RU2789395C1 - Method and installation for packaging products, method for production of installation, and container - Google Patents

Abstract

FIELD: packaging.

SUBSTANCE: object of the invention is a method for packaging products, in particular products sensitive to oxygen, in containers, while the specified containers, each, have a hole. According to the invention, a controllable atmosphere is created in transportation chamber (4), inside which open containers are moved towards a closing chamber by means of following combined actions: a) pumping of a gas processing flow (G) to specified closing chamber (3) at an output of transportation chamber (4) in accordance with a direction of movement of open containers, b) vacuuming of open containers (1) present inside transportation chamber (4). A packaging installation for implementation of the specified method and containers obtained by this method are also disclosed.

EFFECT: obtainment of an installation and a method for packaging products.

25 cl, 5 dwg

Description

The invention relates to a method for packaging products, in particular those sensitive to oxygen, in containers, as well as to a corresponding packaging plant for carrying out the method.

The invention finds its particular application to the packaging of foodstuffs in a liquid state, or in a pasty state, or in a solid state, or products in these different states. The invention finds a preferred, but non-limiting, application for solid products when it is necessary to remove intermediate air between products in a layer of products with significant porosity, and in particular for packaging corn, green peas, mushrooms or carrots (in limited juice).

The invention also relates to a method for producing the claimed packaging machine based on an existing machine for vacuum closing a container, well known from the prior art in the field of the food industry and hereinafter referred to as a vacuum seamer.

The invention also relates to a container (not sterilized) obtained in accordance with the claimed packaging method, as well as to a sterilized container when the method contains a sterilization step carried out continuously or cyclically.

These containers are remarkable in that they contain low residual oxygen, while the layer of (solid) products has (significant) porosity, while the containers are pressurized relative to atmospheric pressure at ambient temperature (20°C).

The field of technology to which the invention belongs

The invention relates to methods used to reduce the amount of oxygen present in a container and, in particular, at the level of the upper space, i.e. the space above the products, until the container is hermetically closed and/or at the level of the intermediate spaces between the products below the upper space.

Reducing the amount of oxygen makes it possible to reduce the phenomenon of oxidation of the products contained within the container and/or to avoid the appearance of undesirable taste/smell and/or discoloration of the products.

The level of technology

The first method for reducing the oxygen content, very common in the food industry, is to create a vacuum in the container while sealing it. The decrease in the amount of oxygen after the rolling step occurs due to the reduction in the volume of residual air under the action of vacuum.

From the prior art in the field of food industry known device for closing the container by vacuum sealing, hereinafter referred to as a vacuum sealing machine, which allows you to seal the lid on a can pre-filled with food. To do this, the vacuum seamer contains:

- a gas-tight chamber, called a seaming chamber,

- a closure system configured to close the top opening of each container within said seaming chamber by adding a lid and rolling the lid onto the container,

- a partially sealed transport chamber, often in the form of a tunnel, which communicates with the seaming chamber and into which a conveyor enters, ensuring that open containers are fed into the seaming chamber at the entrance of the closing system and the closed containers are removed at the exit of the seaming chamber,

- a partially sealed closure supply system, often in the form of a vertical shaft, which communicates with the seaming chamber and ensures the distribution and stacking of said closures before the seaming step,

- a source of vacuum and regulation connected to said seaming chamber.

The specified transport chamber also performs the function of setting the pace and the function of the gateway; to do this, it contains movable shutters that allow you to limit the flow of air from the inlet of the transport chamber for open containers to the exit of the transport chamber, which communicates with the seaming chamber, in which a vacuum is created.

The amount of oxygen in the seaming chamber is reduced by vacuum to about 800 millibars below atmospheric pressure, ie 224 absolute millibars. In this application, conventionally atmospheric pressure will be considered equal to 1024 absolute millibars. In the following, all indicated pressure values will be absolute pressure values.

The first disadvantage of this method is that it only reduces the oxygen concentration in the container to a significant minimum level of 4.5% by volume after closing.

A second disadvantage of this method is that it is only compatible with containers whose walls, after closing, must withstand the pressure difference between the interior and exterior of the container.

Indeed, when a closed container is again exposed to atmospheric pressure, the pressure difference between the inside of the container, which is at a pressure much lower than atmospheric pressure, and the space outside of the container, which is at atmospheric pressure, makes it necessary to choose cans with sufficient wall thickness so that they do not deform. and did not flatten under the influence of pressure difference. This phenomenon is exacerbated during the sterilization of containers, when pressures much higher than atmospheric pressure can act on the containers.

A third disadvantage of this method is that it greatly limits the temperature of the products when they are canned, as the vacuum tends to lower the boiling point, which can cause liquids to evaporate when boiling inside the cans.

A second method for reducing the oxygen content is to purge the top space of the container with a neutral inert gas such as nitrogen or carbon dioxide.

Examples of such technology are described in WO9531375, EP 0761541, EP0806354, FR 2960858 and FR 2979327. Such methods remove air from the upper space by forcing a stream of neutral gas into this upper space. Such methods are satisfactory when the air to be expelled is contained mainly in the upper space of the container, ie in the space above the products.

However, in the case of solid products, a large amount of air can be contained not only in the upper space (above the products), but also at the level of the gaps between the products (below the upper space). In this case, a short-term blowing of the upper space with neutral gas basically allows you to expel the air from the upper space, but not the air in the gaps. Removal of intermediate air by such a method requires a lengthy purging treatment. Therefore, these methods are ineffective when there is a significant amount of intermediate air inside the container. This method, by simple blowing, does not allow the amount of oxygen to be reduced below 4.5% by volume with respect to the total volume of gas contained (in the volume of the upper space and intermediate spaces), if the product layer has a significant porosity.

A third technique, described by the Applicant in document FR2964949 A1, consists in expelling air from a container by filling the container to capacity with liquid, then the filled container is placed in a controlled non-oxidizing atmosphere chamber, and the container is completely or partially emptied in a non-oxidizing atmosphere, keeping said products in said container such that said non-oxidizing gas replaces said liquid in said container.

