JP5682746B2 - Sterilization method of package - Google Patents

Description

  The present invention can sterilize a package, in particular, heat sterilization without deteriorating the color gloss, flavor, fragrance, texture and umami of the packaged contents, The present invention relates to a method for sterilizing a package that enables distribution.

  Due to recent developments in high-barrier packaging materials, advances in packaging technology, sterilization technology, and logistics system technology, various types of cooked packaged food that can be stored at room temperature have been distributed and lined up in stores. In the heat sterilization of such cooked packaged food, it is extremely important not to deteriorate the quality such as the color luster, flavor, aroma, texture and umami of the food, so-called flavor components. For this reason, there is a particular demand for a technique for heat sterilizing the food inside at a high temperature in a short time.

  In the high frequency dielectric heating method, by applying a high frequency electric field (electric field) to a material to be heated (dielectric or insulator), positively and negatively polarized molecules existing inside the material to be heated are rotated and vibrated by the high frequency electric field. This is a method of inducing internal heat generation in the heated material itself and heating the heated material itself by the internal heat generation. Since the high-frequency electric field acts in the form of electromagnetic waves deep inside the material to be heated, the high-frequency dielectric heating method can heat not only near the surface of the material to be heated but also deep inside, in a short time. Excellent heating uniformity for the material (thick dielectric).

  And as such a heat sterilization apparatus for sealed packaged food by the high frequency dielectric method, a counter electrode for applying a high frequency in a state where both surfaces of the sealed packaged food are sandwiched, a sealing member sandwiched between the counter electrodes, and this sealing member Is provided with a heat medium supply means for supplying a heat medium of a high-temperature fluid such as a high-temperature liquid or pressurized hot air in the room formed by the above, and the counter electrode is not contacted by introducing the heat medium for heating into the room There has been proposed a high-frequency heat sterilization apparatus and method for heating a peripheral portion of food with a heat medium and preventing breakage of the sealed packaged food (see Patent Document 1).

Japanese Patent Laid-Open No. 10-304855

  However, the high-frequency dielectric heat sterilization apparatus and method of Patent Document 1 can heat and sterilize the peripheral portion of the sealed packaged food that the counter electrode does not contact with the heating medium as described above. Since food is sterilized by heating with the counter electrode and heat medium in close contact, the sterilization of the inner peripheral surface of the packaging material that wraps the food is insufficient, It is not possible to obtain a hermetically sealed packaged food that has been sterilized by heating with a higher sterilization value than spore bacteria.

In other words, in order to enable normal temperature distribution of a packaged product that is filled and sealed with contents such as cooked food, not only sterilization of the contents, but also the inner peripheral surface of the packaging material that contacts the contents is highly sophisticated. Sterilization is required. In the heat sterilization according to Patent Document 1, the contents are sterilized by the counter electrode and the heat medium on the outer peripheral surface of the sealed packaged food. Therefore, it cannot be made into a sealed packaged food with a high sterilization level in which the contents and the packaging material are sufficiently heat-sterilized.
Moreover, since heat sterilization of sealed packaged food is performed with high-frequency dielectric heating and a heat medium, the food surface of the contents may be deteriorated due to overheating.

  The present invention has been made in view of such problems of the prior art, and its purpose is to deteriorate the quality of the contents to be packaged, such as the color luster, flavor, fragrance, texture and umami. Without sterilizing the contents and the inner peripheral surface of the packaging material, in particular, the sterilization method of the package that enables heat sterilization exceeding the sterilization value for spore bacteria and enables normal temperature distribution of high-quality packaged foods Is to provide.

