US3750362A

US3750362A - Method of packaging granular material

Info

Publication number: US3750362A
Application number: US00239076A
Authority: US
Inventors: A Kishpaugh; D Hagen
Original assignee: Standard Packaging Corp
Current assignee: Standard Packaging Corp
Priority date: 1972-03-29
Filing date: 1972-03-29
Publication date: 1973-08-07
Anticipated expiration: 1990-08-07
Also published as: JPS5223316B2; CA1008410A; JPS4915593A; JPS52146386A

Abstract

A package for a granular material includes a bottom package member and a top package member. A gas-permeable intermediate package member is disposed between the bottom package member and the top package member to facilitate the evacuation of the package by retaining the granular material in the package during such evacuation. A method is provided for packaging the granular material which includes fully sealing the gas-permeable intermediate package member to the bottom package member and thereafter evacuating the package through the face of the gaspermeable intermediate package member.

Description

United States Patent Kishpaugh et al.

[111 3,750,362 [451 Aug. 7, r973 METHOD OF PACKAGING GRANULAR MATERIAL Inventors: Allan Kishpaugh; Donald J. Hagen,

both of Wayne, NJ.

Standard Packaging Corporation, New York, N.Y.

Filed: Mar. 29, 1972 Appl. N0 239,076

Assignee:

US. Cl. 53/22 A, 53/112 A, 206/46 F Int. Cl. B65b 31/02 Field of Search 53/22 R, 22 A, 22 B;

206/46 F, DIG. 12

References Cited UNITED STATES PATENTS 7/1972 Canamero et al. 53/22 A 3,3] l,5l7 3/1967 Kes lar et al. 53/22 B X lir irnary Examiner-Travis S. McGehee Attorney- Morton Amster, Alfred B. Engelberg and Barry A. Cooper et al.

[57] ABSTRACT A package for a granular material includes a bottom package member and a top package member. A gaspermeable intermediate package member is disposed between the bottom package member and the top package member to facilitate the evacuation of the package by retaining the granular material in the package during such evacuation. A method is provided for packaging the granular material which includes fully sealing the gas-permeable intermediate package member to the bottom package member and thereafter evacuating the package through the face of the gaspermeable intermediate package member.

8 Claims, 5 Drawing Figures PATENTED AUG 7 I973 SHEET 1 OF 2 PATENTEDAUB H975 SHEET 2 OF 2 FIG.4.

METHOD OF PACKAGING GRANULAR -MATERIAL This invention relates generally to vacuum packages and, more particularly, to a vacuum package for a granular material and to the method for packaging such granular material.

A multitude of prior art packages and methods have ben devised for vacuum packaging products. Most frequently, the packages are formed from a heat-scalable, flexible packaging material. Such packages have found wide acceptance in the food packaging field because of the extended shelf life afforded to the packaged product by the use of such materials and by the fact that the packages are vacuum-sealed. For example, food products have been protected from oxidizing influences, such as atmospheric oxygen, by vacuum-sealing of packages for preservation purposes.

However, although various packaging machines ave been devised, and although varous methods have been suggested, the vacuum packaging of grandular materials has been both difficult and ineffective. More particularly, when the product or material to be packaged is 'granular, as the package is evacuated to provide the vacuum-seal, the granular material is drawn into the sealing area along the top edge of the package. Thus, when the package is sealed to maintain the vacuum, the granular material is the sealing area causes leaks to result in the seal. Lacking an effective seal, the prior art packages have been unable to rovide the requisiste vacuum which, in turn, results in the early oxidation of the granular material in the package. Consequently, shelf life is greatly reduced. Additionally, loss of granular material and clogging of the vacuum apparatus results if the grandular material is not retained in the package during evacuation.

Accordingly, a primary object of the present invention is to provide a vacuum-sealed package for granular materials and a method therefor which overcomes the difficulties experienced with prior art packages and methods.

A further and more particular object of the present invention is to provide a vacuum-sealed package for granular materials which adequately vacuum-seals the granular material within the package.