Such an inertization method is extremely effective in terms of oxygen removal, since it is possible to effectively remove not only the air contained in the upper space, but also the intermediate air. With this technology it is possible to reduce the residual air to very low amounts, in contrast to the two technologies mentioned above. However, the implementation of such a method requires corresponding relatively expensive equipment to provide the step of filling containers to capacity, and then emptying the containers in a controlled atmosphere chamber.

The fourth method consists in injecting liquid nitrogen just before closing the container at the level of the upper space. The difficulty in carrying out such a method mainly lies in ensuring the correct dosage of liquid nitrogen, as well as in accurately observing the timing of the closing step.

For example, overdosing liquid nitrogen or closing the container too early can create too much pressure inside the container, which can weaken and even damage the container. On the other hand, if the closing step is carried out too late, air will reappear at the level of said top space and the package will be defective.

The disadvantage of this method of inertization is that it is based only on the addition of liquid nitrogen before closing and basically allows to remove air present at the level of the upper space, but is not effective enough in terms of removing residual oxygen when the container contains a significant amount of intermediate air between products. WO 2011/077034 provides an example of a tin in which the internal pressure exceeds atmospheric pressure due (only) to the addition of liquid nitrogen. By itself, the addition of liquid nitrogen does not achieve good results in terms of residual oxygen when the contained products have a significant porosity, that is, in terms of removal of intermediate air from the product layer. This technology of adding liquid nitrogen does not allow proper preservation of solid products with significant porosity, that is, having a significant amount of intermediate spaces in the layer of products, with an oxygen content below 4.5 volume percent in relation to the total volume contained (in the upper volume and in the intermediate spaces) gas. Therefore, this technology is not suitable for canning foods such as corn, green peas, mushrooms or carrots (in limited juice).

Disclosure of the invention

These known solutions do not allow the amount of oxygen inside the containers to be reduced below 4.5 volume percent residual oxygen in relation to the total volume of gas contained (in the volume of the upper space and in the intermediate spaces), when there is a significant amount of intermediate air intended to be removed between the products contained, with maintaining high rates of production and with controlled production costs.

The object of the invention is to improve this situation.

The present invention aims to provide a continuous packaging process that overcomes the above disadvantages and provides good results in reducing oxygen inside containers even when there is a significant amount of intermediate air between the contained products, without changing the nominal production rate when using vacuum seamers.

In particular, the claimed method achieves very high efficiency in reducing the amount of oxygen inside the containers in the range from 4.5% to 0.2 oxygen by volume in relation to the total volume of gas contained (in the volume of the upper space and in the intermediate spaces), strictly below 4.5%, such as 3% to 0.2% and even 2% to 0.2% or 1% to 0.2% oxygen, while maintaining high production rates in excess of 100 units per minute, in in particular exceeding 300 units per minute, for example, 600 units per minute or more, even in the presence of an intermediate air to be removed between the contained products.

The present invention aims to provide, at least in an embodiment, a method that can be carried out on the basis of a known vacuum seamer after making small changes to this equipment and, therefore, at a lower cost if this equipment already exists at the place of production.

The present invention is also intended to provide, at least in an embodiment, a method that can be carried out without limitation on the types of containers, i.e. rigid containers such as cans even with a small wall thickness, glass or plastic jars and even soft containers.

The present invention also aims to provide a container obtained by the packaging process having a low residual air content even in the presence of intermediate spaces between products and allowing optimized sterilization.

Other objects and advantages of the present invention will become more apparent from the following description, which is provided by way of example only and is in no way limiting of the invention.

First of all, the subject of the invention is a method for packaging products, in particular oxygen-sensitive products, in containers, said containers each having an opening, said method comprising the following steps:

- the container is partially filled with products,

— the top of the containers is subjected to a gas atmosphere treatment to remove all or part of the air present in the container and to create the required controlled atmosphere,

- carrying out the closing of the container, hereinafter referred to as the closing step, in the closing chamber,

- in this case, the creation of a controlled atmosphere is carried out before and/or during the closing step.

According to the invention, the creation of a controlled atmosphere is carried out in a transport chamber, inside which open containers are moved towards the closing chamber, by means of the following combined actions:

- action a) of forcing the treatment gas stream into said closing chamber at the outlet of the transport chamber in accordance with the direction of movement of the open containers,

- action b) vacuuming open containers present inside the transport chamber,

so as to remove the air present in the open containers and reduce the oxygen concentration in the containers as a result of the combined action of the vacuum created in said transport chamber and the replacement of the removed air with a treatment gas that circulates in countercurrent relative to the open containers in said transport chamber, and for due to the effect of diluting the oxygen of the air with the treatment gas.

The method may also have the following optional features, considered alone or in combination:

said action a) of the treatment gas stream also includes, in addition to injecting the gas stream, injecting an amount of liquefied gas with evaporation (at least partially) of the liquefied gas after closing the container in such a way as to increase the pressure inside the container over the pressure in the closing chamber;

- the pressure P inside the closing chamber may exceed the atmospheric pressure P _O and range from 1024 absolute millibars to 1224 absolute millibars, for example, from 1024 absolute millibars to 1074 absolute millibars, for example, from 1024 absolute millibars to 1054 absolute millibars;

- the vacuum created in the transport chamber can be between 600 millibars absolute and 900 millibars absolute, in particular between 700 millibars and 900 millibars;

- the flow rate of gas injection into the closing chamber is from 100 m ³ /hour to 500m ³ /hour, for example, from 200 m ³ /hour to 300 m ³ /hour;

- the movement of open containers in the specified transport chamber is provided by means of a conveyor with a lock function, which contains closures;

- the container contains intermediate spaces between the products, filled with gas treatment after closing the container; the number of intermediate spaces in the layer of products filled with the treatment gas, called the degree of porosity, may be from 20% to 60%, for example, from 30% to 40%;

- the container contains the upper space between the products and the upper part of the container, filled with gas treatment after closing the container;

- action b) evacuation of open containers located inside the transport chamber is carried out by suction of the atmosphere inside said transport chamber in several suction zones distributed along the length of said transport chamber;

- action b) is carried out by means of a distribution and vacuum control chamber, as well as a plurality of suction parallel channels connecting the distribution chamber with said suction zones distributed along the length of said transport chamber;

- the treatment gas is nitrogen or CO ₂ ;

- Foods are food.

