US20050029151A1

US20050029151A1 - Gas flushable tray

Info

Publication number: US20050029151A1
Application number: US10/634,951
Authority: US
Inventors: Bradley Shepard
Original assignee: Frito Lay North America Inc
Current assignee: Frito Lay North America Inc
Priority date: 2003-08-05
Filing date: 2003-08-05
Publication date: 2005-02-10

Abstract

A food tray for use in a modified atmosphere package is provided by the present invention. The tray includes product area for holding food items, which may be specifically shaped for holding particular types of items, and at least 25% void area that does not hold any product due to the shape of the tray. The tray has air vents that facilitate gas flushing of the void area during packaging of the tray, wherein the air vents may also provide communication between the product area and void area. In addition, the air vents are not visible when food items are placed in the product area. The tray may be made of a single piece of folded material, wherein the folds form the void area.

Description

BACKGROUND OF THE INVENTION

1. Technical Field
The present invention relates to modified atmosphere packaging, and more specifically, to a food tray design that facilitates more efficient gas flushing.
2. Description of Related Art
Maximizing the shelf life of packaged foods requires the removal of particular gasses from the sealed packaging. In particular, oxygen can cause fats to become rancid. This is especially true of unsaturated cooking oils, which are often used in baked and fried food products. It is also well known that oxygen contributes to staling of food products. To extend shelf life, many food packages are flushed with nitrogen just before the package is sealed. Because nitrogen is an inert gas, it does not react with foodstuff, thus preventing or significantly reducing oxidation and staling of the food product in the sealed package and otherwise extending the shelf life of the product.
The efficiency of nitrogen flushing depends on how much oxygen and other reactive gases are removed from the packaging before it is sealed. This depends on several factors, including the contents of the package. For example, potato and tortilla chips are typically packages in a loose or stacked manner. Flexible film bags are used for loose fill packaging, in which the film is formed into an open-ended bag and the food product (e.g., potato chips) is simply dropped or poured in. Before the bag is sealed, it is flooded with nitrogen to flush out any remaining air in space not occupied by the food.
Stacked products are typically packaged in non-flexible containers. The food items have a standard shape, which allows them to be uniformly stacked on top of each other, forming a column. The non-flexible container helps maintain the orderly stack. When the stacked food items are placed in the container, there is a small space between the food and the sides of the container, which is flushed with nitrogen gas just before the container is sealed.
The introduction of food trays into food packaging creates problems for efficient gas flushing, because the shape of the tray might create “void” areas that are not used for holding food. These void areas can trap air and impair the ability to efficiently flush oxygen and other reactive gases from the packaging.
Therefore, it would be desirable to have a method for increasing the efficiency of gas flow throughout food packages containing trays during the nitrogen flushing process just before packaging.

SUMMARY OF THE INVENTION

The present invention provides a food tray for use in a modified atmosphere package. The tray includes product area for holding food items, which may be specifically shaped for holding particular types of items, and at least 25% void area that does not hold any product due to the shape of the tray. The tray has air vents that facilitate gas flushing of the void area during packaging of the tray, wherein the air vents may also provide communication between the product area and void area. In addition, the air vents are not visible when food items are placed in the product area. The tray may be made of a single piece of folded material, wherein the folds form the void area.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will be best understood by reference to the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings, wherein:
FIG. 1 depicts a side view schematic diagram illustrating a nitrogen flushing system in which the present invention can be implemented;
FIG. 2 is a plan view of an unfolded paperboard tray used for holding packaged food items in accordance with the present invention;
FIG. 3 depicts a perspective view of one embodiment of a folded paperboard tray for holding packaged food items in accordance with the present invention;
FIG. 4 depicts an end view, cross section diagram illustrating the assembled tray in accordance with the present invention;
FIG. 5 depicts a perspective view illustrating one embodiment of the folded paperboard tray containing food items; and
FIG. 6 is a plan view of an unfolded paperboard tray used for holding packaged food items in accordance with an alternate embodiment of the present invention.

