JP2598874B2 - Improved method of sterilizing canned foods with a sterilizing pot - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for sterilizing canned foods, and more particularly to a method for sterilizing canned foods in a sterilizing pot.

[0002]

2. Description of the Related Art At present, sterilization of canned foods in Japan is almost a conventional sterilization method using steam exhaustion. First, air in a sterilization pot is removed by steam until the content in the pot is reduced to some extent. After the temperature becomes uniform, steam is continuously introduced, and the temperature in the pot is raised to the sterilization temperature to perform sterilization. After sterilization is completed, cooling is performed by pressurized cooling or direct cold water according to demand.

According to the Food Research Institute, Jinji Wang (Research Report No. 227, 1981), the energy consumption of the traditional sterilization method using the steam exhaust system is mostly concentrated in the exhaust stage, and steam that escapes from the pot is used. About one-third of the total steam needs to be used to improve the energy use efficiency of traditional sterilization methods. In addition, the high-temperature steam in the pot after the sterilization is completed is not directly discharged into the atmosphere and collected, and the heat energy of the high-temperature pot and the can in the pot is also taken and collected by the cooling water. The problem of inefficient use of energy by the law is becoming more severe.

[0004] The main object of the present invention is to provide an improvement in energy efficiency for a sterilization method using a sterilization pot.

[0005]

SUMMARY OF THE INVENTION To achieve the above objects of the present invention, there has been disclosed an improved method for sterilizing canned foods in a sterilizing kettle comprising the following features: About 95 ° C hot water is introduced from the tank, and the air in the kettle is discharged from the top of the pot with the hot water introduced until the sterilizing pot is full,
The hot water of about 95 ° C. is reduced to about 85 ° C. by preheating the can and the pot, and (b) the hot water of about 85 ° C. is removed from the bottom of the pot until the hot water at about 85 ° C. is no longer in the pot. Two tanks, steam is introduced from the top of the sterilization kettle at the start of the outflow, and the amount of introduced steam is sufficient to maintain a positive pressure in the kettle, and that air does not enter the kettle; c) steam introduction is continued until the temperature in the sterilization pot reaches a predetermined sterilization temperature, and after maintaining the temperature at a predetermined sterilization time, the steam introduction is stopped; and ℃ hot water is introduced into the sterilization pot and sprayed from the top of the pot, and the introduced hot water of about 85 ° C. cools the steam in the pot and exchanges heat with the high temperature pot and the can in the pot. ℃, and after a period of time, the hot water heated to about 95 ℃ in the sterilization pot flows out from the bottom of the pot Because, is introduced into the first tank, about the amount of hot water is introduced into the sterilization kettle 該約 85 ° C. of (a) 95
(E) After the hot water heated to 95 ° C. in the above (d) is drained, cooling water is introduced into the sterilizing pot. First, after cooling the cans in the pot, the cooled sterilized canned food is taken out from the pot.

In the method of the present invention, the temperature is about 95%.
The preferred temperature of hot water at ℃ is 93-97 ° C hot water,
A preferred temperature for hot water at a temperature of about 85 ° C is hot water at 83-87 ° C.

The method of the present invention has a remarkable improvement in energy efficiency as compared with a traditional sterilization method using a steam exhaust system due to the following reasons: In step (a), hot water at about 95 ° C. The use of steam is saved by changing the method of discharging air outside the kettle with traditional steam by the method of eliminating air. In the step (d), high-temperature steam in the pot after completion of sterilization with hot water of about 85 ° C. and heat energy of the canned pot are recovered.

In addition, since most of the heat energy in the high-temperature sterilization pot is effectively recovered, the temperature in the pot is lowered, and the amount of cooling water used jointly in the step (e) is the cooling water used in the traditional method. It requires less than the amount of water.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION FIG. 1 is a flow chart of a preferred embodiment of the sterilization method of the present invention. I drew each. As shown in FIG. 1, the preferred embodiment of the present invention includes five steps in the order of the exhausting step, the drainage heating step, the sterilizing step, the heat recovery step and the cooling step.

In the evacuation stage, hot water of about 95 ° C. is injected from the first tank 10 via the pump 11 to the sterilization pot 100 in which cans to be sterilized are previously placed, to the full water level. Since the exhaust valve (not shown) installed at the top of the sterilization pot has already been opened beforehand, the air in the pot is discharged from the exhaust valve at the top of the pot by the flowing hot water, and the can and the pot are preheated. The water temperature also drops to about 85 ° C.