According to an embodiment, the containers are metal tins, and the closing of the containers mainly consists of adding lids and rolling the lids on the containers.

In an alternative embodiment, the containers are soft containers. In this case, closing the container can be done by compressing the walls of the opening and making a weld between the compressed walls.

According to another alternative, the containers may be rigid plastic containers or glass jar type containers. Closing can be done by means of a lid or the installation of an equivalent means such as a stopper.

Preferably, the method makes it possible to obtain the following features, considered alone or in combination:

- obtaining containers (closed) with increased pressure relative to atmospheric pressure. According to an embodiment, the pressure inside the containers may exceed but be close to atmospheric pressure, ie exceed 1024 millibar absolute at 20° C. and be between 1024 millibar absolute and 1224 millibar absolute after closing. In this case, the pressure inside the containers after closure is substantially equal to or close to the pressure inside the closure chamber, which is greater than but close to atmospheric pressure. This internal pressure is obtained when the packaging method does not involve injection of liquefied gas in step a). If the method involves the injection of a certain amount of liquefied gas in said action a), the pressure inside the closed containers is significantly higher than the pressure inside the closing chamber and can thus be much higher than atmospheric pressure, in particular, exceed 1424 absolute millibars,

- a low amount of (residual) oxygen in a closed container, ranging from 4.5% to 0.2% by volume relative to the total volume of gas contained (in the upper volume and in the intermediate spaces), strictly less than 4.5%, for example, ranging from 3% to 0.2%, e.g. 2% to 0.2% and e.g. 1% to 0.2% oxygen, even in the presence of intermediate air to be removed, between products: number of intervening spaces in the product layer filled with treatment gas, called the degree of porosity, can be from 20% to 60%, for example, from 30% to 40%,

- a production rate exceeding 100 units per minute, even 300 units per minute and even greater than or equal to 600 units per minute.

The subject of the invention is also a container (not sterilized) containing products sensitive to oxygen, obtained using the claimed method, while the layer of products has intermediate spaces filled with processing gas; while the amount of (residual) oxygen in the container is from 4.5% to 0.2% by volume relative to the total volume of gas contained in the upper space and in the intermediate spaces, strictly below 4.5%, for example, is from 3% to 0 .2%, even from 2% to 0.2% and even from 1% to 0.2% oxygen, and the pressure inside the container exceeds atmospheric pressure, namely, exceeds 1024 absolute millibars at 20°C. The amount of intervening spaces in the product bed filled with the treatment gas, referred to as the degree of porosity, is significant, in particular 20% to 60%, for example 30% to 40%.

According to an embodiment, the pressure inside the container can be between 1024 millibar absolute and 1224 millibar absolute, in particular between 1075 millibar absolute and 1224 millibar absolute, for example 1075 millibar absolute when the process does not involve injection of liquefied gas in step a). The pressure inside an unsterilized container can exceed 1424 absolute millibars in the case of liquefied gas injection.

These characteristics of residual oxygen and pressure can be obtained for a container (not sterilized) even in the presence of intervening spaces between products filled with process gas: the number of interspaces in the layer of products filled with processing gas, called the degree of porosity, can be from 20% to 60% , for example, from 30% to 40%. The product may be corn (in limited juice) with the presence of intervening spaces filled with said treatment gas between the corn kernels. Products can also be green peas, or champignons, or carrots in limited juice.

The subject of the invention is also a packaging method according to the invention, in which, after closing, the container passes through a sterilization step by heat treatment at a temperature exceeding 100°C, for example between 110°C and 130°C.

The object of the invention is also a sterilized container obtained in accordance with the method of packaging (and sterilization by heat treatment), in which the layer of products has intermediate spaces filled with a processing gas; while the amount of oxygen in the container is from 4.5% to 0.2% by volume relative to the total volume of gas contained in the upper space and in the intermediate spaces, strictly below 4.5%, in particular, is from 3% to 0.2 %, even from 2% to 0.2%, and even from 1% to 0.2%, and in which the pressure inside the container exceeds atmospheric pressure, namely exceeds 1024 absolute millibars. The internal pressure can be between 1024 millibar absolute and 1424 millibar absolute at 20° C. and even between 1024 millibar absolute and 1224 millibar absolute, in particular when the process does not involve injection of liquefied gas in step a). The internal pressure in the container may also exceed 1424 absolute millibars in the case of injection of liquefied gas in the above action a) and substantially exceed the pressure inside the closing chamber.

The amount of interstitial spaces in the layer of products filled with the treatment gas, called the degree of porosity, may be from 20% to 60%, for example, from 30% to 40%.

According to an embodiment of the sterilized container, the product is corn with the presence of interspaces filled with said treatment gas between the corn kernels, wherein the pressure inside the container is between 1124 millibar absolute and 1424 millibar absolute at 20° C., even between 1124 millibar absolute and 1224 millibar absolute. millibar, in particular, is equal to 1194 absolute millibars. Products can also be green peas, or champignons, or carrots (in limited juice).

