A method of sealing a glass bottle for use in ambient temperature drinks

Abstract

The present application relates to the field of food processing, and particularly relates to a sealing method of a glass bottle for normal-temperature drinks. The method comprises: sealing the glass bottle and an aluminum foil film through hot-pressing; wherein the bottle mouth of the glass bottle is provided with an ethylene-acrylic acid copolymer coating; the aluminum foil film is provided with a PE (polyethylene) layer on the side adhered to the bottle mouth of the glass bottle, and the coating area of the PE layer covers at least the area adhered to the bottle mouth of the glass bottle. The present application can realize effective long-term sealing of the glass bottle at normal temperature only by relying on the sealing capacity of the aluminum foil film, and the opening force of the aluminum foil film after sealing is moderate. Meanwhile, the sealing property and the easy-tearing degree of the aluminum foil film do not obviously decrease after long-term (up to 84 days) preservation at normal temperature, so that the sealing effect on the normal-temperature drinks can be guaranteed, and the shelf life requirement can be met. In addition, the present application is simple and easy to operate, and can be easily popularized and applied in actual production.

Description

Technical Field

[0001] This invention relates to the field of food processing, and more specifically to a sealing method for glass bottles used for room-temperature beverages. Background Technology

[0002] Glass has excellent barrier properties, effectively preventing the intrusion of gases such as oxygen into the contents and preventing the release of volatile components into the atmosphere. Furthermore, it is safe and hygienic, with good resistance to corrosion and acid corrosion, making it suitable for packaging acidic substances (such as yogurt, fruit and vegetable juices, etc.). In addition, glass bottles can be reused multiple times, which helps reduce packaging costs.

[0003] The introduction of glass bottle packaging into the room-temperature yogurt market can provide consumers with a better shopping experience, allowing them to directly see the contents and enhancing the product's appearance. However, glass is a non-crystalline melt with no fixed melting point. Even under heat sealing, it is not easy to effectively bond with the adhesive layer at the bottom of the aluminum foil film, leading to poor sealing and packaging defects during the shelf life, thus affecting the product's shelf life. Therefore, the most common packaging materials for room-temperature yogurt in China are currently aluminum-plastic composite paper-based materials or polyester materials.

[0004] Given the significant technological barriers and broad application prospects of using glass bottles for room-temperature yogurt, solving the sealing problem of glass bottles is crucial for new product development and market launch.

[0005] Currently, the common method of sealing glass bottles with aluminum foil composite film requires heat sealing and screw capping to compress the aluminum foil film. It is impossible to achieve effective long-term sealing of room-temperature yogurt in glass bottles by relying solely on the sealing ability of the aluminum foil cap film without the need for compression from the outer packaging.

[0006] Furthermore, while CN105197399A mentions an easy-open aluminum-plastic composite single-piece sealing film for glass bottles, made from a mixture of low-density polyethylene, linear low-density polyethylene, and ethylene-(meth)acrylate copolymer resin, ensuring moderate sealing strength, moderate peeling force, clean peeling interface, and no significant degradation after refrigeration, the low-temperature environment itself can inhibit oxidation of the contents caused by poor sealing. Additionally, the shelf life of low-temperature dairy products is generally 21 days, far less than the 3-6 months of room-temperature dairy products. Therefore, compared to room-temperature dairy products, low-temperature refrigerated products have lower requirements for sealing conditions in terms of production environment, cold chain transportation, and sales environment. The sealing film in CN105197399A can only be applied to low-temperature dairy products or beverages with small inner diameter bottle openings, and has no potential application for room-temperature products. Summary of the Invention

[0007] This invention, after multiple tests, combined with tests on various factors such as heat sealing equipment, sealing gaskets, aluminum foil film structure, aluminum foil film thickness, sealing stroke, and sealing temperature, finally determined an effective sealing method that meets the shelf life requirements of room temperature yogurt, and also provides a sealing method for glass bottles that can be used for room temperature beverages.

[0008] Specifically, the present invention first provides a method for sealing a glass bottle, which includes:

[0009] The glass bottle and aluminum foil are sealed together by heat pressing;

[0010] The glass bottle has an ethylene-acrylic acid copolymer coating at its mouth; the aluminum foil film has a PE (polyethylene) layer on the side that is bonded to the glass bottle mouth, and the coating area of ​​the PE layer at least covers the area that is bonded to the glass bottle mouth.

