JPS5915027A - Method of sterilizing can vessel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for sterilizing canned containers, and more particularly to a method for sterilizing consequential containers for aseptic filling by a combination of ultraviolet irradiation and high-frequency induction heating.

Conventionally, when manufacturing canned goods, it is common practice to fill the container with food or other contents, then seal it with a seal, and then heat and sterilize the resulting canned product in a pressure sterilization device called a retort. It is being done. In this sterilization of packed cans, it takes a relatively long time to transfer heat to the resultant center, so the contents may be heated for a long time, causing tissue destruction, vitamins and pigments to disintegrate, browning, etc. There is a problem that deterioration occurs.

In addition, in such heat sterilization of canned containers, the container is subjected to large internal pressure during heating or cooling, and during normal storage, the interior becomes vacuum or reduced pressure and is subjected to external pressure. There is a problem in that a can that uses a large amount of metal must be used.

Therefore, as an alternative method for producing sterilized products such as soups, fruit juices, and other liquid foods that require preservation of flavor, these liquid foods are heated and shortened by means such as heat exchange outside the packaging container. It is known to sterilize a liquid food for a period of time, fill a sterilized liquid food into a sterilized or sterilized packaging container, and immediately seal the container after filling. Sterilization or sterilization of packaging containers is carried out using dry heat in a heating oven, taking into account the ease of handling the containers later on.Dry heat sterilization is a more severe sterilization process than wet heat sterilization. The problem is that the conditions must be perfect.

For example, to sterilize Bacillus subtilis, moist heat at '120'0 for 4 to 8 minutes is sufficient;
It is unacceptable that dry heat requires heating at 180°C for 7 to 10 minutes. Thus, although the conventional production of aseptically filled containers is generally satisfactory in terms of the quality of the food contents, it requires heating at high temperatures and for a long time to sterilize the container, which is not advantageous in terms of thermoeconomics. However, the container is also subject to significant limitations in terms of its ability to withstand the high heat mentioned above.

Therefore, an object of the present invention is to provide a method for effectively sterilizing aseptic filling containers in a relatively short period of time.

Another object of the present invention is to provide a method for dry and effective sterilization of consequential containers by a combination of ultraviolet irradiation and high frequency induction heating.

According to the present invention, a radiation dose of 60 mF sec/cm2 is applied to at least the inner surface of a consequential container whose bottom portion is made of metal and which has a sealed joint between the bottom portion and the line portion.
Provided is a method for sterilizing a resultant container for aseptic filling, comprising the steps of: (1) irradiating ultraviolet rays so that .

The present invention will be explained in detail below based on specific examples shown in the accompanying drawings.

In FIG. 1 showing an example of a consequential container used in the present invention,
The resulting container shown as 1 as a whole consists of a line part 2 and a can bottom part 6, and the lower end of the barrel part 2 and the periphery of the can bottom part are sealed by a double seam part (sealing joint part) 4. ing. A flange 5 is provided at the upper end of the wire portion 2 for double seaming with a shim (not shown).

In the resulting container used in the present invention, it is important that the can bottom 6 is made of metal in connection with the sterilization operation described in detail later. The wire portion 2 may of course be made of metal, or may be made of plastic, paper, glass, or a laminate of these materials or a laminate of these and metal foil. 2 has a seam 6 formed by rolling a generally flat blank side into a wire shape and joining the opposite ends.Joining of the materials can be done, for example, by welding,
This is done by means known per se, such as soldering or bonding with adhesive.

An important feature of the invention is that for the consequential vessel described above, at least the inner surface is exposed to a dose of 3 Q mH7-sec/
A step of irradiating ultraviolet rays so that cyrL2 or more,
This process is performed in combination with the step of high-frequency induction heating of the sealing joint of the container.

Figure 2 shows a high-performance ultraviolet lamp (UV lamp manufactured by Ushio Inc.).
This figure shows the relationship between the height from the can bottom seam and the purity rate (illuminance) when the inner surface of the leprosy container is irradiated with ultraviolet rays using a C lamp. In general, the lethal dose for each type of microorganism varies considerably depending on the type of microorganism, with Q for E. coli being 7 mT! ', from small yes values such as sec/Crfil to 4, 8m, W- for general bacteria and yeast.
sec/at,, for mold 26.4 yn, lI
It changes to a large value such as '-sec/csE'. However, according to the results shown in Fig. 2, within the inner surface of the wire, except for the seaming part and its vicinity, the water droplet was extremely short.
It is understood that irradiation can kill microorganisms.

