JPS6058668B2 - Sterilization method using microwave - Google Patents

Description

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

More specifically, the present invention relates to a method of sterilizing the product by maintaining the temperature of the product at a predetermined sterilization temperature by adjusting the pressure inside the sterilization pot, that is, the irradiation chamber, during microwave irradiation. When a water-containing substance such as food is heated under atmospheric pressure, the temperature inside the tissue remains at 100℃ until the water is completely evaporated from the tissue.
The temperature does not rise above °C, and for this reason, even if foods are processed by normal cooking methods such as baking or frying, no significant sterilization effect can be expected.

The same is true when heating foods and the like using microwaves, and the purpose of the currently widely used microwave ovens is also to cook and reheat foods.

Therefore, in order to expect a sterilizing effect using microwaves, it is necessary to irradiate and heat with microwaves under pressure, similar to so-called retort sterilization. To date, research using this method has been carried out domestically and internationally in the U.S., S.A.
Several studies have been carried out at RMY's Meiteitsu Research Institute in the United States, and a patent application has also been filed. For example, Tokko Sho 53-1
This is a method of sterilizing hermetically packaged foods, as disclosed in Japanese Patent Publication No. 19183, by irradiating microwaves at a sterilization pot internal pressure of 0.1 to 0.5 at 91 cfi.

However, in these studies, the pressure range was too wide, and it was insufficient to maintain the product temperature at a constant temperature and obtain a certain sterilization effect.

That is, with microwave irradiation under simple pressure, it is difficult to control the product temperature, it is difficult to obtain a certain reproducible sterilization effect, and there is also the risk of non-uniform heating.

The present invention was invented in order to eliminate the above-mentioned drawbacks.The inside of the sterilization pot is pressurized to a pressure equal to the saturated vapor pressure at a predetermined sterilization temperature, and the temperature of the product is maintained at a predetermined level by irradiating it with a microphone and low wave. It maintains the temperature at sterilization temperature and makes it possible to perform sterilization with a certain level of reproducibility.

In other words, if the pressure is set to 1.91 cft, heat sterilization can be performed while maintaining the product temperature at 120°C, and if the pressure is set to 9'd to 1.3, heating can be performed while maintaining the product temperature at 125°C. Can be sterilized.

By being able to maintain the sterilization temperature constant in this manner, the sterilization effect increases reproducibility and is effective for improving the uniformity and quality of products.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below using embodiments and drawings.

What is shown in FIGS. 1 and 2 is an object to be heated, which is a sponge cake 2 placed in a baking carton 1 and wrapped in a film 3.

Note that the sealed portion of the film 3 is partially opened 3''.

FIG. 3 shows a pressurized microwave sterilizer for heating the object to be heated as described above.

The number 4 is open so that it can be pressurized, and pressurization is performed by a pressurizing vibrator 5 that communicates with a compressor (not shown).
It is designed to be heated by microwaves irradiated by the waveguide 6.

Example 1 Pressure inside the open 4 was 2.5k91c
When microwave irradiation was carried out at 1 t and the microwave output was 1.0 KW, a product temperature curve was drawn as shown in Figure 4, and the product temperature could not be kept constant or the surrounding area of the sponge cake 2 would burn. Uniform heating was observed.

Example 2 The pressure inside the open 4 was set to 1.0k91c1t, the microwave output was set to 1.0KW, and microwave irradiation was performed.
The F value can be maintained at 0 C, and the value determined by an F value computer or an automatic temperature recording type sterilization value (F value) calculation device is F.

= 6.0, the microwave irradiation was stopped (irradiation time: 1 minute) and the product was cooled. When the temperature of the product had cooled to 50°C, the baking carton 1 was taken out from the open 4 and the opening of the film 3 was opened with an impulse pulse. It was sealed with a seal. The value determined by the F value computer is F. =1, this is equivalent to the sterilizing effect of heating at 121.1°C (250'F) for 1 minute. Also, canned food is F in Ministry of Health and Welfare notification No. 17. = Sterilization of 4 or more is required. As a result of repeating the above experiments, the product temperature curve was reproducible, almost no uneven heating was observed, the quality was good, and no decomposition was observed even after 30 days of storage.

As described above, as a result of pressurizing the inside of the sterilization pot to a pressure equal to the saturated water vapor pressure and irradiating the product with microwaves, the product temperature can be maintained at a predetermined sterilization temperature, making it possible to control the sterilization temperature.

[Brief explanation of drawings]

Figures 1 and 2 are a slope view and a cross-sectional view of the object to be heated. FIG. 3 is an explanatory cross-sectional view of the sterilization pot. Figures 4 and 5 are graphs showing the relationship between product temperature and irradiation time when the pressure inside the sterilization pot was 2.5 k9 nod and 1 k9 nod. 1... Baking carton, 2... Sponge cake, 3...
...Packaging film, 4...Open, which is a sterilization pot.

Claims (1)

[Claims] 1. When sterilizing foods, medicines, etc., the inside of the sterilization pot is pressurized to a pressure equal to the saturated water vapor pressure at a predetermined sterilization temperature, and the temperature of the product is controlled to the predetermined sterilization temperature by irradiating microwaves. A sterilization method characterized by sterilization.