JPH0525437Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial application field] This invention relates to a support for microwave heating sterilization, and to a support that can reduce the variation in temperature rise at each point after microwave irradiation of food and heat the food uniformly. [Prior art and problems] High-temperature heat sterilization using microwaves has been carried out for a long time. However, uniform heating by microwave irradiation is difficult depending on the shape of the package that contains the heated object,
Due to differences in physical properties, especially dielectric constant and thermal conductivity, the temperature rise of the heated object varies, making it difficult to heat it uniformly. On the other hand, the microwave propagation direction changes depending on the structure of the cavity of the microwave heating sterilizer, the position and number of the waveguides, and the factors of the transport speed of the package in the cavity and the irradiation time of the microwave are added, making it very difficult to adjust all of these and heat it uniformly. One method to solve this problem is, for example, to use a stirrer with a metal plate to change the propagation direction of the microwave and to diffuse the energy density of the microwave. With this method, if the heated object is a liquid with low viscosity such as water or consommé soup, it is possible to heat it uniformly by the convection phenomenon caused by the temperature rise, but it is difficult to heat it uniformly for solid objects such as hamburger steak and beef stew, or foods in which objects with different dielectric constants are mixed together. With non-uniform heating with variations in the temperature rise at each point of the heated object,
This causes insufficient sterilization or overheating, resulting in microbial problems and deterioration of the quality of food, such as color, texture, and taste. [Problems to be solved by the present invention] The present invention aims to adjust the microwave energy absorbed by the package through the support in accordance with the condition of the heated object, regardless of the shape of the package that contains the heated object, its physical properties such as dielectric constant, and to enable uniform heating. [Means for solving the problems] The present invention uses the microwave shielding properties of metal to solve the problems by using a support for heat sterilization in which metal foil is attached to the outside, inside, or both of the support made of a micro-permeable material that corresponds to the part of the package that is likely to heat up. Also, when the package is made of a molded tray, metal foil may be provided on the side of the support as well. Next, the present invention will be explained in detail with reference to the drawings. FIG. 1 is an explanatory diagram of a support for heat sterilization for bags with metal foil 2 attached to the corners, and FIG. 2 is an explanatory diagram of a support for heat sterilization for bags with metal foil 2 attached to the corners.
It is a cross-sectional view from Figure A-A, and is made of a support 1 having a space 3 for storing a package inside. When a molded tray is used for the package, the metal foil 2 is attached to the side of the support 1 in addition to the position shown in Figure 1, as shown in Figures 3 and 4. The support 1 may be made of any material having bending strength that transmits microwaves, such as glass filler-filled polyphenylene sulfide, glass filler-filled modified polyphenylene oxide,
Reinforced plastics such as glass cloth impregnated silicon are suitable. Either conductive or magnetic materials can be used for the metal foil 2, depending on the physical properties of conductivity and magnetic permeability. Of these metal foils, materials with high conductivity and magnetic permeability, such as silver, copper, and aluminum, reflect microwaves due to impedance mismatch, and absorb and block microwaves due to their magnetic properties. [Function] In order to solve the above problems, the present invention utilizes a support that transmits microwaves, places a package filled with food in a bag or molded tray made of a plastic film with heat resistance and gas barrier properties on the support, and irradiates microwaves,
By understanding the heating characteristics of the food, a microwave shielding material such as metal foil is applied to the corners where the temperature rises easily, and also to the sides when a molded tray is used, to locally shield the microwaves, thereby preventing localized excessive heating of the heated object and enabling uniform heating. Next, an embodiment of the present invention will be described. [Example 1] A glass cloth impregnated silicone resin is used as a support 1, and metal foil 2 made of aluminum foil of a size that reaches the space 3 for storing the package 4 is attached to the front and back corners of the support, as shown in Figure 1. The package 4 to be stored in the space 3 of the support 1 is then placed on the support 1.
The pouch is made of oriented nylon film (15 μm) / polyvinylidene chloride film (25 μm) / non-oriented polypropylene film (70 μm).

[Example 2]

Glass cloth-impregnated silicone resin is used as the support 1, and metal foil 2 made of aluminum foil is attached to the front and back corners of the support 1, and the metal foil 2 is large enough to reach the space 3 in which the package 4 is accommodated on the top surface of the support 1. The structure shown in Fig. 3 was adopted. A package 4 is stored in the space 3 of the support 1.
As, polypropylene (500μm)/ethylene-
A molded tray consisting of saponified vinyl acetate copolymer (50 μm)/polypropylene (500 μm) is filled with mixed vegetables (300 g), and mixed vegetables (300 g) are mixed with polyethylene terephthalate (12 μm)/polyvinylidene chloride (25 μm)/unstretched polypropylene (70 μm). A container sealed with a lid material was used. This package 4 has 4 parts on the front as shown in FIG.
A heat label 5 was pasted at several locations to enable temperature measurement in some areas. This package 4 was stored in the space 3 of the support 1 and heat sterilized using a microwave heat sterilizer that continuously transferred it to a belt conveyor as shown in FIG. At the same time, as a comparative example, the same package was housed on a support under the same conditions except that metal foil 2 was not pasted, and was similarly heat sterilized using a microwave heat sterilizer, and the temperature distribution was measured. The microwave irradiation conditions were an output of 3KW and an irradiation time of 6 minutes. The results are shown in Table-2.

【table】

〔effect〕

By using the support of the present invention, it is possible to reduce the temperature variation in the temperature rise value of the heated object during microwave heat sterilization, prevent quality deterioration and bag breakage due to excessive heating, and improve sterilization defects. It was done. Furthermore, since the support is provided with a metal foil which is a microwave-impermeable material, it can be used repeatedly, and ordinary packaging bags can be used. Furthermore, since it is placed in a support and heated, it can maintain its shape even at temperatures above 100°C.

[Brief description of the drawings]

1 and 3 are explanatory diagrams showing an example of the support of the present invention, FIG. 2 is a sectional view taken along the line AA in FIG. 1, and FIG. 4 is a sectional view taken along the line AA in FIG. 2. , FIG. 5 shows the location where the temperature distribution of the package in Example 1 is measured,
FIG. 6 is an explanatory diagram showing the method, FIG. 6 is an explanatory diagram of the apparatus used for microwave sterilization, and FIG. 7 is an explanatory diagram showing the locations where temperature distribution is measured in Example 2. 1...Support, 2...Metal foil, 3...Space, 4
...Packaging.

Claims (1)

[Scope of utility model registration request] 1. A support for heat sterilization, comprising a support made of a microwave-transparent material and having a space for accommodating a package therein, and a metal foil provided at least at a corner portion of the support.