Only 1. However, the secret seam on the inner surface of the wire and the vicinity thereof are recessed, making it difficult for them to come into direct contact with ultraviolet light, and these areas are exposed to ultraviolet light! The distance from the light source is also far,
Therefore, the purity rate (illuminance) is also low, making it nearly impossible to kill microorganisms in these areas. According to the present invention, the bottom of the can is made of a metal material 17, a metal spring material is present in the seaming part, and the original seaming part is heated by high-frequency induction heating, so that the seaming part and its vicinity are heated. Existing microorganisms can be killed dryly and in a very short time. In other words, high-frequency induction heating is a method of heating a metal material using Joule heat based on an induced current (eddy current) generated in the material. It is possible to (
2) It is possible to significantly increase the temperature increase rate, (3)
It has a remarkable advantage that other heating methods do not have: extremely high thermal efficiency. As mentioned above, the only parts of the container that are sterilized or insufficiently sterilized after being irradiated with ultraviolet rays are the seams and the parts near the holes.
When high-frequency induction heating is applied to a seamed part containing a metal material, only these parts are heated to a temperature of 160 to 18
The temperature is raised to a high temperature such as 0°C, and then selectively heated within 40 seconds, especially within 10 seconds, to sterilize the entire inner surface of the wire or 1 liter.
-1: It becomes possible to perform dry sterilization within a short time.

In Figures 5-A to 3-B for explaining the manufacturing process of the aseptic filling consequent according to the present invention, the consequent container 1 is first placed on a suitable conveying device 10 and introduced into an ultraviolet irradiation area equipped with an ultraviolet light source 11. and subjected to ultraviolet irradiation (Figure 3-A)
.

As the ultraviolet light source 11, a low-pressure water lamp, particularly a light source that emits ultraviolet light having a remarkable spectral intensity at wavelength 25,572 in terms of sterilization effect, is advantageously used.

In terms of sterilization effect, it is advantageous for the dose rate of ultraviolet rays to be above a certain level.
It is advantageous to perform the processing so that the value is greater than or equal to rrdF'/am''.

Ultraviolet irradiation can be carried out batchwise or intermittently, but it is generally advantageous to irradiate while continuously transporting the container, and in particular, by irradiating while rotating the container, Uniform sterilization treatment of the surrounding surface becomes possible. It is desirable that the UV irradiation be completed within 1 to 20 seconds, particularly 5 to 15 seconds.

Next, the resultant container 1α after being irradiated with ultraviolet rays is introduced into a heating area equipped with a high-frequency induction coil 12 while being placed on a conveying device 10, as shown in FIG. 6-B.

This high frequency induction coil 12 is connected to the winding portion 11 of the resultant container 1α.
2, thereby resulting in a consequent container 1
The seam portion α or the vicinity thereof is selectively heated to a high temperature.

In the present invention, it is desirable to heat the seaming part or its vicinity to a temperature of 150 to 190°C, particularly 160 to 180°C, and the heating time and holding time vary significantly depending on the temperature, 0.2 to 40 seconds,
In particular, it is desirable to set the time to 5 to 20 seconds.

It is also desirable to carry out high-frequency induction heating while continuously feeding the resultant container.In particular, by performing induction heating while rotating the resultant container, uniform heating can be performed over the entire circumference of the seamed portion or its vicinity. Become.

In the present invention, the desired purpose can be achieved by induction heating only the seamed part of the resulting container or the vicinity thereof, but of course, depending on the necessity, heating may be performed on the lower part of the end or the vicinity of the end bottom. Parts may also be heated by induction.

The frequency of the high frequency used for induction heating is not particularly limited.
Generally, 10 to 50 DKJ12 can be used.

Next, as shown in Fig. 3-C, the heat exchanger 1 is placed in the steel container 1h that has been sterilized by ultraviolet irradiation and high-frequency induction heating.
The contents sterilized at high temperature for a short time outside the container by step 7 are filled through the piping 18 and the filling nozzle 19.

Finally, if necessary, after replacing the air in the head space of the container by steam injection, nitrogen gas blowing, etc.
As shown in Figure 3-D, the product is double-sealed with a sterilized belt.

In the embodiment shown in the accompanying drawings of the present invention, ultraviolet irradiation and high frequency induction heating are performed in this order, but these two steps may of course be performed in the reverse order or may be performed simultaneously.

