JPS6058669B2 - Microwave sterilization method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for sterilizing foods, medicines, etc. using microwaves.

More specifically, it relates to a method of maintaining the product temperature at a predetermined sterilization temperature for a certain period of time by adjusting the output of microwaves.

When high-temperature sterilization of foods, medicines, etc. is performed using microwaves, the microwave must be irradiated at a pressure higher than atmospheric pressure. When sterilizing hermetically packaged foods, medicines, etc., the saturated water vapor pressure at the specified sterilization temperature +
If pressure of 91clt or more is not applied to O.5 from the outside,
The packaging material ruptures due to internal pressure.

However, irradiation sterilization using microwaves heats up rapidly even under the above pressure, so the peripheral area of the contents rises in temperature before the central area, resulting in only the peripheral area being overcooked. There was a problem that it would burn or burn.

The present invention has been made to solve this problem. Next, the present invention will be described with reference to examples.

Example 1 FIG. 1 shows an object to be heated 8, in which a sponge cake 2 buried in a baking carton 1 is sealed with a protective film 3, and this object to be heated 8 is a pressurized open container. It can be placed in 4.

The open 4 is provided with a pressurizing pipe 5 communicating with a compressor for pressurizing the inside, a waveguide 6 for irradiating microwaves, and a cooling water pipe 7. The pressure inside the open 4 is increased to 2.5 through the pressure pipe 5.
When the temperature is increased to 9lcTl and irradiated with microwaves at an output of 1, OKW through the waveguide 6, the sponge cake 2, which is the object to be heated 8 housed in the open 4, exhibits a temperature rise curve as shown in Fig. 3. As a result, F0=~9.0, and the surrounding area of the sponge cake 2 was overcooked and burnt.

Next, in the same way as above, increase the pressure inside open 4 to 2.5 to 9.
lclt, the microwave output is 1.0kW, and immediately after the product temperature reaches 120℃, the output is O,
The pressure was reduced to 25 kW, and the pressure was further finely adjusted.
As shown in the figure, when the product temperature is maintained at the sterilization temperature of 120℃, the Fo
Heat retention for 0 days was obtained.

Example 2 A pouch filled with 200 cc of bouillon soup and sealed was placed in the same open 4 as in the first example, the pressure inside the container was set to 2.5 and 91 clt, and the output of the microwave was set to 1. Irradiated at 5kW, and the product temperature was 1.
Immediately after reaching 20℃, the output was reduced to 0.4kW and fine-tuned, and the product temperature was maintained at 120℃.
The FO was 9.0, the color change was the same as that of the untreated product, and the product had a shelf life of 90 days.

In both Examples 1 and 2, after heat sterilization, cooling water is introduced through the cooling water vibrator to cool the object to be heated 8 or the pouch. The following table shows the results of various experiments, and according to this table, the output of the microwave is 30
It can be seen that the results are better when the percentage decreases.

As described above, the present invention raises the temperature of a product to a predetermined temperature by irradiating it with microwave output at 100% under a pressure higher than atmospheric pressure, and then reduces the output to 30% or less. By further fine-tuning the output according to temperature changes and maintaining the product temperature at a predetermined sterilization temperature for a certain period of time, food, medicine, etc. can be sterilized safely, quickly, and well without any qualitative changes. However, it has the effect of increasing its storage stability.

[Brief explanation of drawings]

FIG. 1 is a sectional view schematically showing an object to be heated. FIG. 2 is a cross-sectional view schematically showing a pressurized microwave sterilizer. Figures 3 and 4 are diagrams showing the relationship between product temperature and microwave irradiation time. In the figure, the temperature of the product is raised, the irradiation output is lowered, the sterilization temperature is maintained at a predetermined sterilization temperature for a certain period of time, and then the irradiation is cut off. 1
... Baking carton, 2 ... Sponge cake, 3 ... Protective film, 4 ...
・Open for pressurization, 5...pressurization vibrator,
6... Waveguide, 7... Cooling water vibe, 8...
...Object to be heated.

Claims (1)

[Claims] 1 Under pressure higher than atmospheric pressure, microwave is irradiated at 100% output until the product temperature rises to the predetermined sterilization temperature, and after reaching the predetermined sterilization temperature, the output is reduced to 30%.
0% or less, continue irradiation while finely adjusting the output according to changes in the product temperature, maintain the product temperature at a predetermined sterilization temperature for a certain period of time, and then cool the product. Wave sterilization method.