Packaging method

Abstract

To provide a packing method reducing residual oxygen in a container after inert gas replacement packing.SOLUTION: In a packing method, a content is stored in a decompression chamber and sealed, the decompression chamber is evacuated and decompressed to a primary decompression degree, then, while evacuating, inert gas is injected into the decompression chamber, and then the injection of the inert gas into the decompression chamber is stopped, and the decompression chamber is further decompressed to a secondary decompression degree, evacuation of the decompression chamber is stopped, and the inert gas is injected again into the decompression chamber. When the pressure in the decompression chamber is made equal to the atmospheric pressure, the content is taken out of the decompression chamber, and packed by inert gas replacement.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a packaging method.

Background Art

[0002] Conventionally, in order to prevent deterioration due to oxidation of the contents and quality degradation due to the growth of aerobic bacteria and enable long-term storage, the contents are filled and sealed while replacing the air in the packaging container with an inert gas such as nitrogen. So-called gas replacement packaging is known. Regarding gas replacement packaging, JIS Z 0108:2012 states that "During filling of the contents, air is sucked and exhausted from the container and replaced with an inert gas such as nitrogen and carbon dioxide and then sealed, or the air inside the container is forcibly replaced with an inert gas and sealed, for the purpose of preventing deterioration of the article. For the container, a packaging material with excellent gas barrier properties is used." (Number: 1079).

[0003] Also, in such gas replacement packaging, since it is difficult to completely remove oxygen in the container, for example, Patent Document 1 proposes gas replacement packaging of the contents in a packaging container made of a laminate provided with a resin layer having an oxygen absorption function together with an oxygen barrier layer.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, according to the study by the present inventors, even when the contents are gas-substituted and packaged in a packaging container with an oxygen absorption function, a phenomenon is observed in which the oxygen concentration in the container increases after the gas-substituted packaging. Focusing on this point and conducting intensive studies, it was found that the oxygen contained in the contents was affecting. Therefore, the present inventors conducted further intensive studies to reduce the oxygen remaining in the container after gas-substituted packaging by removing as much oxygen as possible contained in the contents, which had not been considered at all in the past, and as a result, completed the present invention.

Means for Solving the Problems

[0006] In the packaging method according to the present invention, when gas-substituting and packaging the contents in a packaging container, the contents are housed and sealed in a decompression chamber, the inside of the decompression chamber is evacuated, and after the inside of the decompression chamber is decompressed to a primary decompression level, while continuing the evacuation, an inert gas is caused to flow into the decompression chamber, and then, While continuing the exhaust, the inflow of the inert gas into the decompression chamber is stopped, the inside of the decompression chamber is further decompressed to a secondary decompression level, then the evacuation of the decompression chamber is stopped, an inert gas is caused to flow into the decompression chamber again, and after the pressure in the decompression chamber is made equivalent to the atmospheric pressure, the contents are taken out of the decompression chamber and gas-substituted and packaged.

Effects of the Invention

[0007] According to the present invention, prior to gas-substituting and packaging the contents in a packaging container, by efficiently removing the oxygen contained in the contents, the oxygen remaining in the container after gas-substituted packaging can be further reduced.

Modes for Carrying Out the Invention

[0008] Hereinafter, the packaging method according to the present invention will be described while showing its embodiments.

[0009] As an embodiment of the present invention, the packaging method is a packaging method for reducing the oxygen remaining in the container after gas replacement packaging by efficiently removing the oxygen contained in the contents prior to gas replacement packaging of the contents into the packaging container, so that the contents can be stored for a longer period of time.

[0010] In this embodiment, the contents to be packaged can be exemplified by, for example, foods such as steamed buns, roll bread, steamed bread, mochi, and senbei as typical contents, but are not limited thereto. Non-food items in which the oxygen remaining in the container can have an adverse effect on storage can also be the packaging targets.

[0011] In this embodiment, first, the contents to be packaged are accommodated in a decompression chamber connected to a vacuum pump under atmospheric pressure. When accommodating the contents to be packaged in the decompression chamber, the contents may be accommodated in plural or individually according to the size of the contents and the volume of the decompression chamber.

[0012] Next, the decompression chamber is closed, the contents are sealed in the decompression chamber, and the vacuum pump is operated to evacuate the inside of the decompression chamber. Then, when the inside of the decompression chamber is decompressed to the primary decompression level, an inert gas is allowed to flow into the decompression chamber while continuing the evacuation.