Yet another object of this invention is to provide a vacuum-sealed package for granular materials which is inexpensive, yet lands itself to efficient manufacture. and objects, are accomplished in an illustrative embodiment thereof in which a vacuum-sealed package for a granular material includes a bottom package member having upstanding side walls termnating in an upper peripheral edge. An intermediate package member, substantially permeable to the flow of gases therethrough, but substantially impermeable to the flow of granular material therethrough, is also provided to overlie the peripheral edge of the bottom package member. The bottom package member and the-gaspermeable intermediate package member define a continuous, uniform and full seal along the upper peripheral edge of the bottom package member A top package member is constructed and arraned to be sealed to the bottom package member and the gas-permeable intermediate package member to maintain the vacuum in the package.

In accordance with an illustrative mebodiment denionstrating objects and features of method aspects of the present invention, a method for packaging a granulat materail from a bottom package member, a top package member and a gas-permeable intermediate package member includes the steps of loading the granular material into the bottom package member and fully sealing the gas-permeable intermediate package member to the bottom package member at the peripheral edges thereof. The top package member is then placed on top of the bottom package member and the gas-permeable intermediate package member and is partially sealed to the bottom package member and the gas-permeable intermediate package member at the peripheral edges thereof. Thereafter, the space between the bottom package member and the top package member is evacuated, through the face of the gaspermeable intermediate package member and the unsealed portion of the top package member. The unsealed portion of top package member is then sealed to bottom package member and the gas-permeable intermediate package member to maintain the vacuum within the package) The above brief description as well as further objects, features and advantages of the present invention will be more fully appreciated by reference to the following detailed description of a preferred, but nontheess illustrative embodiment, when taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic, elevation view of the apparatus utilized in performing the method of the present invention;

FIG. 2 is a top plan view of a typical die used to form the package of the present invention and showing the packaging sequence according to the present invention;

FIG. 3 is a side elevational view, partly in section, showing a die, an evacuation element and a sealing head elemen t useful in the method of the present invention, the representation of elements depicting inoperative positions thereof;

FIG. 4 is an enlarged view of part of the die, evacuation element and sealing head element of FIG. 3, showing the evacuation element in an operative position; and,

FIG. 5 is a perspective view of the vacuum-sealed package of the present invention with the gaspermeable intermediate package member and the top package member broken away to show more particularly the details of the construction of the package.

Referring to the drawings, and in particular to FIG. 5 thereof, a vacuum-sealed package for granular materials is generally designated 10. Vacuum-sealed package 10 includes a bottom package member 12 which is adapted to receive, as will be explained hereinafter, granular material 14. By way of example, granular ma terial 14 may be a food product, such as instant coffee or the like. Bottom package member 12 includes upstanding side walls I2a which terminate at an outwardly extending peripheral edge 12b. Bottom package member 12 thus defines a material-receiving cavity for receiving granular material. Bottom package member 12 is advantageously of a heat-scalable flexible packaging material, such as plastic.

In order to maintain the granular material 14 within package 10 while the package is evacuated, a gaspermeable intermediate package member 16 is provided. By way of xample, gas-permeable intermediate package member 16 may be of Delnet" or a similar type of material. Gas-permeable intermediate package member 16 defines a face 16a having a porosity which allows gas to be withdrawn from the granular material within bottom package member 12. l loweventhe porosity of gas-permeable intermediate package member 16 is such as to prevent the granular material 14 from escaping from the bottom package member as package is evacuated. This will be explained in more detail hereinafter.

Gas-permeable intermediate package member 16 is heat or otherwise sealed to the peripheral edge 12b of the bottom package member 12 after the granular material 14 has been loaded or unloaded into the bottom package member. A continuous, uniform and full seal is thus provided between gas-permeable intermediate package member 16 and bottom package 12 along peripheral edge 12b. A top package ember 18 of a heatsealable plastic or other material is provided and is placed on top of bottom package member 12 and gaspermeable intermediate package member 16 in a position overlying the peripheral edges of the gaspermeable intermediate package member and the bottom package member. The top package member 18 is partially sealed to the bottom package member and the gas-permeable intermediate package member as will be explained in more detail hereinafter.

One the gas-permeable intermediate package member 16 has been ully sealed to bottom package member 12 and the top package member 18 has been partially sealed to the gas-permeable intermediate package member and the bottom package member, the space between the bottom and top package members, containing the granular material 14, is evacuated through face 160 of the gas-permeable intermediate package member and through the unsealed portion of the top package member. Since gas-permeable intermediate package member 16 allows the flow of gases through face 16a but is ofa porosity to prevent the flow of granular material therethrough, the granular material is retained in bottom package member 12 during evacuation and the granular material is not drawn into the sealing area at peripheral edge 12b. Further, since the granular material is kept within package 10, there is no loss of the granular material and/or clogging of the vacuum apparatus.