[0011] The present invention unexpectedly discovered that, compared with the method of simply setting composite adhesive material or composite coating on aluminum foil film, by setting the above coating on the bottle mouth of glass bottle and the surface of aluminum foil film to be bonded respectively and then performing hot pressing and sealing, the bonding effect between glass bottle and aluminum foil film can be significantly improved, which is beneficial to greatly improving the sealing performance after bonding.

[0012] Preferably, the thickness of the PE layer is 45-60 μm.

[0013] Preferably, the density of the ethylene-acrylic acid copolymer coating is 0.8-1.2 g / cm³. 3 More preferably 1 g / cm 3 .

[0014] The present invention also found that the bonding and sealing effect can be further optimized by optimizing the thickness of the PE layer and / or the density of the ethylene-acrylic acid copolymer coating.

[0015] Based on the application environment of this invention, those skilled in the art can obtain the corresponding ethylene-acrylic acid copolymer and polyethylene raw materials through commercial channels. When applied in this invention, they can all achieve good technical effects, and no further limitations are made here.

[0016] Preferably, during hot-press sealing, the sealing head pressure of the glass bottle and aluminum foil film bonding surface is controlled to be 2-3 bar, more preferably 2.5±0.2 bar, and the surface to be bonded is controlled to reach 230-260°C through a heating time of 1-2 seconds.

[0017] As a preferred option, the specific operations during hot-press sealing include:

[0018] The heating head is set to a temperature of 230-260℃ and a drop stroke of 84-86μm, and the heat is transferred to the surface to be bonded through a gasket.

[0019] The above methods can provide more ideal pressure and temperature to the surfaces to be bonded, which is more conducive to optimizing the bonding effect.

[0020] Preferably, the gasket includes a silicone gasket; more preferably, the thickness of the silicone gasket is 1.3-2 mm; even more preferably, the ratio of the thickness of the silicone gasket to the thickness of the PE layer is 0.025-0.035 mm: 1 μm.

[0021] This invention reveals that the above-mentioned arrangement further facilitates a more ideal heating rate on the surfaces to be bonded, thereby further improving the bonding and sealing effects. Furthermore, the silicone gasket can compensate for unevenness at the bottle opening through soft contact, ensuring a more thorough seal.

[0022] Preferably, the gasket includes a stainless steel gasket and a silicone gasket, wherein the silicone gasket is disposed on the side near the bottle opening. More preferably, the thickness of the stainless steel gasket is 0.5-1.5 mm, further preferably 1 ± 0.2 mm, and most preferably 1 mm.

[0023] Stainless steel gaskets not only transfer heat but also protect and cushion silicone gaskets, thus extending the lifespan of the instrument without affecting the bonding effect.

[0024] As a preferred embodiment of the present invention, the specific operations during hot-press sealing include:

[0025] The heating head is set to a temperature of 240±5℃ and a drop stroke of 85±0.5μm. Heat is transferred to the surface to be bonded by passing through a stainless steel pad with a thickness of 0.2-1.8mm and a silicone pad with a thickness of 1.5±0.2mm in sequence.

[0026] This solution allows for both excellent sealing performance of glass bottle packaging and ideal tearability of aluminum foil film.

[0027] In actual processing, it is generally necessary to disinfect and / or sterilize the glass bottles and aluminum foil before sealing. This may involve dust removal and hydrogen peroxide spraying of the glass bottles, or immersing the aluminum foil in hydrogen peroxide, etc. Those skilled in the art can easily determine the disinfection and / or sterilization procedures based on common knowledge, and no further limitations are made here.

[0028] Those skilled in the art can combine the above preferred solutions based on common sense to obtain a preferred embodiment of the glass bottle sealing method of the present invention.

[0029] The present invention further provides the application of the glass bottle sealing method in beverage processing.

[0030] Preferably, the beverage is a room temperature beverage, and more preferably, room temperature yogurt.