[0013] The inert gas is not particularly limited as long as it is chemically inert to the contents. For example, at least one inert gas selected from the group consisting of nitrogen, carbon dioxide, argon, and helium can be used.

[0014] In this way, by introducing an inert gas into the decompression chamber, the surroundings of the contents are gas-substituted with the inert gas, creating a difference in the partial pressure of oxygen gas between the inside of the contents and the outer peripheral part of the contents. As a result, the oxygen contained inside the contents is effectively diffused and released into the atmosphere of the outer peripheral part of the contents where the partial pressure of oxygen gas is relatively low. Moreover, since the evacuation of gas inside the chamber continues, the oxygen diffused and released to the outer peripheral part of the contents is effectively discharged outside the decompression chamber.

[0015] When operating a vacuum pump connected to the decompression chamber to evacuate the inside of the decompression chamber, generally, the evacuation speed of the vacuum pump is fast at a stage where the degree of decompression inside the decompression chamber is low, and gradually slows down as the degree of decompression inside the decompression chamber increases. For this reason, when attempting to gas-substitute the outer peripheral part of the contents with an inert gas at a stage where the degree of decompression is low, it is necessary to increase the inflow amount of the inert gas. To introduce an amount of inert gas into the decompression chamber that matches the evacuation speed of the vacuum pump while preventing a large fluctuation in the degree of decompression inside the decompression chamber, not only does the flow rate adjustment become complicated, but it also results in an unnecessary inflow of the inert gas, which is disadvantageous in terms of cost.

[0016] On the other hand, when performing gas substitution at a high degree of decompression, the removal efficiency of oxygen contained in the contents tends to decrease. This is thought to be because the discharge of the inflowing inert gas outside the decompression chamber is prioritized over the diffusion and release of the oxygen contained inside the contents into the surrounding inert gas atmosphere. Furthermore, if the gas substitution of the outer peripheral part of the contents is continued at a high degree of decompression, the removal of components related to the flavor and quality of the contents, such as moisture and flavor components originally present in the contents, is also promoted, which may lead to a deterioration in the quality of the contents.

[0017] Considering these factors, as a condition for selectively removing the oxygen remaining inside the contents, the primary degree of decompression is preferably 20 kPa to 80 kPa, more preferably 30 kPa to 70 kPa, in terms of absolute pressure.

[0018] Also, the exhaust speed V1 [L / min] for evacuating the inside of the decompression chamber varies depending on the performance of the vacuum pump (exhaust speed under standard atmospheric pressure, ultimate vacuum) and the volume of the decompression chamber, and the inflow speed V2 [L / min] for allowing an inert gas to flow into the decompression chamber is also determined in relation to the exhaust speed V1 for evacuating the inside of the decompression chamber.

[0019] In this embodiment, when an inert gas is allowed to flow into the decompression chamber while continuing to evacuate after the inside of the decompression chamber has been decompressed to the primary decompression level, the degree of decompression (absolute pressure) inside the decompression chamber is measured with a vacuum gauge, and while monitoring its variation, the inflow speed of the inert gas (inert gas inflow speed under the primary decompression level) V2 can be adjusted. At this time, if V1 = V2, the degree of decompression inside the decompression chamber changes with a constant value. If V1 > V2, the degree of decompression inside the decompression chamber rises, and if V1 < V2, the degree of decompression inside the decompression chamber falls. In any case, it is preferable to adjust the inflow speed V2 of the inert gas under the primary decompression level so that the variation in the degree of decompression inside the decompression chamber falls within the aforementioned range defined for the primary decompression level, that is, within a range of preferably 20 kPa to 80 kPa, more preferably 30 kPa to 70 kPa, in terms of absolute pressure.

[0020] Also, when allowing an inert gas to flow into the decompression chamber, the inflow time (inert gas inflow time under the primary decompression level) is preferably 5 seconds to 1200 seconds, and more preferably 10 seconds to 600 seconds. If the inert gas inflow time under the primary decompression level is a short time of less than 5 seconds, there is a risk that the surrounding of the content cannot be sufficiently gas-replaced with the inert gas, resulting in a decrease in the removal efficiency of oxygen contained in the content. On the other hand, if the inert gas inflow time under the primary decompression level is longer than 1200 seconds, the removal of moisture, flavor components, etc. of the content is promoted, which may lead to a deterioration in the quality of the content.

