JPH035792B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a microwave heat sterilization method, and particularly to a microwave heat sterilization method that reduces variation in heating temperature during sterilization of objects to be sterilized. [Prior art and its problems] A method of continuously heating and sterilizing a package in which the object to be sterilized is filled in a bag or container using microwaves is as follows:
Although many reports have already been made, no matter which method is used, the heating temperature during sterilization of the package tends to be higher at the periphery and lower at the center. This tendency is particularly high for objects to be sterilized, such as solid objects or highly viscous products, where convection does not occur, and therefore, in actual sterilization, it is necessary to control the temperature at the central heating temperature where the temperature is lower. As a result, the peripheral area, where the temperature is high, becomes overheated, which has an adverse effect on quality. Another option is to irradiate the package intermittently with microwaves and use heat conduction to uniformize the temperature of the package during non-irradiation periods. , at least 3 minutes are required, making short-time heating, which is a characteristic of microwave heating, impossible. [Problems to be Solved by the Invention] The present invention provides a microwave heat sterilization method that takes advantage of the short-time heating characteristics of microwaves and can minimize the final temperature variation of the object to be sterilized inside the package. The purpose is to provide. [Means for solving the problem] When carrying out heat sterilization by irradiating microwaves while transporting a package containing a microwave-heatable object to be sterilized in a container or bag, first the package is This problem was solved by sterilizing the package by heating it by heating a portion of the package with microwaves, and then by heating the entire package. This will be explained in detail below. FIG. 1 is an explanatory diagram of a microwave heat sterilization device used in the present invention, in which microwaves are irradiated from microwave oscillators 10A and 10B via waveguides 11A and 11B onto the conveyance path of package A. A first heating chamber 1A and a second heating chamber 1B are provided, and the waveguide 11A of the first heating chamber 1A extends to a position close to the conveyance path, and the waveguide 11A of the second heating chamber 1B
1B is located on the chamber wall. Then, the package A is supplied to the conveyor 8,
The object to be sterilized in the package A is transported through the microwave trap 5 to the first heating chamber 1A, where it is partially heated, and then passed through the microwave trap 6 and packaged in the second heating chamber 1B. The whole body is heated and the sterilized package is removed again through the microwave trap 7. Here, the waveguide 11A in the first heating chamber 1A
The distance between the microwave irradiation port and the package is 10~
All you have to do is move the waveguide within a range of 100mm.
Further, the size of the irradiation port of the waveguide 11A 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 1A, the package A is moved intermittently and stopped so that it is directly above or below the irradiation port of the waveguide 11A. Effective. For example, as shown in FIG. 2, a bag-shaped package A
In the first heating chamber 1A, microwaves are irradiated to the central portion 22 to heat it, and in the next second heating chamber 1B, the entire area including the peripheral portion 21 is irradiated and heated. [Function] In the first heating chamber, the waveguide extends close to the package, so the irradiated microwaves
It is absorbed directly into the center of the package without being diffused. On the other hand, in the second heating chamber, the waveguide does not extend inward, so the irradiated microwaves are diffused and absorbed throughout the package. [Example] The microwave oscillation devices 10A and 10B in the first heating chamber 1A and the second heating chamber 1B are microwave oscillation devices with an output of 1.3 KW (SMG-130 manufactured by Sanyo Electric Co., Ltd.)
Two units of each were installed using the . Then, the two waveguides 11 of the first heating chamber 1A
A and 11A were installed so as to extend so that the position of the irradiation port approached the package, and the two waveguides 11B and 11B of the second heating chamber 1B were provided so as not to come out from the wall surface of the heating chamber. The packages were transferred continuously and intermittently, using the following objects to be sterilized. The objects to be sterilized are water, carboxymethylcellulose (CMC) aqueous solution A (concentration 1.2%, viscosity
4000cps), CMC aqueous solution B (concentration 2.5%, viscosity
64000cps), and Konyakutoshi. Heat sterilization was carried out using a package in which 130 g of the above-mentioned material to be sterilized was filled in a bag made of a laminated film of stretched nylon/unstretched polypropylene. When the set temperature was 100°C or higher, the package was housed in a support made of silicone resin containing glass fibers and heated. The temperature of the package after heating is determined by a thermocouple.
The central portion 22 and peripheral portion 21 shown in the figure were measured. Table 1 and Table 1 show the conditions for continuous and intermittent transfer.
Shown in 2. In any transfer, four packages were present in the first and second heating chambers 1A and 1B.

【table】

[Table] In the case of continuous conveyance, the first
In the heating chamber, the peripheral area was heated more than the center area, and after the second heating, the temperature difference further widened, and no effect of direct irradiation was observed. However, in the case of water, the temperature difference was smaller than that of other objects to be heated, and the influence of convection was observed. Since CMC aqueous solution and konjac showed almost the same tendency under all conditions, the temperature measurement results for 1.2% CMC aqueous solution are shown in Table 3.

〔effect〕

According to the method of the present invention, by partially heating the package with microwaves, the temperature variation during heating becomes large, but ultimately the entire package can be heated almost uniformly. Uniform heating has become possible with microwave heating, which was impossible with conventional microwave heating methods. This makes it possible to reduce temperature variations within the package during continuous microwave heat sterilization, prevent quality deterioration due to excessive heating, and achieve uniform heating in a short time.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of a microwave heat sterilizer used in the method of the present invention, and FIG. 2 is an explanatory diagram showing an example of the shape of a package. 1A...First heating chamber, 1B...Second heating chamber, 1
0A, 10B...Microwave oscillator, 11A,
11B...Waveguide, A...Packaging body.

Claims (1)

[Claims] 1 When heating and sterilizing an object to be sterilized that can be heated with microwaves by irradiating it with microwaves while transporting the package containing the object to be sterilized in a container or bag, first, the central part of the package is partially microwaved. A microwave heat sterilization method characterized by heating the entire package by microwave irradiation after heating by irradiation.