In order to achieve the above object, the packaging body sterilization method according to claim 1 is characterized in that in the packaging body sterilization method in which the contents are filled and sealed with a packaging material, the pressure in the room in which the packaging body is placed is saturated with water vapor. After sterilizing the contents by high-frequency dielectric heating with a pin electrode while pressurizing at a pressure of +0.04 MPa, the pressure in the chamber is reduced, and moisture in the contents is vaporized using a pressure reduction process. moisture is deposited on the allowed Rutotomoni the packaging material in the peripheral surface expands and is characterized by performing the wet heat sterilization of the said packaging material peripheral surface by said water is heated.
Note that. As the high-frequency dielectric heating means, a high-frequency dielectric heating device using a pin electrode described later is desirable, but a known high-frequency dielectric heating device can be sufficiently employed.

In the packaging body sterilization method according to claim 2, sterilization of the contents of the packaging body by high frequency dielectric heating is pressurized with gas.
In the packaging body sterilization method according to claim 3, the heating of the inner peripheral surface of the packaging material in the wet heat sterilization step is performed with steam.
In the packaging body sterilization method according to claim 4, the packaging body is a vacuum packaging body.

  According to the method for sterilizing a package of the present invention, the contents are sterilized at high temperature and in a short time by high-frequency dielectric heating, and the packaging material is also sterilized efficiently by wet heat sterilization in a short time by high-temperature sterilization. Therefore, compared to conventional high-frequency sterilization method, retort sterilization method or high-temperature steam sterilization method, the color gloss, flavor, aroma, texture and taste of the contents immediately after cooking are good after sterilization of the package. It is expected to obtain a package that can be maintained for a long time in normal temperature and can be distributed for a long period of time, and in which a high-quality content that can be distributed at normal temperature is hermetically sealed with a packaging material.

In the sterilization method of the present invention, in order to uniformly sterilize the inner peripheral surface of the packaging material not with dry heat but with moist heat, the packaging body is subjected to high-frequency dielectric heating under pressure to sterilize the contents, and the packaging material of the packaging body is expanded. The moisture on the inner peripheral surface of the packaging material is sterilized by, for example, steam heating from the outer peripheral surface of the packaging material with the moisture (contents, etc.) inside the package adhered to the inner peripheral surface of the packaging material. Thus, the inner peripheral surface of the packaging material can be uniformly sterilized by wet heat.
Further, since the high frequency dielectric heating is performed with the pin electrode, the heating can be pressure-bonded to the package regardless of the outer shape of the package, and the contents can be sterilized in a short time by the high frequency dielectric heating.
In addition, the contents of the package are sterilized by high-frequency dielectric heating. At this time, the product temperature of the contents by the heating can be set to a high temperature state. Rupture can be suitably suppressed.

In the sterilization method of the present invention in which sterilization of contents by high frequency dielectric heating of the package is pressurized with gas, the contents are sterilized by high frequency dielectric heating, and the inner peripheral surface of the packaging material is wet heat sterilization using moisture as a heat medium. Therefore, overheating and heat denaturation of the contents surface can be prevented, and the contents and the packaging material can be surely heat sterilized in a short time at a high temperature.
Further, after sterilization by high frequency dielectric heating, the pressure inside the room in which the package is placed is reduced, and the package is expanded using a pressure reduction process. The package can be easily expanded.

In the sterilization method of the present invention in which the heat treatment of the inner peripheral surface of the packaging material is performed with steam, the moisture attached to the inner peripheral surface of the packaging material is easily converted into steam by spraying the steam on the outer peripheral surface of the packaging material. The steam makes it possible to sufficiently sterilize the entire inner peripheral surface of the packaging material with wet heat.

In the sterilization method of the present invention in which the package is a vacuum package, the contents of the vacuum package are in close contact with the packaging material, and the contents are efficiently sterilized by high-frequency dielectric heating.
In addition, the vacuum package can minimize the entry of air (oxygen) into the package, and in combination with the sterilization method described above, the contents have a high gloss, flavor, aroma, texture and umami. It can be a quality package.

It is explanatory drawing of the sterilization system for enforcing the sterilization method of the package of this invention. It is a graph which shows the temperature profile and sterilization value of the contents at the time of high frequency dielectric heating sterilization. It is a graph which shows the pressure | voltage fall profile of the pressure in the sterilization chamber by a high frequency dielectric heating. It is a graph which shows the temperature profile and sterilization value of the packaging material of the package body at the time of steam heat sterilization.