[0031] Based on the above technical solution, the beneficial effects of the present invention are as follows:

[0032] This invention achieves effective long-term sealing of glass bottles at room temperature solely through the combination of aluminum foil film and bottle neck coating, while maintaining moderate opening force of the aluminum foil film after sealing. Furthermore, even after long-term storage at room temperature (up to 84 days), the sealing performance and tear resistance do not significantly decrease, thus ensuring a reliable seal for room-temperature beverages and meeting their shelf-life requirements. In addition, this invention is simple and easy to implement, making it readily applicable in actual production. Attached Figure Description

[0033] Figure 1 The results are from the preference test in Experiment Example 3.

[0034] Figure 2 These are the descriptive test results from Experiment Example 3.

[0035] Figure 3 The results of the sensory attribute changes in Experiment Example 3. Detailed Implementation

[0036] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the invention.

[0037] To facilitate comparison, the glass bottles in the following examples and comparative examples were treated with dust removal and hydrogen peroxide spraying before hot-press sealing, and the aluminum foil film was treated with hydrogen peroxide soaking. In addition, the glass bottles in each example and comparative example were filled with yogurt, and the yogurt belonged to the same batch.

[0038] The ethylene-acrylic acid copolymer and PE used in the following examples are conventional commercially available raw materials that can be used in adhesive coatings. Those skilled in the art can obtain the corresponding ethylene-acrylic acid copolymer and polyethylene raw materials through commercial channels, and their application in this invention can achieve technical effects comparable to those in the following examples.

[0039] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0040] Example 1

[0041] This embodiment provides a method for sealing glass bottles, the specific operation of which is as follows:

[0042] The glass bottle and aluminum foil are sealed together by heat pressing;

[0043] The glass bottle has an ethylene-acrylic acid copolymer coating at its mouth, and the density of the ethylene-acrylic acid copolymer coating is 1 g / cm³. 3 The aluminum foil film has a PE layer on the side that is bonded to the glass bottle opening, and the thickness of the PE layer is 50μm.

[0044] The specific procedures for hot-press sealing include:

[0045] The heating head is set to a temperature of 240℃ and a drop stroke of 85μm. Heat is then transferred to the surfaces to be bonded by passing through a 1mm thick stainless steel pad and a 1.5mm thick silicone pad in sequence.

[0046] Example 2

[0047] This embodiment provides a method for sealing glass bottles, the specific operation of which is as follows:

[0048] The glass bottle and aluminum foil are sealed together by heat pressing;

[0049] The glass bottle has an ethylene-acrylic acid copolymer coating at its mouth, and the density of the ethylene-acrylic acid copolymer coating is 1 g / cm³. 3 The aluminum foil film has a PE layer on the side that is bonded to the glass bottle opening, and the thickness of the PE layer is 50μm.

[0050] The specific procedures for hot-press sealing include:

[0051] The heating head is set to a temperature of 260℃ and a drop stroke of 85μm. Heat is then transferred to the surfaces to be bonded by passing through a 1mm thick stainless steel pad and a 1.5mm thick silicone pad in sequence.

[0052] Example 3

[0053] This embodiment provides a method for sealing glass bottles, the specific operation of which is as follows:

[0054] The glass bottle and aluminum foil are sealed together by heat pressing;

[0055] The glass bottle has an ethylene-acrylic acid copolymer coating at its mouth, and the density of the ethylene-acrylic acid copolymer coating is 1 g / cm³. 3 The aluminum foil film has a PE layer on the side that is bonded to the glass bottle opening, and the thickness of the PE layer is 50μm.

[0056] The specific procedures for hot-press sealing include:

[0057] The heating head is set to a temperature of 240℃ and a drop stroke of 86μm. Heat is then transferred to the surfaces to be bonded by passing through a 1mm thick stainless steel pad and a 1.5mm thick silicone pad.

[0058] Example 4

[0059] This embodiment provides a method for sealing glass bottles, the specific operation of which is as follows:

[0060] The glass bottle and aluminum foil are sealed together by heat pressing;

[0061] The glass bottle has an ethylene-acrylic acid copolymer coating at its mouth, and the density of the ethylene-acrylic acid copolymer coating is 1 g / cm³. 3 The aluminum foil film has a PE layer on the side that is bonded to the glass bottle opening, and the thickness of the PE layer is 60μm.

[0062] The specific procedures for hot-press sealing include:

[0063] The heating head is set to a temperature of 240℃ and a drop stroke of 85μm. Heat is then transferred to the surfaces to be bonded by passing through a 1mm thick stainless steel pad and a 2mm thick silicone pad in sequence.