After evacuation has been completed, the unsealed portion of top package member 18 is sealed to gaspermeable intermediate package merrgber l6 and bottom package member 12 along peripheral edge 12b. The evacuated state of package 10 is thus maintained by the hermetic seal between these package members, the hermetic seal being provided since ther is no granular material along the sealing area (peripheral edge 12b) of package 10.

Referring now to FIGS. 1 and 2, a package loading and forming apparatus useful with the present invention is generally designated 20. Reference is made to application Ser. No. 157,228, filed June 28, 1971, for Package Machine and Method, which application, assigned to the assignee of the present invention, shows in more detail aspects of package loading and forming apparatus 20.

Package loading and forming apparatus 20 includes a chain conveyor 22 which carries a plurality of conveyor molds or dies 24. Chain conveyor 22 and dies 24 are caused to be moved in a direction, as indicated by the arrows 26, by appropriate motive means (not shown). As the chain conveyor 22 and the dies 24 move in direction 26, the chain conveyor and the dies enter and leave various stages, designated A-H for convenience, wherein various steps in loading and forming vacuum-sealed package 10 is accomplished, as will be explained hereinafter.

At one side of package loading and forming apparatus 20, there is provided a roll 28 which supplies a heatsealable plastic packaging material 12' utilized to form bottom package member 12. Roll 28 may be mounted on an appropriate play-out roller 30 which is controlled by means (not shown) for supplying heat-sealable plastic packaging material 12' from roll 28 at a predetermined rate. ldler rollers 32a and 32b may also be provided for controlling the tension of heat sealable plastic packaging material 12'.

Similarly, rolls 34 and 36 are disposed at the other side of apparatus for supplying, respectively, a gaspermeable packaging material 16' and a heat-sealable plastic packaging material 18'. Rolls 34 and 36 are mounted, respectively, on play-outs rollers 38 and 30 which are used with appropriate means (not shown) for controlling the rate or supply of gas-permeable packaging material 16' and heat-sealable plastic packaging material 18'. A tensioning mechanism, generally designated 42, is provided for controlling the tension of gaspermeable packaging material 16' and heat-sealable plastic packaging material 18' as these materials are supplied from rolls 34, 36 in the direction of arrows 44 and 46, respectively. Such tensioning mechanisms are well known in the art and take the form of idler rollers 43, springs 45, etc.

ldler rollers 48, 50, disposed near the top of the flow path for dies 24, are provided to change the direction of movement of gas-permeable packaging material 16' and heat-sealable plastic packaging material 18' as these materials exit tensioning mechanism 42. Thus, gas-permeable intermediate packaging material 16 is caused to travel in a horizontal direction by idler roller 48 while heat-sealable plastic packaging material 18 is caused to travel in a horizontal direction by idler roller 50.

By way of stages A, B,'C and granular material is loaded into the formed bottom package member by a loading element 54 at stage D. Gas-permeable intermediate package material 16' is introduced to die 24 at stage E where a sealing head element 58 seals this material to the peripheral edge of the bottom package member to form gas-permeable intermediate package member 16. Heat-sealable plastic packaging material 18 to bottom package member 12 and gas-permeable intermediate package member 16 along peripheral edge 12b to form top package member 18. At stage G, evacuation element and sealing head element 62 evacuates the space between bottom package member 12 and top package member 18 through the face 16a of intermediate package member 16 and the unsealed portion of top package member 18. Evacuation element and sealing head element 62 then seals the unsealed portion of top package member 18 to maintain the vacuum within vacuum-sealed package 10. At stage H, vacuum-sealed package 10 is cut from other like packages and removed from die 24.

Referring now to FIGS. 3 and 4, the construction details of conveyor mold or die 24 and evacuation element and sealing head element 62 are shown. Die 24 includes a main body member 64 defining die cavities 66. Two such die cavities 66 are provided, although it is to be understood that a different number of die cavities may be provided if so desired. Disposed within each die cavity 66 is a spacer element 68 having a shape which conforms to the die cavity. Spacer element 68 allows the die cavity to form packages of various sizes, the size depending on' the shape of the spacer element inserted into the die cavity.