[0011] In the drainage temperature raising step following the exhausting step, the hot water in the pot is discharged from the pot bottom of the sterilization pot 100 and the second tank 2 is discharged.
Closed the control valve that releases water when the inside of the kettle becomes water-free, and introduces steam from the top of the sterilizing kettle simultaneously with the start of the discharge, the amount of which makes the steam pressure in the kettle higher than the external pressure The temperature of the water discharged into the second tank 20 is about 85 ° C.

After completion of the drainage heating step, steam is introduced from the bottom of the pot, the temperature in the pot is continuously raised to the sterilization temperature, and the temperature is maintained for the specified sterilization time. If water has accumulated, open the drain valve at the bottom of the kettle to remove the condensed water.

After completion of the sterilization step, a heat recovery step is performed. First, hot water of about 85 ° C. stored in the second tank 20 is sent to the sterilization pot 100 by the action of the pump 21 and sprayed from the top of the pot. This allows the cans at the sterilization temperature to be evenly and gradually cooled while condensing the steam in the kettle, minimizing the pressure difference between the inside and outside of the cans, eliminating the need to maintain compressed kettle pressure by adding compressed air, eliminating air. Electric energy used for compression can also be saved. 8
When exchanging heat with 5 ° C hot water to recover heat energy,
When the boiling water heated to 95 ° C has accumulated a considerable volume in the pot,
The water is started to be discharged from the bottom of the kettle and introduced into the first tank 10, so that the time required for the hot water to move out of the kettle can be saved. When the amount of the hot water of about 85 ° C. introduced into the sterilization pot 100 is substantially the same as the amount required for the preheating by the hot water of 95 ° C. and the evacuation in the evacuation stage, 8
Stop the introduction of 5 ° C hot water.

After the discharge of the hot water of 95 ° C. in the heat recovery stage is completed, the drain valve for discharging the water is closed, and ordinary cooling water is supplied to the sterilizing pot 1.
00, and also sprayed from the top of the kettle to uniformly cool the cans in the kettle so that the cooling temperature is approximately the same as that of the upper and lower cans in the kettle. This is the cooling stage. Since the heat exchange in the heat recovery stage has been performed first, the canning temperature in the kettle is already low, the temperature of the cooling water may be low, and the temperature of the canned discharged from the kettle is low and uniform.

Before the exhausting step, a part of the hot water of 95 ° C. can be sprayed from the top of the pot to wash the cans. The purified water is discharged from the bottom of the pot and discarded. By replenishing the two tanks, it is possible to avoid problems such as contamination of canned hot water and deterioration of water quality due to repeated use.

Next, the present invention will be described with reference to comparative examples and examples, but the examples are merely illustrative and do not limit the scope of the present invention.

Comparative Example: Use of steam exhaust system sterilization method The canned food to be sterilized is 350 g of canned tea beverage.
The maximum capacity of one can is 330 g. Sterilization pot is 4 × 14f
It is a t (D × L) horizontal sterilization pot. There are four baskets inside, and one basket has 13 cans x 15 cans x 7 layers of products, with a total of 5460 cans per kettle.

Saturated steam is introduced into the kettle in which canned food is previously introduced, and exhaust is performed. The air in the kettle is exhausted from the exhaust valve and the leak valve at the top of the kettle, and the pressure is reduced to 0.32 kg / cm ² gauge pressure. After the evacuation was completed, the exhaust valve was closed, and steam was continuously introduced. In about 2 minutes, the steam pressure in the kettle increased from 0.32 to 0.92 kg / cm ² gauge pressure, and the temperature was increased. reached sterilizing temperature 118.5 ° C. of the target (relative saturation vapor pressure 0.92 kg / cm ² gauge pressure), the temperature from the sterilization is completed by keeping 20 minutes, stop the introduction of steam, open the exhaust valve, steam And introduce cooling water. Table 1 shows the results of the experiment.

Table 1 Amount of steam used, kg Test Exhaust temperature rise Sterilization Total

Example: Use of sterilization method by hot water exhaustion method The canned food and sterilization pot of Comparative Example 1 were used for the sterilization method of this example. When hot water of 95 ° C. is introduced from the first tank to the bottom of the sterilization pot in which cans are previously placed by a pump, and when the first level gauge installed in the leak pipe of the sterilization pot detects that water is present, Indicates that the kettle is already full and air has been exhausted from the exhaust valve at the top of the kettle.