[0021] In this way, by appropriately reducing the pressure inside the decompression chamber and gas-substituting the outer peripheral portion of the content with an inert gas, it becomes possible to selectively remove the oxygen contained in the content without impairing the flavor of the content. However, since oxygen is also adsorbed or sorbed on the inner wall portion of the apparatus of the decompression chamber made of metal, it is also necessary to remove the oxygen adsorbed or sorbed on the inner wall of the decompression chamber apparatus. This is because, in a subsequent process, there is a risk that the oxygen adsorbed or sorbed on the inner wall portion of the decompression chamber is released and transferred to the content.

[0022] In the present embodiment, in order to effectively avoid such a problem, after the inflow of the inert gas into the decompression chamber is stopped at the primary degree of decompression, the evacuation inside the decompression chamber is continued until the degree of decompression inside the decompression chamber reaches a secondary degree of decompression with a higher degree of vacuum. By this evacuation, by further increasing the degree of decompression inside the decompression chamber to a higher vacuum, the oxygen adsorbed or sorbed on the inner wall portion of the decompression chamber is also promoted to be released and removed from the inner wall portion of the decompression apparatus. As a result, the oxygen adsorbed or sorbed on the inner wall portion of the decompression chamber can be discharged outside the decompression chamber, thereby promoting the removal of oxygen that may migrate to the content. te At this time, the secondary degree of decompression can be appropriately set according to the performance of the vacuum pump within a range that does not impair the appearance of the content or promote the removal of moisture, flavor components, etc. of the content. The secondary degree of decompression is preferably, for example, from 0.1 kPa to 10 kPa, more preferably from 1 kPa to 8 kPa, in terms of absolute pressure.

[0023] At this time, the secondary degree of decompression can be appropriately set according to the performance of the vacuum pump within a range that does not impair the appearance of the content or promote the removal of moisture, flavor components, etc. of the content. The secondary degree of decompression is preferably, for example, from 0.1 kPa to 10 kPa, more preferably from 1 kPa to 8 kPa, in terms of absolute pressure.

[0024] After the degree of vacuum in the vacuum chamber reaches the secondary degree of vacuum, the evacuation in the vacuum chamber is stopped, and an inert gas is allowed to flow into the vacuum chamber again to restore the pressure in the vacuum chamber to atmospheric pressure. At this time, the inflow rate of the inert gas into the vacuum chamber is not particularly limited as long as the contents in the vacuum chamber are not deformed, collapsed, scattered, etc. due to the inflow of the inert gas and there is no problem with the appearance and quality of the contents. Also, the pressure in the vacuum chamber may be returned to atmospheric pressure by opening the vacuum chamber under an inert gas atmosphere.

[0025] Further, after the pressure in the vacuum chamber is made equal to atmospheric pressure, an inert gas can be further introduced into the vacuum chamber to increase the pressure in the vacuum chamber above atmospheric pressure. In this case, it can be expected that the oxygen remaining in the contents is further replaced by the inert gas and more oxygen is removed from the contents. However, it goes without saying that before taking out the contents, the pressure in the vacuum chamber is reduced to be equal to atmospheric pressure.

[0026] Thereafter, the contents are taken out from the vacuum chamber and subjected to gas replacement packaging. As the packaging container used for gas replacement packaging, it is preferable to use a known packaging container provided with an oxygen absorption function so that the oxygen remaining in the container can be absorbed. However, even without using such a packaging container, a known oxygen absorber may be enclosed so that the oxygen remaining in the container is absorbed.

[0027] According to the present embodiment as described above, prior to gas replacement packaging of the contents in the packaging container, by efficiently removing the oxygen contained in the contents, particularly in the case where the contents to be packaged are bulky and contain more oxygen, the oxygen released from the contents and remaining in the container is reduced so that it can be sufficiently absorbed by the oxygen absorption function provided in the packaging container or the oxygen absorbent enclosed in the container, and the contents can be stored for a longer period.

Example

[0028] Hereinafter, the present invention will be described in more detail with specific examples.

[0029] [Examples 1 to 7, Comparative Examples 1 to 7] A vacuum pump with an exhaust speed of 200 L / min under standard atmospheric pressure and an ultimate vacuum of 0.067 Pa was connected to a decompression chamber with a volume of 70 L. One bun with a weight of 50 g was placed in such a decompression chamber. After sealing the decompression chamber, the inside of the decompression chamber was evacuated.

