JPH01215269A - Sterilization of microwave heating - Google Patents

Abstract

PURPOSE:To heat and to sterilize a solid material, a high-viscosity material, etc., in a short time without causing variability of heating rate range and temperature and heating unevenness, by partially irradiating the top and the bottom of a container having a material to be sterilized with microwave and then irradiating and heating the whole container. CONSTITUTION:A material to be sterilized such as a solid material or high- viscosity material capable of being heated by microwave is packed into a container or a bag to give a packaged material A, which is sent to a first heating chamber 1A by a conveyor 8. In the heating chamber 1A, the packaged material is irradiated with microwave from a microwave oscillator 10A through wave guide 11A and 12A, preferably 10-50mm distance from an irradiation hole and heated. Then the material is sent to a second heating chamber 1B, the whole packaged material is irradiated from a microwave oscillator 1B through a wave guide 11B and heated to the aimed sterilized packaged material.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a microwave heat sterilization method,
In particular, the present invention relates to a microwave heating sterilization method that reduces variation in heating temperature during sterilization of objects to be sterilized, such as solid objects and viscous objects that can be heated with microwaves.

[Prior art and its problems]

Many methods have already been reported for continuously heating and sterilizing packages in which items to be sterilized are filled in bags or containers using microwaves. Temperature tends to be high at the periphery (and low at the center).This tendency is particularly high for objects to be sterilized, such as solids or high viscosity products where convection does not occur, so the temperature is lower during actual sterilization. It was necessary to control the temperature by controlling the heating temperature in the center.As a result, the periphery and edges, where the temperature is high, were overheated, which had a negative impact on quality.

Another option is to irradiate microwaves intermittently and make the temperature of the package uniform by heat conduction during non-irradiation periods, but for objects to be sterilized where no convection occurs, a temperature difference of 10°C is not enough. However, at least 3 minutes are required, making short-time heating, which is a characteristic of microwave heating, impossible.

[Problem that the invention seeks to solve]

The present invention takes advantage of the short-time heating characteristics of microwaves,
It is an object of the present invention to provide a microwave heat sterilization method that minimizes temperature variations during heating of objects to be sterilized in a package and in the final temperature.

[Means for solving problems]

A method of heat sterilization by irradiating microwaves while transporting a package containing a microwave-heatable solid, viscous, or other object to be sterilized in a container or bag, in which the package is placed in a heating chamber. After partially heating one side of the top and bottom,
The problem was solved by heating the whole thing.

This will be explained in detail below.

FIG. 1 is an explanatory diagram of an embodiment of the microwave heat sterilization device used in the present invention, in which microwaves are transmitted from the microwave oscillation device 10A and the IOB to the waveguide 11A on the conveyance path of the package A.
, , 12A, , the first heating chamber I is irradiated via IIB.
A, a second heating chamber IB is provided, the waveguides 11A and 12A of the first heating chamber IA extend to a position close to the conveyance path, and the waveguide 11B of the second heating chamber IB is connected to the chamber. It is located on the wall.

The package A is then supplied to the conveyor 8 and conveyed through the microwave trap 5 to the first heating chamber IA, where the object to be sterilized inside the package A is partially heated from above and below. , then passes through the microwave trap 6 and the second
The entire package is heated from above in the heating chamber IB and the package is sterilized and then passed through the microwave trap 7 again and taken out.

Here, the waveguides 11A and 12A in the first heating chamber lA
The distance between the microwave irradiation port and the package is 10 to 50
This can be done by moving the waveguide within the range (2), and the size of the irradiation ports of the waveguides 11A and 12A is adjusted by changing the size of the slit attached to the irradiation port.

Note that in order to partially heat the first heating chamber, the package A is moved intermittently and stopped so that it is directly above or below the irradiation ports of the waveguides 11A and 12A. and effective.

For example, in the bag-shaped package A, in the first heating chamber IA, the central part of the upper surface and the central part of the lower surface are heated by irradiation with microwaves,
In the second heating chamber, the entire package including the peripheral portion is heated by irradiation.

Here, the upper and lower surfaces of the package may be partially heated in the heating chamber IA in the reverse order.

In addition, the heating chamber is not limited to two, but if necessary, the heating chamber may be
Heating may be performed by repeatedly providing two heating chambers.

Although the irradiation position of the first heating chamber was at the center of the package, it is more effective to shift the irradiation position perpendicularly to the conveyance direction and sequentially irradiate different positions.

C Effect] In the first heating chamber, the two upper and lower waveguides extend close to the package, so even if the object to be sterilized does not generate convection due to heating, the irradiated microwaves will It is directly absorbed into the upper and lower parts of the package without being diffused, and is heated evenly from top to bottom.

〔Example〕

A microwave transmitter (SMG-130 manufactured by Sanyo Electric) with an output of 1.3 KH was used for the adjacent waveguide, and the irradiation port with a slit width of 28 - x 59 gems was placed 30 m above and below the package. They were extended and provided at the - positions, respectively.

The object to be sterilized was a carboxymethyl cellulose aqueous solution (viscosity 58.000 cp).

The above items to be sterilized were placed in a bag made of a laminated film of stretched nylon (25μ)/unstretched polypropylene (70μ).
Heating was carried out using a package filled with 5 g each.

The support for housing this package was made of silicone resin containing glass fibers.

After heating, the temperature at the top and bottom of the package was measured using an optical fiber thermometer (3Z4D, manufactured by Kyuu Denki Co., Ltd.) at locations marked ■ and ■ in FIG. 2.

The heating conditions were as follows: continuous irradiation, temperature measurements after 20 seconds and after 40 seconds, and the results are shown in Table 1.

At the same time, an experiment was also conducted for Comparative Example 1.2, which was the same as the example except that the light was irradiated from a waveguide located either above or below, and the results are shown in Table 1.

() 1#, white) Table 1 In the table, ■ and ■ indicate the temperature measurement points of the package, respectively, the left side indicates the temperature above the package, and the right side indicates the temperature below the package.

〔effect〕

According to the method of the present invention, by partially heating the package from above and below using microwaves in the same heating chamber, temperature variations between the front and back sides of the object to be sterilized, such as solids and highly viscous objects, can be reduced. It is small, and ultimately the entire package can be heated almost uniformly, making it possible to achieve uniform heating by microwave heating, which was impossible with conventional microwave heating methods.

This makes it possible to reduce temperature variations during continuous microwave heat sterilization, both at the time of temperature rise and at the end of the package, and to prevent quality deterioration due to differences in heating distribution during temperature rise and excessive heating. Uniform heating can be achieved over time.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of a microwave heat sterilizer used in the sterilization method of the present invention, and FIG. 2 is an explanatory diagram showing temperature measurement points of a package. IA...First heating chamber 1B...Second heating chamber 10A, IOB...Microwave oscillator 11A, II
B, 12A...Waveguide A...Packaging body

Claims (2)

[Claims] (1) In a device that heat-sterilizes objects to be sterilized, such as solid objects or highly viscous objects that can be heated with microwaves, by irradiating microwaves while transporting a package containing a container or bag, a heating chamber is used. A microwave heating sterilization method characterized by partially heating the top and bottom of the package and then heating the entire package. (2) The microwave heating sterilization method according to claim (1), wherein the package is transferred intermittently.