HK1099492B - Using carbon dioxide regulators to extend the shelf life of plastic packaging - Google Patents

Description

Extending shelf life of plastic packages using carbon dioxide regulators

Cross Reference to Related Applications

This application claims priority from the following patent applications: provisional patent application 60/548,286 filed on day 2/27 of 2004 and provisional patent application 60/628,737 filed on day 11/17 of 2004 and provisional patent application entitled "extending shelf life of plastic packages using carbon dioxide regulators" filed on day 2/24 of 2005.

Background

In the field of bottled beverages where ease of handling, low weight and uncrushability are required, plastic and metal containers have been replacing glass. Plastic packaging, particularly polyethylene terephthalate (PET) bottles, have been widely used for packaging carbonated products such as beer, soft drinks, distilled water, and some dairy products. Each of these products has optimal carbonation or carbon dioxide (sometimes referred to herein as "CO") within its package₂") pressure to maintain its optimum quality. In conventional plastic packaging, it is difficult to introduce CO over a long period of time₂The pressure is maintained at this optimum level.

CO₂Can penetrate the plastic packaging, thereby causing the pressure in the bottle to decrease over time. Eventually, after a certain amount of carbonic acid gas is lost, the product will no longer be suitable for use, which is often manifested as a noticeable and unacceptable change in taste or flavor. The point at which this occurs typically determines the shelf life of the package. CO 2₂The rate of loss depends largely on the weight and size of the package and the temperature at which it is stored. Lighter, thinner bottles lose carbonation more quickly and fail to maintain high internal pressure, resulting in shorter shelf life. As the plastic bottle becomes smaller, the relative rate of carbonic acid gas loss becomes faster. The higher temperatures allow faster permeation, which reduces shelf life and makes it difficult to store carbonated beverages in plastic containers in hot weather and still maintain a reasonable shelf life. The longer shelf life, lighter, cheaper plastic bottles and the ability to store the bottles longer without cooling have many economic advantages.

Various methods have been adopted to solve the above problems. A convenient way to extend the length of a carbonated beverage is to add additional carbon dioxide at the time of filling. This method is commonly used for carbonated soft drinks and beer, but is responsible for product quality due to overcarbonationThe effect of (a) and the resulting negative impact on the physical properties of the bottle is hindered. Small differences in internal pressure in the package can cause significant differences in the quality of the beverage upon foaming. Dissolved CO₂Taste can also be affected. These precise requirements vary from product to product.

Overcarbonation can also be hindered by the pressure limitations of the package. It is possible to make the bottle more pressure resistant, but this requires the use of additional materials in the bottle structure or requires more highly functional plastics.

Can be used for reducing CO₂Permeation rate while maintaining carbonation. This typically involves applying a second barrier coating to the PET bottle, using a more expensive, more difficult to penetrate polymer than PET, making a multi-layer bottle structure, or using a combination of the above methods. These manufacturing processes are much more expensive than the processes used in the production of conventional polyester bottles and often create new problems, particularly recycling.

In the prior art, carbon dioxide generating materials have been used to extend the shelf life of carbonated beverages. Molecular sieves treated with carbon dioxide have been used for carbonated beverages by reacting the bound carbon dioxide with water.

U.S. patent 6,852,783 to Hekal and U.S. patent application 2004/0242746A 1 to Freedman et al describe a CO₂A delivery composition which can be incorporated or inserted into the packaging of a carbonated beverage. The compositions of these references describe the incorporation of more than 25% by weight of an inorganic carbonate as a carbon dioxide source into the thermoplastic. A 32g PET bottle filled with 25% sodium bicarbonate has the potential to release 4.5g of carbon dioxide. This is about ten times higher than what is required in the use of PET beer bottles, which may result in unsafe pressurization of the package. Moreover, these structures release carbon dioxide too quickly to regulate the pressure over a long period of time, especially if the structures are made of polyethylene terephthalate, compared to structures made of polyethylene having a lower moisture permeation rate. It has been found that such high loadings are not suitable for application, since they do not result inWith the possibility of releasing too much carbon dioxide into the package.

Summary of The Invention

The present invention relates to a method of replenishing carbon dioxide gas in a carbonated beverage container. The method comprises inserting a carbon dioxide regulator into the beverage container or into the lid of the container and releasing carbon dioxide from the carbon dioxide regulator by a chemical reaction. The rate of release of carbon dioxide is adjusted to be about equal to the rate of carbon dioxide loss from the vessel.

The invention also relates to a method of replenishing carbon dioxide gas in a carbonated beverage container. The method comprises inserting a carbon dioxide regulator into a container or into a lid of a container and then adjusting the rate of release of carbon dioxide from the carbon dioxide regulator to about equal the rate of loss of carbon dioxide from the container.

The present invention also relates to a packaging system for maintaining pressure consistency of a carbonated beverage comprising a lid, a plastic container, and a carbon dioxide regulator.

The present invention also relates to a method of manufacturing a packaging system for maintaining pressure consistency of a carbonated beverage, the method comprising overmolding a preform (prerorm) around an assembly for a carbon dioxide regulator.

The present invention also relates to a method of manufacturing a packaging system for maintaining pressure consistency of a carbonated beverage, the method comprising mixing a carbon dioxide regulator into a plastic material used to form the container body of the carbonated beverage.

The present invention also relates to a carbon dioxide regulator composition for replenishing carbon dioxide gas in a carbonated beverage container, the composition comprising polycarbonate alone, organic carbonate alone, or a combination thereof.

The present invention also relates to a carbon dioxide regulator composition for replenishing carbon dioxide gas in a carbonated beverage container, the composition comprising a material that absorbs and subsequently releases carbon dioxide.

As used herein, a "carbonated beverage" is an aqueous solution in which the amount of dissolved carbon dioxide gas is from about 2 to about 5 volumes CO for a carbonated soft drink₂Volume H₂O, preferably about 3.3 to about 4.2 volumes CO₂Volume H₂O, dissolved carbon dioxide gas amount of about 2.7 to about 3.3 volumes CO for beer₂Volume H₂O。

As used herein, a "carbon dioxide regulator" is a composition that releases CO slowly, either by a controlled chemical reaction process₂Or by absorption and release of CO by physical processes₂Wherein the rate of release is approximately equal to the packaged CO₂The rate of loss, thereby keeping the carbon dioxide pressure in the package more constant over time.

Suitable CO₂The regulator comprises: polycarbonates, cyclic organic carbonates, such as alkyl carbonates, ethylene carbonate, propylene carbonate, polypropylene carbonate, ethylene carbonate, glycerol carbonate, butylene carbonate, diethyl carbonate, ethyl pyrocarbonate, methyl pyrocarbonate, dialkyl dicarbonates, or mixtures thereof; inorganic carbonates such as sodium bicarbonate, ferrous carbonate, calcium carbonate, lithium carbonate, and mixtures thereof; molecular sieves, zeolites, activated carbons, silica gels and coordination polymers, metal organic frameworks ("MOF's") and isoreticular metal organic frameworks ("IRMOF's"). CO 2₂The amount of regulator used depends on the amount of carbon dioxide release required, which depends on the amount of carbon dioxide lost from the container over its shelf life.