Die 24 includes top clamps 70, disposed at the top of the die, for clamping the bottom package member 12 to the top of the die (see FIG. 2). Each top clamp 70 defines an aperture 70a through the top of the top clamp and an aperture 70b, in the side of the top clamp adjacent bottom package member 12 (FIG. 4). Apertures 70a, 70b are provided to evacuate the space between the bottom package member 12 and the top package member 18 through face 160 of gas-permeable intermediate package member 16 as will be explained hereinafter. Top clamps 70 are associated with top clamp release mechanisms 72 which operate to release the top clamps after the package has been evacuated and vacuum-sealed. Die 24 may also include a rubber cushion or gasket 74 which insures that the vacuum will be maintained as an evacuation element and sealing head element 62 engages die 24 to vacuate and seal the package. Another rubber cushion or gasket 75 insures that an adequate seal is made between top package member 18 and bottom package member 12 and gaspermeable intermediate package member 16.

The evacuation element and sealing head element, generally designated 62, includes an evacuation member, generally designated 76, and a sealing head member, generally designated 78. The evacuation member is adapted to evacuate the space between bottom package member 12 and top package member 18 through face 16a of gas-permeable intermediate package member 16 and through the unsealed portion of the top package member. After the evacuation has been completed, sealing head member 78 is adapted to seal the unsealed portion of top package member 18, thereby providing a hermetic seal for vacuum-sealed package 10.

Evacuation member 76, which is shown in an inoperative position in FIG. 3, defines an evacuation channel 80 which is connected to a source of suction or vacuum (not shown) by a hose 82. Evacuation member 76 includes a downwardly extending shoulder 84 which is adapted to engage the rubber cushion or gasket 74 of die 24 as evacuation element and sealing head element 62 is moved downwardly to the evacuation position indicated in FIG. 4. In the evacuation position shown in FIG. 4, evacuation member 76 moves to an operative position, in contact with die 24, while sealing head member 78 remains in an inoperative position, out of contact with the die. An annular rubber cusion or gasket 86, which is disposed at one end of the evacuation channel 80, is adapted to engage top clamp 70, about aperture 700, when the evacuation member is in the operattive position of FIG. 4. This insures that the suction from vacuum channel 80 will draw the air or gas from the granular material. A suction or vacuum path is thus provided between bottom package member 12 and top package member 18 (in the direction of arrows 88) from granular material 14, through the face 16a of gas-permeable intermediate package member 116 and the unsealed portion of the top package member 18, through aperture 70b and aperture 70a of top clamp 70. Thus, quick and efficient evacuation of the loaded package is provided.

After the package has been evacuated, the unsealed portion of top package member 18 is sealed to bottom package member 12 and gas-intermediate package member 16. In order to accomplish this, sealing head member 78 is provided. Sealing head member 78 includes a heating element 90 (see FIG. 3) which is inserted between sealing

elements

92, 94. Projections 94a, which extend downwardly from sealing element 94, are constructed and arranged to seal the unsealed portion of top package member after the package has been evacuated. To provide an efficient seal, projections 94a make contact with top package member 18 which is disposed on top of cushion or gasket (see FIG. 4).

Thus, in a typical operational sequence, evacuation element and sealing head element 62 moves downwardly, as a unit, from an inoperative position (FIG. 3) to a first operative position (FIG. 4) wherein evacuation member 76 engages die 24. It is in this first operative position that the package is evacuated. After evacuation is completed, sealing head member 78 moves downwardly, in the direction of arrow 96, to seal the unsealed portion of top package member 18, thereby maintaining the vacuum-sealed package 10. The movement of evacuation element and head sealing element 62 may be accomplished by spring elements, generally designaed 98, which may be connected to an appropriate control mechanism (not shown).

In order to provide a more complete understanding of the operation and method for loading and sealing vacuum-sealed package 10, a typical operational sequence will now be described with reference particularly to FIGS. 1 and 2. For convenience, FIG. 2 illustrates the sequential movement of a typical die 24 from state D to stage G, the movement being in the direction of arrows 100. It is to be understood, however, that all operations of package loading and forming apparatus 20 take place simultaneously, so that while one package may be at loading stage E, for example, another package may be at another stage, for example, evacuation and final sealing stage G, etc.

