EP1647489A2 - Method and apparatus for packaging fresh vegetables - Google Patents

Abstract

The apparatus (20) for packaging fresh fruit and vegetables in containers (21 - 24) covered with a sealed layer of film (32) incorporates a perforator (51) to make holes in the film with variable density, adapted to the metabolism of the contents. The film is delivered from a roll (31) and passes under the perforating system, including an activator (42) and a perforator with a light source (44), especially a CO2 laser. A regulator (47) connected to the actuator permits manual control of the density of the perforations according to a characteristic of the packaged product such as its respiratory intensity, weight or type. The film is between 25 and 90 microns thick and the perforations are betwen 30 and 70 microns in diameter.

Description

The present invention relates to a process for packaging fresh vegetable products and to a device for carrying out this method.

The technical field of the invention is that of the manufacture of packaging machines for fresh plant products.

It is known to package whole and / or fresh fruits and vegetables in a container at least partly made of a film material; generally used for this purpose a packaging machine which comprises a substantially sealed closure means of the container, such as a heat sealer.

In order to prolong the preservation of the living tissues of these plants, it is necessary to control the gaseous exchanges between the plant product and the environment surrounding it; when the plant is packaged in a sachet or other closed container, it is necessary to take into account the diffusion of gas exchanges through the wall of the container; the gases concerned are essentially oxygen, carbon dioxide, ethylene and water vapor; the respiration of plant tissues evolves as a function of temperature; in addition, the respiratory intensity of the plants is not constant after harvesting.

The mastery of these complex phenomena remains to be improved; in general, it seeks to produce a closed package or container which limits the desiccation of the products without leading to a gaseous medium bathing the product which is saturated with moisture; it is also generally desired to reduce the respiration, maturation and weathering of plant products in their packaging.

To produce a package containing a plant product, it is known to use a perforated film that can be sealed to form and / or close a low gas permeable container, such as a tray or bag.

The permeability to each of the gases mentioned above generally varies according to the size of the perforations and according to the density of the perforations. Patent EP351115 describes a method of packaging plants using a perforated polymer film; the film has a perforation density ranging from 10 to 1000 perforations per square meter, a water vapor transmission rate of less than 800 m ^-1 , per day and per atmosphere at 25 ° C and at 75% relative humidity as well as an oxygen permeability of less than 200000 cm ³ / m / day; the perforations have a diameter of around 50 microns.

The disadvantage of perforated films is that their use is optimal only for one or more specific plants and for certain conditions (particularly for certain temperatures) determined conservation products.

An object of the invention is to provide an improved process for packaging fresh plant products and a device for its implementation.

An object of the invention is to provide a method of packaging fresh plant products and a device for its implementation, which remedy, at least in part, the disadvantages of known systems of plant packaging.

According to a first aspect of the invention, there is provided a method for packaging plant products in a container sealed with a perforated film, in which the film is perforated in particular according to at least one characteristic of the container such as its volume. and / or at least one characteristic of the plant product such as its respiratory intensity and / or its mass and type, and preferably at least one conservation feature such as the conservation temperature provided for the plant products considered .

Preferably, identical perforations are produced, and the number of perforations per unit area of the film is varied to adapt the gas permeability of the perforated film to a predetermined container and product, as well as to the expected storage temperature for this product.

In other words and according to another aspect of the invention, there is provided a device for packaging a plant product in a container comprising a wall made of a film material, which comprises a substantially sealed closure means of the container. The packaging machine or device further comprises a means for perforating the film material with a variable density of perforation; this makes it possible to optimize the conservation of the vegetable product packaged in the container, by adapting the permeability of the container to the metabolism of the plant product.

