JPH01267130A - Method for disinfecting packaging material - Google Patents

Abstract

PURPOSE:To sharply reduce the malodor originating from oxidation and decomposition, by accommodating in an exterior case such as corrugated fiberboard case an enclosure having a number of packaging materials consisting of polyolefin sealed in an atmosphere thereof at a specific oxygen concentration and applying in as-accommodated condition electron rays thereto from above and below in a specific dose. CONSTITUTION:An enclosure having packaging materials consisting of polyolefin sealed in an atmosphere thereof at an oxygen concentration of not more than 1.0% by nitrogen substitution or the use of oxygen absorbent is received in an exterior case and electron rays are thereafter applied thereto in a dose of not less than 0.5M Rad. Said packaging materials consisting of polyolefin is at least a simple substance of polyolefin or laminated product consisting of aluminum foil, papers and plastic film such as polyester and the polyolefin is formed at least as the innermost layer of said packaging material.

Description

[Detailed Description of the Invention] <Technical Field of the Invention> The present invention relates to a sterilization method for sterilizing a large number of polyolefin-containing packaged rice cake materials, particularly food packaging materials, at the same time, and in a packaging form that is still in distribution condition. The present invention relates to a sterilization method in which the sterilization is performed using an electron beam.

<Prior art> Conventionally, methods for sterilizing packaging materials include hydrogen peroxide, ethylene oxide gas (hereinafter abbreviated as EOG),
There are methods using radiation such as ultraviolet rays, electron beams, and T-rays. First, sterilization methods using hydrogen peroxide and EOG are sterilized by adhesion of the drug and gas to the surface of the packaging material, penetration into the interior, etc., and therefore there is a safety problem due to residual substances. In addition, although UV sterilization does not cause any problems such as residue as mentioned above, due to its weak penetrating power, it can only sterilize the surface of packaging materials, and it is extremely difficult to kill resistant molds. be. Furthermore, electron beam and T
- Sterilization with radiation such as rays requires a high irradiation dose, which tends to cause changes in the physical properties of the packaging material. Especially when irradiated with radiation in the presence of oxygen, oxidation and decomposition reactions occur in the synthetic resin that makes up the packaging material. This occurs actively, and the resulting odor poses a major practical problem.

To solve this problem, when sterilizing by T-ray irradiation, the atmosphere in which the packaging material is packaged is irradiated in an oxygen-free state, thereby suppressing the oxidation and decomposition reactions of the synthetic resin and reducing the generation of odors. Sterilization methods are being proposed to reduce the amount of sterilization. (For example, Japanese Patent Publication No. 57-7978, Japanese Patent Publication No. 57-7978,
77421 Publication) <Problem to be solved> The atmosphere in which the packaging material is packaged is made close to an oxygen-free condition, and the T.
As mentioned above, the generation of odor is suppressed by irradiating with - radiation.

However, since γ-rays have a large penetrating power, they easily decompose plastics, and the irradiation dose required for sterilization is, for example, 1.5 Mr.
It takes time to reach ad, which is disadvantageous for efficient sterilization.

In addition, if the packaging format is maintained while still being distributed, that is, the packaging material is sterilized while still being packed in a cardboard box, etc., and then transported as is to a place where the contents are filled, and the sterilized packaging material is used, γ - Since the odor caused by radiation irradiation remains as it is, a sterilization method with less odor has been desired.

The present invention relates to a sterilization method for sterilizing a large number of packaging materials with electron beams while they are still in circulation. In other words, it is characterized by suppressing the generation of oxidation and decomposition odors of packaging materials to an extremely small amount, at least to an extent that does not pose a problem in practical terms, compared to conventional sterilization methods using T-rays, etc., which were considered to be disadvantageous. The purpose of this invention is to provide a method for sterilizing packaging materials using electron beams.

<Means for Solving the Problems> The present invention relates to a sterilization method in which a sealed body containing a large number of packaging materials, particularly food packaging materials, is irradiated with radiation while it is housed in an exterior body such as a cardboard box. This type of radiation sterilization method is characterized by drastically reducing the occurrence of off-odors caused by oxidation and decomposition odor of packaging materials caused by radiation irradiation, which has been a particular problem in the past.

That is, the present invention provides a method for sterilizing packaging materials, particularly food packaging materials, by electron beam irradiation, in which a large number of packaging materials made of at least polyolefin are packaged in a system containing an atmosphere with an oxygen concentration of 11% or less. A sealed body consisting of
This sterilization method is characterized by irradiating electron beams from the top and bottom of the packaging at a dose of 0.5 Mrad or more, respectively, while the product is housed in an packaging such as a cardboard box.

Specifically, a packaging material made of at least polyolefin is sealed in an atmosphere with an oxygen concentration of 1.0% or less by nitrogen substitution or an oxygen absorber, and then a sealed body is stored in an exterior body. This is a sterilization method characterized by electron beam irradiation at a dose of .5 Mrad or more.

In the present invention, a packaging material composed of at least polyolefin is a single polyolefin or a composite laminate with a plastic film such as A1 foil, paper, or polyester, and at least polyolefin is comprised in the innermost layer of the packaging material. It means to do something. Furthermore, among packaging materials, it is the most suitable sterilization method for food packaging materials, which require particularly strict quality against off-odors, especially sake cartons.

