JPS6025107B2 - How to sterilize packaged food - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of sterilizing packaged foods, and particularly to a method of sterilizing packaged foods using a hot water rotary retort.

Heat sterilization of food is an excellent sterilization method that has been used since the invention of canned goods, but because it is processed at high temperatures for a long time, the quality of the food deteriorates, resulting in the so-called ``canned taste'' and the taste.
There was a drawback that the scent and texture were significantly lower than before sterilization.

In order to overcome this drawback, various sterilization methods have been developed in recent years, and it has become possible to obtain high-quality sterilized foods.

Typical methods are the high temperature short time sterilization (HTST) method and the ultra high temperature short time sterilization (u-HT) method. These sterilization methods utilize the difference in heat sensitivity between the food itself and bacteria. That is, although the time required to kill bacteria rapidly shortens as the temperature rises, the rate of deterioration of the food itself does not increase as rapidly. However, the longer the sterilization time, the greater the deterioration of the food itself, so in the HTST and u-day T sterilization methods, it is important to shorten the sterilization time as much as possible in order to obtain high-quality sterilized food. This is an extremely important requirement. The present inventors have repeatedly studied the current sterilization equipment and sterilization methods, but
At present, there are almost no devices that fully satisfy the requirements for HTST sterilization and u-day T sterilization as described above, and there are many technical problems in developing new devices, and there are many technical problems in developing new devices. It has been found that this method is extremely expensive compared to a retort.

By the way, in conventional HTST sterilization and u-HT sterilization, the sterilization time is from several minutes to more than ten minutes, and the time the food is exposed to the sterilization temperature (for example, 135 to 15 and 0) is long, and the food cannot escape deterioration. On the other hand, HTST sterilization or u-
Even if you try to perform HT sterilization, it takes several minutes to ten minutes just to raise the temperature inside the retort for sterilization and to lower the temperature for cooling, and during that time the quality of the food deteriorates, making it impossible to sterilize using conventional HTST. And even the quality obtained with u-HT sterilization cannot be obtained. By the way, in recent years,
Hot water rotary retorts have become popular, and because they have a better heat conduction effect than conventional steam-type static torts, they are used to sterilize canned foods, retort pouched foods, etc., and produce sterilized foods of better quality. We are now able to provide it.

However, simply increasing the temperature of hot water for the purpose of performing HTST sterilization and u-HT sterilization does not sufficiently shorten the time required for heating and cooling, and the quality of foods is inevitably degraded. This invention was made against the background of the above circumstances, and its purpose is to minimize the deterioration of food quality and to sterilize packaged foods efficiently and with relatively simple operations. The objective is to provide a sterilization method.

The present inventors used the current hot water rotary retort to perform HTS.
As a result of intensive research into methods for T sterilization and u-HT sterilization, the present invention has been completed. That is, the method for sterilizing packaged foods of the present invention involves introducing a heating liquid into the retort, which has a built-in rotating body that stores and holds the packaged food, and is located at the bottom of the retort, to the extent that the packaged food is slightly covered. The preheated packaged food is preheated by the heating liquid, high temperature and high pressure steam is introduced into the upper space of the tort, and the rotating body is reversed to bring the preheated packaged food into contact with the high temperature and high pressure steam. sterilizing the packaged food product by inverting the rotating body again to bring the sterilized packaged food into contact with a cooling liquid previously present in the lower part of the tort;
It consists of cooling, if necessary by further introduction of a cooling liquid.

Cooling of the packaged food after sterilization can be achieved by draining the heated water used for preheating from the retort and instead contacting it with cold water that has been injected into the lower part of the retort during sterilization.

In this case, cold water may be introduced into the retort if desired. Alternatively, the heated water used for preheating may be used as it is for precooling the packaged food without being discharged, and then cold water may be introduced into the retort without being discharged or cooled. The present invention will be described in detail below with reference to the drawings.