Heat-scalable plastic packaging material 12, supplied from roll 28, is placed on die 24 with top clamps 70, at the top of die 24, holding the heat-scalable plastic packaging meateril 12 in place. At stage A, a conventional heating element 52 heats the heat-sealable plastic packaging material 12 causing the material to become malleable in shape. The die proceeds to stage B where suction from an appropriate source (not shown) causes the material 12 to be drawn into die cavity 66. The material 12' will conform to die cavity 66 (or will conform to spacer element 68 which is inserted into the die cavity 66 if a smaller bottom package member 12 is desired). However, part of the material 12 remains at the top of the die 24 and this part will form peripheral edge 12b of vacuum-sealed package 10. At the next stage, stage C, the material 12' is allowed to cool within the die 24 to provide bottom package member 12.

At stage D, a predetermined amount of granular material 14 is deposited or loaded into the formed bottom package member 12 by loader 54. Die 24, with bottom package member 12 filled with granular material 14, is shown in the D illustration of FIG. 2.

Die 24 containues to move to tage E where gaspermeable packaging material 16', supplied from roll 34, is placed on top of granular material 14 and the peripheral edge 12b of the bottom package member 12. Material 16' is advantageously chosen to be of a width such that the material will not rest on top clamps 70 as the material is placed on die 24 (see illustration E of FIG. 2). Conventional sealing head element 58 then fully seals the gas-permeable packaging material 16 to the peripheral edge 12b of bottom packaging member 12 thereby forming the gas-permeable intermediate package member 16. The gas-permeable intermediate package member 16 and the bottom package member 12 define a continuous, uniform and full seal 16b along the peripheral edge 12b of the bottom package member. The gas permeable intermediate packaging material 16 further defines a face 16a which is porous to the flow of gases but imporous to the flow of granular material therethrough. Die 24 is shown as exiting stage E in illustration E of FIG. 2.

Die 24 then moves to stage F where heat-scalable plastic packaging material 18', supplied from roll 36, is provided and is placed on the gas-permeable intermediate packaging member 16. The width of material 18 is such that when this material is placed on the top of die 24, it also rests on the top of a portion of top clamp 70. However, the width of this material is such that the material will not cover aperture 70a at the top of the clamps (see illustration F" of FIG. 2). Sealing head element 60, at stage F, then seals part of the heatsealng plastic packaging material 18 to both gaspcrmeable intermediate packaging material member 16 and bottom package member 1, along a portion of peripheral edge 12b, thereby forming top package member 18. This is shown as sealed portion 18b in the illustration F of FIG. 2. However, an unsaled portion, designated 18a, is provided between the top package member 18 and the gas-permeable intermediate and the bottom package members. It is through this unsealed portion 18a (and face 16a of gas-permeable intermediate package member 16) that evacuation of the package occurs.

Evacuation occurs at stage G, shortly after evacuation member 76 moves downwardly to engage the top of die 24 (see FIG. 4). Thus, the space between bottom package member 12 and top package member 18 is evacuated through the face 16a of the gas-permeabl intermediate package member and through the unsealed portion 18a of the top package member. This removes gas, etc., from the granular material. However, as has been explained hereinbefore, the gas-permeable intermediate package member retains the granular material 14 within the confines of bottom package member 12 so that none of this material is drawn up to the sealing area (peripheral edge 12b) of the package.

After evacuation has occurred, sealing head member 78 moes downwardly, in the direction of arrow 96 in FIG. 4, and sealing projections 94a seal the heretofore unsealed portion 18a of top package member 18 to the bottom package member 12 and the gas-permeable intermediate package member 16 along peripheral edge 12b. This provides a hermetic seal for a vacuum-saled package 10. More particularly, package may be her metically seald to maintain the vacuum within the package since the gas-permeable intermediate package member 16 prevents the granular material 14 from being drawn up into sealing ara 12b during evacuation.

Since there is no material in the saling area, an effctive vacuum seal is provided when the package is sealed. This is shown in illustration G" in FIG. 2.

After the package has been fully loaded and sealed, in stages D-G, the package proceeds to stage H (FIG. 1) where knife elements (not shown) cut and trim the packages formed in dies 24 to provide the vacuumsealed pckage 10 illustrated in FIG. 5.