Can contain CO₂Bottle regions for the modulator include, but are not limited to: bottle caps, bottle necks/necks, bottle bottoms, or into the plastic resin that makes up the bottle.

Brief Description of Drawings

FIG. 1 depicts the effect of carbon dioxide regulator on the performance of PET beer bottles.

Figure 2 depicts the effect of a carbon dioxide regulator on the performance of carbonated soft drink bottles.

Figure 3 depicts a carbon dioxide regulator cap with a disk insert and gasket.

Figure 4 depicts a carbon dioxide regulator assembly with a disk and a liner.

Figure 5 depicts a carbon dioxide regulator cap with a plug-in assembly.

Fig. 6 depicts a carbon dioxide regulator bottle mouth insert assembly.

FIG. 7 depicts carbon dioxide production by water vapor activation of organic carbonates.

Figure 8 depicts the effect of bagged material on carbon dioxide release rate.

Figure 9 depicts the loss of carbon dioxide as a function of pressure in the bottle.

Fig. 10 depicts pre-saturation of carbon dioxide in a 20 oz bottle.

Detailed Description

A number of compositions can be used as carbon dioxide regulators. These compositions fall into two categories. The first type are compositions that generate or release carbon dioxide by controlled chemical reactions. These compositions comprise: a) polymers such as aliphatic polyketones, which when reacted with oxygen produce carbon dioxide as a dehydration by-product, or when hydrolyzed, especially in the presence of acids, produce organic and inorganic carbonate radicals which release carbon dioxide. Catalysts, binders, and other additives may be combined with these materials to assist in controlling the carbon dioxide release process; and b) organic carbonates such as alkyl carbonates, ethylene carbonate, propylene carbonate, polypropylene carbonate, ethylene carbonate, glycerol carbonate, butylene carbonate, diethyl carbonate, ethyl pyrocarbonate, methyl pyrocarbonate, cyclic carbonate acrylates such as trimethylolpropane carbonate acrylate, and dialkyl dicarbonates, which liberate carbon dioxide upon hydrolysis, the hydrolysis may be enhanced by reaction with an acid such as citric acid or phosphoric acid.

The second type are sorbent compositions that store carbon dioxide and subsequently release the carbon dioxide into a container when the carbon dioxide is lost from the package. These compositions comprise: sorbents such as silica gel; molecular sieves, zeolites, clays, activated alumina, activated carbon and coordination polymers, metal organic frameworks or "MOF's" and isoreticular metal organic frameworks or "IRMOF's", which are crystalline materials of metal oxides and organic acids similar to zeolites. These materials can be processed to various pore sizes and various carbon dioxide storage capacities.

The various carbon dioxide generators described above may be incorporated into the polymer from which the container or lid is made. It may also be present in layers in a multi-layer lid, liner or bottle. Alternatively, they may be moulded as inserts or discs which may be placed on top of the closure or in an insert which may be placed into the mouth region of the container. Figures 3-6 illustrate such designs.

In the conditioning of CO with moisture₂In a release rate system, the carbon dioxide regulator may be encapsulated or mixed with a suitable polymer, the polymer being selected based on its resistance to moisture and CO₂Permeability of (2). By appropriate selection of the encapsulating or barrier polymer, the rate of moisture permeation can be used to control CO₂CO in a package₂The loss rates are matched to obtain CO over a period of time₂The internal pressure remains close to constant packaging. This period of time is referred to as the conditioning period.

In the regulation of CO by oxygen₂In a release rate system, the carbon dioxide regulator may be encapsulated or mixed with a suitable polymer selected fromOxygen and CO depending on it₂Permeability of (2). Also by suitable selection, CO₂The rate of generation can be adjusted to the CO with the packaging₂The loss rate is matched and the CO is allowed to flow over a period of time₂The internal pressure remains nearly constant.

When made of CO₂When the adsorbent material is made into a carbon dioxide regulator, the additional CO required for prolonging the shelf life can be obtained by overcarbonation during filling₂And (4) doping. The package can be used with precise amounts of the desired CO₂For overcarbonation, the amount is based on the desired shelf life increase of the package, the conditioning time and the CO₂Permeability. The CO is₂The regulating material must be used for controlling the excess CO₂Rapidly adsorbing these excess CO before causing package deformation₂. The adsorption should occur within about six hours, preferably within about one hour. The CO is₂The regulator should then release the adsorbed carbon dioxide at a rate lower than, or preferably about the same as, the rate at which carbon dioxide is lost from the package. This ensures that a homogeneous and stable CO is maintained₂The internal pressure. The properties of a particular conditioner composition can be optimized by appropriate drying, impregnation and manufacturing conditions, all of which are well known to those skilled in the art. It is preferable to minimize the volume of the carbon dioxide regulator so that the space of the package can be effectively utilized.

Alternatively, a carbon dioxide regulator may be placed in the CO₂Gas environment, allowing it to adsorb and store sufficient CO₂Gas thereby using CO₂Prefilling a carbon dioxide regulator so as to replace CO lost from the vessel during normal use of the vessel₂。

The carbon dioxide regulator may be incorporated into the package in any manner. These methods include, but are not limited to: either in a small cup or as a prepared dish to place the conditioner in the lid. These are shown in figures 3-5. These designs have several components: a lid, a carbon dioxide regulator material, and a liner or cup material that carries the carbon dioxide regulator and can separate it from the package contents. The liner material can be coveredCO designed to assist in controlling carbon dioxide moderator material₂The loss rate is controlled by directly controlling CO₂Permeation rate or controlling the rate at which the activator can contact the carbon dioxide regulator. Water and water vapor can be used as activators in many systems. The amount of carbon dioxide regulator may vary depending on the needs of the package. For a small number of cases that increase shelf life, a thin insert may be placed into the lid. For situations where more carbon dioxide regulator is needed to increase shelf life to a greater extent, a cup or plug-and-lid design may be used to allow a larger amount of carbon dioxide regulator to be used.

The carbon dioxide regulator can be placed in the bottle by placing the formed sheet into a suitable position in the bottle after the carbon dioxide regulator is prepared. This is shown in figure 6. One method is to place a short tubular piece in the groove formed in the mouth region during or after blow moulding. Another method may be to remould the bottle preform around the carbon dioxide regulator component by: the assembly is placed on the center pin of a conventional injection mold, after which the preform is re-molded around the assembly using a polymer such as PET. The preform containing the carbon dioxide regulator component can then be blown into a bottle using conventional equipment. Another idea is to use a stretch rod to place the regulator assembly in the bottle during blow molding.

The carbon dioxide regulator may be mixed into a plastic material for forming a package or a lid. The preform containing the carbon dioxide regulator component is then blown into a bottle using conventional equipment. For such systems, it is advantageous that the carbon dioxide regulator is not active until the package is filled.