The apparatus shown in FIG. 1 is a sterilizer having a conventional hot water rotary retort. The retort 101 has a built-in rotating body 12 that can house and hold objects to be sterilized. This rotating body is vertically symmetrical and rotates around the center of the retort 10,
For example, a plate 14 is used for storing objects to be sterilized therein.
It has multiple. An overflow tank 16 for storing heated water is provided above the retort 10, and the hot water tank 16 is connected to the tort 10 by a connecting pipe LI. A steam introduction pipe L2 is connected slightly above the center of the retort 10, a drainage pipe L3 and a water supply pipe L4 are connected to the bottom, and an exhaust pipe and a pressurized air introduction pipe are connected to the top. has been done.

A water supply pipe L7 and a steam introduction pipe L3 are connected to the hot water tank 16. Note that P is a pump for pressurizing cold water from the hot water tank 16 to the tort 10, and P is a pump for pressurizing heated water. To perform sterilization using such a sterilizer, proceed as follows.

First, as shown in FIG.
(e.g. canned food, vacuum packaged food, etc.)

The preheating temperature of packaged foods is usually 50 qo to 110 qo, but in consideration of the temperature drop when the heated water tank 101 is introduced into the hot water tank 16, the preheating temperature may be slightly higher than that temperature (for example, the preheating temperature If is 9 and 0, then 9
5oo). This heated water can be prepared by introducing water from the water supply pipe L7 and heating this water with high-temperature steam introduced from the pipe L7. In addition, packaged foods should be stored to a point below 1/1 of the height of the rotating body. Next, the heated water 18 is injected into the mustard tort 10 through the piping L9, and the packaged food 20 is placed at the top.
(Figure 3).

Excess heated water is discharged from the piping. In this way, preheating of the packaged food is started. After the start of the preheating, high-temperature, high-pressure saturated steam is introduced into the upper space of the retort 10 from the pipe L2, and the air inside the retort 10 is discharged from the pipe L2 in order to prevent temperature unevenness caused by residual air. The temperature in the head space of the retort 10 is then brought to a desired sterilization temperature (usually 135°C to 15°C).

In order to maintain this sterilization temperature and prevent temperature unevenness, it is preferable to introduce steam into the upper space of the retort 10 while discharging a portion of it from the pipe L5. Further, if necessary, pressurized air may be introduced from the pipe L6 to pressurize the upper space of the retort. In this case, temperature unevenness in the upper space of the retort should be avoided. On the other hand, hot water tank 16
Prepare cold water 22 for cooling (Fig. 4). During this time, preheating is performed, and the preheating time is usually 3 to 10 minutes. Next, the rotating body 12 is reversed to position the packaged food 20 upward, and sterilization is started by bringing it into contact with high-temperature, high-pressure steam (FIG. 5).

Next, as shown in FIG. 6, heated water 18 is poured into retort 1.
Discharge from 0.

At this time, the pressure inside the retort that continues to introduce steam is kept constant. After that, pipe L7 mustard tort 10
Inject cold water 24 into the bottom of the tank.

At this time, cold water 24 is added to the extent that it does not come into contact with the packaged food 20 (FIG. 7). Next, as shown in FIG. 8, the introduction of steam is stopped, the rotating body is reversed again, and the sterilized packaged food 20 is brought into contact with the cold water 24 to begin cooling. At this time, in order to perform cooling more efficiently, it is preferable to press the cold water 22 into the retort from the hot water tank 16 using the pump P. On the other hand, in order to prevent deformation and bag breakage of the packaged food 20, pressurized air is introduced from the pipe L6 and exhausted from the pipe L5 as necessary to adjust the pressure inside the retort. Furthermore, cold water is introduced into the retort from the pipe L4 as necessary (FIG. 9). The sterilization time for packaged foods, that is, the time they are exposed to high-temperature, high-pressure steam, is usually 2 to 5 minutes.

Cooling is performed until the packaged food is sufficiently cooled (20° C. to 30° C.), and if necessary, the cooling water in the retort may be discharged and new cold water may be injected from the pipe L4.

