US20080116098A1

US20080116098A1 - Food container with breathable patch

Info

Publication number: US20080116098A1
Application number: US11/600,634
Authority: US
Inventors: Ira Marooflan; Terry Vovan
Original assignee: PWP Industries Inc
Current assignee: Pactiv Packaging Inc
Priority date: 2006-11-16
Filing date: 2006-11-16
Publication date: 2008-05-22

Abstract

A rigid polymer food container system for holding fruit and vegetables is described. The system essentially comprises a lid and a tray with complementary mating rims that when assembled together form an airtight seal and which is further releaseably lockable to each other. Additionally, an opening formed into either the lid and/or tray member to permit the flow of air, the opening being further covered with a gas-permeable membrane that is held to the plastic surface by an adhesive. The opening permits some level of oxygenation to delay senescence of the food product and the gas-permeable membrane contributes to minimize bacterial infection and fluid leakage.

Description

FIELD OF THE INVENTION

The invention described herein is related to the food packaging industry. More specifically, the invention relates to plastic food trays that also ensure that certain perishable foods are kept as fresh as possible for the benefit of the consumer.

BACKGROUND OF THE INVENTION

Plastic bags are used to hold fruits and vegetables for sale at markets. They are convenient and food processors are able to print descriptive literature required by governmental authorities, as well as advertising on the product contents. In order to ensure that the product contents are not crushed, the bag is sometimes sealed airtight so that there is a volume of air in the bag to prevent the bag from collapsing. However, such perishable products have a relatively short time of freshness after it as been harvested, and this imposes a severe constraint on the food processor, the distribution logistics operator to the market destinations, as well as the retail markets that provide the final product to the consumer. The time from packaging at the food processor facility to shelf at the retail store must be minimized in order to maximize the freshness of the product contents.
In an attempt to address this difficulty, some food processors have turned to rigid plastic packaging. Rigid plastic packaging differs from soft, flexible plastic bags in that they generally comprise a lid member and a tray member, which may be a one- or two-piece construction. The lid and tray members are generally designed with rim configurations that are complementary to each other so that they mate to form an enclosure into which the perishable food, such as vegetables or fruits, is placed. Additionally, the rims of the lid and tray members comprise male ribs and female grooves that permit them to be releaseably lockable to each other. The releaseably lockable function is typically achieved using either discrete or annular snap-fit grip features that seal in the food contents.
Rigid plastic packaging serves an additional purpose in that they are preferred over soft plastic bags. Consumers generally rely on appearance when making a decision on the freshness of the product. Food processors have consequently focused on clarity, gloss, and stiffness of packaging because the public associates these features with freshness. As an example, a number of beverage producers are packaging their products in glass containers, rather than plastic, because they glass conveys an orientation toward health. Similarly, herbs are often packaged in rigid plastic containers as opposed to plastic bags because it connotes a higher level of freshness.
Consumers increasingly demand fresh fruits and vegetables which have a long shelf-life without the use of preservatives. It is recognized the fresh-cut vegetables is one of the fastest-growing retail food categories in the nation, and one of the most significant problems facing this industry today challenge is prolonging the products' freshness so that it can make it from the field to the retail store and to the consumer's table. Upon harvesting, the natural photosynthesis process of vegetables is reversed. Plants that were consuming carbon dioxide (CO₂) and releasing oxygen (O₂) begin to do the opposite, and the process called “senescence”—aging and deterioration—begins. Cutting the vegetables by the food processor so that they may be placed into packages further exacerbates the situation since more of the surface of the vegetable is exposed, enabling it to absorb oxygen more rapidly. However, the complete removal of oxygen is not the appropriate solution since O₂is essential in the packaging of fresh fruits and vegetables as they continue to respire after harvesting. The absence of O₂can lead to anaerobic respiration in the package, which accelerates senescence and spoilage. Too high levels of O₂do not retard respiration significantly and it is around 12% of O₂where the respiration rate starts to decrease. So oxygen is used in low levels (3-5%) for positive effect.
In order to meet this challenge, food processors have resorted to a variety of novel approaches. One has been the introduction of vents into the lid or tray member to permit airflow to oxygenate the produce. This simple approach, however, little to hinder the senescence process; in fact, it further opens the product contents more easily to contamination, as well as tampering. On the other extreme, complete sealing of the food product using plastic packaging or further shrink-wrapping the contents is also a commonly accepted practice. Unfortunately, in this approach, unless the polymer material comprising the shrink-wrap is gas-permeable, it is not suitable in situations where the time-to-market exceeds the window of time permissible before the product visibly deteriorates.
Alternatively, food processors have tried to minimize the impact of senescence by transporting the packaged product either in freezer trucks or place ice in the shipment containers. This requires the food processor and/or the trucking company that is contracted to deliver the goods to either manufacture or purchase ice, thereby adding to the cost of the food product at the retail end.
Another alternative has been the introduction of a modified atmosphere into the sealed package. In this approach, the produce is encased in a lowered oxygen environment to extend the life of these foods. The lowered amount of O₂slows down the growth of aerobic lifeforms and the speed of oxidation reactions. The removed O₂is replaced with nitrogen (N₂) or CO₂, which can lower the pH or inhibit the growth of bacteria. It is the altered ratio of these gases that makes a difference in the prolongation of shelf life. By reducing the O₂level and increasing the N₂or CO₂level, ripening of fruits and vegetables can be delayed, respiration and ethylene production rates can be reduced, softening can be retarded and various compositional changes associated with ripening can be slowed down. Attempts to maintain the freshness of produce without the use of refrigeration and modifying the atmosphere within the package are disclosed in U.S. Pat. No. 4,079,152, issued Mar. 14, 1978, to Bedrosian et al. This patent discloses a gas-permeable film, which allows the produce to convert the atmosphere to an environment containing a specific percentage of CO₂and O₂. In order to achieve this, the package contains chemical within the package capable of absorbing moisture and CO₂from the environment. Another means of controlling atmosphere within a food package is disclosed within U.S. Pat. No. 4,883,674, issued Nov. 28, 1989, to Fan. This patent discloses a package, which includes a gas-permeable portion, which allows specific amount of O₂into the package per unit of time. Fan's method, however, includes controlling the initial atmosphere within the package. Another attempt is described in U.S. Pat. No. 5,254,354, issued on Oct. 19, 1993, to Stewart. This patent discloses a means of controlling the atmosphere within package by using packages comprised of “intelligent” polymers, i.e. polymers, which are formulated so that they will have permeability, which can change in either direction with temperature.
However, there are numerous challenges associated with offering modified atmosphere packaging. Besides the difficult challenge of determining the optimal O₂/CO₂composition, there is the cost of implementing such a manufacturing system. Though beneficial, it is very costly requiring additional capital equipment and trained personnel on a generally 24/7 basis to implement and maintain. Only a few food processors that possess the capital, infrastructure and resources to undertake the requisite experimentation and project implementation costs can assume the risks associated with such an undertaking; the vast majority of small- and medium-sized food processors would be unable to make similar investments necessary to set up packaging operations in modified atmosphere rooms.
There is a need for a simply, cost-effective packaging system that provides for the use of a breathable structure or membrane, and yet retains the advantages of traditional structures such as resistance to puncturing, good sealing, and is aesthetics pleasing to the consumer and allows displaying of the product in the best manner possible. The need additionally includes a food container system that is simple and is not cost-prohibitive for food processors to implement and operate. The present invention provides for a unique approach that achieves this objective.

