JPS6356098B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for heat sterilization of plastic packaged foods.

The conventionally commonly used method of sterilizing this type of food is the so-called retort method, in which cooked food is placed in a container such as a tray, sealed with a plastic film sheet, and then heated and sterilized in a retort (heated steam oven). However, this method has problems in that the equipment costs are high and the work is complicated. Furthermore, when heat sterilization is performed in a general steamer without using a retort, there is a problem that the air inside expands during heating, causing damage to the film sheet.

In order to solve these problems, the inventor has developed a fourth
We developed the method shown in the figure. In this method, when cooking food is placed on a tray a and the opening thereof is covered with a film sheet b, a through hole c is formed in at least one of the tray a or the film sheet b.
After heat sterilization, the through hole c is sealed with a sealing material d under aseptic conditions. This method has the advantage that even if heated in a general steamer, the expanded air inside will escape to the outside through the through hole c, so that the film sheet b will not be damaged. However, according to this method, the inside sealed with the sealing material d becomes negative pressure as the temperature decreases (due to condensation of water vapor), and as shown in FIG. 4, the film sheet b is bent into a concave shape and the tray a is also deformed. The drawback was that it significantly reduced the commercial value of packaged foods.

Therefore, as a result of further research, the present inventor developed the method shown in FIG. This method uses tray a
The entire periphery of the plastic bag e is covered with a plastic bag e having a slightly larger volume, and a through hole f is provided in the plastic bag e. As a result, even if the inside becomes negative pressure, the effect is
This appears as a reduction in the volume of the tray a, and it is possible to obtain the effect of not causing deformation of the tray a. However, the drawback that the plastic bag e is curved in a concave manner above the opening of the tray a remains. Due to this drawback, for example, when the food to be packaged is rice, the concave portion g of the plastic bag e presses down on the rice grains in the top layer, causing the rice to lose its fluffy feel and significantly reducing its commercial value. . Another disadvantage is that water droplets adhering to the back surface of the concave portion g directly touch the rice grains, causing the rice to become soggy. In particular, eel bento boxes, tempura bento boxes, etc. have a serious drawback in that the eel etc. placed on top of the rice are deformed, resulting in a significant decrease in the product value and at the same time causing a decrease in appetite.

The present invention aims to solve the above problems all at once. The present invention will be specifically described below based on embodiments shown in the drawings.

After placing the cooked food 2 in a container 1 such as a tray made of heat-resistant plastic, aluminum foil, etc., a spacer member 3 made of heat-resistant plastic that is ventilated and has a predetermined shape-retaining strength is inserted into the opening of the container 1. Then, the entire periphery thereof is covered with a plastic bag 4 having barrier properties and heat resistance. The plastic bag 4 is formed to have a slightly larger volume than the container 1, and has at least one through hole 5 previously provided therein. Thereafter, this is guided into a heating equipment 6 such as a general steamer, and after being heated and sterilized, the through hole 5 is sealed with a sealing material 7 under aseptic conditions to shut off outside air.

In the illustrated example, a stepped portion 8 is provided on the inner side of the mouth edge of the tray 1.
It is formed to be suitable for fitting the spacer member 3 thereinto, and the cross-sectional shape of the peripheral flange portion 9 is formed into a wavy shape. Further, the spacer member 3 has a dish shape and is composed of a peripheral frame portion 10 and a lattice portion 11. This member 3 may also be formed flat. still,
In the illustrated example, a part 12 of the lattice part 11 is closed, and a hole 13 in the part 12 communicates with the through hole 5.
The reason for providing this is to use the closed portion 12 as a support during sealing. When sealing the sealing material 7 using a spray sealing machine, the closed portion 12 is not necessary. As the sealing material 7, in addition to sealing using an adhesive, a material using heat welding can be used. Furthermore, instead of the through hole 5, a part of the plastic bag 4 may be provided with an unsealed material, and this part may be sealed under aseptic conditions after heat sterilization. The through hole 5 and the unsealed portion are referred to as a ventilation portion in the claims.
In addition to the above-mentioned tray, a cup-shaped container or the like may be used as the container 1, if necessary.

As the heating equipment 6, a general steamer can be used, but if the steam temperature is to be 100° C. or higher, it is necessary to use a pressurized steamer.
An appropriate heating temperature is selected depending on the target food, such as bento boxes, dumplings, boiled beans, side dishes, etc., and is generally selected within the range of 75°C to 120°C.

Since the present invention is constructed as described above, after the through hole 5 of the plastic bag 4 is sealed, the inside of the plastic bag 4 becomes negative pressure as the temperature decreases, and the container 1
Even if the plastic bag 4 attempts to approach the food product 2 at the opening, this can be prevented by the spacer member 3. Therefore, the plastic bag 4 does not directly adhere to the food 2, and the appearance is improved, and
It is possible to prevent the upper layer of the food product 2 from being deformed by pressure, and also to prevent water droplets on the back surface of the plastic bag 4 from adhering to the food product 2, so that the product value can be maintained at a high level.

Further, according to the present invention, damage to the packaging and deformation of the container 1 due to expansion of air etc. inside can be avoided, and
Heat sterilization can be performed using inexpensive equipment 6 such as a general steamer, and the cost can be reduced significantly.

Further, according to the present invention, since the upper part of the food 2 can be protected by the spacer member 3 having a predetermined shape-retaining strength,
This makes it possible to store and transport packaged foods such as boxed lunches in a stack.

Furthermore, if the spacer member 3 is formed in a convex shape as shown in the embodiment, even if the food 2 is placed higher than the opening surface, the plastic bag 4 will not come into close contact with the food, thereby increasing its commercial value. After the food 2 has been consumed, a through hole is made in the bottom of the container 1 and a convex spacer member 3 is inserted.
It can also be used as a soap box by turning it upside down and fitting it into the opening of the container 1.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing the principle of the method of the present invention,
Fig. 2 is a longitudinal sectional view of the packaged food after sealing, Fig. 3 is a plan view thereof, and Figs. 4 and 5 are longitudinal sectional views of the packaged food after heat sterilization treatment by a method preceding the method of the present invention. It is. 1... Container such as a tray, 2... Food, 3... Spacer member, 4... Plastic bag, 5... Ventilation section, 6... Heat sterilization equipment.

Claims (1)

[Claims] 1. After food is placed in a container such as a tray, a spacer member that is freely ventilable and has a predetermined shape-retaining strength is placed at the opening of the container, and the entire periphery of the spacer member is covered with a plastic bag having a vent. . A method for heat sterilization of packaged food, characterized in that the food is heat sterilized and the ventilation portion is sealed under aseptic conditions.