Cooling is usually performed for 5 to 10 minutes. Finally, the cooling water in the retort 10 is discharged to complete the sterilization operation (first
Figure 0). In another aspect of the invention, sterilization is started in the steps described with respect to FIGS. 2 to 5, and after a predetermined period of time, the heated water is not discharged but is used for pre-cooling, and as described with respect to FIG. As described above, the rotating body may be reversed to pre-cool it, and then the heated water may be discharged or cold water may be introduced into the retort 10 without discharging it to perform cooling.

Examples 1 and 2 Seasoned and roasted beef (thickness 8~
Sterilization temperature (135~150q)
A number of products were prepared that were filled in plastic film containers that could withstand the above conditions and vacuum packaged.

This packaged food was sterilized according to the steps shown in FIGS. 2 to 10. The preheating temperature was 90°C. The sterilization temperatures were 150qo and 135°C, respectively. The operating conditions and quality of the food after sterilization are summarized in the table below in comparison with the conventional hot water rotary retort sterilization method (Comparative Example 1) and the conventional steam retort sterilization method (Comparative Example 2). x Reverse the rotating body and move the food from the bottom of the retort to the top of the retort K
Loss of time required to move * Time required to reverse the rotating body and move the sterilized food from the top of the retort to the bottom of the retort * Concubine * How to calculate the rating: 110... - Quality? Very good, 10...
・The quality is quite good, 10...The quality is good, soil...
...Quality is excellent (same level as normal heat sterilized food) Example 3 After sterilizing according to the steps in Figures 2 to 5 in the same way as in Example 1, immediately proceed as shown in Figure 8 and below. Sterilization and cooling were performed according to the process.

Although the food sterilized by this method had slightly deteriorated tissue compared to the food sterilized by Example 1, it had a much better quality than the food sterilized by the conventional method. As described above, in this invention, the packaged food is preheated, and during this time, high-temperature, high-pressure steam is introduced into the upper space of the retort, and the preheated packaged food is immediately heated to the high-temperature, high-pressure steam by reversing the rotating body. The packaged food can be heated to a predetermined sterilization temperature in an extremely short time.

Also, during sterilization, a cooling liquid is prepared in the lower part of the retort, and after sterilization, the rotating body can be reversed to bring the packaged food into contact with the cooling liquid in a very short time, making it possible to perform rapid cooling. can. That is, according to the present invention, conditions close to ideal for HTST sterilization and u-HT sterilization, such as rapid high-temperature heating and rapid cooling of packaged foods, can be satisfied.
Therefore, the packaged food sterilized according to the present invention has a sufficient sterilization rate and excellent quality with almost no deterioration.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a conventional hot water rotary retort sterilizer used in the method of the present invention, and Figs. 2 to 10 show the method of the present invention using the sterilizer shown in Fig. 1. A schematic diagram for explaining the steps to be performed. 10... Retort, 12... Rotating body,
16... Warm water tank. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10

Claims (1)

[Scope of Claims] 1. The heating liquid is introduced into the retort, which has a built-in rotating body for storing and holding the packaged food, and is located at the lower part of the retort, to the extent that the packaged food is slightly covered. The preheated packaged food is preheated with a liquid, high temperature and high pressure steam is introduced into the upper space of the retort, and the rotating body is reversed to bring the preheated packaged food into contact with the high temperature and high pressure steam to sterilize it. Then, by reversing the rotating body again, the sterilized packaged food is brought into contact with the cooling liquid previously present in the lower part of the retort, and further cooling liquid is introduced as the case requires. A method for sterilizing packaged food comprising cooling it by cooling. 2. Cooling is performed by discharging the heating liquid used for preheating from the retort, introducing a cooling liquid into the lower part of the retort in place, and bringing the cooling liquid into contact with the packaged food. A sterilization method according to claim 1. 3 The heating liquid used for preheating is brought into contact with the packaged food after sterilization without being discharged to perform preliminary cooling, and then the heating liquid is discharged or placed in the retort for cooling without being discharged. The sterilization method according to claim 1, characterized in that cooling is performed by introducing a liquid.