[0030] When the pressure in the decompression chamber was reduced to the primary degree of decompression, while continuing the evacuation, nitrogen gas was introduced into the decompression chamber at an inflow rate V2 and an inflow time T. Table 1 and Table 2 show whether the inflow of the inert gas under the primary degree of decompression was stable or unstable, together with the primary degree of decompression, the inflow rate V2, and the inflow time T at this time.

[0031] Thereafter, the evacuation was continued until the pressure in the decompression chamber was reduced to the secondary degree of decompression. After stopping the evacuation, nitrogen gas was introduced into the decompression chamber at the same inflow rate as the inflow rate of the inert gas under the primary decompression, and the pressure in the decompression chamber was restored until it became equal to the atmospheric pressure. Table 1 and Table 2 show the secondary degree of decompression at this time. In Comparative Example 7, the pressure in the decompression chamber was restored to be equal to the atmospheric pressure without reducing it to the secondary degree of decompression.

[0032] After the inside of the decompression chamber was restored to atmospheric pressure with nitrogen gas, the bun was taken out of the decompression chamber under a nitrogen gas atmosphere and gas replacement packaging (pillow packaging using an oxygen-absorbing film (manufactured by Toyo Seikan Kaisha, Ltd.: Oxideck (registered trademark))) was performed with nitrogen gas. In Comparative Example 1, only gas replacement packaging with nitrogen gas was performed, and the operation of removing oxygen contained in the contents was not carried out.

[0033] The headspace in the container after gas replacement packaging was 82 mL. Tables 1 and 2 show the oxygen concentration in the container immediately after gas replacement packaging and the oxygen concentration in the container after storage at 5°C for 24 hours. For the measurement of oxygen concentration, an oxygen concentration meter (LC-750F) manufactured by Toray Engineering was used.

[0034] In addition, the appearance of the contents after gas replacement packaging and the flavor of the contents after storage at 5°C for 24 hours were evaluated according to the following evaluation criteria. [Evaluation Criteria] ◎: All 5 evaluators evaluated it as passing. 〇: 3 or more of the 5 evaluators evaluated it as passing. ×: 2 or fewer of the 5 evaluators evaluated it as passing. The evaluation results are shown in Tables 1 and 2.

[0035]

Table 1

[0036]

Table 2

[0037] As described above, the present invention has been described by showing preferred embodiments. However, it goes without saying that the present invention is not limited only to the above-described embodiments, and various modifications can be made within the scope of the present invention.

Claims

1. When gas-replacing and packaging the contents in a packaging container, accommodating the contents in a decompression chamber and sealing it, evacuating the inside of the decompression chamber, decompressing the inside of the decompression chamber to a primary decompression level, and then while continuing the evacuation, flowing an inert gas into the decompression chamber, thereafter, while continuing the evacuation, stopping the inflow of the inert gas into the decompression chamber, further decompressing the inside of the decompression chamber to a secondary decompression level, then, stopping the evacuation inside the decompression chamber, flowing an inert gas into the decompression chamber again, making the pressure inside the decompression chamber equal to the atmospheric pressure, and then taking out the contents from the decompression chamber and performing gas-replacing packaging. A packaging method characterized by this.

2. The packaging method according to Claim 1, wherein the primary decompression level is 20 kPa to 80 kPa in absolute pressure.

3. When flowing an inert gas into the decompression chamber while continuing the evacuation after decompressing the inside of the decompression chamber to the primary decompression level, adjusting the inflow rate of the inert gas so that the variation in the decompression level inside the decompression chamber is within a range of 20 kPa to 80 kPa in absolute pressure. The packaging method according to Claim 2.

4. When flowing an inert gas into the decompression chamber while continuing the evacuation after decompressing the inside of the decompression chamber to the primary decompression level, the inflow time of the inert gas is 5 seconds to 1200 seconds. The packaging method according to any one of Claims 1 to 3.

5. The packaging method according to any one of Claims 1 to 4, wherein the secondary decompression level is 0.1 kPa to 10 kPa in absolute pressure.

6. The packaging method according to any one of Claims 1 to 4, wherein the secondary decompression level is 1 kPa to 8 kPa in absolute pressure.

7. The packaging method according to any one of claims 1 to 6, wherein the inert gas is at least one selected from the group consisting of nitrogen, carbon dioxide, argon, and helium.

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