JP2017181134A - Method for inspecting sealing performance of container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for inspecting sealing performances which can accurately detect even a slight sealing failure (micro-leak) of a container to be filled with sealed liquid.SOLUTION: The method for inspecting sealing performances of a container to be filled with sealed liquid includes the steps of filling pure water into a container and sealing the pure water in the container; performing an invasion processing on a water-soluble organic compound into the container filled with sealed pure water by holding the container in an aqueous solution of the water-soluble organic compound; and inspecting the sealing performance of the container by taking the pure water out of the container and determining the amount of the water-soluble organic compound mixed in the pure water by a liquid chromatograph and a mass spectrometer.SELECTED DRAWING: None

Description

  The present invention relates to a method for inspecting a sealing property of a container filled and sealed with a liquid.

  Containers such as bottles and cups made of flexible resin are not only easily molded and mass-produced, but also lightweight, so they are widely used as beverage stuffing containers filled with liquids such as various beverages. It is used.

  In such a beverage stuffing container, from the viewpoint of hygiene, it is necessary that both the beverage and the container (including the lid) are sterilized. In general, a filling and sterilization method is used in which a container is filled and sealed, or a liquid is filled and sealed in a container and retort sterilized. There is also an aseptic filling method in which the container and cap are sterilized with a sterilizing agent or hot water, and all filling and sealing processes, such as filling and sealing liquids such as heat sterilized and cooled, are performed in an aseptic environment. Widely adopted.

Furthermore, a method using high-pressure treatment is also known as a sterilization method not involving heating (for example, Patent Document 1).
In this method, a flexible container filled and sealed with a liquid to be treated such as food is filled into an empty processing chamber having no pressure medium in a high-pressure cylinder, and then the container is filled. By compressing, an isotropic pressure is generated in the liquid surrounding the liquid to be processed, and the liquid to be processed is subjected to a high-pressure treatment, whereby sterilization or bacteriostasis (bacterial inactivation) is performed. In this method, it is not necessary to heat the liquid to be processed such as food, so that various components in the liquid to be processed are prevented from being deteriorated by heating, and no off-flavor is generated. Accordingly, such a high-pressure sterilization method is particularly useful for filling and sealing non-carbonated beverages such as various fruit juices and vegetable juices represented by tomatoes. This is because non-carbonated beverages are required to be fresh, and thus are required to prevent a decrease in freshness due to heating.
From such a background, the present applicant has proposed a method for producing a container-packed beverage in which a container filled with a non-carbonated beverage is subjected to high-pressure treatment (Japanese Patent Application No. 2015-093019).

  By the way, as a beverage stuffing container, it is important to ensure the sealing property of the container simultaneously with the various sterilization methods described above. For example, a means for sealing a container by physical contact or fitting using a lid, regardless of fusion such as heat sealing, requires confirmation of this sealed state. In particular, in a sterilization method using high-pressure treatment using water as a pressurized medium, a container filled with a liquid (inner solution) is sealed and pressurized in water in a pressure chamber. When the intrusion of water is extremely small, specifically, even if only one drop of water enters (micro leak), microorganisms enter the container through the water that is the pressurized medium. In some cases, the liquid content may deteriorate. For this reason, it is very important to accurately inspect the sealing performance of the container filled and sealed with the liquid.

  As a method for inspecting the sealing property of a container, a method of measuring chlorine concentration by colorimetry (DPD method) utilizing the color development of diethyl paraphenylenediamine (DPD) by oxidation with chlorine is generally employed. .

  The detection limit in the DPD method is 0.1 ppm in terms of residual chlorine concentration, which is at a level that does not cause a problem as the detection limit, but the color development of this reaction is extremely unstable, and even when there is no residual chlorine, There is a problem that color develops in a few seconds. That is, the accuracy of the sealing test based on the residual chlorine concentration is low. Further, it can be used for concentration measurement of a sample in which residual chlorine exists at a certain concentration, but cannot be used for concentration measurement of a sample that does not contain residual chlorine or has a very low residual chlorine concentration. For example, it is not suitable as an inspection method for judging whether or not it has a sealing property that can be applied to the above-described high-pressure treatment using water as a pressurized medium.