The carbon dioxide regulator may also be added to the multilayer article of manufacture in the form of a layer, which may be a layer of a bottle, a layer of a cap, or a layer of a liner. The layer can be made by any conventional multilayer extrusion process and manufacturing techniques common in the art, including multilayer fabrication, multilayer film extrusion, coating, and lamination. The number of layers in the final package shaped body may be two to ten layers, preferably three to five layers.

The release rate of the carbon dioxide regulator from the carbonic acid gas can be further controlled by laminating with a film, coating the carbon dioxide regulator assembly, or mixing the carbon dioxide regulator into another material, particularly into a plastic. This may also facilitate the manufacture of the carbon dioxide regulator into a form suitable for the application of the present invention. One method includes mixing the carbon dioxide regulator material into the polymer used to form the cap liner or mixing the carbon dioxide regulator material into the material used to make the cap itself.

Molecular sieves are preferred carbon dioxide modifiers of the present invention. Pure, uncompressed molecular sieves have high levels of CO absorption₂The ability of the cell to perform. The 13X molecular sieve absorbs about 18% of its weight of CO under bottle pressure₂. Thus, for a 12 ounce carbonated soft drink bottle carbonated to 4.0 volumes, about 0.525 grams of CO is required₂Gas to replace CO lost from packaging₂Thereby doubling the shelf life. Molecular sieves suitable for use as carbon dioxide regulators include, but are not limited to: aluminosilicate, faujasite and borosilicate sieves commonly known as 13X, 3A, 4A and 5A sieves. These materials can be modified by ion exchange processes to alter their physical properties and can be combined with fillers, binders, and other processing aids.

Another group of carbon dioxide modifiers are coordination polymers, metal-organic frameworks ("MOF's"), and isoreticular metal-organic frameworks ("IRMOF's"). These materials are polymeric structures made by reacting metal and organometallic reagents with organic spacer molecules to form open porous structures. Any associated high porosity lattice system that is produced by such reactions and is capable of adsorbing and releasing carbon dioxide should be included.

Another group of carbon dioxide modifiers includes organic and inorganic carbonates. These materials react with water to form carbon dioxide, especially in the presence of an acid catalyst. It is a preferred embodiment of the invention to mix these materials into PET and fill the package with an acidic beverage so that it becomes activated. Suitable inorganic carbonates include sodium bicarbonate, calcium carbonate, and ferrous carbonate. Suitable polycarbonates include cyclic carbonate copolymers, such as poly (vinyl alcohol) cyclic carbonates and poly cyclic carbonate acrylates, or linear aliphatic carbonate polymers. The poly (vinyl alcohol) cyclic carbonate is prepared by the catalytic reaction of polyvinyl alcohol and diethyl carbonate. The polycyclocarbonate acrylate may be prepared by polymerizing a trimethylolpropane carbonate acrylate monomer prepared by the catalytic reaction between 2-ethyl-2 (hydroxymethyl) -1, 3-propanediol (trimethylpropane) and diethyl carbonate.

Another group of carbon dioxide regulators are polymers that oxidize to form carbon dioxide. One example of such polymers is aliphatic polyketones, including polymers made by reacting ethylene and/or propylene with carbon monoxide.

One of the parameters important for optimizing the present invention is to make CO₂CO in the Source₂The density is maximized. CO per unit volume₂Molar CO₂The higher the source density, the more CO can be added₂Incorporation into packaging to extend shelf life while allowing CO₂The volume occupied by the source is minimized. Various materials and their CO₂The densities are shown in table 1 below.

TABLE 1

Concentration of carbon dioxide source material

		Effective density	CO2Density of
							g/cc	g/cc
Solid, CO2
					The temperature is-80 DEG C		1.565	1.565
Liquid, CO2
					Temperature is 0 deg.C and vapor pressure is 490 psi		0.929	0.929
25 degrees celsius and 917 pounds per square inch vapor pressure		0.713	0.713
					Gaseous, CO2
Temperature 0 deg.C and pressure 44.07 psi		0.008	0.008
					Sorbent
Adsorption: 0.8g/gIRMOF-1@ -77C		0.620	0.496

Adsorption: 0.18g/g 13X compressed molecular sieve @22C		0.766	0.139
					Adsorption: 0.022g/g amorphous PET @22C, 20 bar		1.335	0.030
					Stoichiometric pairing				Ionization of
Inorganic carbonates	Acid(s)
					Sodium bicarbonate, NaHCO3	Ascorbic acid, C6H8O6	1.797	0.304	Is single
Sodium bicarbonate, NaHCO3	Benzoic acid C7H6O2	1.578	0.337	Is single
					Sodium bicarbonate, NaHCO3	Citric acid C6H8O7	1.696	0.270	Is single
Sodium bicarbonate, NaHCO3	Fumaric acid C4H4O4	1.833	0.403	Is single
					Sodium bicarbonate, NaHCO3	Maleic acid C4H4O4	1.799	0.396	Is single
Sodium bicarbonate, NaHCO3	Oxalic acid C2H2O4	1.836	0.384	Is single
					Sodium bicarbonate, NaHCO3	Succinic acid C4H6O4	1.693	0.369	Is single
Sodium bicarbonate, NaHCO3	Terephthalic acid C8H6O4	1.688	0.297	Is single
					Superstrong Alka Seltzer	Citric acid, non-stoichiometric	1.574	0.121	Is single
Ferrous carbonate (divalent), CFeO3	Citric acid, C6H8O7	2.040	0.275	Is single
					Ferrous carbonate (divalent), CFeO3	Fumaric acid, C4H4O4	2.353	0.414	Is single

Lithium carbonate, Li2CO3	Citric acid, C6H8O7	1.667	0.276	Is single
					Potassium bicarbonate, KHCO3	Citric acid, C6H8O7	1.712	0.258	Is single
Sodium bicarbonate, NaHCO3	Citric acid, C6H8O7	1.792	0.438	Two of each
					Sodium bicarbonate, NaHCO3	Fumaric acid, C4H4O4	1.928	0.597	Two of each
Calcium carbonate (calcite), CaCO3	Citric acid, C6H8O7	1.714	0.301	Two of each
					Calcium carbonate (calcite), CaCO3	DL-malic acid	1.828	0.418	Two of each
Calcium carbonate (calcite), CaCO3	dl-tartaric acid, C4H6O6	1.886	0.398	Two of each
					Carbonic acidCalcium (calcite), CaCO3	Fumaric acid, C4H4O4	1.885	0.476	Two of each
Dolomite, CaO, MgO, 2CO2	Citric acid, C6H8O7	1.815	0.28	Two of each
					Dolomite, CaO, MgO, 2CO2	Fumaric acid, C4H4O4	2.020	0.427	Two of each
					Organic carbonates				Hydration of
Ethylene carbonate, C3H4O3		1.344	0.671	Is single
					Propylene carbonate, C4H6O3		1.204	0.519	Is single

Butylene carbonate, C5H8O3		1.146	0.434	Is single
					Glycerol carbonate, C4H6O4		1.390	0.518	Is single
Vinylene carbonate, C3H2O3		1.353	0.692	Is single
					Pyrocarbonic acid diethyl ester, C6H10O5		1.122	0.304	Is single

Pyrocarbonic acid diethyl ester, C4H6O5		1.122	0.609	Two of each
					Pyrocarbonic acid dimethyl ester, C4H6O5		1.250	0.410	Is single
Pyrocarbonic acid dimethyl ester, C4H6O5		1.250	0.820	Two of each
					Diethyl carbonate, C5H10O3		0.976	0.364	Is single

Another challenge is to regulate CO₂From CO₂Liberation of the source so that it generally corresponds to the loss of CO from the package₂The rate. Can be selected by selecting CO₂Source, control of CO₂Activation of the release reaction or by selecting a suitable membrane, coating or film to release CO₂The source being isolated from the beverage, thereby allowing CO to flow₂The release is optimized. Various methods are explained in the examples section below.