The object of the invention is also a packaging plant in which the claimed method of packaging can be carried out and which contains:

- a gas-tight chamber, called a closing chamber,

- a closure system configured to close the top opening of each container located inside said closure chamber,

- a partially sealed transport chamber, which communicates with the closing chamber and into which a conveyor enters, ensuring the supply of open containers to the closing chamber at the inlet of the closing system and the removal of closed containers at the exit of the closing chamber, while this conveyor has the function of a lock and contains movable gates,

- if necessary, a conveyor for feeding caps, ensuring delivery from atmospheric pressure (outside the closing chamber) to the inside of the closing chamber,

- a source of treatment gas without oxygen, such as nitrogen, and a system for injecting said treatment gas into the closing chamber,

- a vacuum source connected to the vacuum distribution and control chamber, as well as a plurality of suction channels connecting the distribution and control chamber with said suction zones distributed along the length of said transport chamber,

so as to remove all or part of the air present in the open containers and reduce the oxygen concentration in the containers as a result of the combined action of the vacuum created in said transport chamber and the replacement of the removed air with a treatment gas which circulates in countercurrent relative to the open containers in said transport chamber , and due to the effect of diluting the oxygen in the air with the treatment gas.

Finally, the object of the invention is a method for obtaining the claimed installation on the basis of an existing installation for vacuum closing a container, hereinafter referred to as a vacuum seamer, containing:

- a gas-tight chamber, called a closing chamber,

- a closure system configured to close the top opening of each container located inside said closure chamber,

- a partially sealed transport chamber that communicates with said closing chamber and into which a conveyor with a sluice function enters, ensuring that open containers are fed into the closing chamber at the inlet of the closing system and the closed containers are removed at the exit of the closing chamber, while said conveyor with a sluice function contains movable Gotes,

- a conveyor for feeding caps, providing delivery from atmospheric pressure (outside the closing chamber) to the inside of the closing chamber,

- a vacuum source connected to said closing chamber,

in which the specified claimed packaging installation is obtained by changing the specified vacuum closing installation as follows:

- adding a distribution and vacuum control chamber, as well as a plurality of suction channels connecting the distribution chamber with the indicated suction zones distributed along the length of the specified transport chamber, disconnecting the vacuum source from the specified closing chamber and connecting the specified vacuum source to the specified distribution and control chamber,

- add a source of treatment gas without oxygen and connect it to the specified closing chamber.

A brief description of the drawings

Other features, details and advantages will become more apparent from the following detailed description and from the accompanying drawings, in which:

In FIG. 1 is a schematic plan view of a known vacuum seamer, commonly referred to as a vacuum seamer, with a linear feed conveyor.

In FIG. 1bis is a schematic plan view of a known vacuum seamer, commonly referred to as a vacuum seamer, with a circular feed conveyor.

In FIG. 2 - a schematic view of the above the declared packaging installation, which can be obtained by changing the vacuum -chat machine shown in FIG 1, and in which the transport chamber is a tunnel containing a conveyor.

In FIG. 3 is a schematic side view of the plant shown in FIG. 2, in particular illustrating the combined effects of tunnel vacuum and replacement of vented air with non-oxidizing treatment gas circulating in countercurrent relative to open containers in said tunnel, in accordance with the claimed packaging method.

In FIG. 4 is a schematic view of equipment for measuring the amount of oxygen in the total volume of gas contained in the upper space and in the intermediate spaces of the container.

Implementation of the invention

The following drawings and description mainly contain the most characteristic elements. Therefore, they not only allow a better understanding of the present invention, but, if necessary, can serve to define it.

Thus, the invention primarily relates to a method for packaging products, in particular oxygen-sensitive products, in containers 1.

The products may be foodstuffs (solid), such as vegetables, cereals, meat, fish or other products alone or in a mixture with or without juice. The invention finds its particular application, for example, when intermediate air is present between products, for example, between products in limited juice: thus, the invention finds its application for packaging corn in limited juice with the presence of gaps in the container between corn kernels.

Each of the containers has a top opening that allows you to fill the containers with products.

The product packaging method includes the following steps:

- container 1 is partially filled with products 2,

- the top of the containers is brought into contact with the treatment gas atmosphere in order to remove all or part of the air present in the container and obtain the necessary controlled atmosphere,

- the opening of the container is closed, hereinafter referred to as the closing step, in the sealed closing chamber 3,

- in this case, the creation of a controlled atmosphere is carried out before and/or during the closing step.

According to the invention, they create a controlled atmosphere in a partially sealed transport chamber, inside of which open containers move in the direction of the 3 -closing camera, using the following combined actions:

- action a) of injecting the treatment gas stream G and possibly injecting a volume of liquefied gas into said closing chamber 3 at the outlet of the transport chamber 4 in accordance with the direction of movement of the open containers,

- action b) of vacuuming open containers 1 present inside the transport chamber 4.

Optionally, and during step a), a small amount of liquefied gas can be pumped into the container in the closing chamber. In other words, said action a) of injecting the treatment gas stream G includes, in addition to injecting the gas stream, injecting an amount of liquefied gas to vaporize the liquefied gas after closing the container, so as to increase the pressure inside the container, which will exceed the pressure in the closing chamber.

According to the invention, the pressure inside the container after it has been closed can thus be controlled and maintained between 1024 millibar absolute and 1224 millibar absolute at 20° C., i.e., as will be described below, at a pressure value substantially equal to or close to pressure inside the chamber 3 closing. In this case, said action a) does not involve the step of injecting the aforementioned amount of liquefied gas. For some types of container, in particular in the case of metal cans, an internal pressure in the container that is too close to atmospheric pressure, i.e. in the range of 1024 millibar absolute to 1224 millibar absolute at 20°C, can create shape stability problems, in in particular, when the storage temperature of the cans ranges from 10° C. to 37° C., and during temperature changes, the shape of the can changes (bloating/flattening).

The addition of an amount of liquefied gas during injection action a) provides a significant increase in pressure in the container, typically in excess of 1424 absolute millibars, and solves this problem of can shape stability.

The removal of the air present in the open containers 1 is carried out by the combined action of the vacuum created in said transport chamber 4 and the replacement of the removed air with treatment gas G, which comes from the closing chamber and circulates in countercurrent with respect to the open containers in said transport chamber 4.