JP-A-5-23118

  Accordingly, it is an object of the present invention to provide a container sealability inspection method capable of detecting with high accuracy even a slight sealing failure (micro leak) for a container filled and sealed with a liquid.

According to the present invention, in the method for inspecting the sealing property of a container filled and sealed with liquid,
Sealing and filling pure water in the container,
By holding the container filled and sealed with pure water in an aqueous solution of a water-soluble organic compound, the water-soluble organic compound is infiltrated into the container,
After this, a container sealing test method is provided in which pure water filled in the container is taken out and the amount of the water-soluble organic compound mixed in the pure water is quantified by a liquid chromatograph / mass spectrometer. Is done.

In the inspection method of the present invention,
(1) The container is a bottle, and after the bottle is filled with the pure water, a sealing cap is secured by screwing a cap on the mouth of the bottle.
(2) The container is to be subjected to high pressure treatment after filling and sealing with the pure water.
(3) Insert the container filled and sealed with pure water into the pouch, then fill the pouch with the aqueous solution of the water-soluble organic compound, and then heat-seal the opening of the pouch. Performing an intrusion treatment of the water-soluble organic compound by performing a high-pressure treatment in a state;
(4) The water-soluble organic compound has a solubility (w / v%) in water at 20 ° C. of 1 g / 100 ml or more.
(5) The water-soluble organic compound is an organic carboxylic acid, amino acid or polyphenol,
(6) The water-soluble organic compound is citric acid,
(7) calculating the amount of water penetrating into the pure water from the quantified amount of the water-soluble organic compound in the pure water;
Is preferred.

In the container sealability inspection method of the present invention, pure water is filled and sealed in a container, and this is held in an aqueous solution of a water-soluble organic compound to perform an intrusion treatment of the aqueous organic compound into the container. The amount of the water-soluble organic compound transferred into the pure water is quantified by a liquid chromatograph / mass spectrometer, and it is inspected whether or not the sealing property of the container is sufficiently secured by this amount.
According to such an inspection method, it is possible to confirm a very slight sealing failure. For example, by calculating the amount of water that has infiltrated into the pure water from the amount of the water-soluble organic compound in the quantified pure water, the amount of intrusion water that causes deterioration of the content liquid is calculated. Thus, it is possible to inspect whether or not the sealing property is secured so as not to cause deterioration of the content liquid. Specifically, when the detection limit of the liquid chromatograph / mass spectrometer is 0.1 ppm, the amount of intrusion water of a 20 w / v% water-soluble organic compound can be calculated in a 250 ml container, and the detection limit is 0. .125 μl can be calculated.
Further, since a slight sealing failure can be detected, for example, the sealing property inspection method for a container according to the present invention is applied to a sealing means for securing a sealing property by attaching a screw cap to the container mouth portion. Can determine the proper tightening angle of the screw cap, which is a great advantage of the present invention.

In the container sealing test method of the present invention, a total ion current chromatograph obtained by a liquid chromatograph / mass spectrometer used for quantifying the amount of a water-soluble organic compound (citric acid) invading pure water. The figure which shows the example of the chart of a gram.

  The container sealability inspection method of the present invention uses pure water as a test sample solution and an aqueous solution of a water-soluble organic compound as a detection solution. That is, after filling a container for confirming the sealing property with pure water as a test sample solution and sealing, predetermined intrusion treatment is performed, and the amount of the water-soluble organic compound transferred into the pure water is quantified. By this, the sealing property is inspected.

  Pure water used as a test sample solution is obtained by removing various salts (ions), residual chlorine and other impurities by distillation, ion exchange, reverse osmosis, etc., for example, having a conductivity of 1 to 10 MΩ · cm Is used.