Another parameter important to optimizing the present invention is the generation of sufficient CO₂The volume or thickness of carbon dioxide regulator required. To calculate the carbon dioxide modifier inserts or thicknesses for the various reaction materials, 100% conversion to CO of the carbonic acid reactant was assumed₂A series of calculations were performed on the basis of (a). In the case of di-or trifunctional organic acids, one or more of the acid groups may be reacted, but for the calculations in the following tables, it is assumed that only one acid group is reacted. CaCO₃And fumaric acid was used to demonstrate greater density (higher CO per volume)₂Yield) effect of reactant pairing. Finally, ethylene carbonate is shown as an example of an organic carbonate source that decomposes upon reaction with water and does not require a water sourceAnd (4) acidifying. Table 2 below shows the effect of the reactants on the insert thickness.

TABLE 2

Effect of reactants on insert thickness

Bottle (Ref. TM. bottle)	Type (B)	Reactants	Calculated insert thickness
				12 oz of gas	CSD	1mol NaHCO3+1mol of citric acid	0.2889″
12 oz of gas	CSD	1mol CaCO3+1mol of fumaric acid	0.1602″

12 oz of gas	Beer with improved flavor	1mol NaHCO3+1mol of citric acid	0.1134″
				12 oz of gas	Beer with improved flavor	1mol CaCO3+1mol of fumaric acid	0.0628″
12 oz of gas	Beer with improved flavor	Ethylene carbonate	0.0423″
16 oz of rice	Beer with improved flavor	1mol NaHCO3+1mol of citric acid	0.0758″
				16 oz of rice	Beer with improved flavor	1mol CaCO3+1mol of fumaric acid	0.0420″
16 oz of rice	Beer with improved flavor	Ethylene carbonate	0.0283″

In the above table, it is assumed that both are unionized and that the total volume of the insert or plate also increases with the addition of the non-reactive binder.

Some carbon dioxide regulator can be placed in the CO₂In a gas environment, make it absorb and store enough CO₂Gas thereby using CO₂Prefilled so as to replace CO lost from the vessel in normal use of the vessel₂. Preferably, the CO is₂The rate of release from the carbon dioxide regulator is about equal to the loss of CO from the vessel₂The permeation rate.

With CO₂One method of filling the carbon dioxide regulator is to place a dish or insert of the carbon dioxide regulator composition into the lid or mouth of a carbonated beverage bottle, followed by the application of the CO necessary to extend the shelf life of the container to the desired target₂The gas was pressurized to vaporize the bottle. Excess CO₂Then quickly absorbed by the carbon dioxide regulator so that the bottle is no longer over-pressurized. Then when the product CO₂CO loss from packaging₂The gas pressure is reduced and the absorbed CO is₂Released into the top of the carbonated beverage. Another method is to use CO₂A disk or insert pre-filled with carbon dioxide regulator and placing the pre-filled disk into the cap or spout during bottle and/or cap processing.

Examples

Example 1

Test ofVarious carbon dioxide modifiers, specifically organic carbonates, were tested to determine if they could be activated by water vapor alone and in the absence of organic acids. The results shown in FIG. 7 illustrate that water vapor activates CO derived from organic carbonates initiated by hydrolysis₂No organic acid is needed.

Example 2

Various gasket materials were tested to determine the permeability of the gasket material to CO₂The effect of the rate of generation. The mixture of sodium bicarbonate and citric acid was sealed in a small hanging bag that was placed above 25mL of water in a sealed bottle. The bag is made of three different materials with different moisture permeability: paper tea bags, polylactic acid and polyethylene. The results in FIG. 8 demonstrate that the extremely low moisture barrier results in CO₂The fastest rate of formation, while the higher moisture barrier provided by polyethylene provides the slowest rate. Thus, a moisture barrier material between the carbon dioxide regulator composition and the carbonated beverage can be used to control CO₂The rate is generated.

Example 3 adsorption of CO₂Saturation and release of

Testing of various carbon dioxide-generating agents, particularly adsorbent materials, to determine their storage and release of CO at high pressures₂And thus the ability to extend the shelf life of carbonated beverages. First, the selected adsorbent material is subjected to high pressure CO₂Saturation is carried out under the environment. The adsorbent material was then placed in a 20 oz bottle, and the bottle was rapidly carbonated with dry ice and capped. Molecular sieves are commercially available and are either used directly or dried under vacuum by heating. The 13X molecular sieves discussed below were obtained from Aldrich Chemical Company and were either used directly or dried under vacuum prior to use. Recording CO₂The rate of loss from the bottle over time. The results are shown in table 3 below.

TABLE 3

CO₂Summary of saturation experiments

Sample (I)	% improvement in shelf life
		Control bottle (without saturated additive)	-
W/8416 saturated film bottle	32.6％

W/4A molecular sieve bottle	104.2％
		W/13x molecular sieve bottle	61.4％
Presaturation @300 psi CO2Bottle (Ref. TM. bottle)	0.2％

The results demonstrate that CO can be obtained by reacting₂Saturated products are placed in bottles to extend the shelf life of carbonated beverages and molecular sieves are particularly effective regulators.

Experiment 4 will have a filling with CO₂Of molecular sieves of (2) bottle overpressure

This experiment was conducted to test the following ideas: bottles were over pressurized and excess CO was stored in molecular sieves₂And absorbing CO₂Released back into the top of the bottle. Four sets of 12 oz bottles were tested, each containing 15cc of water and carbonated with dry ice. The first group was control bottles filled with 4.0 volumes of CO only₂. The second group of bottles was filled with 4.75 volumes of CO₂And about 3 grams of finely powdered 13X molecular sieve, dried under vacuum and contained in a test tube, was also sealed in the bottle. The third group of bottles was filled with 4.75 volumes of CO₂And about 3 grams of the finely powdered 13X molecular sieve, which was not dried and contained in the test tube, was also sealed in the bottle.

The results shown in FIG. 9 show the CO of the control bottle₂The loss rate was normal. However, both sets of bottles containing molecular sieves showed initial CO₂The pressure drops rapidly, which means that CO₂Is absorbed by the molecular sieve. CO at the top of the rear bottle₂The level rises because the molecular sieve will CO₂Released back into the bottle. These two groups of bottles showed a theoretical increase in shelf life of 11 weeks compared to the control bottles.

