JPH03206872A - Method for microwave heating sterilization - Google Patents

Abstract

PURPOSE:To prevent mutual supporting plates from sliding and a package from bursting in microwave heating sterilization by forming protruding parts and recessed parts on peripheral parts of two supporting plates for housing the package to be heated in the interior by mutual superposing thereof and providing a construction for closely adhering both the supporting plates with engagement of the protruding and recessed parts. CONSTITUTION:A material to be heated is hermetically sealed and the resultant package is housed in a housing part 2 of two microwave-transmitting supporting plates 11 and 12 for forming the housing part 2 of nearly the same shape as that of the package in the interior by mutual superposing thereof and then irradiated with microwaves to carry out thermal sterilization. In the aforementioned method, the following means are adopted: That is protruding parts (1a) formed on the peripheral part in one of the supporting plates (e.g. 11) are mutually engaged with recessed parts (1b) formed on the other supporting plate (e.g. 12) to closely adhere the two supporting plates 11 and 12. (The numeral 3 indicates a holding tool).

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method of microwave heating sterilization of a sealed package filled with an object to be heated.

(Prior art) When performing high temperature sterilization at 100°C or higher under normal pressure on a sealed package filled with an object to be heated, heat-resistant and pressure-resistant support plates are attached to each other in order to prevent the package from breaking. Microwave heat sterilization or the like is performed by stacking the packages to form a support, storing the package in the support, and heating the package. (Special Public Showa 5B
-26949) Usually two support plates are used, and by overlapping the two support plates, a package accommodating portion is formed between them. FIGS. 7 and 8 are cross-sectional views at this time, in which (11) and (12) are support plates, and (2) is a package storage section. With the two support plates stacked one on top of the other, ring-shaped holders (3) are fitted from both the left and right sides to prevent the package from expanding and bursting due to microwave heating.

(Problem to be Solved by the Invention) However, in the above method, since the support plates tend to slide together, it is difficult to fit the support plates together, and even after they have been fitted, they may still slide and cause rupture. .

In addition, the support plate warped, creating a gap, which sometimes caused the package to burst.

The present invention solves these drawbacks and provides a microwave heat sterilization method that does not cause sliding of support plates against each other during microwave heat sterilization, prevents warpage of the support plates, and does not cause rupture. The purpose is to .

(Means for Solving the Problems) In order to achieve this object, the present invention has microwave-transparent packaging bodies in which the heated object is sealed, and which are stacked on top of each other. In a method in which two support plates forming a housing part are housed in the housing part and then heated and sterilized by irradiation with microwaves, a convex part provided on the peripheral edge of one support plate and a convex part corresponding to this convex part are used. Provided is a microwave heating sterilization method characterized in that the two support plates are brought into close contact with each other by fitting the four parts provided on the other support plate to each other.

The package according to the present invention is one in which an object to be heated is sealed in a packaging material.

The object to be heated is one that generates heat using microwaves. Although any material may be used, a liquid containing water, a viscous material, a solid material, or a mixture thereof can be used. Usually food.

Although any packaging material may be used, it is preferably made of plastic material because it is transparent to microwaves. for example,
Polystyrene, polypropylene, ethylene-propylene copolymer, ionomer ethylene or random copolymer of propylene and unsaturated carboxylic acid, polyester, polyamide, polyvinyl chloride, polyvinylidene chloride, ethylene-vinyl acetate copolymer or its saponified product, polyurethane , or a laminate of these.

The packaging material can be of any shape. For example, if it is in the form of a flexible film, a bag-like package can be obtained.

In addition, if the tray-shaped packaging material and the lid material are used, both can be heat-sealed at the periphery to form a package.

In the present invention, "sealed" refers to a state in which bacteria do not enter or exit the package. This is to prevent re-contamination of the heated object after microwave sterilization.

The support plate according to the present invention prevents the sealed package from expanding and bursting during microwave sterilization. For this reason, it is necessary to have heat resistance that can withstand the heat during sterilization, and pressure resistance that can withstand the expansion force of the package during sterilization and not deform. Furthermore, since microwaves are irradiated through the support plate, the support plate must be transparent to microwaves. Examples include laminated products of glass cloth impregnated with silicone resin, and molded products of sheet molding compounds whose main component is unsaturated polyester.

Two support plates are used. This is because a housing portion is formed inside by stacking two support plates on top of each other, and the package is stored in this housing portion. FIG. 1(a) is a perspective view of one support plate (11), and FIG. 1(b) is a perspective view of the other support plate (12). As can be seen, the support plate (11)
(12) both have a recess (2) in their center, and by overlapping the support plates (11) and (12) together, a package accommodating portion is formed. The package accommodating section needs to have substantially the same shape and volume as the package in order to prevent the package from expanding due to microwave heating.

Further, the peripheral edge of the support plate is provided with a concave portion and a convex portion that fit into each other to prevent the support plates from sliding and warping in the lateral direction.

In the support plates shown in FIGS. 1(a) and (b), convex portions (1a) are provided at the four corners of one support plate (upper support plate) (11), and convex portions (1a) are provided at the four corners of the other support plate (lower support plate). ) (12) is provided with corresponding recesses (16) at the four corners. By overlapping both, the convex part (1a) and the concave part (lb)
are fitted into each other (Fig. 2).