In addition, as the water-soluble organic compound used in the detection solution, those having a solubility (w / v%) in water at 20 ° C. of 1 g / 100 ml or more are preferably used. Those having low solubility in water are not suitable as a detection solution because the amount of transfer into the container (pure water) is small due to the intrusion process described later.
Examples of water-soluble organic compounds having such solubility include organic carboxylic acids such as citric acid, malic acid and tartaric acid (preferably excluding formic acid and acetic acid which are frequently used as a mobile phase of a liquid chromatograph / mass spectrometer), Amino acids such as glutamic acid and polyphenols such as catechin can be mentioned, and citric acid is most preferable from the viewpoint that it has the highest solubility in water and is readily available.

Further, the form of the container to be inspected and the sealing means applied to the container are not particularly limited. For example, the present invention can be applied to a cup-shaped container sealed by heat sealing. However, the present invention is preferably applied to a bottle in which a lid is physically brought into contact with a mouth portion of a container to form a seal. When such a sealing type is adopted, the sealing property becomes a problem in particular, so that the present invention is suitable for the sealing inspection of the bottles adopting such a sealing type in order to effectively utilize the advantages of the present invention. It is.
Further, among the sealing types by the lid as described above, a screw type that attaches a cap, which is a screw engaging lid, to the mouth of the bottle can maximize the advantages of the present invention. . That is, in the sealing type in which the cap is plugged into the bottle mouth portion, even though the sealing performance can be inspected, the sealing performance cannot be adjusted according to this result. This is because, as described above, the sealing performance can be adjusted by adjusting the tightening angle of the cap, for example, by tightening at a tightening angle larger than the setting.

In the present invention, a container employing the above-described sealed form is filled with pure water as a test sample solution, and after sealing the container, this container (hereinafter sometimes referred to as a test container) is detected. An intrusion treatment is performed by holding the solution in an aqueous solution of a water-soluble organic compound.
At this time, the concentration of the water-soluble organic compound aqueous solution to be used may be a saturated concentration for the purpose of maximizing the detection sensitivity of the mass spectrometer, but if it is a sufficiently soluble substance such as citric acid. The concentration may be 20 w / v% or less.

  Intrusion processing is performed, for example, by placing a cuvette in a pouch, and further filling the above-described detection liquid so that a head space is not formed, and then closing the opening of this pouch by heat sealing. The holding condition is set so that an equivalent load is applied according to the sterilization method in which the container to be inspected is adopted.

  For example, in a container that is sterilized by high-pressure treatment, the container is held so that the same pressure is applied for the same time at the same temperature as the high-pressure treatment. Further, in a container that is cooled after being hot-filled with the content liquid, the intrusion process is performed so that the inside of the cuvette is maintained in a reduced pressure state by heating to the same temperature and then cooling.

  The pouch used for the intrusion treatment is not limited as long as it has an appropriate hermeticity that prevents entry of foreign substances and does not cause oxidative deterioration of the water-soluble organic compound. For example, it may be made of a polyolefin film such as polyethylene, or may be a multilayer film provided with an intermediate layer of a gas barrier resin such as an ethylene vinyl alcohol copolymer.

  After completion of the above intrusion process, the inspection container is taken out from the pouch, washed with water and dried so that the detection liquid (aqueous solution of water-soluble organic compound) does not remain on the surface of the container. Remove a portion of the pure water with a pipette etc. into a test tube bottle for liquid chromatography measurement so that there is no contamination. Specifically, a hole may be formed in the bottom or body of the container with a soldering iron or the like and taken out with a pipette.

Thus, the density | concentration of the water-soluble organic compound in the pure water taken out from the test container is quantified using a liquid chromatograph / mass spectrometer known per se.
Such quantification is performed, for example, by preparing a calibration curve using an aqueous solution of a water-soluble organic compound having a known concentration and calculating the concentration of the water-soluble organic compound based on the calibration curve.