Obviously, other modifications of the present invention are possibile in light of the above teaching. For example, at stage G where the packages are evacuated, the package may be gas flushed, if so desired. For example, vacuum channel 80 (see FIG.4) may also define a gas flow channel for providing a gas flush for package 10. If a gas flush is utilized, package 10 is evacuated as indicated in FIG. 4, that is, air is drawn out of the package in the direction of arrows 88. Once this has been accomplished, and prior to completing the sal of top package member 18, a flushing gas, such as an inert gas, is forced to package 10. Vacuum channel 80 then becomes a gas flow channel with the flushing gas flowing in the opposite dirction of arrows 88 from channel 80 through aperture a, aperture 70b, intermediate package member 16, into package 10. The top package member 18 is then fully sealed to maintain the inert gas within the package. Similarly, a trace gas, uch as freon or the like, may be introduced into the package to detect leaks if so desired. It is to be understood, therefore that the term vacuum-sealed package includes gas flushed packages and the term evacuating or similar term includes gas flushing. Further, although heat sealable materials have been shown it is apparent that pressure sensitive, ultrasonic etec., sealing may be utilized. It is to be understood, therefore, that the embodiments described are merely an example of the principles of the invention. Additional embodiments may be devised by those skilled in the art without departing from the spirit or scope of thepresent invention.

What is claimed is:

1. A method for packaging a granular material from a bottom package member, a gas-permeable intermediate package member and a top package member comprising the steps of loading said granular material into said bottom package member, fully sealing said gaspermeable intermediate package member to said bottom package member to form a package having a gaspermeable face, thereafter evacuating said package through said gas-permeable face and while evacuated completing said package by sealing said top package member to said bottom package member.

2. The invention according to claim 1 further comprising the steps of placing said top package member over said gas-permeable face and partially sealing said top package member to said bottom package member prior to evacuation of said package.

3. The invention according to claim 2 wherein evacuation is accomplished through an unsealed portion of said top package member.

4. The invention according to claim 1 wherein said top package member is also sealed to said gaspermeable intermediate package member.

5. A method for packaging a granular material comprising the steps of forming a bottom package member having a material-receiving cavity, depositing sai granular material in said material-receiving cavity, overlying said granular material with a gas-permeable intermediate package member, fully sealing said gaspermeable intermediate package member to said bottom package member, thereafter overlying said gaspermeable intermediate package member with a top package member, partially sealing said top package member to said bottom package member, evacuating said material-reciving cavity through said gaspermeable intermediate package member and through the unsealed portion of said top packagem member, and fully sealing said top package member to said bottom package member.

6. The invention according to claim further comprising the step of sealing said top package member to said gas-permeable intermediate package member.

7. A method for packaging a granular material from a bottom package member, a gas-permeable intermedipermeable face.

Claims

1. A method for packaging a granular material from a bottom package member, a gas-permeable intermediate package member and a top package member comprising the steps of loading said granular material into said bottom package member, fully sealing said gaspermeable intermediate package member to said bottom package member to form a package having a gas-permeable face, thereafter evacuating said package through said gas-permeable face and while evacuated completing said package by sealing said top package member to said bottom package member.

4. The invention according to claim 1 wherein said top package member is also sealed to said gas-permeable intermediate package member.

5. A method for packaging a granular material comprising the steps of forming a bottom package member having a material-receiving cavity, depositing said granular material in said material-receiving cavity, overlying said granular material with a gas-permeable intermediate package member, fully sealing said gas-permeable intermediate package member to said bottom package member, thereafter overlying said gas-permeable intermediate package member with a top package member, partially sealing said top package member to said bottom package member, evacuating said materail-receiving cavity through said gas-permeable intermediate package member and through the unsealed portion of said top package member, and fully sealing said top package member to said bottom package member.

6. The invention according to claim 5 further comprising the step of sealing said top package member to said gas-permeable intermediate package member.

7. A method for packaging a granular material from a bottom package member, a gas-permeable intermediate package member and a top package member comprising the steps of loading said granular material into said bottom package member, fully sealing said gas-permeable intermediate package member to said bottom package member to form a package having a gas-permeable face, thereafter gas flushing said package through said gas-permeable face and completing said package by sealing said top package member to said bottom package member.

8. The invention according to claim 7 wherein said gas flushing of said package further includes the step of withdrawing air from said package through said gas-permeable face.