SUMMARY OF THE INVENTION

The improved food container system design of the current invention overcomes the above-described disadvantages associated with current food containers. In all embodiments of the invention, the tray and lid members of the container system are manufactured using rigid plastic material. Rigid plastic food containers are typically manufactured from Polystyrene, Polypropylene, Polyethylene Terephthalate (PET), Polylactide, Polyvinyl Chloride (PVC), or other rigid polymers. Furthermore, they are available in a variety of shapes and cross-sections—circular, rectangular, square, and elliptical, etc. Therefore and advantageously, the food container system according to this invention retains largely all the positive mechanical qualities—resistance to puncture and bending, load bearing strength—and physical characteristics—clarity, gloss, ability to meet FDA-approval standards—that food processors find so attractive. Additionally, the food container system of the current invention, while providing these characteristics is simple to implement, operate and maintain. Specifically, the food container system of the current invention comprises a tray and lid member that may be of constructed of two parts or may be a one-piece construction with a hinge that modifies one portion of the container to act as the tray and the other connected portion to act as a lid. The lid and tray members are further are designed to mate with and be releaseably lockable to each other. When engaged the releaseably lockable retaining mechanism forms an airtight seal that encases the product contents thereby preventing contamination. In this preferred embodiment of the present invention, the container system comprises a rectangular main tray member, with multiple recesses so that a variety of foodstuff, e.g. carrots, celery, cauliflower and broccoli, can be placed in them, and a complementary lid member that is formed to mate with and be releaseably lockable to the rim of the main tray member. When assembled the mating lid and tray rims form an airtight seal. Furthermore, to ensure that the airtight seal is maintain from the time the food is packaged at the food processing until the time that the consumer purchaser opens the package, tamper-evident tamper-resistant fastening means may employed. Previously disclosed tamper-evident tamper-resistant fastening means that may be incorporated into snap-fit grip mechanism include, but is not limited to, U.S. patent application Ser. No. 11/311,503, filed on Dec. 19, 2005 and entitled “Multi-Compartment Container System” and is incorporated herein by reference.
In order to permit some level of oxygenation, an airway opening or orifice is formed or cut into the lid member and a breathable film or membrane placed over it and held in place by an adhesive. In this way, freshness of the product is promoted and yet the advantages associated with traditional structures, such as resistance to puncturing, sanitation, clarity and good sealing are retained.
The perforation in the lid permits the exchange of gases between the package enclosure and the exterior. CO₂that would otherwise be trapped is permitted to escape and be replaced with air. In addition to acting as a barrier to moisture, the breathable film maintains the low-oxygen atmosphere environment in the package, and is selected at the discretion of the food processor for the specific produce to be packaged. If so desired, the food processor may select a film or structure a combination thereof to, for example, allow gas to escape but keeps oxygen out. A proprietary combination of films can be structured so that it permits the optimum barrier/permeation of gases corresponding to the respiration rate of the product content to maximize shelf and food product freshness.
This invention is a novel plastic packaging solution that improves significantly on the convenience and therefore marketability of food product. Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 is an exploded isometric view showing the elements comprising an embodiment according to the present invention.