For example, referring to FIG. 1 showing a chart of the total ion current chromatogram, there is no peak in the pure water chart, but the citric acid concentration is about 0.5 min in an aqueous solution having a citric acid concentration of 1 ppm. A derived peak is present. In this way, a calibration curve is prepared from the peak height using an aqueous citric acid solution with a known concentration.
FIG. 1 shows a sample No. 1 together with the chart of pure water and citric acid 1 ppm. 1 to 3 charts are shown. That is, from this chart, the sample No. In Nos. 1 and 3, the citric acid peak was not expressed, and when the detection limit of the liquid chromatograph / mass spectrometer was 1 ppm, the citric acid concentration was below the detection limit, and citric acid had entered. Thus, it can be seen that the sealing performance is effectively maintained.
Sample No. In No. 2, the peak of citric acid is expressed, and it can be seen from this peak intensity that 0.93 ppm of citric acid has entered the container, and it is necessary to adjust the sealing property. Further, from this amount of citric acid, the amount of water that has entered the container (intrusion water amount) can also be calculated by a method for calculating the amount of intrusion water from the determination of the water-soluble compound described later. For example, when a 20 w / v% aqueous citric acid solution is used as the detection solution and the filling water amount of the container is 250 ml, it can be calculated that 1.25 μl of water has entered the container.

According to the present invention, the sealing property of the container to be inspected can be inspected with high accuracy in this manner, and the sealing property can be adjusted according to the inspection result.
In particular, the present invention is suitably applied to confirm the sealing property of a container in which high-pressure treatment is performed for sterilization without impairing freshness in a container filled and sealed with non-carbonated beverages such as various fruit juices and juices. Is done.

The superior advantages of the present invention are illustrated in the following experimental example.
The following analysis and quantification were performed in order to confirm the possibility of determining the amount of intrusion water from the quantification of the water-soluble organic compound and the quantification of the water-soluble organic compound using a liquid chromatograph / mass spectrometer.

<Analysis conditions for liquid chromatograph / mass spectrometer>
(1) Analytical instruments / analysis conditions Liquid chromatograph: 1260 Infinity Series manufactured by Agilent Technologies
Mass spectrometer: 6430 Triple Quad LS / MS manufactured by Agilent Technologies
Column: SB-C18 ZORBAX (φ1.8 μm, 2.1 × 50 mm)
Mobile phase: 0.1% formic acid, flow rate 0.4 ml / min
Fragmentor voltage: 75V
Drying gas: Nitrogen gas (350 ° C)
Dry gas flow rate: 12 l / min
Nebulizer pressure: 60 psig
Capillary voltage: 3500V
Oven temperature: 40 ° C
Injection volume: 5 μl
Ionization method: ESI (Selected ion monitoring method (m / z 191.1))
Measurement: Negative detection mode Measurement time: 1 minute (2) Preparation of a citric acid calibration curve A 10 ppm standard solution is prepared step by step using a citric acid reagent (special grade, purity> 98%) manufactured by Wako Pure Chemical Industries, Ltd. Dilution was performed to prepare 0.1 ppm, 0.25 ppm, 0.5 ppm, and 1.0 ppm citric acid aqueous solutions. Then, it filtered for 0.45 micrometer membrane filter and used for the measurement. A calibration curve was created from the integrated value of the citric acid-derived signal (m / z 191.1) obtained from the measurement.
(3) Intrusion water amount calculation method from determination of water-soluble compound When the amount of water charged is Xml, the concentration of the water-soluble compound is Yw / v%, and the amount of water-soluble compound detected by a liquid chromatograph / mass spectrometer is Zppm, The amount of intrusion water (μl) can be calculated by the following formula.
<Calculation formula>
Intrusion water volume (μl) = Z / 10000Y * 1000X
For example, when the amount of water filled in the container is 250 ml and a test is performed by the method described later using a 20 w / v% citric acid aqueous solution, the amount of intrusion water (μl) when the detected amount of citric acid is 1 ppm is 1 / (10000 * 20) * 1000 * 250 = 1.25.