In the following examples, PET bottles can be made using conventional injection-blow molding processes. The PET bottle was made from conventional PET bottle resin. Carbonated Soft Drink (CSD) bottles weigh 26.5 grams and have a volume of 12 ounces. The beer bottle used in the following examples weighed 37 grams, had a volume of 500mL, had a champagne base and a 1716 finish, which was the neck and mouth of the bottle, and used a conventional CSD cap.

The effect of carbon dioxide regulator on the internal pressure of PET bottles was tested as follows: weighed conditioner samples were placed into test tubes and the test tubes were placed into PET bottles. Ten milliliters of water was added to the bottle as follows: only the water vapor is in contact with the sorbent. The bottle was then carbonated according to the method taught in us patent 5,473,161. All tested bottles were evaluated in triplicate.

The amount of carbon dioxide in the bottle was measured using FT-IR under the approval of Coca Cola according to the method described in U.S. Pat. No. 5,473,161. This corresponds directly to the CO in the bottle₂The internal pressure. Timed measurements to track CO remaining in the bottle₂Amount of the compound (A). Conversion of FT-IR results to CO using conversion coefficients of the signal₂Volume, the term is commonly used in the packaging industry to describe the amount of carbonation in carbonated beverages. One volume of CO₂Is the amount required to increase the package by one atmosphere at 20 c. The determination method of the conversion constant comprises the following steps: a known amount of CO₂Put into a bottle and measure CO over a one hour seal time₂And (4) concentration. The conversion constant was measured at various pressures and was found to be constant within the accuracy of the test.

From CO in the package₂The time required for the pressure to drop to a minimum acceptable value determines the shelf life. The requirements for this shelf life vary with the product being packaged. For carbonated soft drinks, it is desirable to use an initial carbonation level of about 4.0 volumes, and the minimum acceptable level is about 3.3-3.4 volumes. This is a loss of 15-17.5%. For beer, the minimum carbonation level is typically 2.7 volumes and the initial concentration is 3.0 volumes. By measuring CO in the package immediately after sealing₂Level, thus determining the initial carbonation level for each test. In the case where the shelf life has not been reached at the end of the test, the value is determined by extrapolation as shown in fig. 1 and 2. Most packs are used well before they reach their final shelf life.

It is important for product quality that the carbonation levels of a large number of packages remain very consistent during use. Introducing CO₂The time during which the internal pressure is kept relatively constant is defined as the adjustment time. This is illustrated in figures 1 and 2.

Comparative example 5

Will be provided with1716 PET beer bottle with bottle mouth and CSD cap carbonated to 3.3 volume CO₂The level of (c). This is slightly higher than the industry's conventional initial carbonation level. In beer, shelf life is terminated when the carbonation level reaches 2.7 volumes. Shelf life and CO₂The loss rate results are shown in table 4 and figure 2.

Comparative example 6

Carbonating a 12 ounce CSD bottle with a CSD cap to 4.0 volumes CO₂The level of (c). For soft drinks, CO is present in 3.3-3.4 volumes₂The shelf life is terminated. The results are shown in Table 4.

Example 5: influence of 13X sieve on preservation life of PET beer bottle

One gram of the 13X molecular sieve dry powder was placed in a test tube in the same PET bottle-cap combination as comparative example 5. Addition of CO in the absence of sorbent₂To 3.6 volumes of CO₂The carbonation level of. The results are shown in FIG. 1 and Table 4. Carbonation was continuously monitored until the minimum required beer amount of 2.7 volumes of CO was reached₂. Placing the sorbent into the package results in CO in the bottle₂The measured level decreased rapidly, so that the shelf life of the package was extended by 36 days compared to comparative example 5.

Example 6: effect of 13X molecular sieves on shelf life of 12 ounce CSD bottles

This experiment was performed in the same manner as in example 5, except that a 12 oz CSD bottle and a CSD cap were used. One gram of the molecular sieve dry powder was placed in a test tube in the same PET bottle. Addition of CO in the absence of sorbent₂To 4.35 volumes of CO₂The carbonation level of. The carbonation level is monitored over time. The results are shown in FIG. 2 and Table 4. Placing the sorbent into the package results in free CO₂Rapidly decreased, and the shelf life of the package was extended by 42 days as compared with comparative example 6.

TABLE 4

SorbentFor shelf life and CO₂Influence of internal pressure loss

Examples of the present invention	Volume of addition (CO)2Volume)	Measured initial volume (CO)2Volume)	End point volume (CO)2Volume)	Regulating period (sky)	Storage life (Tian)
						Comparative example 5	3.30	3.34	2.7	0	80

Comparative example 6	4.0	3.98	3.4	0	60
						Example 5	3.60	3.38	2.7	30	116
Example 6	4.35	3.89	3.4	34	91

Comparison of various molecular sieves

Various commercially available molecular sieves (as indicated by the letters in the table below) were tested in the manner described above using one gram of molecular sieve. These materials were obtained from various manufacturers (indicated by "Mfr" in the following tables) and were used directly. One gram of each material was tested in a twelve ounce CSD bottle with a PCO (plastic only cap) neck finish and a carbon dioxide addition of 4.5 volumes of carbon dioxide. Initial carbon dioxide pressure was measured 1 hour after filling. The data relating to these molecular sieves are shown in table 5.

TABLE 5

Shelf life extension using various molecular sieves

Channel acquisition	Molecular sieve type	Volume of addition (CO)2Volume)	Initial pressure (CO)2Volume)	Regulating period (sky)	Storage life (Tian)
						4.0 control	-	4.0	4.0	0	62
Aldrich	13X	4.5	4.1	44	102
						Mfr1	A	4.5	4.2	44	114
Mfr1	B	4.5	4.2	44	110
						Mfr2	C	4.5	4.2	44	100
Mfr2	D	4.5	4.3	44	100
						Mfr3	E	4.5	4.1	44	110
Mfr3	F	4.5	4.2	44	110
						Mfr3	G	4.5	4.3	44	114

The effect of drying temperature on carbon dioxide retention was also tested. Drying of the molecular sieve generally increases its adsorption capacity. The molecular sieves were dried at 120 ℃ for 15.5 hours and tested as described above. The results are shown in Table 6.

TABLE 6

Performance of molecular sieve after 120 deg.C drying

Channel acquisition

Molecular sieve type

Volume of addition (CO)2Volume)

Initial pressure (CO)2Volume)

Regulating period (sky)

Storage life (Tian)

4.0 control	-	4.0	4.0	0	62
						Aldrich	13X	4.5	4.2	46	105
Mfr1	A	4.5	4.2	46	105
						Mfr1	B	4.5	4.2	46	110
Mfr2	C	4.5	4.2	46	112
						Mfr2	D	4.5	4.3	46	99
Mfr3	E	4.5	4.2	46	114
						Mfr3	F	4.5	4.1	46	105
Mfr3	G	4.5	4.3	46	110

The molecular sieves were dried at 240 ℃ and tested as described above. The results are shown in Table 7.