Such a phenomenon is shown in Fig. 3, it can be noted that the non-oxidizing treatment gas supplied directly to the closing chamber 3 (outlet) is sucked out in the transport chamber 4 by the vacuum generated at the inlet. The treatment gas is sucked off in countercurrent relative to the open containers 1 moving along the transport chamber 4 in the direction of the closing chamber 3 . In this transport chamber 4, the treatment gas displaces air from the containers which exits said containers, this expulsion action being enhanced by the vacuum acting on the open containers in said transport chamber 4. This makes it possible to reduce the oxygen concentration in the containers, and this reduction is enhanced by the effect dilution of the oxygen of the air with the treatment gas, which takes place in said transport chamber 4 and even in said closing chamber 3 .

As an example, you can specify:

- the vacuum created in the transport chamber 4 in step b) can be between 600 millibar absolute and 900 millibar absolute, in particular between 700 millibar absolute and 900 millibar absolute (measured in the middle of the transport chamber 4 according to the direction of movement of the containers );

- the flow rate of gas injection into the closing chamber in step a) can be from 100 m ³ /h to 500 m ³ /h, for example, from 200 m ³ /h to 300 m ³ /h, and the possible flow rate of liquefied gas (for example, liquid nitrogen ) can range from 0.5 ml to 5 ml per container.

As the inventors have found, these two combined actions preferably remove air from containers, i.e. remove air from the upper space of the container (above the products) and, if necessary, intermediate air between the products (below the upper space), and very quickly.

Thus, a decrease in the oxygen concentration in the containers is achieved, which is enhanced by the above dilution. The amount of oxygen in a closed container is between 4.5% and 0.2% oxygen by volume relative to the total volume of gas contained (in the upper space and in the intermediate spaces), and strictly below 4.5%, for example, from 3% to 0.2%, eg 2% to 0.2%, eg 1% to 0.2% oxygen. Such reduction rates are achieved even if intermediate air is present in a significant amount. Thus, the invention finds its particular application for the removal of air when the product is corn in limited juice with the presence of intermediate air between the corn kernels.

The invention makes it possible to reduce residual air to very small amounts, in contrast to oxygen reduction technologies based only on purging with a non-oxidizing treatment gas or only on evacuating the container before closing, preferably without consequences for plant operating rates, which can remain high, typically over 100 units per minute, in particular, more than 300 units per minute, for example, 600 units per minute and even more.

According to the embodiment shown in FIG. 2 and 3, the pressure P inside the closing chamber 3 can be above atmospheric pressure and be close to atmospheric pressure Po, in particular between 1024 millibar absolute and 1224 millibar absolute, for example between 1024 millibar absolute and 1074 millibar absolute, and for example between 1024 absolute millibars to 1054 absolute millibars.

According to this embodiment, the hermetic closure of the container is carried out at a pressure close to atmospheric pressure and substantially at the pressure of the closure chamber. Preferably, containers such as cans, even small thicknesses less than 0.14 mm, and even glass or plastic jars or soft containers, can be used for carrying out the method.

Preferably, it is possible to obtain containers, in particular metal cans, with a (controlled) pressure increase relative to atmospheric pressure, i.e. with a pressure exceeding 1024 absolute millibars at 20°C, ranging from 1024 absolute millibars to 1224 absolute millibars, for example, from 1054 absolute millibars. millibars to 1224 absolute millibars. In the case where the method involves the injection of liquefied gas in step a), the internal pressure in the container may exceed 1454 absolute millibars at 20°C.

According to an embodiment, the movement of the open containers 1 in the transport chamber 4 is provided by a conveyor 5 with a lock function, which contains movable closures 50. During the movement of the containers 1, these closures are located between the open containers, providing relative gas tightness. These closures 50 make it possible to provide a certain level of vacuum in the transport chamber 4, which is necessary for the implementation of the method.

Such a conveyor 5 is shown schematically by way of example in FIG. 2. It may comprise a soft belt 51 in the form of a loop driven by two rollers 52, 53, each with a vertical axis, distributed at the level of the two ends of the tunnel 4. The gates 50 are plates installed at regular intervals on the soft belt 51.

During the movement of the conveyor 5, the soft belt is rotated and synchronizes the containers 1 moving in said transport chamber 4, in particular in the tunnel. On the side of the transport chamber 4, the first branch of the soft belt accompanies the open containers 1 from the inlet of the transport chamber 4 at atmospheric pressure (and under controlled atmosphere) to the closing chamber 3, which is under the action of a non-oxidizing treatment gas.

The top openings of the containers are then closed by any appropriate means, such as by fitting a lid or other means. The return branch of the soft belt 51 then accompanies the hermetically sealed containers from the closing chamber 3 to the exit from the transport chamber 4 under atmospheric pressure.

As an alternative to a belt conveyor, a circular conveyor, shown in plan in FIG. 1bis, which contains one or more sequentially installed and synchronized in the rotation of the drums, each of which has one or more cells for containers. In such a circular conveyor, the containers move from one drum to another as they rotate, as is known per se in the art.

According to an embodiment, the containers 1 are cans, and closing the containers mainly consists of adding lids and rolling the lids on the containers. In the case of a container with a soft wall, closing can be done by compressing the walls of the opening and providing a seal between the compressed walls.

According to an embodiment (shown as a non-limiting example in FIG. 3), the action b) of evacuating the open containers inside the transport chamber 4 is carried out by sucking out the internal atmosphere of said transport chamber 4 in several different suction zones 7 distributed along the length of said transport chamber. chamber 4. These suction zones are provided, in particular, on the upper wall of said transport chamber 4. In particular, action b) is carried out by means of a distribution and regulation chamber 70 under vacuum, as well as by a plurality of parallel suction channels 71 connecting distribution and regulation chamber 70 with said suction zones 7 distributed along the length of said transport chamber 4.

This distribution and control chamber is subjected to a vacuum source V, such as a vacuum pump. The distribution chamber then makes it possible to evenly distribute the suction between said suction zones 7 . The vacuum inside the distribution and regulation chamber 70 can be between 100 millibar absolute and 700 millibar absolute.

Typically, the treatment gas is nitrogen, or CO ₂ , or another non-oxidizing gas, or a mixture of non-oxidizing gases.

The object of the invention is also the above-described packaging installation 10, designed to implement the claimed method.

This installation contains:

- a gas-tight chamber, called the closing chamber 3,

- a closure system configured to close the top opening of each container located inside said closure chamber 3,

- a partially sealed transport chamber 4, which communicates with the closing chamber 3 and into which a conveyor 5 with a lock function enters, ensuring the supply of open containers 1 to the closing chamber 3 at the inlet of the closing system and the removal of closed containers at the exit of the closing chamber 3, while the specified conveyor with sluice function contains 50 moving gates,

a source of oxygen-free treatment gas, such as nitrogen, for example, and a system 8 for injecting said treatment gas into the closing chamber 3 with optional liquefied gas injection,

- a vacuum source V connected to the vacuum distribution and regulation chamber 70, as well as a plurality of suction channels 71 connecting the distribution and regulation chamber 70 with said suction zones 7 distributed along the length of said transport chamber 4,

- if necessary, a conveyor for feeding caps 9, providing delivery from atmospheric pressure (outside the closing chamber) to the inside of the closing chamber.

It is preferable to such a declared packaging installation by changing the existing installation, such as a well-known vacuum-roll machine 20, shown in FIG. 1 or 1bis, that is, at minimal cost.

Such a plant 20, in particular the known vacuum seamer, is shown schematically in FIG. 1.

It contains:

- a gas-tight chamber, called the closing chamber 3,

a closure system adapted to close the top opening of each container within said closure chamber, typically by rolling the lid,

- a partially sealed transport chamber 4, such as a tunnel that communicates with the closing chamber 3 and into which a conveyor 5 with a lock function enters, ensuring that open containers are fed into the closing chamber at the inlet of the closing system and the closed containers are removed at the exit of the closing chamber, while the specified the conveyor with the function of the lock contains movable gates 50,

- a vacuum source V connected to said closing chamber,

- a conveyor for feeding caps 9, providing delivery from atmospheric pressure (outside the closing chamber) to the inside of the closing chamber.

Such known apparatus 20, typically a vacuum seamer, makes it possible to reduce the amount of oxygen in the closure chamber by creating a vacuum in the closure chamber, for example a vacuum of about 800 millibars absolute below atmospheric pressure (224 millibars absolute).

The first disadvantage of this method is that it only reduces the air oxygen concentration in the container by lowering the internal air pressure in the container during its closing in the closing chamber: a significant amount of oxygen is still present in the closed container.

A second disadvantage of this method is that it is only compatible with containers whose walls are thick enough to withstand the pressure difference between the inside and outside of the container after it has been closed and when exposed to atmospheric pressure.

Preferably, the packaging of products can be significantly improved by the following changes made to such a vacuum seamer 20, namely (see Fig. 3):

- adding the camera 70 of the distribution and regulation of vacuum, as well as many channels 71 of the suction connecting the camera 70 of the distribution and regulation with the specified zones 7 of the suction, distributed along the length of the transport chamber 4, discingering the source of the vacuum from the specified closing camera and connecting the indicated source of the vacuum V to the specified distribution and regulation chamber 70,

adding an adjustable source 8 of treatment gas G having no oxygen by connecting it to said closing chamber 3 and optionally injecting liquid nitrogen.

Residual air can be reduced to very small amounts, unlike what a vacuum seamer allows. The method can also be improved by the possibility of using metal cans with a small wall thickness, namely with a wall thickness of less than or equal to 0.14 mm, for example 0.12 mm, as cans.

Preferably, these results are achieved without reducing the performance of the plant.

The packaging method preferably allows you to get containers containing products sensitive to oxygen, while the layer of products has intermediate spaces filled with gas processing with a small amount of residual oxygen. The amount of oxygen in the container can be from 4.5% to 0.2% in volume relative to the total volume of the contained gas in the upper space and in intermediate spaces, even from 3% to 0.2%, or from 2% to 0.2% And even from 1% to 0.2%, which gives good characteristics from the point of view of residual oxygen even in the presence of the remote intermediate air between products that are replaced by gas gas. The pressure inside the container is greater than atmospheric pressure. It can be from 1024 absolute Millibar to 1224 absolute millibar at 20 ° C, for example, from 1054 absolute millibar to 1224 absolute millibar, in particular, if the method does not provide for the stage of injection of liquefied gas under the action of a). The pressure inside the container can also much exceed atmospheric pressure, for example, to exceed 1424 absolute millibar at 20 ° C, when the method provides for the specified injection of liquefied gas under the action of a). It should be noted that the indicated increased pressure is present in the container when the products did not pass sterilization.

It is noted that these containers (not sterilized) are characterized by a small content of oxygen and internal pressure, which can exceed the pressure values obtained using known packaging methods, in particular, the methods in which vacuum or gas purge and which in both cases allow you to create a vacuum , ranging from 224 absolute millibars to 824 absolute millibars.

This increased pressure may facilitate the application of sterilization.

The invention also relates to the claimed packaging method, in which, after closing, the container passes through a sterilization step by heat treatment at a temperature in excess of 100°C, for example, from 110°C to 130°C, in particular, in excess of 122°C.

Sterilization can be carried out on a sterilizer operating continuously or intermittently.

This method (with a sterilization step) makes it possible to obtain a sterilized container, while the product layer has intermediate spaces filled with a treatment gas with a small amount of residual oxygen. The amount of oxygen in the container can be from 4.5% to 0.2% by volume, relative to the total volume of gas contained in the upper space and in the intermediate spaces, strictly below 4.5%, in particular from 3% to 0.2%, even from 2% to 0.2% and even from 1% to 0.2%. The pressure inside the container is greater than atmospheric pressure, i.e. greater than 1024 absolute millibars at 20°C. The pressure inside the container can be from 1024 absolute millibar to 1424 absolute millibar at 20 ° C, even from 1124 absolute millibar to 1424 absolute millibar, if the method does not provide for the discharge of liquefied gas under the action of a). In the case of the bumping of liquefied gas with the specified action a), the pressure inside the container can much exceed 1424 absolute millibar at 20 ° C, according to the option of performing a sterilized container, the product is corn with the presence of intermediate spaces filled with gas processing, while the internal pressure of the container is from 1124 Absolute Millibar up to 1424 absolute Millibar, in particular, 1194 absolute millibar at 20 ° C.

It should be noted that the pressure inside the container may be slightly higher in a sterilized container than in a non-sterilized container at the same temperature (e.g. 20°C) due to possible degassing of the products (if they were not pre-blanched) during the heat treatment. For example, if the product is corn, sterilization results in outgassing, which increases the pressure inside the closed container. On the other hand, in the case of pre-blanched products such as green beans, sterilization does not result in significant outgassing during sterilization, since the products have already been degassed during blanching prior to sterilization.

The invention finds its application when the amount of interspaces in the layer of products filled with treatment gas, called the degree of porosity, is from 20% to 60%, for example, from 30% to 40%.

The degree of porosity t _P is calculated using the following formula:

Formula 1)

Where:

- D: actual density of a product (e.g. maize), which is expressed as the ratio between the mass of a certain volume of this product and the mass of the same volume of water,

- D': apparent bulk density, often referred to as apparent density, namely the ratio between all products considered and the total volume (including spaces) they occupy.

In the case of corn in kernels, the degree of porosity t _P is usually on the order of 42% and often ranges from 41% to 43%, depending on the batch.

In the case of green peas (extra fine), the degree of porosity t _P is on the order of 34% and often ranges from 33% to 35% depending on the batch.

The equipment shown in FIG. 4 and containing:

- a container filled with water and large enough to be handled,

- a column graduated in volume, having at one end an expanding neck designed for immersion in the water of the container, and at the other, upper end, a sealed double adapter that provides adaptation of the PP pump, and a calibrated oximeter (Dansensor ® CheckPoint 3), equipped with a needle for determining the percentage content of gaseous oxygen.

The measurement protocol is as follows. The container is pre -filled with water, while the graduated column is turned over above the container, immersing its neck. The pumping begins, the air is replaced by water, the level of which increases, completely displacing the air present in the column.

The container (particularly a can) in which the volume percentage of oxygen is to be determined is placed under the expanding neck, then opened to collect the entire volume of gas contained (in the upper space and in the intermediate spaces). The released gas displaces water from the column, and reading its scale allows you to determine the total volume of gas contained.

The oximeter pointer is inserted through a sealed adapter into a gaseous medium to determine the percentage of oxygen.

Tests were carried out on the declared vacuum seamer under the following conditions:

- discharge flow into the closing chamber: 280 m ³ /hour,

- pressure in the closing chamber: 1074 absolute millibars,

- pressure in the transport chamber: 750 absolute millibars (in its middle in the direction of movement of the containers).

The product is corn with a porosity of 42%.

The containers used are 1/4 size cans (height 70 mm x diameter 65 mm). These containers were packed in accordance with the claimed method, with the displacement of oxygen contained in the upper space and in the intermediate spaces, using the combined action of a flow of nitrogen from the closing chamber 3 and a vacuum in the transport chamber 4. These cans were tested immediately after rolling by measuring the residual oxygen using the above method.

The results obtained are presented in the following table 1.

Table 1 Banks Tp Internal pressure (abs. mbar) at 20°C Residual oxygen 1 42% 1074 0.2% 2 42% 1074 0.6% 3 -42% -1074 0.4%

When these jars are sterilized in a continuous sterilizer at 128°C and then cooled again to a stabilized temperature of 20°C, an increase in internal pressure of 100 millibars is noted due to outgassing of corn (not blanched), while the internal pressure reaches 1174 absolute millibars.

List of symbols

1. Containers

2. Products (filling)

3. Closing chamber

4. Transport chamber such as a tunnel

5. Conveyor

50. Gotes

51. Soft tape

52. Drive roller with vertical axis

53. Drive roller with vertical axis

6. covers

7. Suction zones

8. Treatment gas injection system

9. Cap feeding conveyor

70. Distribution and regulation chamber

71. Suction channels

V. Vacuum source

Pr. Air pump

Claims (40)