<Experiment 1>
Filled with 268 ml of PET bottle with a full volume of 268 ml, filled with 250 ml of 3.3 ° C pure water, fitted with a 38φ polyethylene resin cap at the zero position at the bottle mouth, wound around a predetermined angle of 365 degrees, and sealed various sample bottles. Created.
After that, various sample bottles are inserted into a pouch made of a nylon / polyethylene multilayer film, and a 20 w / v% aqueous citric acid solution (detection solution) is filled without forming a head space to heat the opening of the pouch. The pouches were sealed and subjected to high pressure processing at a water temperature of 3.3 ° C. and 600 MPa for 2 minutes.

After the above high-pressure treatment, the bottle is removed from the pouch, washed with tap water so that no citric acid solution remains on the bottle surface, dried, then a hole is made in the barrel with a soldering iron, and pure water in the bottle is removed with a pipette. 2 ml was collected in a PS screw tube bottle so that there was no contamination.
The collected pure water was analyzed using a liquid chromatograph / mass spectrometer, and the citric acid concentration was quantified from the calibration curve obtained by the above-described pre-analysis, and the amount of intrusion water was determined from the citric acid concentration. The citric acid concentration at the limit of quantification was 0.1 ppm or less, and the amount of intrusion water was 0.125 μl or less.
The S / N (signal / noise) ratio was calculated from the measurement data of the 1 ppm citric acid standard solution, and the result was calculated with the detection limit being three times as the detection limit. As a result, detection by the test method using the analytical instrument and analysis method described above was performed. The limit was 0.1 ppm or less. That is, when the amount of filling water is 250 ml and an aqueous citric acid solution having a concentration of 20 w / v is used, the amount of intruding water is 0.125 μl or less by calculation. However, since the detection limit described above depends on the detection sensitivity of the analytical instrument, the detection limit when a highly sensitive apparatus is used is not limited to the above, and a lower concentration may be used as the detection limit.

  On the other hand, a sample in which the predetermined angle of the cap was loosened and tightened by 10 degrees up to 180 degrees was prepared, and the citric acid concentration was similarly quantified. As a result of obtaining the intrusion water amount from this citric acid concentration, the predetermined angle was 250 degrees. It was found that the citric acid concentration was 56 ppm, the intrusion water amount was 0.07 ml, the predetermined angle was 200 degrees, the citric acid concentration was 240 ppm, and the intrusion water amount was 0.3 ml.

<Experiment 2>
A PET bottle having a full injection volume of 268 ml and a cap made of 38φ polyethylene resin each sterilized with γ rays were prepared.
Aseptically fill the PET bottle with 250 ml of sterilized sweetened bouillon medium, and fix the cap so that the amount of intrusion water determined by the liquid chromatograph / mass spectrometer in Experiment 1 is 0.07 ml. One hundred sample bottles were wound and sealed aseptically at an angle of 250 degrees.
These sample bottles were inserted into a pouch made of a nylon / polyethylene multilayer film filled with 10 ⁵ cell / ml solution of Bacillus subtilis spores, heat-sealed without forming a head space, a water temperature of 3.3 ° C., The high pressure processing of 600 Mpa and 2 minutes was performed.
As a result, all 100 sample bottles were not deteriorated.

<Experiment 3>
In Experiment 2, 100 sample bottles were prepared in the same manner except that the cap was tightened at a predetermined angle of 200 degrees so that the amount of intrusion water obtained by the liquid chromatograph / mass spectrometer in Experiment 1 was 0.3 ml. Then, high-pressure processing was performed.
As a result, 11 deteriorations were observed in 100 sample bottles.

<Experiment 4>
A heat resistant PET bottle having a full injection volume of 268 ml sterilized with γ rays and a cap made of 38φ polyethylene resin were prepared.
Next, 250 ml of sweetened bouillon medium sterilized at 120 ° C. is filled at 88 ° C. into the above heat-resistant PET bottle so that the amount of intrusion water obtained by the liquid chromatograph / mass spectrometer in Experiment 1 is 0.07 ml. 100 sample bottles were prepared by sealing the above cap with a predetermined angle of 250 degrees.
Each of these sample bottles was cooled to 3.3 ° C. in a bucket filled with Lactobacillus brevis 10 ⁵ cell / ml solution.
As a result, all 100 sample bottles were not deteriorated.