In the present invention, the working bottom part 3 of the resultant container is made of any metal material conventionally used in the field of can manufacturing, for example, light metal such as aluminum, tin plated steel plate (tinplate), aluminized steel plate, chrome plated steel plate, electrolytic steel plate, etc. A chromic acid treated steel plate, a phosphoric acid and/or chromic acid treated steel plate, etc. can be used. These metal materials generally have a thickness of 0.15 to 0.
It is preferable to have a thickness of between 35 and 35 mm.

The wire portion 2 of the resulting container can also be made of the metal material exemplified above, similarly to the can bottom portion 6.

Therefore, the present invention can be applied as is to the all-metal side, which has been conventionally used for retort sterilization and difficult-to-fill products.However, according to the method of the present invention, Because the L surface 1 pressure strength is almost unnecessary due to the pressure difference between the inside and outside, the thickness of the metal layer at the bottom of the wire part and can can be significantly reduced (rided)! - It should be understood that Of course, the inner surfaces of the torso and bottom of these samurai can be provided with a resin retention coating, which is known per se.

In addition, in the present invention, the wire portion is formed from a material other than metal, and even if metal foil is used, it is used as a carcass in the form of a thin layer such as metal foil, and the wire portion is made of a material other than metal. Container costs can be significantly reduced.

FIG. 4 shows a 7F cross section h1/Y construction of the barrel body 2 of a composite can that can be particularly advantageously used for the purpose of the present invention. That is, this thickened body part 2 includes a paper substrate 7, a liquid-impermeable Hjμ layer 8 provided on the inner surface of the paper substrate, and an outer pupil-retaining layer provided on the outer surface of the paper substrate as desired. It consists of 9. The liquid-impermeable inner protection layer 8 may be a plastic film such as polyethylene or polypropylene, a metal foil such as aluminum foil, or a plastic film/metal foil/ A plastic film or the like is used.

As the outer insulation layer 9, the above-mentioned plastic film or other resin coating may be used. Wire sections with particularly excellent content preservation properties are those equipped with metal foil as a gas barrier and plastic inner coating, such as polyethylene/aluminum foil/polyethylene/paper substrate/polyethylene from the inside to the outside. It has a similar agency structure.

Double seaming of the line part and the bottom of the can is performed through a sealant interposed between the two. Such sealants include
For elastomers such as styrene-butadiene rubber,
If necessary, a composition containing a filler and a tackifying agent such as rosin is used. When inductively heating the seamed part,
This sealant will still be heated to that temperature, but the sealant is surrounded by the complex body material and the can bottom material, and is there no pressure difference in this seamed part? (As a result of being heated in the J8 state and being heated in a relatively short time, it is confirmed that there is almost no deterioration of the sealant that would cause leakage.

The sealing joint between the wire portion and the can bottom may be formed by so-called heat sealing, in addition to the double seaming described above. For example, the wire portion and the can bottom may be made of heat-sealable thermoplastic resin. , for example, those bonded through layers of polyethylene, polyglopyrene, acid- or acid anhydride-modified olefin resins, ethylene-vinyl acetate copolymers, various polyamides, various polyesters, and the like. The heat sealant layer may melt during high-frequency induction heating of the joint, but in this case, there is no pressure difference between the inside and outside, so there is little risk of the sealing joint breaking or causing a seal failure. do not have.

The invention is illustrated by the following example.

Example 1 A metal can (inner diameter 52.5 mm, height 132.8 lines) whose inner surface was coated with phenol and epoxy resin was coated with 105 Bacillus and Stearothermophilus spores per can.゛Spray it and leave it overnight to dry.
GU16-70 model powerful ultraviolet lamp was irradiated 1Cr from the top of the can for 2, 4, 6i8, 10, 15.20 seconds respectively, then output 5KF, frequency 5[1ff]
The sealed seam was heated to 150.16 using Z's high frequency heating device.
0.170.

Heating was performed to 180 and 190'C, respectively.

Next, it was filled with water that had been sterilized beforehand, and then a sterilized metal lid was wrapped around it. After storing these sample cans at 45°C for 5 days, the cans were opened aseptically to detect any remaining bacteria and to confirm whether or not they had a bactericidal effect.The following results were obtained.