Furthermore, FIG. 3 shows a support plate (13) having convex portions at two of the four corners located diagonally, and concave portions at the other two corners. By using two supporting plates (13) and overlapping each other at different angles, the convex portion (
1a) and the recess (1b) can be fitted together (FIG. 4).

Figures 5 and 6 are cross-sectional views of a package consisting of a tray and a lid, in which the upper support plate (14) is provided with a convex portion and the lower support plate (15) is provided with a concave portion. The part and the recess are fitted into each other. FIG. 5 shows an example in which the convex portion and the concave portion are continuous through a tapered connecting portion (IC), and FIG. 6 shows an example in which the convex portion and the concave portion are provided substantially perpendicularly.

In addition, support plates (11) (12) (13) (14) (15
) is composed of a flat part and sloped parts provided with steps on both sides of the flat part.

Further, (3) in the figure is a ring-shaped holder for preventing the support plates from opening from each other due to expansion of the package due to heating.

For the holder (3), an epoxy resin molded product mixed with glass fiber can be used.

After the holder (3) overlaps the support plates (2),
It slides into place from the inclined parts (22) on both sides and is firmly fixed by coming into contact with the step.

The support body containing the package is sterilized by irradiating it with microwaves. The object to be heated generates heat as it is irradiated with microwaves, and is sterilized by this heat.

The temperature is 100°C or higher to improve the sterilizing effect.

Usually 100 to 105°C is sufficient.

After heat sterilization, in order to prevent the package from bursting, the package is cooled to a temperature of 100° C. or less and removed from the support. In addition,
It is desirable to take it out after cooling it to room temperature. Cooling may be done by air cooling or water cooling.

(Example 1) A plastic film bag-shaped packaging material was used as the packaging material. The plastic film has a laminated structure of stretched nylon/unstretched nylon/unstretched polypropylene from the outside.

This packaging material was filled with 180 g of water, and the films were heat-sealed together to form a sealed package.

The support plate used had the shape shown in FIGS. 1(a) and 1(b). The support is made of an unsaturated polyester-based gitomolding compound. The package accommodating portion had approximately the same volume as the package, and the heat-sealed portion at the periphery of the package was sandwiched and fixed between support plates. The support plates (11) and (12) each have
The concave portion (lb) and the convex portion (1a) were overlapped so that they fit together, and the ring-shaped holder was slid from left and right to abut against the step and fixed. The ring-shaped holder is an epoxy resin molded product mixed with glass fiber.

Further, for comparison, a support plate shown in FIG. 7 was used.

As a result, in the comparative example, the support plates slid against each other when inserting the holder, resulting in a 3% insertion failure.

However, in all of the examples, this did not occur.

(Example 2) Example 1 except that the support plate shown in Fig. 3 was used.
The experiment was conducted in the same way.

As a result, there were no insertion defects.

(Example 3) A tray and lid material were used as packaging materials.

The tray is made of polypropylene, and the lid material is a laminated material of stretched nylon/unstretched nylon/unstretched polypropylene from the outside.

The support plate shown in FIG. 5 was used. On the lower support plate,
A package accommodating section having approximately the same shape and the same volume as the tray was provided, and after accommodating the package, the upper support plate was stacked and fixed.

Note that the support plate is a laminated product of glass cloth impregnated with silicone resin.

Next, the ring-shaped holder was slid from left and right, and was fixed by coming into contact with the step.

For comparison, a support plate shown in FIG. 8 was used.

As a result, in the comparative example, a 5% insertion failure occurred when inserting the holder, but in the example, there was no insertion failure.

Next, each packaging material was heated using a microwave sterilizer (M-HT1320) manufactured by Toppan Printing Co., Ltd. until the center temperature of the package reached 130''C. The temperature was measured using a glass fiber thermometer.

When heated to 130°C, warping occurred in the upper support plate in the comparative example, and a gap of 2 mm was created between the support plates. On the other hand, no warpage occurred in the examples.

After heating to 130'C, the sample was immersed in water with the holder still attached, and the time required to cool down to 100'C was measured, and it was 5 minutes for the comparative example and 2 minutes for the example.

(Effects) As described above, according to the present invention, it is possible to obtain a microwave heating sterilization method that prevents the support plates from sliding against each other and the support plates from warping, and does not cause rupture of the package.

In addition, the cooling speed after heating is fast, allowing efficient sterilization.

[Brief explanation of drawings]

Figures 1 (a) and 3 are perspective views showing examples of support plates, Figures 2 and 4 are front views of the package housed between two support plates, and Figure 5 Figure and No. (11) (12)
(13) (14) (15)...Support plate (la)...Convex portion (lb)...Concave portion (2)...Package housing section (3)...Holder 3rd Figure 4 Figure 15 Figure 5

Claims (1)

[Claims] (1) A package containing a sealed object to be heated is housed in the accommodation section of two supporting plates that are microwave transparent and that are stacked on top of each other to form an accommodation section that has approximately the same shape as the package inside. Then, in a method of heat sterilization by irradiating microwaves, a convex part provided on the peripheral edge of one support plate and a concave part provided in the other support plate corresponding to this convex part are fitted together. hand,
A microwave heating sterilization method characterized by bringing two support plates into close contact.