<Experiment 5>
In Experiment 4, 100 sample bottles were prepared in the same manner except that the cap was tightened at a predetermined angle of 200 degrees so that the amount of intrusion water obtained by the liquid chromatograph / mass spectrometer in Experiment 1 was 0.3 ml. And cooled.
As a result, 20 deteriorations were observed in 100 sample bottles.

  In the above experiment, regarding the relationship between the amount of intrusion water and deterioration, J.A. The amount of water intrusion was 0.069 ml in the research (biotest using Lactbacillus) for the relationship between the amount of water intrusion into the metal can and deterioration of Gilchurst et al. Based on the report that it occurred.

<Discussion>
According to the above experiments 1 to 5, the water-soluble organic compound is quantified by a liquid chromatograph / mass spectrometer using the water-soluble organic compound, and the amount of invading water is determined from the concentration of the water-soluble organic compound. The predetermined angle of the tightening, the water-soluble organic compound concentration, and the intrusion water amount can be associated with each other very easily. As a result, it can be seen that the sealability can be confirmed with high accuracy and speed by applying to the confirmation of the sealability of bottles and caps in the manufacture of bottled beverages.

Further, according to Experiments 2 and 3, for example, a non-carbonated beverage prepared under a low temperature condition of 10 ° C. or less is filled and sealed in a bottle, and the bottle filled with the beverage is subjected to high pressure processing. In the production of beverages, by applying the association in Experiment 1 described above, as a method for confirming the sealing properties of bottles and caps that prevent the beverage from being damaged due to micro leaks during high-pressure processing and contamination of treated water, It can be seen that it can be done quickly and accurately.
Further, according to Experiments 4 and 5, for example, in the manufacture of a bottled beverage in which a hot-filled beverage is filled in a bottle, by applying the association of Experiment 1 described above, by sucking negative pressure after cooling It can be seen that this method can be performed with high accuracy and speed as a method for confirming the sealability of the bottle and the cap to prevent the beverage from being damaged.

Claims (8)

In the method for inspecting the sealability of containers filled and sealed with liquid,
Sealing and filling pure water in the container,
By holding the container filled and sealed with pure water in an aqueous solution of a water-soluble organic compound, the water-soluble organic compound is infiltrated into the container,
Thereafter, the container is checked for hermeticity by taking out pure water filled in the container and quantifying the amount of the water-soluble organic compound mixed in the pure water with a liquid chromatograph / mass spectrometer.   2. The container sealing test according to claim 1, wherein the container is a bottle, and after the bottle is filled with the pure water, a sealing cap is secured by screwing a cap on the mouth of the bottle. Method.   The container sealing method according to claim 1 or 2, wherein the container is subjected to high-pressure treatment after being filled and sealed with the pure water.   A container filled and sealed with pure water is inserted into a pouch, and then the aqueous solution of the water-soluble organic compound is filled into the pouch. Thereafter, the opening of the pouch is heat-sealed. The container sealing test method according to claim 3, wherein an intrusion process of the water-soluble organic compound is performed by performing a process.   The container water-tightness inspection method according to claim 1, wherein the water-soluble organic compound has a water solubility (w / v%) at 20 ° C. of 1 g / 100 ml or more.   The container water-tightness inspection method according to claim 5, wherein the water-soluble organic compound is an organic carboxylic acid, an amino acid, or polyphenol.   The container water-tightness inspection method according to claim 6, wherein the water-soluble organic compound is citric acid.   The container sealability inspection method according to any one of claims 1 to 7, wherein the amount of water that has entered the pure water is calculated from the determined amount of the water-soluble organic compound in the pure water.