  Hereinafter, the present invention will be described in more detail with reference to embodiments shown in the drawings.

FIG. 1 is an explanatory view showing a sterilization system for carrying out the packaging body sterilization method according to the present invention.
This sterilization system for a package includes a sterilization process by high-frequency dielectric heating for sterilizing the contents of the package PF, and a sterilization process for sterilizing the inner peripheral surface of the packaging material of the package PF by wet heat.
The high-frequency dielectric sterilizer 1 in the sterilization process by high-frequency dielectric heating that sterilizes the contents of the package PF supplies the sterilization chamber 2 in which the package PF is subjected to high-frequency dielectric heating, and a gas that increases the pressure in the sterilization chamber 2. A pressure valve 3 and an exhaust valve 4 for exhausting the gas are provided to reduce the pressure in the sterilization chamber 2 after sterilization.
The high-frequency dielectric sterilizer 1 includes an upper and lower pin electrode portion composed of a plurality of pin electrodes 5 for high-frequency dielectric heating the contents of the package PF, a pin support base 6 that supports the pin electrode portion, and each pin electrode. In order to drive the pin driving chamber 7 for storing gas for driving the gas 5 and the shape of the package PF, clean air supplied into the pin driving chamber 7 or nitrogen, etc. A pressure regulating valve 8 that regulates the pressure of the inert gas to a desired pressure and an exhaust valve 9 that exhausts the gas in the pin drive chamber 7 are provided.

  In the pin electrode portion, each pin electrode 5 is displaced in the axial direction by being supported by a pin support base 6 connected to a high frequency power source (not shown) so as to be slidable in the axial direction. While touching the shape of the package PF, a high frequency electric field is applied to heat the contents of the package PF.

  On the other hand, the steam sterilizer 10 in the sterilization process in which the inner peripheral surface of the packaging material of the packaging body PF is subjected to wet heat sterilization includes a sterilization chamber 11 and a sterilization chamber 11 in which the inner peripheral surface of the packaging material PF receives steam sterilization (humid heat sterilization). A pressure regulating valve 12 for regulating the pressure of the supplied steam to a desired pressure, an exhaust valve 13 for exhausting steam sterilized on the inner peripheral surface of the packaging material of the packaging body PF, and a packaging body PF during wet heat sterilization are supported. A package body support 14 is provided, steam is supplied from the pressure regulating valve 12 to the package body PF on the package body support 14 in the sterilization chamber 11, and the steam is exhausted from the exhaust valve 13 after the sterilization is completed. Yes.

In the sterilization system described above, first, the package PF is put into the sterilization chamber 2 of the high-frequency dielectric sterilizer 1 in order to sterilize the contents of the package PF.
Next, the pressure in the sterilization chamber 2 is increased, a gas enabling high-temperature sterilization by high-frequency dielectric heating is supplied from the pressure regulating valve 3, and the contents of the package PF are sterilized by the high-frequency dielectric heating by the pin electrode 5. . Then, after sterilization, the gas is exhausted from the exhaust valve 4, the pressure in the sterilization chamber 2 is reduced, and the package PF is expanded by vaporizing the moisture of the contents using the pressure reduction process, and then sterilized. Remove from chamber 2.

Next, the expanded package PF is supplied to the sterilization chamber 11 of the steam sterilizer 10 in order to perform a wet heat sterilization process on the inner peripheral surface of the packaging material.
In the steam sterilizer 10, steam is supplied from the pressure regulating valve 12 to the package PF supported by the package support 14 in the sterilization chamber 11, and the expanded package PF is heated by the steam, and the package PF After the moisture vaporized from the contents adhering to the inner peripheral surface of the packaging material is heated , the packaging body PF is taken out after the heat treatment of the inner peripheral surface of the packaging material is performed. Expansion of the sterilized package PF is eliminated as the contents are cooled. (Not shown)
In this way, the contents of the package PF are sterilized by high-frequency dielectric heating, while the inner peripheral surface of the packaging material of the package PF is sterilized by wet heat sterilization to complete the sterilization of the package PF.