Neither UV-C irradiation nor high-frequency heating was applied, and the flies with residual bacteria 50 Irradiation time (seconds) for UV-C irradiation only 2 4 6 8 10 15 20
Confucianism with residual bacteria +3928124 5 5 2
Combined use of UVC irradiation and high frequency heating 2 65" 36 32 39 344 32
30 26 27 206 15 4
10 5 280000 10 2 0 0 0 015
3 0 0 0 020 2
0 0 0 0 Deterioration of coating film due to UV C irradiation Irradiation time (seconds) 6 None 10 None 15 Yes 20 Easily oxidized and clear Both values in 50 cans Example 2, Jul is polypropylene/aluminum foil/paper/ Spiral type composite can (inner diameter 106 m) made of aluminum foil and wrapped with TFS (Ten Free Steel) at the bottom.
106 spores of Bacillus and Zupchelus per can were sprayed onto the inner surface of the chisel and left overnight to dry. This sample can was irradiated with a strong ultraviolet lamp manufactured by Ushio Inc. (trade name: UNILIZER) for 6, 8, and 10.15 seconds at a distance of 1 CWL from the top of the polarized portion, and then the output was 5KW.
The sealed seam was heated to 160, 170, and 180°C using a high-frequency heating device with a frequency of 30 KHz. Then, it was filled with sterile physiological saline and sealed. After storing each of these 50 sample cans at 67°C for 5 days, the remaining bacteria were examined to confirm the bactericidal effect, and the following results were obtained.

Irradiation time High frequency heated water, maximum temperature achieved by high frequency application °O (seconds) 160 170 18
06 15” 0 0 07000 10 8 0 0 015
3 0 0 0 50 Fractional Example in which Bacteria Remains in the Can 6゜The open part has an inner diameter of 65 x m, the bottom part has an inner diameter of 35 m, and the body part is wax-coated paper, the bottom car, PET, aluminum foil (
90tt), Aspes dillus, niger mold J [-1 per can per t1] in a paper cup made of polyethylene.
05 was sprayed onto the inner surface of the can and left overnight to dry. This sample can was heated with a strong ultraviolet lamp of the BBC GU15-70 type at a distance of 1 Crn from the top of the container No. 11.
4, 6, 8.10 seconds each irradiation 1-7, then output 5 K
IV, using a high frequency heating device with a frequency of f'1.30 K11z, the sealed seam was heated to 150.1. ri0゜170.
Heat to 180°C [7.

When the same post-treatment as in Example 1.2 was performed and the bactericidal effect was confirmed, the following results were obtained.

Irradiation time High-frequency heated water, maximum temperature reached by high-frequency heating ((force (seconds)) 150 160
170 1802 29” 7 2
0 0418100.0 6 50000 8 10000 1010000 Fraction of bacteria remaining in 450 system

[Brief explanation of the drawing]

Figure 1 is a side cross-sectional view showing one example of a condensation container used in the present invention, and Figure 2 is a side sectional view showing an example of the condensation container used in the present invention. Diagrams showing the relationship between height and p2 quantity rate (illuminance), Figures 3, 4 and 31) are diagrams for explaining the manufacturing process of aseptic filling according to the present invention, Figure 4 is a diagram showing the relationship between height and p2 quantity rate (illuminance). 1 is a diagram showing a cross-sectional structure of a wire portion of a composite can that can be particularly advantageously used for the purpose of Sealing part (sealed seam part), flange 5.6 is seam, 7 is paper substrate, 8 is protective layer, 9 is outer surface protective layer, 10 leaf conveying device, ``path, 11 t ultraviolet light)
12 indicates a high-frequency induction coil, 18 indicates piping, and 19 indicates a charging nozzle. Patent applicant Sho Kishimoto 1 Figure 2 Figure 1g 躬碌↑ Figure 3-A 1 Figure 3-C

Claims (3)

[Claims] (1) A radiation dose of 3 Q rrjV-sec/crrLt is applied to at least the inner surface of a canned container whose bottom is made of metal and which has a sealed joint between the can bottom and the can body.
A method for sterilizing a resultant container for aseptic filling, comprising a combination of the step of irradiating ultraviolet rays as described above and the step of high-frequency induction heating the sealed joint portion of the canned container. (2) The method according to claim 1, wherein the ultraviolet rays have a significant spectral intensity at a wavelength of 2537.4. (3) The method according to claim 1, wherein the seamed portion is heated by high frequency induction to a temperature of 160'0 or more.