When the full signal is transmitted to the steam controller, steam is introduced from the top of the kettle, and when the pressure in the kettle rises to 0.2 kg / cm ² , drainage is started from the bottom of the kettle, and the pressure of the steam controller is reduced to 0.2 kg. /
Set to cm ² , the drained water was introduced into the second tank and the water temperature was about 85 ° C.

When the second liquid level gauge installed in the drain pipe of the sterilizing pot indicates that the inside of the pot is anhydrous, the drain valve at the bottom of the pot is closed.
When a signal is transmitted to the steam controller indicating that water in the pot is anhydrous, steam is introduced, the pressure is increased, and the temperature in the pot is raised to a sterilization temperature of 118.5 ° C.

The sterilization temperature is maintained for 20 minutes, the steam is shut off,
The hot water of 85 ° C in the second tank is introduced into the sterilizing pot with a pump and sprayed from the top of the pot. After the water reaches about half the pot, the drain valve under the pot is opened and the hot water of about 95 ° C in the pot is opened. Into the first tank and store it, and after one minute, 85 ° C introduced from the second tank
After the water in the kettle has been stopped and the hot water in the pot has been drained, the drain valve is closed. Next, cooling water of 30 ° C. was introduced into the sterilizing pot to cool the pot. After about 7 minutes, the pot was filled with water, the introduction of the cooling water at 30 ° C. was stopped, and the water in the pot was discharged. Open and take out the sterilized canned food. Table 2 shows the results.

Table 2 Amount of steam used, kg Test Exhaust temperature rise Temperature Sterilization Total

By comparing the data in Tables 1 and 2,
It can be calculated that the hot water exhaust sterilization method of the present invention can save steam over the traditional steam exhaust sterilization method:

From the above, it can be seen that the method of the present invention can save 34% of steam consumption in one sterilization cycle, the electric consumption of two pumps is 7.5 HP × 2 × 2.5 minutes, and the meter is about 0.
5 degrees and the cost is minimal. Therefore, the amount of steam saved by the circulation operation for a long time and a large number of times is very large, and has a great industrial value.

[Brief description of the drawings]

FIG. 1 shows a flowchart of a preferred specific embodiment of the sterilization method of the present invention.

Claims (1)

(57) [Claims] 1. A method for sterilizing canned foods using a sterilizing pot, wherein (a) hot water at 93-97 ° C. is introduced from a first tank into a sterilizing pot in which cans to be sterilized are previously placed; The hot water of 93-97 ° C is lowered to 83-87 ° C by preheating the can and the kettle, with the hot water introduced therein until the air in the kettle is discharged from the top of the kettle.
(B) The hot water at 83-87 ° C. in the kettle was drained from the bottom of the sterilization kettle to the second tank until the hot water disappeared in the kettle, and steam was introduced from the top of the sterilization pot at the start of the outflow. The amount of steam is sufficient to maintain the positive pressure in the kettle. Air must not enter the kettle, and (c) steam introduction is continued until the temperature in the sterilization pot reaches a predetermined sterilization temperature. After the scheduled sterilization time is maintained, the introduction of steam is stopped, and (d) hot water of 83-87 ° C. in the second tank is introduced into the sterilization pot, and is sprayed from the top of the pot, and the introduced 83- The hot water of 87 ° C. cools the steam in the kettle, performs heat exchange with the high-temperature kettle body and the can in the kettle, is heated to 93-97 ° C., and after a period of time, 93-97 ° C. in the sterilizing pot. The heated hot water starts flowing out of the bottom of the kettle and is introduced into the first tank.
The amount of hot water of 7 ° C. introduced into the sterilization pot was adjusted to 93-9 of (a).
The amount of hot water of 7 ° C. is set to be substantially the same as the amount to be introduced into the sterilizing pot. (E) After the hot water heated to 93-97 ° C. in the above (d) is drained, cooling water is supplied to the sterilizing pot. A method of sterilizing canned food in a sterilizing pot, wherein the canned food in the pot is cooled after the introduction of the canned food, and then the cooled sterilized canned food is taken out from the pot.