• le dispositif comporte en outre un moyen de distribution du matériau en film à partir d'un rouleau de film, et le moyen de perforation du matériau en film est disposé entre le moyen de distribution de film et le moyen de fermeture du conteneur ;
• le moyen de fermeture du conteneur comporte un dispositif de scellage à chaud ;
• le moyen de perforation du matériau en film comporte une source lumineuse, en particulier un laser CO₂ ;
• le dispositif comporte un moyen d'activation pour activer le moyen de perforation en fonction de l'avancement du film, du moyen de distribution vers le moyen de fermeture ;
• le dispositif comporte en outre un organe de réglage, de préférence manuel, de la densité de perforation, qui est relié au moyen de déclenchement du moyen de perforation.

According to preferred characteristics of the packaging device according to the invention:

• the device further comprises means for dispensing the film material from a roll of film, and the perforating means of the film material is disposed between the film dispensing means and the container closing means;
• the means for closing the container comprises a heat sealing device;
• the means for perforating the film material comprises a light source, in particular a CO ₂ laser;
• the device comprises an activation means for activating the perforation means according to the advancement of the film, the dispensing means to the closing means;
• the device further comprises an adjustment member, preferably manual, the perforation density, which is connected to the trigger means of the perforation means.

In addition, the device comprises alternately means for controlling the diameter of the perforations on the one hand and the perforation density on the other hand, which comprises a camera and a screen for viewing the images of the camera.

The display screen also displays the image of a target perforation diameter and the image of the target perforation density. A drift of the effective diameter of perforation relative to the target diameter can thus be corrected by appropriate adjustment of the perforation density with the aid of said adjustment member. This body of This setting will also be used if there is a deviation of the perforation density from the corresponding setpoint.

• on utilise avantageusement un film d'un matériau choisi parmi le polyéthylène, le polyéthylène-téréphtalate, le polypropylène, le polyamide;
• on dispose les perforations selon au moins une ligne droite parallèle aux bords d'une bande du film, selon un pas variable d'espacement des perforations qui peut être de l'ordre de 1 à 10 centimètre par exemple, pour une bande de film dont la largeur est de l'ordre de 10 à 50 centimètres par exemple;
• on utilise un film d'une épaisseur située dans une plage allant de 25 à 90 microns ; on effectue des perforations présentant un diamètre situé dans une plage allant de 30 à 70 microns ; on effectue des perforations de contour sensiblement circulaire et délimitées par un bourrelet du matériau formant le film ;
• on synchronise la réalisation des perforations avec l'avancement du film et/ou avec le fonctionnement du dispositif de scellage du film, par des moyens de synchronisation reliant le dispositif de scellage au moyen de perforation du film.

According to preferred features of the packaging method according to the invention:

• a film of a material chosen from polyethylene, polyethylene terephthalate, polypropylene and polyamide is advantageously used;
• the perforations are arranged in at least one straight line parallel to the edges of a strip of the film, according to a variable spacing pitch of the perforations, which may be of the order of 1 to 10 centimeters for example, for a strip of film of which the width is of the order of 10 to 50 centimeters for example;
• a film with a thickness in the range of 25 to 90 microns is used; perforations having a diameter ranging from 30 to 70 microns; perforations of substantially circular contour and delimited by a bead of the material forming the film;
• the perforations are synchronized with the advance of the film and / or with the operation of the film sealing device, by synchronization means connecting the sealing device by means of perforation of the film.

The invention makes it possible, by adjusting - which can be manual - the perforation density achieved, to produce successively, from a single roll of film (which can be perforated or not), a multitude of portions of the tape. this film which have different densities of perforations.

Furthermore, the invention makes it possible to verify by visual control that the diameter of the perforations on the one hand and the perforation density on the other hand are in accordance with the set values, and makes it possible to anticipate, in the event of observed differences, by a correction of the perforation density using said adjustment.

The invention is particularly suitable for packaging fruit, vegetables, flowers, or mushrooms in sachets or trays, by simultaneous heat-sealing of two trays for example.

• La figure 1 illustre schématiquement un dispositif d'emballage selon l'invention.
• La figure 2 illustre les principales étapes d'un procédé selon l'invention.
• La figure 3 illustre schématiquement, en perspective, un rouleau de matériau d'emballage en film utilisé et perforé conformément à l'invention.

Other features and advantages of the invention appear in the following detailed description, which refers to the accompanying drawings and illustrates, without any limiting character, preferred embodiments of the invention.

• Figure 1 schematically illustrates a packaging device according to the invention.
• Figure 2 illustrates the main steps of a method according to the invention.
• Figure 3 schematically illustrates, in perspective, a roll of film packaging material used and perforated in accordance with the invention.

With reference to FIG. 1 in particular, the plant packaging machine 20 according to the invention comprises, successively arranged in this order, a post 50 for unwinding a heat-sealable film material packaged in a roll 31 of axis 38. , a perforation station 51 of the strip 32 of the previously unwound film material, and a station 52 for closing containers 21 to 24 by heat sealing a portion 32a of the strip 32 on these containers.

A drive means of the film material comprises two rollers 27 rotating in opposite directions to cause the advancement of the film strip 32 of the station 51 to the station 52, before the evacuation according to the arrow 26 of the heat-sealed containers.

The station 52 comprises a heat sealing tool 25 and receives two trays 23 and 24 which have respectively been extracted from two stack of trays 21 and 22; for simultaneous closure of the trays 23, 24 by sealing on their upper face of the film portion 32a, the tool 25 and the trays 23, 24 are respectively brought into contact with two opposite faces (upper and lower respectively) of the portion 32a, along an axis substantially orthogonal to the plane of this portion 32a.

Before its introduction to the sealing station 52, the band 32 is perforated, as illustrated schematically in FIG. 3, according to - for example at least two - distinct densities of perforations which are respectively determined according to the type of container, the type of plant, and where appropriate the type of conservation that have been chosen. Band 32 extends along a longitudinal axis 34 orthogonal to the axis 38 of roller 31 and comprises two portions 36 and 37 clear: in the portion 36, perforations 33 are spaced along the axis 34 of a ¹ pitch spacing which is adapted to a 1 ^st type of package, while in the portion 37, perforations 35 are spaced along the axis 34, a second spacing pitch whose value is greater than the first step : this second step is adapted to a ^2nd type of separate package ¹ type of package (packaged product).

The realization, according to a variable spacing pitch, perforations 33, 35 of substantially identical diameter, is achieved by the perforation means of the station 51.

These means essentially comprise a laser transmitter 44 whose operation is controlled by a control unit 42 to which is connected a member 47 for controlling the variation of spacing of the perforations to be made.

For this purpose, the transmitter 44 is connected by a link 43 to the control unit 42; in order to allow the synchronization of the emission of successive pulses of a pulse train of the laser beam 45 for producing the perforations in the film strip 32, with the advance of this band 32, a sensor 40 for moving the the band 32 may be provided, which is connected by a link 41 to the control unit 42. Alternatively or cumulatively, the control unit 42 is connected (by a synchronization link schematically represented by a line 60) to the drive actuators of the rollers 27 and / or of the tool 25.

To achieve the perforations in the film, the axis 46 of the beam 45 emitted by the laser 44 is substantially perpendicular to the plane of the band 32 to be perforated.

Alternatively, another means of perforation could be provided, including a mechanical means or a means of perforation by electric discharge; however, laser perforation is preferred.

Depending on the nature of the film material and the location of the packaging device, there may be provided a capture and treatment system for emitted gases resulting from perforation of the film by the laser.

The use of the device 20 is as follows: the user determines a spacing step perforations to achieve depending on the nature and mass of fruit or vegetable to be placed in a tray 23, 24, according the volume and permeability of this tray, and if necessary depending on the storage temperature provided by this fruit or vegetable in this tray. This determination is made based on tables or charts, from which the user determines the adjustment value of the adjusting member 47 corresponding to this spacing step desirable. After adjusting the member 47 and placing the fruit or vegetable in the two containers 23, 24 (step 11, Figure 2), the unit 42 causes the advance of the film (step 12 Figure 2) for the establishment of the portion 32a opposite the tool 25 and trays 23, 24 containing the plants to be packaged. During this advance of the film strip 32, the unit 42 successively causes the realization (step 13 figure 2) of a number of perforations adapted, according to the pitch provided between two successive perforations; the unit 42 then causes the tool 25 (step 14) to close the trays 23, 24; these full and sealed trays are evacuated, and a new conditioning cycle can be realized.

A control means 61 makes it possible to verify that the perforation diameter on the one hand and the perforation density on the other hand are in accordance with the corresponding setpoint values. This means 61 essentially comprises a camera disposed between the perforation means 51 and the means 52 for closing the container, which is connected to a display screen associated with this camera. Since the target diameter and the set value of the perforation density are also displayed on this control screen, an evaluation of the drifts of the actual diameter or the effective perforation density is made by the operator who can initiate a correction by modifying the perforation density to compensate for the drifts observed both for the diameter of the perforations and for the perforation density.

The invention makes it possible to produce a compact apparatus, which can be easily transported to the fruit and vegetable production sites for their immediate conditioning after harvest, which makes it possible to further improve their conservation.

Claims (11)

Device (20) for packaging a plant product in a container (21 to 24) having a wall made of a film material (32), which comprises means (52) for substantially sealing the container, characterized in that that it comprises: means (51) for perforating the film material with a variable density of perforation, which makes it possible to optimize the conservation of the vegetable product packaged in the container, by adapting the permeability of the container to the metabolism of the plant product, means (50) for dispensing the film material from a film roll (31), the perforation means of the film material being disposed between the film dispensing means and the container closing means, an activation means (42) for activating the perforation means as a function of the advance of the film, of the dispensing means towards the closing means, and in that the means for perforating the film material comprises a light source (44), in particular a CO ₂ laser. Device according to claim 1, which further comprises a member (47) for manually adjusting the perforation density, which is connected to the means (42) for triggering the perforating means. Device according to claim 1 or 2, which further comprises means (61) for visually inspecting the size or the perforation density, which is arranged between the perforating means and the means for closing the container. Device according to Claim 3, in which the visual control means (61) comprises a perforated film observation camera as well as a display screen for the images delivered by the camera and a set of perforation dimension or density. . Device according to any one of claims 1 to 4, wherein the means for closing the container comprises a device (25) for heat sealing. A method of packaging plant products in a container having a perforated film wall, characterized in that the film is perforated according to a variable density according to at least one characteristic of the container - such as its volume - or products in that the number of perforations per unit area of the film is varied in order to adapt the gas permeability of the perforated film to a specific container, to a predetermined product, and / or to the conservation temperature provided for this product. , in that the production of the perforations is synchronized with the advance of the film and / or with the operation of a device (52) for sealing the film, by means (60) of synchronization connecting the sealing device to the means (44) of perforation of the film, and in that perforations of substantially circular contour with a diameter in a range of 30 to 70 microns and delimited by a filling are made. elet of the material forming the film. The method of claim 6, wherein the diameter or the perforation density of the film is visually monitored. Method according to claim 6 or 7, wherein the film is perforated according to at least one characteristic of the plant product such as its respiratory intensity and / or mass and type. Method according to one of claims 6 to 8, wherein the film is perforated according to at least one conservation feature such as the conservation temperature provided for the plant products considered. A method according to any one of claims 6 to 9, wherein the perforations are arranged in a straight line (34) parallel to the edges of a strip of the film, with a variable pitch spacing perforation. A method according to any of claims 6 to 10, wherein a film of a material selected from polyethylene, polyethylene terephthalate, polypropylene, polyamide, and a thickness in the range of 25 at 90 microns.

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