FIG. 2 shows a frequency 60 MHz output using the above-described pin electrode 5 in order to satisfy the bactericidal value (F ₀ ) for spore bacteria by heating the contents of the packaged body PF to 140 ° C. It is a graph which shows the temperature profile and sterilization value of the package PF at the time of sterilization by the high frequency dielectric heating in the conditions of 200 W and sterilization time of 60 seconds. The product temperature of the contents starts to gradually increase from 0 seconds when high-frequency oscillation is started, and is gradually naturally cooled after 60 seconds from the end of oscillation. From this graph, it can be seen that, under the above conditions, the bactericidal value for spore bacteria is satisfied.

Similarly, FIG. 3 is a graph showing a pressure drop profile of the pressure in the sterilization chamber 2 in the sterilization under the above conditions (FIG. 2).
As described above, the reason why the internal pressure of the sterilization chamber 2 is reduced is to expand the inside of the package PF so that moisture is sufficiently adhered to the inner peripheral surface of the packaging material. Due to the expansion of the packaging body PF, moisture contained in the contents adheres to the inner peripheral surface of the packaging material when the packaging body PF is sterilized by steam sterilization or the like. The pressure reduction rate for reducing the pressure in the sterilization chamber varies depending on the packaging material type and contents used, but expands while maintaining the sealing property of the packaging material so that moisture adheres to the inner peripheral surface of the packaging material. It can be set in a timely manner. The pressure setting of the sterilization chamber 2 in the case of the above conditions (FIG. 2) requires at least 0.26 MPa as a saturated water vapor pressure to heat the contents of the package PF to 140 ° C. In order to suppress the expansion of the package PF, pressurization of 0.04 MPa is required. Accordingly, the pressure setting of the sterilization chamber 2 under the above conditions is a total of 0.30 MPa (= 0.26 MPa + 0.04 MPa) in terms of gauge pressure. When the pressure reduction time is 15 [sec], the pressure reduction rate of the sterilization chamber 2 is 0.30 [MPa] / 15 [sec] = 0.02 [MPa / sec] in gauge pressure.
In the above-described sterilization system, the saturated vapor pressure +0 in terms of preventing the generation of sparks due to the generation of water vapor from the contents accompanying the temperature rise and the pressure resistance of the sterilization chamber 2. 0.04 MPa is preferred.

FIG. 4 is a graph showing the temperature profile and sterilization value of the packaging material of the package PF during steam heat sterilization.
From this graph, it can be seen that the inner peripheral surface of the packaging material reaches about 140 ° C. after the elapse of 28 seconds from the introduction of the steam, and satisfies the bactericidal value for spore bacteria.