FIG. 2 is an isometric view of the assembled container system in FIG. 1.

FIG. 3 is a cross-sectional view of the food container system taken along the line A-A in FIG. 2.

FIG. 4 is an exploded fragmentary view of the container system in FIG. 3 taken along the line B-B in FIG. 3.

FIG. 5 is an isometric view of two embodiments of the present invention as in FIG. 1 stacked ready for shipment or display at a market.

FIG. 6 is a cross-sectional view of the stacked container systems taken along the line C-C in FIG. 5.

FIG. 7 is an exploded isometric view showing the elements comprising another embodiment according to the present invention.

FIG. 8 is an isometric view of the assembled container system in FIG. 7.

FIG. 9 is a cross-sectional view of the food container system taken along the line D-D in FIG. 8.

FIG. 10 is an isometric view of two embodiments of the present invention as in FIG. 7 stacked ready for shipment or display at a market.

FIG. 11 is a cross-sectional view of the stacked container systems taken along the line E-E in FIG. 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, the embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art.
Referring to the drawings and in particular to FIG. 1, therein is shown an exploded isometric rendition of a rigid polymer plastic construct food container system 1 according to the present invention. The food container system includes a main tray member 4 that is rectangular viewed from above, with a multiple recesses 10, 12 into which a food items such as cut fruits and vegetables is place. As opposed to prior practices, a polymer film or foil is not disposed over the recesses in order to retain the foodstuffs contained in it. The lid member 2 is formed with a lid member rim 6 that mates with and is complementary with tray member rim 8 in such manner that they are releaseably lockable to each other. The lid member 2 and tray member 4 can be molded, through known thermoforming manufacturing means, from a single sheetline of polymer material work piece into a predetermined shape and thickness as required. The lid member 2 includes, in lid surface 3, lid member opening 17, which is an airway opening over which is placed a breathable patch 16, the breathable patch 16 being selected from one of a number of available gas-permeable membranes or films available in the marketplace. More specifically, the breathable patch 16 is located over and further covers the entire lid member opening 17. Additionally, the gas-permeable membrane from which the breathable patch is formed preferably exhibits water-resistant or water-proof characteristics. The cross section area of the lid member opening 17 and the gas-permeable film from which the breathable patch 16 is produced are preferably selected as function of the type of fruit and/or vegetable, the anticipated environmental temperature that the packaged product will experience prior to purchase and consumption by the consumer, the optimal or preferred O₂/CO₂composition to minimize the effect of senescence. Placement of the breathable patch onto the lid member surface is achieved by using an adhesive. The assembled food container system is depicted in FIG. 2. The lid member rim 6 and tray member rim 8 are formed so that they create a releaseably lockable mechanism 5 that is complementary to each other and mate together to form an airtight seal that that resists both leakage and bacterial contamination. Annular interference type snap-fit grip mechanisms comprising the releaseably lockable mechanism 5 is well-known in the food and other industries and is not a subject of the present invention other than that it enables an airtight seal. The inventor points out that the thermoforming process mentioned herein is able to form such food container systems into a many shapes of varying curvilinear geometry to thereby provide the food processor with a wide variety of available polygonal shapes.
It is anticipated that greater convenience is achieved and that the food packager and retailer's end user client, the consumer, will be able to select such food combination product more easily and readily. In the embodiment shown, the tray member 4 may be made from material that is dissimilar from the material used to make the lid member 2.
FIG. 3, which is a cross-sectional view of the assembled container in FIG. 2, illustrates the placement of the breathable patch over the lid member opening 17, as well as the annular type snap-fit grip mechanism 5. Also shown are raised male ribs 14 formed on the lid member 2 and complementary raised male ribs 18 formed into the tray member 4. The raised male ribs 14, 18 provide two benefits. Firstly, such “ribbing” provides structural integrity to the rigid polymer sheetline material from which the lid member 2 and tray member 4 are formed, and secondly and as will be further illustrated, they provide a means for mechanical fit that enables stacking of identically formed containers. This feature is illustrated in more detail in FIGS. 5 and 6. FIG. 4 is an exploded fragmentary view of the breathable patch and lid member interface shown in FIG. 3.