[0064] Example 5

[0065] This embodiment provides a method for sealing glass bottles, the specific operation of which is as follows:

[0066] The glass bottle and aluminum foil are sealed together by heat pressing;

[0067] The glass bottle has an ethylene-acrylic acid copolymer coating at its mouth, and the density of the ethylene-acrylic acid copolymer coating is 1 g / cm³. 3 The aluminum foil film has a PE layer on the side that is bonded to the glass bottle opening, and the thickness of the PE layer is 50μm.

[0068] The specific procedures for hot-press sealing include:

[0069] The heating head is set to a temperature of 240℃ and a drop stroke of 85μm. Heat is then transferred to the surfaces to be bonded by passing through a 1mm thick stainless steel pad and a 2mm thick silicone pad in sequence.

[0070] Comparative Example 1

[0071] This comparative example provides a glass bottle sealing method, which differs from Example 1 only in that it is sealed by electromagnetic induction.

[0072] The aluminum foil cap is placed at the bottle mouth, and the glass bottle runs on the conveyor belt of the equipment. It passes through the electromagnetic induction sealing head of the equipment, and the sealing time is 3.9 seconds per cycle. The operation ends after the electromagnetic sealing by the sealing head.

[0073] Comparative Example 2

[0074] This comparative example provides a glass bottle sealing method, which differs from Example 1 only in that the glass bottle is replaced with a glass bottle without an ethylene-acrylic acid copolymer coating, and the aluminum foil film is coated with the mixture coating of Example 1 in CN105197399A. The coating body is composed of the following components by weight percentage: 29.47% low-density polyethylene, 40.81% linear low-density polyethylene, and 29.72% ethylene-(meth)acrylate copolymer resin.

[0075] The aluminum foil cap film coated with the mixture is placed at the bottle mouth, and the operation is completed after the heat sealing process by the sealing head.

[0076] Experimental Example 1

[0077] This test example examines the sealing performance and tear resistance of the sealed glass bottles obtained from each embodiment and comparative example.

[0078] Sealing test method: A vacuum is drawn using a sealing tester to create a negative pressure environment inside the sealing test chamber. Each group consists of 10 bottles, and the leakage is tested under a pressure environment of -60 kPa for 1 minute. If none of the 1000 glass bottles leak, the test is considered passed (excellent sealing effect); otherwise, it is considered failed (insufficient sealing effect).

[0079] Opening force test method: The aluminum foil film is torn manually, and the results are divided into three different categories according to the difficulty of tearing: easy to tear; acceptable tearing; difficult to tear.

[0080] The test results are shown in Table 1 below.

[0081] Table 1

[0082]

[0083]

[0084] As can be seen from the above, the sealed glass bottle obtained by the method of Example 1 has the best performance, not only passing the sealing test, but also having a moderate opening force.

[0085] Experimental Example 2

[0086] This experiment conducted follow-up tests on the sealing performance and opening force performance of the sealed glass bottle obtained in Example 1 (20 tests were conducted for each test item, and the sealing test method and opening force test method were the same as in Example 1). The results are shown in Table 2 below:

[0087] Table 2

[0088] Storage time at room temperature Sealing test Opening force test 7 days pass Tearing is acceptable 14 days pass Tearing is acceptable 21 days pass Tearing is acceptable 28 days pass Tearing is acceptable 35 days pass Tearing is acceptable 42 days pass Tearing is acceptable 49 days pass Tearing is acceptable 56 days pass Tearing is acceptable 63 days pass Tearing is acceptable 70 days pass Tearing is acceptable 77 days pass Tearing is acceptable 84 days pass Tearing is acceptable

[0089] The results show that the sealing performance and opening force performance of the sealed glass bottle obtained in Example 1 did not significantly decrease within 84 days, meeting the requirements for degradation during the shelf life.

[0090] In addition, the present invention also conducted follow-up tests on the sealing performance and opening force performance of the glass bottles that did not leak under the sealing test in Examples 2-5, referring to the above method. Examples 2-4 showed no sealing failure on day 84, while Example 5 showed sealing failure on days 30-35.

[0091] Experimental Example 3

[0092] This experimental example involves sensory testing and analysis of the yogurt in the sealed glass bottle obtained in Example 1.