Furthermore, in the present invention, a sealed body in an atmosphere with an oxygen concentration of 1.0% or less refers to a sealed body in which a packaging material made of at least polyolefin, which is an object to be sterilized, is sealed in a sealing material and then replaced with nitrogen. It means sealing by heat sealing, or enclosing a so-called oxygen absorber such as the oxygen absorbing side described in Japanese Patent Publication No. 62-24067 and Japanese Patent Publication No. 62-9376 and the object to be sterilized and sealing by heat sealing. do.

In the radiation irradiation method of the present invention, it is necessary to reduce the transmission to at least 5 mm or less, and therefore, in this case, the packaging material, which is the object to be sterilized, is limited to a single package. On the other hand, when the electron beam energy is 5 MeV or more, its penetrating power is greatly increased, and if the size of a thin cardboard box is used, it is possible to sufficiently sterilize the material by irradiating it twice, above and below.

<Function> Even if a sealed body in which a large number of packaging materials made of at least polyolefin are sealed is housed in an exterior body, so-called distribution state, the oxygen concentration in the sealed body can be lowered and electron beams under certain conditions can be used. By irradiating the exterior body from above and below, it is possible to sterilize the product in a short period of time and with little odor.

<Example-1> Fifty liquid packaging materials (liquid carton sleeves for 500D) consisting of the following configuration were packed into an oxygen absorber (Special Publication Publication No. 62-2
No. 4067 composition) was sealed in a package made of nylon/unstretched polypropylene and heat sealed to obtain a sealed body (a).

Composition of packaging material for liquids> PE/Gi/PE/AL/PET/PE (innermost layer) (P
E: polyethylene, PET: polyethylene terephthalate) The sealed body (a) obtained above was left for 3 days after heat sealing, and the oxygen concentration in the system was measured and found to be 0.1% or less.

The sealing body is a cardboard box (W = 140mm, L = 240n
*, H = 200 M) and irradiated once each in the upper and lower directions of the cardboard box using a 10 MeV linear accelerator at a setting of 1.5 Mrad (specifically, first, irradiate from the top of the cardboard box, Then, the cardboard was turned over a second time and irradiated from above) to complete the sterilization. As a method for evaluating sterilization, a bioindicator (trade name: Eiken Tesper G, bacterial species HBacill) was added to several pieces of packaging material for liquids.
A sterilizing agent (US Sub 1 is ATCC 6633) was attached in advance, and after electron beam irradiation, it was stored at 37°C for 3 days to determine the bactericidal effect. In addition, odor was determined based on a sensory test.

Comparative Example-1> Fifty pieces of the liquid packaging material described in Example-1 were put into a cardboard box (W=140 mm, L/240 W, H=
200ffI11) and completed electron beam irradiation sterilization using the same method described in Example-1. Then, the same evaluation as in Example 1 was performed regarding the bactericidal effect and odor.

<Comparative Example-2> The sealed body (a) described in Example-1 was left at room temperature for about 10 hours, and then sterilized under the same conditions as Example-1, and the sterilization effect and odor were compared with Example- The same evaluation as in 1 was performed. Note that the oxygen concentration in the sealed body was about 5%.

<Example 2> When the oxygen concentration of the liquid packaging configured as described in Example 1 was measured, it was 0.1% or less.

Next, electron beam irradiation sterilization was completed using the method described in Example-1. Examples of bactericidal effects and odor
The same evaluation as in 1 was performed.

Comparative Example-3> The sealed body of Example-1 with an oxygen concentration of 0.1 or less was packed in a cardboard box (W-140mo+, Lyo240M, H=200
mm), and sterilization was completed by irradiating with gamma rays at an irradiation dose of 1.5 Mrad. Then, the same evaluation as in Example 1 was performed regarding the bactericidal effect and odor.

Table 1 shows the evaluation results of the bactericidal effect and odor of the above Examples and Comparative Examples.

Table-1 Bactericidal effect ○: Effective odor O: Almost none Δ: Slightly present×・ ・
Yes <Effects of the Invention> As described above, even if a large number of polyolefin-containing packaging materials are packaged in a distribution state, the present invention can irradiate electron beams under certain conditions from the top and bottom of the exterior body, so that the same conditions can be achieved. This makes it possible to sterilize in a shorter time and with less odor than when irradiating with γ-rays.

In addition, little odor is generated during sterilization, making it an excellent method for conveniently sterilizing packaging materials for foods, especially alcoholic beverages.

Special permission person Toppan Printing Co., Ltd. Representative: Kazuo Suzuki

Claims (2)

[Claims] (1) A large number of packaging materials made of at least polyolefin are hermetically packaged in an atmosphere with an oxygen concentration of 1.0% or less, and the sealed body is stored in an exterior body such as a cardboard box, and then the top and bottom of the exterior body are 0.5 Mrad each from the direction
A method for sterilizing packaging materials, characterized by irradiating the above electron beam. (2) The packaging material is alcoholic beverage filling packaging material (food packaging material)
The method for sterilizing packaging materials according to claim 1, characterized in that: