipe 8, and the circulation water is supplied from the injection nozzle 9 into the sterilization tank 1. It comes to inject.
The pressure in the sterilization tank 1 is adjusted by supplying a compressed air to the sterilization tank and exhausting the air from the sterilization tank 13, and compressing the pressure in the tank. When air is supplied and the pressure in the tank is lowered, air is discharged.

  The sterilization tank 1 is provided with a tank temperature detector 11 for detecting the tank temperature and a tank pressure detector 12 for detecting the tank pressure. The operation control of the steam introduction control valve 6, the water supply control valve 7, the circulation pump 4, the tank pressure control device 13, and the like is performed by the operation control device 10, and the operation control device 10 includes the tank temperature detector 11. And the tank pressure detector 12 is also connected. The operation control device 10 is set with an expected product temperature calculation program for calculating the temperature in the aerated container based on the temperature in the tank detected by the temperature detector 11 in the tank. The predicted product temperature calculation program sets a “delay time” corresponding to the temperature in the tank, and after the “delay time” has elapsed since the temperature in the sterilization tank was detected by the tank temperature detector 11. The predicted product temperature is calculated assuming that the product temperature, which is the temperature of the sterilized product, becomes that temperature.

  The lag time is determined by placing the actual object to be sterilized in the sterilization tank and conducting a test operation for heat sterilization, and actually measuring the temperature in the tank and the temperature of the object to be sterilized. Check and set the relationship. The relationship between the temperature in the tank and the product temperature varies depending on factors such as the size and viscosity of the object to be sterilized and the heat transferability of the container, even with the same heat sterilizer. It is necessary to investigate the relationship between product temperatures.

  The delay time is set in a plurality of temperature zones as shown in FIG. The temperature to be set is set at a relatively wide interval in the low temperature range and at a relatively narrow interval in the high temperature range so that the temperature is set at 10 ° C. from 50 ° C. to 90 ° C. and 5 ° C. from 90 ° C. to 135 ° C. . In each temperature range, a delay time at the time of heating and a delay time at the time of cooling are respectively set, and at an intermediate temperature, it is calculated proportionally from the set value. For example, when the temperature in the tank is 55 ° C., the delay time at this temperature is not set, and therefore, it is calculated from the previous and subsequent values. The delay time at 50 ° C is 22 seconds and the delay time at 60 ° C is 54 seconds. Therefore, between 50 ° C and 60 ° C, the delay time changes by 3.2 seconds due to a change of 1 ° C in the tank temperature. Therefore, the delay time at 55 ° C. can be considered to be 38 seconds.

  Although the accuracy of control is higher when a large number of temperatures for setting the delay time are set at narrow intervals, it cannot be expected that the accuracy will increase as much as the effort is increased even if it is set finely. Therefore, the temperature setting of the delay time is set at intervals of 5 ° C. or 10 ° C., and is calculated in proportion between the set temperatures. The reason for narrowing the temperature interval for setting the delay time in the high temperature range is that a large pressure change occurs even in a small temperature change in the high temperature range, and pressure control with large pressure fluctuation and high accuracy is required. In the high temperature range, by setting the temperature interval for setting the delay time to be narrow, it is possible to perform pressure control that does not deform or damage the container. In low temperature range where pressure fluctuation is small and high precision pressure control is not required, even if the temperature interval for setting the delay time is set wide, the container will not be deformed or damaged, and set by widening the set temperature interval Can be simplified.

  It demonstrates based on an actual heat sterilization process. When performing the heat sterilization of the article 2 to be sterilized, first, the article 2 to be sterilized is arranged in a tray, and the trays are stacked and stored in the sterilization tank 1. Next, water is introduced into the bottom of the sterilization tank 1, steam is blown into the water accumulated in the bottom to heat the water to high-temperature water, and the circulating pump 4 is operated to inject the object to be sterilized. High temperature water is jetted toward 2.

  In the operation control device 10, an elapsed time from the start of operation and a target value of the temperature in the tank at that time are set, and the temperature in the tank detected by the temperature sensor 11 in the tank is set to the target temperature. The temperature is adjusted by controlling the opening and closing of the steam introduction control valve 6. When steam is supplied to the sterilization tank 1, the water temperature at the bottom of the sterilization tank rises and the temperature of the spray water sprayed from the spray nozzle 9 rises, so the temperature in the sterilization tank 1 rises. Conversely, when the supply of steam to the sterilization tank 1 is stopped, the water temperature at the bottom of the sterilization tank decreases and the temperature of the spray water sprayed from the spray nozzle 9 decreases, so the temperature in the sterilization tank 1 decreases. Heating to 80 ° C. in the primary heating step, heating to 100 ° C. in the secondary heating step, heating to 120 ° C. in the tertiary heating, and heat sterilization are performed by maintaining the sterilization temperature at 120 ° C. for a predetermined time. Thereafter, cooling water is introduced into the sterilization tank 1, and a cooling process for cooling the sterilized material 2 is performed by circulating and spraying the cooling water, and the sterilized material 2 is taken out from the sterilization tank 1 after the cooling is completed.

  At this time, the operation control apparatus 10 records the temperature in the sterilization tank detected by the tank temperature detector 11 in an expected product temperature buffer provided in the operation control apparatus 10. The operation control device 10 calculates the expected product temperature from the detected tank temperature and the heating delay time determined from the tank temperature. The expected product temperature is the one that predicts the product temperature after the lag time elapses from the detection of the tank temperature, and the predicted product temperature is calculated assuming that the product temperature after the lapse of the delay time is equal to the previously measured tank temperature. I do. By calculating the expected product temperature, the pressure in the aerated container at that time is calculated, and the pressure in the tank is adjusted so that the pressure corresponds to the product temperature.

  For example, when the temperature in the tank at a certain time A is 60 ° C., the operation control apparatus 10 records the temperature at the time A in the expected product temperature buffer. The heating delay time at a bath temperature of 60 ° C. is 54 seconds as shown in FIG. 3, and 54 seconds is calculated as the value of the heating delay time. The operation control device 10 predicts that the product temperature of the article 2 to be sterilized will be 60 ° C. at time B, which is 54 seconds after time A. If the product temperature at time B is obtained, the pressure in the container at time B can be calculated. Since the deformation of the container occurs due to a difference between the pressure in the container and the pressure in the sterilization tank, the tank pressure at time B is set so that the container pressure becomes a pressure corresponding to 60 ° C. The internal pressure adjustment device 13 adjusts the pressure.

  Similarly, for example, at time C when the temperature in the tank reaches 100 ° C., the heating delay time at 100 ° C. is 166 seconds, so the product temperature is expected to be 100 ° C. at time D, which is 166 seconds after time C. And adjust the pressure in the tank at time D. The predicted product temperature is also calculated in the cooling process, and the predicted product temperature is calculated using the cooling delay time during cooling. The expected product temperature is calculated in the same manner during the cooling process, but the expected product temperature is calculated based on the cooling delay time during the cooling process.

  By calculating the expected product temperature based on the delay time and controlling the pressure in the sterilization tank, pressure control will not deform or damage the aerated container even if the object to be sterilized is contained in the aerated container. Is possible.

1 sterilization tank
2 Objects to be sterilized
3 Steam inlet pipe
4 Circulation pump
5 Water supply introduction pipe
6 Steam introduction control valve
7 Water supply control valve
8 Circulation piping
9 Injection nozzle
DESCRIPTION OF SYMBOLS 10 Operation control apparatus 11 In-tank temperature detector 12 In-tank pressure detector 13 In-tank pressure control apparatus

Claims (2)

A heat sterilization apparatus for containing a gas-containing food sealed in a container in a sterilization tank and performing heat sterilization by injecting high-temperature water into the gas container, It has a tank temperature detector that detects the temperature, a tank pressure detector that detects the pressure in the sterilization tank, and a tank pressure regulator that adjusts the pressure in the sterilization tank. In the heat sterilizer that heats and sterilizes sterilized materials, the expected product temperature is calculated by assuming that the current temperature in the tank detected by the temperature sensor in the tank is the temperature in the aerated container after the elapse of a predetermined delay time. may be provided the operation control device having a temperature calculation program, der performs pressure regulation of the sterilizing chamber based on the calculated predicted product temperature is, the delay time, corresponding respectively to the chamber temperature was set multiple The tank temperature for which the delay time is set is set in a low temperature range. Set a relatively wide intervals, heat sterilization apparatus of aerated container, characterized in that set in a relatively narrow interval in a high temperature region.   In the heat sterilization apparatus for an aerated container according to claim 1, the delay time is set corresponding to each of a plurality of set tank temperatures, and the tank temperature for setting the delay time is compared in a low temperature range. The air content is characterized in that it is set at a relatively wide interval, set at a relatively narrow interval in the high temperature range, and the temperature inside the tank and the delay time are calculated proportionally at a temperature intermediate between the set temperatures. Container heat sterilizer.

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