1. A method of packaging products, in particular, sensitive to oxygen, into containers (1), while these containers have, each, a hole, while this method includes the following stages, at which: at: - the container is partially filled with products (2), — the top of the containers is subjected to a gas atmosphere treatment to remove all or part of the air present in the container and to create the required controlled atmosphere, - Produce a container closing, which is subsequently called the closing stage, in the chamber (3) closing, - in this case, the creation of a controlled atmosphere is carried out before and/or during the closing step, characterized in that the creation of a controlled atmosphere is carried out in the transport chamber (4), inside which the open containers are moved towards the closing chamber through the following combined actions: - action a) of injecting the treatment gas stream (G) into said chamber (3) of closing the outlet of the transport chamber (4) in accordance with the direction of movement of the open containers, - action b) of vacuuming open containers (1) present inside the transport chamber (4), so as to remove the air present in the open containers (1) and reduce the oxygen concentration in the containers as a result of the combined action of the vacuum created in said transport chamber (4) and the replacement of the removed air with a treatment gas (G) which circulates in countercurrent relative to open containers in the specified transport chamber (4), and due to the effect of diluting the oxygen of the air with the treatment gas. 2. The method according to claim 1, wherein said action a) of the treatment gas stream (G) also includes, in addition to injecting the gas stream, injecting some amount of liquefied gas with evaporation of the liquefied gas after closing the container so as to increase the pressure inside the container above the pressure in the closing chamber. 3. The method according to claim 1 or 2, wherein the pressure P inside the closing chamber (3) exceeds the atmospheric pressure P _O and ranges from 1024 absolute millibars to 1224 absolute millibars, for example, from 1024 absolute millibars to 1074 absolute millibars, for example from 1024 absolute millibars up to 1054 absolute millibars. 4. The method according to any one of paragraphs. 1-3, in which the vacuum created in the transport chamber (4) has a value of 600 absolute millibars to 900 absolute millibars in the middle of the transport chamber. 5. The method according to any one of paragraphs. 1-4, in which the flow rate of gas injection into the closing chamber is from 100 m ³ /h to 500 m ³ /h, for example from 200 m ³ /h to 300 m ³ /h. 6. The method according to any one of paragraphs. 1-5, in which the movement of open containers in the specified transport chamber is provided by means of a conveyor (5) with a lock function, which contains shutters (50). 7. The method according to any one of paragraphs. 1-6, in which the containers (1) are metal tins, the closure of the containers mainly consists of adding lids (6) and rolling the lids on the containers. 8. The method according to any one of paragraphs. 1-6, wherein the containers are soft containers and/or the containers are rigid plastic containers or glass jars. 9. The method according to any one of paragraphs. 1-8, wherein the container contains inter-product spaces filled with treatment gas after the container is closed. 10. The method according to any one of paragraphs. 1-9, in which the container contains an upper space between the products and the top of the container, filled with processing gas after closing the container. 11. The method according to any one of paragraphs. 1-10, in which action b) of evacuating open containers located inside the transport chamber (4) is carried out by sucking the atmosphere inside said transport chamber (4) in several suction zones (7) distributed along the length of said transport chamber (4), and in which action b) is performed by means of a distribution and regulation chamber (70) in which a vacuum is created, as well as a plurality of parallel suction channels (71) connecting the distribution chamber (70) with said suction zones (7) distributed along the length of said transport chamber (4). 12. The method according to any one of paragraphs. 1-11, wherein the treatment gas is nitrogen and/or CO ₂ . 13. The method according to any one of paragraphs. 1-12, in which the pressure (P) inside the closure chamber (3) exceeds atmospheric pressure, which makes it possible to obtain containers with a higher pressure than atmospheric pressure. 14. The method of claim 13, wherein the pressure inside the containers is greater than 1024 millibar absolute at 20° C. and is between 1024 millibar absolute and 1224 millibar absolute, e.g. between 1074 millibar absolute and 1224 millibar absolute after closing without sterilization, and essentially equal to or close to the pressure in the closing chamber (3). 15. The method of claim 13, wherein the pressure inside the containers exceeds 1424 absolute millibars at 20° C. when said action a) involves injection of some liquefied gas, and substantially exceeds the pressure in the closing chamber. 16. The method according to claim 9 or 10, in which the amount of oxygen in the closed container is from 4.5% to 0.2% by volume relative to the total volume of gas contained in the upper space and in the intermediate spaces, strictly below 4.5%, for example is from 1% to 0.2% oxygen. 17. Packaging unit (10), in which the method according to claim 11 can be carried out, containing: - a gas-tight chamber, called the closing chamber (3), - a closure system configured to close the top opening of each container located inside said closure chamber (3), - a partially sealed transport chamber (4), which communicates with the closing chamber and into which a conveyor (5) with a lock function enters, ensuring the supply of open containers (1) into the closing chamber at the inlet of the closing system and the removal of closed containers at the exit of the closing chamber, when this conveyor with the function of the gateway contains movable gates (50), - if necessary, a conveyor for feeding caps (9), ensuring delivery from atmospheric pressure, from outside the closing chamber to the inside of the closing chamber, - a source of treatment gas without oxygen, such as nitrogen, and a system (8) for injecting said treatment gas into the closing chamber (3), - a vacuum source (V) connected to the vacuum distribution and control chamber (70), as well as a plurality of suction channels (71) connecting the distribution and control chamber (70) with the indicated suction zones (7) distributed along the length of the specified transport chamber ( 4), so as to remove all or part of the air present in the open containers (1) and reduce the oxygen concentration in the containers as a result of the combined action of the vacuum created in said transport chamber (4) and the replacement of the removed air with treatment gas circulating in countercurrent relative to the open containers in the specified transport chamber (4), and due to the effect of diluting the oxygen of the air with the treatment gas. 18. A container containing oxygen sensitive products obtained using the method according to claim 9, in which the layer of products has intermediate spaces filled with a treatment gas in which the amount of oxygen in the container is from 4.5% to 0.2% by volume relative to the total volume of contained gas in the upper space and in the intermediate spaces, strictly below 4.5% by volume, and in which the pressure inside the container exceeds atmospheric pressure, namely, exceeds 1024 absolute millibars at 20°C. 19. A container according to claim 18, wherein the pressure inside the containers is from 1054 absolute millibars to 1224 absolute millibars at 20°C, for example from 1074 absolute millibars to 1124 absolute millibars. 20. Container according to paragraphs. 18 or 19, in which the products are selected from corn, mushrooms and green peas in limited juice. 21. The container according to any one of paragraphs. 18-20, in which the amount of interspaces in the layer of products filled with the treatment gas, called the degree of porosity, is from 20% to 60%, for example from 30% to 40%. 22. The packaging method according to any one of paragraphs. 1-16, in which after closing the container passes through the stage of sterilization by heat treatment at a temperature exceeding 100°C. 23. A sterilized container obtained in accordance with the packaging method according to claim 22, in which the layer of products has intermediate spaces filled with processing gas; whereby the amount of oxygen in the container is between 4.5% and 0.2% by volume relative to the total volume of gas contained in the upper space and in the intermediate spaces, strictly below 4.5%, and in which the pressure inside the container exceeds atmospheric pressure, and it exceeds 1024 absolute millibars at 20°C. 24. The sterilized container according to claim 23, wherein the internal pressure of the container is between 1024 absolute millibars and 1424 absolute millibars at 20°C, or between 1024 absolute millibars and 1224 absolute millibars. 25. A sterilized container according to claim 23 or 24, in which the product is corn with the presence of intermediate spaces filled with treatment gas between corn kernels, while the pressure inside the container is from 1124 absolute millibars to 1424 absolute millibars at 20 ° C or from 1124 absolute millibars to 1224 absolute millibars, in particular equal to 1194 absolute millibars.

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