TABLE 7

Performance of the molecular sieves after drying at 240 deg.C

Modulator materials	Volume of addition (CO)2Volume)	Initial pressure (CO)2Volume)	Regulating period (sky)	Storage life (Tian)
					Without regulators	4.0	4.0	0	56
Without regulators	4.4	4.4	0	80
					13X molecular sieve	4.4	4.2	14	71

Effect of surface area on Performance

A sample of 13X molecular sieve powder was milled using a Spex Mill to reduce its particle size and increase its surface area. The surface area and particle size of the Aldrich 13X molecular sieve before and after grinding are shown in table 8.

TABLE 8

Surface area and particle size of Aldrich 13X molecular sieves before and after grinding

Measuring	Unit of	Initial	After grinding
				Volume weighted mean diameter	Micron meter	5.91	8.45
Surface weighted mean diameter	Micron meter	3.41	3.17

Specific surface area

Square meter/g

1.7618

1.8919

The material properties were tested as described above using a twelve ounce CSD bottle with a PCO finish and a one gram molecular sieve. The results are shown in Table 9.

TABLE 9

Effect of molecular sieve surface area on carbonation Retention

Type of regulator Material	Specific surface area (square meter/gram)	Volume of addition (CO)2Volume)	Initial pressure (CO)2Volume)	Regulating period (sky)	Storage life (Tian)
						Without regulators	-	4.0	4.0	0	56
13X molecular sieve	1.7618	4.5	4.3	44	140
						13X molecular sieve	1.8919	4.5	4.1	44	140

Effect of the flaky molecular sieves

The test was performed by pressing the molecular sieve into a tablet form and exposing the tablet to the vapor space of the bottle or by immersing the tablet in water located in a container. The results are shown in Table 10.

Watch 10

Comparison of molecular sieve flakes and powders

Type of regulator	Molecular sieve forms	Volume of addition (CO)2Volume)	Initial pressure (CO)2Volume)	Regulating period (sky)	Storage life (Tian)
						Without regulators	-	4.0	4.0	0	62
13X molecular sieve	Powder of	4.5	4.1	46	102
						13X molecular sieve	Sheet-like shape	4.5	4.1	46	104

Modification effect of coating on molecular sieve sheet performance

The molecular sieve sheet was prepared by compression and drying at 125 ℃. Coated with a 2% general electric Silicon RTV615A 01P solution formed by mixing 10 parts of elastomer and 1 part of curative in heptane. The molecular sieve sheet was immersed in the coating liquid and dried in air at room temperature. The coated and uncoated zeolite sheets were placed on top of a twelve ounce CSD bottle and tested as described above with the results shown in table 11.

TABLE 11

Effect of Silicone coating on molecular Sieve sheet Performance

Type of regulator

Molecular sieve forms

Coating of

Volume of addition (CO)2Volume)

Initial pressure (CO)2Volume)

Regulating period (sky)

Storage life (Tian)

Without regulators	-	-	4.0	4.0	0	62
							13X molecular sieve	Sheet-like shape	Uncoated	4.5	4.0	46	102
13X molecular sieve	Sheet-like shape	Coating of	4.5	4.1	40	-

Molecular sieve effect in cover insert

A cup that fits into the lid and also acts as a gasket seal is injection molded to make a small insert. The cup contained 1g of molecular sieve material and was fitted into the mouth of a twelve ounce CSD bottle. These cups were injection molded from polyethylene and polypropylene and tested for carbonation retention of the molecular sieve placed in the cup as described above. The data are shown in table 12.

TABLE 12

Effect of placing molecular sieves in the cover insert

Type of regulator	Cup material	Volume of addition(CO2Volume)	Initial pressure (CO)2Volume)	Regulating period (sky)	Storage life (Tian)
						Without regulators	Without cup	4.0	4.0	0	62
Without regulators	Without cup	4.5	4.5	0	98
						Without regulators	70-7931	4.5	4.5	0	100
Without regulators	9551	4.5	4.4	0	92
						13X molecular sieve	Powder of	4.5	4.2	20	76
13X molecular sieve	Sheet-like shape	4.5	4.2	0	82

Note: 70-7931 is polypropylene obtained from BP

9551 is a low density polyethylene obtained from Dow Chemical

Comparison of caustic asbestos agent and molecular sieves

The 13X molecular sieve and the caustic soda asbestos agent as the carbon dioxide adsorbing material were compared in terms of performance as described above using 1g of each of the materials. The results are shown in Table 13.

Watch 13

Comparison of carbonation Retention Performance of molecular sieves and caustic asbestos Agents

Type of regulator	Volume of addition (CO)2Volume)	Initial pressure (CO)2Volume)	Regulating period (sky)	Storage life (Tian)
					Without regulators	4.0	4.0	0	62

Caustic soda asbestos agent	4.5	4.5	0	44
					13X molecular sieve	4.5	4.5	44	108

Acid activated modulator system

CO regulation₂A convenient method of release is to contact the package with the beverage. Many carbonated soft drinks are strongly acidic, thus making the acidity appear to release CO from carbon dioxide regulators incorporated into PET bottles or caps₂A convenient triggering mechanism. Common acids in beverages include phosphoric acid and citric acid.

Suitable carbon dioxide modifiers for this concept include inorganic carbonates such as calcium carbonate, organic carbonate oligomers and polymers as shown in table 14, and combinations thereof. Inorganic carbonate and organic carbonate oligomers were obtained from Aldrich Chemical Company. The cyclic carbonate polymers were obtained from professor Morton h.

PET was dry blended with various carbon dioxide sources and mixed on an APV lab scale twin screw extruder to form a water quenched strand. Approximately three grams of the material was placed in a phosphoric acid solution at pH 2 in a 155mL headspace bottle and sealed with a screw top (crimp top) silicone gasket. The formation of carbon dioxide was monitored by GC. The mL of carbon dioxide generated per gram of conditioner material per day is shown in table 14. The table also shows the CO and CO for a conventional 12 ounce carbonated soft drink container₂Approximate amount of modifier that matches the release rate.

TABLE 14

CO evolution from PET mixtures₂Rate of

Sample (I)	Carbonic acid Compound (wt)%	Weight% of molecular sieve	Weight% of PET	Temperature of	CO2Generation of ml/g regulator/day	Required amount g satisfying the object
							Filled PET
13X molecular sieve powder in PET	0	5	95	22	0.55	7.4
							Butylene carbonate in PET	5	0	95	22	0.39	10.5
Butylene carbonate in PET with 13X molecular sieve	5	5	91	22	0.25	16.5
							Pyrocarbonic acid diethyl ester in PET	4	0	96	22	1.92	2.1
Pyrocarbonic acid diethyl ester in 13X-bearing PET	4	5	91	22	0.39	10.5
							Glycerol carbonate in PET	4	0	96	22	0.54	7.6

Propylene carbonate in PET	5	0	95	22	0.52	7.9
							Propylene carbonate in PET with 13X molecular sieve	5	5	91	22	0.37	11.1
Sodium bicarbonate NaHCO in PET3	5	0	95	22	8.13	0.5
							Sodium bicarbonate NaHCO in PET with 13X molecular sieves3	5	5	91	22	8.76	0.5
Ethylene carbonate in PET	1	0	99	22	2.35	1.8
							Butylene carbonate in PET	5	0	95	52.2	0.69	6.0