Experimental example

[Experimental Example 1]
1. Contents and packaging form One steamed Shumai is vacuum sealed from the outer layer using a packaging material consisting of a three-layer film of polyethylene terephthalate (12 μm) / nylon (15 μm) / polypropylene (50 μm). PF).
2. Sterilization conditions (1) High-frequency dielectric heating sterilization Electrode: Pin electrode, Pin pressing: 0.32 MPa (= Internal pressure of pin drive chamber 7)
Frequency: 60 MHz, output: 200 W, sterilization time (high frequency application time): 60 seconds Sterilization chamber 2 internal pressure (gauge pressure) during sterilization: 0.3 MPa, sterilization value F ₀ ≧ 3.1
Decrease rate: The pressure in the sterilization chamber 2 was reduced to atmospheric pressure in 15 seconds after sterilization, and the vacuum packed product was expanded.
(2) Steam sterilization Vacuum pack product initial temperature: 60 ° C., temperature rise time to sterilization temperature: 20 seconds Sterilization temperature: 140 ° C., sterilization time: 0.1 seconds Internal pressure (gauge pressure) of sterilization chamber 11 during sterilization: 0 .26 MPa
Decrease time: Decrease to atmospheric pressure in 10 seconds after steam sterilization Temperature measurement Measured using a K thermocouple.
4). Evaluation (1) Confirmation of Expansion of Package PF After expansion of the pressure in the sterilization chamber 2 for high-frequency dielectric heat sterilization, the expansion of the package PF was visually confirmed.
(2) State of sealing surface of package PF (sealing property)
After pressure reduction in the sterilization chamber 2 for high-frequency dielectric heat sterilization, the state of the sealing surface of the package PF was visually confirmed.
(3) Confirmation of moisture in packaging material of packaging body PF After pressure reduction in the sterilization chamber 2 of high-frequency dielectric heat sterilization, moisture on the inner peripheral surface of the packaging material of packaging body PF was visually confirmed.
(4) Confirmation of expansion of vacuum packed products (deterioration)
After steam heat sterilization, it was stored at 20 ° C. for 2 weeks, and the expansion of the package PF was visually confirmed.
(5) Shumai's texture The unpacked vacuum pack was opened, and the texture of the eaten contents was confirmed.

[Experiment 2]
In the experimental example 1, the high-frequency dielectric heat sterilization and the steam heat sterilization were performed in the same manner except that the pressure reduction time of the sterilization chamber 2 after sterilization in the high-frequency dielectric heat sterilization was set to 6 seconds.

[Experiment 3]
In the experimental example 1, the high-frequency dielectric heat sterilization and the steam heat sterilization were similarly performed, except that the pressure reduction time of the sterilization chamber 2 after sterilization in the high-frequency dielectric heat sterilization was set to 20 seconds.

The evaluation results of each experimental example are shown in Table 1.
In Experimental Example 2, since the package PF broke, the expansion (deterioration) of the package PF after 2 weeks and the texture of the contents were not evaluated. In Experimental Example 3, Because of the deterioration, the texture of the contents was not evaluated.

  As described above, according to the method for sterilizing a package of the present invention, the contents of the package PF are sterilized at a high temperature and in a short time without deteriorating the quality related to the luster, flavor, fragrance, texture and taste of food. In addition, the packaging material can be sterilized efficiently by high-temperature sterilization in a short time.

  The method for sterilizing a package according to the present invention can be suitably applied to heat sterilization of packaged food, particularly packaged food packaged in vacuum.

DESCRIPTION OF SYMBOLS 1 High frequency dielectric sterilizer 2 Sterilization chamber 3 Pressure regulation valve 4 Exhaust valve 5 Pin electrode 6 Pin support stand 7 Pin drive chamber 8 Pressure regulation valve 9 Exhaust valve 10 Steam sterilizer 11 Sterilization chamber 12 Pressure regulation valve 13 Exhaust valve 14 Packing body support stand

Claims (4)

In the method of sterilizing a package in which the contents are filled and sealed with a packaging material,
Wherein the contents of the pressure chamber package is placed in a high-frequency dielectric heating by pin electrodes while pressurizing with saturated water vapor pressure + 0.04 MPa after sterilization, is stepped down the pressure in the chamber, utilizing a step-down process wherein the package is expanded to adhere the moisture Rutotomoni the packaging material in the peripheral surface, to perform the wet heat sterilization of the packaging material in the peripheral surface by said water is heated by vaporizing moisture contents Te A method of sterilizing a package characterized by the above.   The said package is pressurized with gas, The sterilization method of the package of Claim 1 characterized by the above-mentioned. The packaging body sterilization method according to claim 1 or 2 , wherein the heating of the packaging material inner peripheral surface in a wet heat sterilization step is performed with steam. The said package is a vacuum package, The sterilization method of the package in any one of Claim 1 to 3 characterized by the above-mentioned.

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