[0093] 1. Preference Test - 0d

[0094] The specific testing method is as follows: Prepare 50 tasting cups, each containing 20ml of yogurt. 50 tasters will taste the yogurt and score it according to the set evaluation dimensions using a 9-point evaluation method. 1 point represents extremely dislike, and 9 points represent extremely like. The scores are given in ascending order of preference from 1 to 9. Finally, the preference test results of the samples are inferred through data processing and analysis.

[0095] See results Figure 1 The liking test results show that the overall liking level is between average and somewhat likable, with 56% of respondents scoring 6 points or higher.

[0096] 2. Descriptive Test - 0d

[0097] The specific testing method is as follows:

[0098] The test was conducted by 50 professionals. Each professional tasted the product, analyzed its advantages and disadvantages, described specific product indicators, and provided a detailed account of the consumer experience.

[0099] See results Figure 2 Analysis revealed that the sensory characteristics of BY (the abbreviation for the yogurt sample used in the specific implementation) were as follows: the main characteristic flavors (milky and creamy) and textural characteristics (flavor consistency, fat content, and retention) were relatively weak; the fermented flavor, sourness, and powdery texture were moderate. Furthermore, the yeast flavor and particulate matter had no significant impact on preference.

[0100] 3. Analysis of changes in sensory attributes

[0101] Following the method described in section 2, descriptive tests were conducted on the yogurt in the bottle after 0 days, 42 days of storage at room temperature, and 84 days of storage at room temperature. The results were recorded and statistically analyzed. Figure 3 .

[0102] The results show that as the shelf life is extended, the surface whiteness, sweetness, powdery texture, retention, yeast flavor, particulate matter, and oxidized flavor of the BY sample change significantly. Among them, surface whiteness, powdery texture, yeast flavor, and particulate matter show a significant decreasing trend, while retention and oxidized flavor show a significant increasing trend.

[0103] Furthermore, this invention also conducted sensory testing and analysis on the yogurt in the glass bottle in the comparative example using the aforementioned method. After being left at room temperature for approximately 7 days, it exhibited similar characteristics to the BY sample left for 84 days: the surface whiteness, powdery texture, yeast flavor, and particulate matter of the sample showed a significant decreasing trend, while the retention and oxidized flavor showed a significant increasing trend. The reason for this is that the comparative example could not achieve effective sealing; the glass bottle opening and the inner layer of the aluminum foil did not adhere to each other, resulting in air exchange between the sample and the external environment. Under the influence of oxygen, the product easily underwent oxidation reactions, generating primary or secondary oxidation products such as alcohols, aldehydes, and ketones, leading to a severe oxidized flavor.

[0104] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for sealing glass bottles, characterized in that, It includes: The glass bottle and aluminum foil are sealed together by heat pressing; The glass bottle has an ethylene-acrylic acid copolymer coating at its mouth; the aluminum foil film has a PE layer on the side that is bonded to the glass bottle mouth, and the PE layer coating area at least covers the area bonded to the glass bottle mouth. During hot-press sealing, the sealing head pressure of the surfaces to be bonded is controlled at 2~3 bar, and the surface to be bonded is controlled to reach 230-260℃ through a heating time of 1~2 seconds. During hot-press sealing, the specific operations include: setting the temperature of the heating head to 235~245℃ and the drop stroke to 84.5~85.5μm, and transferring heat to the surface to be bonded by sequentially passing a stainless steel gasket with a thickness of 0.2-1.8mm and a silicone gasket with a thickness of 1.3~1.7mm; the ratio of the thickness of the silicone gasket to the thickness of the PE layer is 0.025-0.035mm:1μm.

2. The glass bottle sealing method according to claim 1, characterized in that, The thickness of the PE layer is 45-60 μm.

3. The glass bottle sealing method according to claim 1 or 2, characterized in that, The density of the ethylene-acrylic acid copolymer coating is 0.8-1.2 g / cm³. 3 .

4. The glass bottle sealing method according to claim 1, characterized in that, The silicone gasket is positioned on the side near the bottle opening.

5. The application of the glass bottle sealing method according to any one of claims 1-4 in beverage processing.

6. The application according to claim 5, characterized in that, The beverage in question is a room temperature beverage.

7. The application according to claim 5, characterized in that, The beverage in question is room temperature yogurt.

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