Diethyl carbonate in PET with 13X molecular sieve	5	5	91	52.2	0.72	5.7
							Ethylene carbonate in PET	1	0	99	52.2	7.60	0.5
Cyclic carbonate polymer	5	0	95	23	0.13	30.9
							Cyclic carbonate polymer	5	0	95	22	0.15	27.4

Effect of Pre-saturation

Pellets of 4A extruded sheet with PET as binder were prepared and pre-saturated. 11.3 g of 4A molecular sieve was used together with 4.8 g of PET. The two materials were mixed together and formed into a cylindrical compact at a pressure of 10000 psi at a temperature of about 100 ℃ and 120 ℃. Subjecting the chips to CO at room temperature and 300 psi₂Saturation was carried out for 36 hours. The tablets adsorbed an average of 1.47 grams of CO₂. The pellet was cut in half so that it could be placed into a bottle. The bottle (6) is sealed and monitored. Figure 10 shows that the use of 4A pre-saturated material extended shelf life. In-bottle CO test₂The level shows a maximum, which shows the evolution of CO from the 4A material₂A slow process.

13X sheets were prepared by a similar method. 3.2 grams of powdered 13X (available from Aldrich as 4A) and 4.8 grams of PET were formed into a sheet, cut in half, and charged with CO at 300 psig at room temperature₂Saturation was carried out for 36 hours. Place saturated sheet into PET bottle and monitor CO₂And (4) horizontal. Additional CO₂The shelf life is prolonged. The pellets adsorbed an average of 0.52 g of CO₂。

A 5.25 square inch, 10 mil thick and unstretched PET film was saturated at 300 psi for 36 hours at room temperature. To each vial was dispensed 29 grams of film. Subjecting PET film to CO at room temperature and 300 psi₂Saturation was carried out for 36 hours. The membrane adsorbed an average of 0.99 g of CO₂. The film was placed in a PET bottle (6) and the internal CO was treated₂The level is monitored. CO evolution from PET films, as shown in FIG. 10₂The shelf life is prolonged.

Further discussion of examples 5 and 6

Will be combinedIncorporation of suitable sorbents into PET carbonated beverage bottles allows additional CO to be added₂The internal pressure of the bottle is not increased. This is readily seen in examples 5 and 6. In example 5, CO was added₂A carbonation level of 3.6 volumes was produced, but only 3.38 volumes were measured after sealing. In example 6, 4.35 volumes were added but only 3.89 volumes were measured within one hour after sealing. In each case, CO₂Are quickly adsorbed and overcarbonation of the bottle is prevented.

Adsorbed CO₂Then slowly released over time into the bottle, resulting in CO in the package₂The pressure is more stable. The conditioning periods for examples 5 and 6 were thirty days and thirty-four days, respectively. This is precisely within the time frame that most high volume carbonated beverages are packaged and sold.

The final shelf life of examples 5 and 6 was much longer than that seen in the comparative examples. The shelf life was extended in each case by over thirty days. Various molecular sieves underlying carbon dioxide regulators have been evaluated. As shown in table 5, a number of materials were found to be effective.

The inventors examined the effect of drying temperature on the performance of carbon dioxide regulators. It was found that drying of the molecular sieve based conditioning agent was not necessary to obtain good performance and that drying to a temperature lower than 120 ℃ for conventional drying of these materials would improve their performance. Drying at a higher temperature of 240 ℃ will result in a considerable reduction of the conditioning period. Avoiding drying these molecular sieves prior to use is advantageous for many carbon dioxide regulator designs.

As shown in Table 5, increasing the particle size and surface area of the sorbent resulted in CO that the carbon dioxide regulator was able to adsorb₂The amount is greatly increased. Optimizing particle size and surface area for a particular carbon dioxide modifier is a matter of routine experimentation.

The physical form of the regulator is important in developing an optimized carbon dioxide regulator. The inventors have found that molecular sieves pressed into tablets can be as effective as molecular sieve powders as a conditioning agent. Optimizing the morphology and shape of the conditioning agent is also a matter of routine experimentation.

Coating molecular sieve sheets is expected to be a particularly effective method of making the conditioning agent. An important feature of this coating is that the CO is allowed to flow during the bottle filling process₂Rapid adsorption, facilitating overpressure as a means of introducing additional carbon dioxide. As shown in table 11, the inventors found that the silicone coating was effective.

The insertion of the cup assembly represents a practical method of manufacturing a carbon dioxide regulator system. As shown in table 12, the inventors found that a polyethylene based insert cup was effective. Other suitable polyolefins for such components include: thermoplastic polyolefin elastomers, ethylene copolymers such as linear low density polyethylene and ultra low density polyethylene, ethylene-propylene copolymers, propylene copolymers and styrenic thermoplastic elastomers. Softer polyolefin materials that can form a surface seal of the package are preferred. Determining the optimal size and materials for insertion into a cup or other form of conditioning agent is a matter of routine experimentation.

As shown in table 13, many of the carbon dioxide adsorbing materials did not readily form a regulator system. Caustic soda asbestos agents are inorganic substances that readily adsorb large amounts of carbon dioxide, but pure caustic soda asbestos agents do not readily form suitable carbon dioxide modifiers because of the CO₂The release rate is the same as that of CO₂The rate of loss from the package is not similar.

Those skilled in the art will appreciate that there are many factors that may further improve the present invention. It is advantageous that the sorbent has as high an ability to adsorb carbon dioxide as possible. The adsorption capacity is characterized by the weight of carbon dioxide that can be adsorbed per unit weight of sorbent. With higher CO₂Sorbent with adsorptive capacity is preferred because less sorbent can be added to the package to extend the desired shelf life.

Operating conditions are also important. It is well known that heating molecular sieves removes trapped material and thereby makes the adsorption capacity stronger. Surprisingly, over-drying destroys this as CO₂The material properties of the regulator.

The molecular sieve may need to be combined with a binder material in order to facilitate its fabrication into a component suitable for the application of the present invention. The type of binder required depends on the properties of the molecular sieve and the properties desired for the final part to be made. The adhesive comprises: inorganic binders, sorbent-miscible organic polymers, sorbent-dispersible low molecular weight resins and oligomers commonly used to improve the mechanical properties of molecular sieves. It may be a natural thermoset or thermoplastic material and may include materials such as silicone rubbers, polyolefins, epoxies, unsaturated polyesters, and polyester oligomers.