DETAILED DESCRIPTION

Referring now to the figures, FIG. 1 depicts a side view diagram illustrating a nitrogen flushing system in which the present invention can be implemented. In order to maximize the shelf life of packaged foods, reactive gases such as oxygen need to be flushed from food containers just before packaging. Nitrogen is the preferred flushing gas as it is inert and will not react with the food while inside the packaging for extended periods. The example nitrogen flushing system illustrated in FIG. 1 is designed specifically for food products that are contained in special trays that are included in the final package.
Two trays 106, 107 containing the food product (deposited in an earlier step, not pictured) and are moved along from right to left by two in-feed chain lugs 108, 109. The trays 106, 107 pass through an enclosed tunnel 103 that is nitrogen flushed by overhead gas rails 104 emitting streams of nitrogen gas 105. As explained above, nitrogen is used to flush other gases, such as oxygen, from the food trays 106, 107 before packaging.
The trays 106, 107 briefly leave the tunnel before entering a film tube 102 on a horizontal flow wrapper. The film 102 is unwound from a roll 101 and wrapped around the first tray 106 and sealed on the bottom to form a tube. After the first tray 106 is completely wrapped, the film tube 102 is sealed at the ends to form the final package. As the first tray 106 is moving from the nitrogen-flushed tunnel 103 into the film tube 102, the film tube is flushed with nitrogen gas from below by means of a gas tube called a nitrogen “lance” 110.
In many packaging systems, the nitrogen lance 110 is the primary means by which packaging is flushed. The enclosed nitrogen flushing tunnel 103 is often a non-standard add on that is only used when necessary for difficult flushing applications.
FIG. 2 is a plan view of an unfolded paperboard tray used for holding packaged food items in accordance with the present invention. FIG. 3 is a perspective view illustrating the paperboard tray folded together, ready to hold the food product. The tray 200 includes a bottom section 220 and folding sections 201-205 that fold together to form the side of triangular rows 210, 211 in the middle of the tray 200, as depicted in the perspective view picture in FIG. 3.
Referring to FIG. 4, an end view, cross section diagram illustrating the assembled tray 200 is depicted in accordance with the present invention. The end view in FIG. 4 clearly illustrates the spaces created when the folding sections 201-205 are folded together as shown in FIGS. 3 and 4. The assembled tray 200 can be divided into product area and “void” area. The triangular rows 210, 211 represent the product area, which is the volume of the tray 200 that is specifically dedicated to holding the food items placed in the tray 200 (shown in FIG. 5). The void area, comprising spaces 401-403 beneath the folded sections 201-205, represents the volume of the tray 200 that does not hold food items due to the shape of the tray and product area. In the present embodiment, the void area accounts for at least 25% of the volume of the tray 200.
The void areas 401-403 have the potential to trap air that will not be effectively removed during the nitrogen flushing process. If the nitrogen gas cannot efficiently flush these air pockets, air and reactive gases may remain in the final package, reducing the shelf life of the product. To allow for more efficient gas flow through the void areas 401-403, venting holes 230 are placed in the folding inner sections 201-205. These holes provide communication between the product area in rows 210, 211 and the void areas 401-403. This communication allows for more thorough flushing of oxygen and other reactive gases from the void areas 401-403 just before packaging.
FIG. 5 illustrates the folded paperboard tray 200 containing food items. In the example depicted, the tray 200 is filled with triangular tortilla chips 500. The triangular shape of rows 210, 211 illustrated in FIGS. 3 and 4, are designed to hold the triangular tortilla chips 500 in ordered rows. Though the venting holes 230 are not seen when the tray 200 is filled with the chips 500, they will still allow efficient gas flow and nitrogen flushing. This is necessary, as the chips 500 must be loaded into the tray 200 before nitrogen flushing. It should be pointed out that the shape of the product space may vary, depending on the shape of the food product held in the tray 200.
FIG. 6 is a plan view of an unfolded paperboard tray used for holding packaged food items in accordance with an alternate embodiment of the present invention. The tray 600 depicted in FIG. 6 has venting holes 630, similar to the tray 200 depicted in FIGS. 2-5. However, tray 600 has the additional feature of venting slots 610 in the bottom surface 620. These additional bottom, venting slots 610 allow for even greater gas flow and nitrogen flushing than the previous tray design 200. The alternate tray design 600 is better suited for larger scale production and packaging, in which the tray 600 would move through the nitrogen flushing chamber more quickly and would therefore require greater gas flow to ensure adequate nitrogen flushing within a shorter period of time.
The present invention can also be applied to other types of tray designs and is not limited to the single-piece, folded paperboard tray example described above. For example, the tray in question might be a multi-piece paperboard tray, a formed paperboard tray, or a plastic tray. Any one of these alternate tray designs can utilize air vents to facilitate nitrogen flushing of void space in modified atmosphere packages.
In addition to improving gas flushing and shelf life, the present invention also has the advantage of reducing the need for additional nitrogen flushing systems such as enclosed flushing tunnel 103 described above. Having a more efficiently vented container may allow adequate nitrogen flushing with a lance only.
While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.

Claims

1. A food tray for use in a modified atmosphere package, the tray comprising:

product area for holding food items;

at least 25% void area; and

at least one air vent that facilitates gas flushing of the void area during packaging of the tray, and wherein the air vent is not visible when food items are placed in the product area.

2. The tray according to claim 1, wherein the tray is made of a single piece of folded material, and wherein the folds form the void area.

3. The tray according to claim 1, wherein the tray is made of paperboard.

4. The tray according to claim 1, wherein the tray is made of plastic.

5. The tray according to claim 1, wherein the product space is specially shaped to hold food items of a particular shape.

6. The tray according to claim 1, wherein the air vent provides communication between the product area and void area.

7. The tray according to claim 1, wherein the at least one air vent is a plurality of air vents.