FIGS. 5 and 6 illustrate one manner in which stacking of the container systems described herein may be achieved. Continuous raised male ribs 14 in the lid member 2 of a first container system 22 are formed so that they slot into and make a mechanical fit with complementary raised male ribs 18 in the tray member 4 of a second container system 20. The slotably connected lid member 2 and tray member 4 have thus a mechanical fit that restrict lateral movement of the container system when they are stacked. In this embodiment of the invention, the formation of multiple recesses create gaps 11, 13 in the tray member 4 that permit airflow to and from the breathable patch 16. This would not otherwise be possible were the tray member formed as a single recess with a continuous raised male rib.
FIGS. 7 through 11 illustrate another embodiment of the present invention. FIGS. 7, 8 and 9 show how the breathable patch 16 is placed on the tray member bottom surface 9 and specifically located over and covers the tray member opening 19. The tray member 4 is necessarily formed with discrete or discontinuous raised male ribs 18 so that gaps 28, 30 are exhibited. As will be later described, when multiple food container systems of the present invention are stacked, gaps 28, 30 enable exterior air to flow through to and from the breathable patch 16.
Turning now to FIGS. 10 and 11, therein is shown a manner of stacking two or more of the container systems of the embodiment illustrated in FIGS. 7 and 8. In a similar manner as previously described continuous raised male ribs 14 in the lid member 2 of a first container system 24 are formed so that they slot into and make a mechanical fit with complementary discontinuous raised male ribs 18 in the tray member 4 of a second container system 26. The slotably connected lid member 2 and tray member 4 have thus a mechanical fit that restrict lateral movement of the container system when they are stacked.
Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.

Claims

1. A rigid polymer food container system comprising:

a lid member, the lid member further comprising an airway opening and a continuous rim formed as a first mating element of a snap-fit grip mechanism;

a tray member, the tray member further comprising a plurality of recesses and a continuous rim formed as a second mating element of said snap-fit grip mechanism;

further wherein assembly of the lid and tray members is achieved by mating the first and second mating elements comprising said snap-fit grip mechanism together to form an airtight seal; and

a breathable patch that is located over and covers the airway opening formed in the lid member.

2. A rigid polymer food container system comprising:

a tray member, the tray member further comprising an airway opening and a continuous rim formed as one mating element of a snap-fit grip mechanism;

a lid member, the lid member further formed with a plurality of recesses and a continuous rim formed as a second mating element of a snap-fit grip mechanism;

further wherein assembly of the lid and tray members is achieved by mating the first and second mating elements to comprising the snap-fit grip mechanism together thereby forming an airtight seal; and

a breathable patch that is located over and covers the airway opening formed in the tray member.

3. The claims as in claims 1 or 2 wherein the snap-fit grip mechanism is releaseably lockable.

4. The claim as in claim 3 wherein the snap-fit grip mechanism further comprises a tamper-evident feature.

5. The claim as in claims 1 or 2 wherein the material of the lid member and tray member is Polystyrene, Polypropylene, Polyethylene Terephthalate, Polylactide, Polyvinyl Chloride, or other rigid polymers.

6. The claim as in claims 1 or 2 wherein the lid member or tray member is constructed using a process taken from the group consisting of thermoforming, injection molding, transfer molding and blow molding.

7. The claim as in claims 1 or 2 wherein the lid member and tray member are hingeably attached to each other.

8. The claim as in claims 1 or 2 wherein the container system is circular, rectangular, square, and elliptical, or other polygonal shape.

9. The claim as in claims 1 or 2 wherein the container system is stackable.

10. The claim as in claim 9 wherein the stacking feature is enabled by forming the top lid member with either raised male ribs or female grooves that slotably interfaces with complementary female grooves or male ribs in the bottom of the tray member.