Controlled adsorption of CO₂Rate of release from sorbent, prevention of liquid water induced adsorption of CO₂Are important to the invention, either to prevent loss of the sensory component of the beverage, or to allow contact of the packaged component with the conditioning agent in a controlled manner. This can be achieved by: the sorbent is placed in a polymer with low water permeability or a thin film of such a polymer is placed between the beverage and the sorbent material. The material is required to be permeable to CO₂Thereby easily adsorbing overcarbonation, which may be formed by semi-permeable membranes, permeable membranes or high CO₂Permeable materials, and combinations thereof. Suitable materials include polyolefins such as low density polyethylene, high density polyethylene, polypropylene, ethylene-propylene elastomers, ethylene-vinyl acetate copolymers, and silicone rubbers. Suitable membrane materials include: such as Gore-Tex or similar structured liquid/gas impermeable materials. A particularly preferred embodiment of the invention is to mix the sorbent into a suitable polymer and use that material to make the closure itself, insert the resulting sorbent disk into the closure behind the closure liner, and use CO to apply₂Protecting tubular inserts by permeable polymeric films or coatings, or by sorbents and CO₂The combination of permeable polymers molds the tubular insert. The preferred method of placing the sorbent into the bottle and optimizing its performance is a matter of further experimentation.

As shown in Table 14, a carbon dioxide regulator may be prepared by mixing CO₂The release material is mixed into PET to form the release material. For such carbon dioxide regulators it is important that no CO is released before the package is filled₂So that the performance of the carbon dioxide regulator is not lost during bottle storage. Various inorganic and organic carbonic acid compounds can be incorporated into PET at concentrations of less than 20% by weight, preferably less than 10% by weight, to yield CO equivalent to conventional PET packaging₂CO of loss rate₂The release rate. These materials are activated by being placed in water at a pH range similar to many carbonated soft drinks.

One aspect of the present invention is to allow carbonated beverages to be stored in a hot environment for longer periods of time without the need for more expensive coating or cold storage conditions. In hot environments, the storage temperature can be very high and the carbon dioxide permeability of the bottle is proportional to the temperature so CO₂The loss rate of (c) will also be higher. Moreover, the internal pressure in the bottle can reach dangerous levels due to these temperatures. Therefore, a system that maintains a stable and consistent internal pressure and extends shelf life would be particularly advantageous.

Another aspect of the present invention is to reduce the weight and maintain the existing shelf life of existing carbonated beverage bottles. The permeation rate of the package is inversely proportional to the thickness of the package wall. It is economically advantageous to make the package as light in weight as possible, but this results in a reduction in wall thickness. A system for extending the shelf life of conventional packages may allow thinner walled packages to have a shelf life comparable to conventional packages. The present technology relates to applications where many bottles are packaged in packages that are not light enough to result in a reduced shelf life and do not use more expensive bottle making techniques.

Another aspect of the invention is that more optimal and stable carbonation levels can be maintained for longer periods of time, resulting in more consistent product taste and quality. The amount of carbon dioxide dissolved in the beverage is proportional to the pressure of the carbon dioxide in the container. The concentration of dissolved carbon dioxide affects the pH and other properties of the beverage. A consistent amount of dissolved carbon dioxide will equate to a more consistent beverage product taste.

Another aspect of the invention is to control the rate of release of carbon dioxide such that the rate does not substantially exceed the permeation rate of the package. Overpressure of carbonated beverage bottles is a big problem, which can lead to packaging rupture, an economic and safety issue. Any available CO of carbonated beverage bottles₂Regulating system, the rate of release of carbon dioxide of which must not be significantly greater than the loss of CO from the package₂The rate of (c). Ideally, the release rate should be equal to or slightly less than the permeation rate from the package and should not exceed 125% of the permeation rate of the package. It must also be able to release CO consistently over a desired long period of time₂This period of time is up to three months and a minimum of two weeks.

Another aspect of the invention is that it is self-regulating with the thermal environment of the package, such that in warmer environments when the carbonic acid loss is higher, the regulator naturally releases greater amounts of carbon dioxide to replace the loss.

Another aspect of the invention is to provide a packaging system that allows overcarbonation without raising the pressure in the package and that allows lighter bottles to be used for carbonated beverages as well. Adding too much carbonation at the time of filling is a very economical method for extending the shelf life of carbonated beverages, and is still used today for packaging soft drinks and beer. But is limited by the ability of the package to maintain a higher initial pressure level. Systems that adsorb and re-release this carbon dioxide can increase the amount of carbonation upon filling, thereby driving the use of lower pressure resistant vessels.

Carbon dioxide regulation also drives the use of lower modulus vessels. Many plastics are not suitable for packaging carbonated beverages because they cannot contain the high internal pressures associated with carbonated soft drinks. Typical examples are polyolefins such as polypropylene. The use of a carbonic acid regulator in combination with a lower modulus plastic, such as polypropylene, makes the lower modulus containers more commonly used for packaging carbonated beverages.

The present invention has been described above by way of example only with reference to certain embodiments. It should be recognized that various alterations, additions, modifications, and adaptations of the illustrated embodiments may occur to those skilled in the art, and are within the scope and spirit of the invention.

Claims (16)

1. A method of replenishing carbon dioxide gas in a carbonated beverage container, comprising:

i. inserting a carbon dioxide regulator into the container or a lid of the container; and

adjusting the rate of release of carbon dioxide from the carbon dioxide regulator to about equal the rate of carbon dioxide loss from the vessel,

wherein the carbon dioxide regulator is a sorbent that absorbs and subsequently releases carbon dioxide gas.

2. The method of claim 1, wherein the carbon dioxide regulator is prefilled with carbon dioxide prior to inserting the carbon dioxide regulator into the container.

3. The method of claim 1, wherein the carbon dioxide regulator is filled as follows: the insert of the carbon dioxide regulator is placed into the cap or neck finish of the container and the container is then over-pressurized with the appropriate amount of carbon dioxide.

4. The process of claim 1, wherein the carbon dioxide regulator is selected from molecular sieves.

5. The process of claim 1, wherein the carbon dioxide regulator is selected from the group consisting of silica gel, molecular sieves, clays, activated alumina, zeolites, coordination polymers, and metal organic frameworks.

6. The method of claim 1, wherein the intercalation of step (i) occurs such that the carbon dioxide regulator does not come into contact with the carbonated beverage.

7. The method of claim 1, wherein the carbon dioxide regulator is directly mixed into the material of the container or the cap.

8. A packaging system for maintaining pressure consistency of a carbonated beverage comprising a lid, a plastic container, and a carbon dioxide regulator,

wherein the carbon dioxide regulator is a sorbent that absorbs and subsequently releases carbon dioxide gas.

9. The packaging system of claim 8 wherein said lid comprises any material used to seal said plastic container.

10. The packaging system of claim 8 wherein the lid further comprises a liner material therein.

11. The packaging system of claim 10 wherein said carbon dioxide regulator is incorporated into any material used in the manufacture of said plastic container, said cap or said liner material.

12. The packaging system of claim 8, wherein the carbon dioxide regulator is inserted into the plastic container or the lid in a form suitable for the plastic container.

13. The packaging system of claim 8 wherein said carbon dioxide regulator is formed as part of a regulator assembly by overmolding a preform around said regulator assembly with PET.

14. The packaging system of claim 13 wherein said preform is formed into a plastic container.

15. The packaging system of claim 8, wherein the carbon dioxide regulator is added to the plastic container in a layer.

16. The packaging system of claim 8, wherein the carbon dioxide regulator is added to the lid in a layer.