EP3450350A1

EP3450350A1 - Container for packaging and for cooking or warming up of foodstuffs in a microwave oven

Info

Publication number: EP3450350A1
Application number: EP17189230.0A
Authority: EP
Inventors: Julia Parlow; Ralf Winklmeier; Matthias Seidl; Zlatin Aleksiev; Miriam Kreuzer; David Messerer
Original assignee: Ostbayerische Technische Hochschule Regensburg (OTH Regensburg)
Current assignee: Ostbayerische Technische Hochschule Regensburg (OTH Regensburg)
Priority date: 2017-09-04
Filing date: 2017-09-04
Publication date: 2019-03-06

Abstract

A container (10) for packaging foodstuffs and for cooking or warming up said foodstuffs in a microwave oven is shown. The container (10) comprises: a first container portion (12) and a second container portion (22), each of said first and second container portions (12, 22) comprising a corresponding first or second end surface (14, 24) and a corresponding first and second wall part (16, 26), wherein said first and second wall parts (16, 26) comprise first and second engaging sections (20, 26), respectively, wherein said first engaging section (20) of the first wall part is configured to engage with said second engaging section (26) of the second wall part in a close fit that allows a sliding movement of the first and second container portions (12, 22) relative to each other, provides a sufficient degree of fluid tightness, and provides a predetermined degree of friction defining a corresponding vapor pressure to be developed inside the container (10) upon heating in said microwave oven causing the first and second container portions (12, 22) to move apart. An opening (28) is provided in one of the first and second engaging sections (20, 26), which opening is covered by the other of the first and second engaging sections (20, 26) when the first and second container portions (12, 22) are in a pushed-together state, and which is at least partially exposed when the first and second container portions (12, 22) are in an extended state, wherein the volume of the container (10) in the extended state exceeds the volume of the container (10) in the pushed-together state by at least 10%.

Description

FIELD OF THE INVENTION

The present invention is in the field of food packaging. More particularly, the present invention relates to a container for packaging foodstuffs and for cooking or warming up said foodstuffs in a microwave oven. The invention further relates to a method of packaging foodstuffs, in particular instant food, using such container.

BACKGROUND OF THE INVENTION

In a microwave oven, foodstuffs or liquids are heated by exciting rotations of water molecules contained therein by means of microwaves. In commercially available microwave ovens, typically microwaves having a wavelength of about 12.2 cm are used, corresponding to an excitation frequency of 2.45 GHz.
In addition to the direct heating of foodstuffs via the water molecules contained therein, it is also possible to cook foodstuffs in a microwave oven with steam generated by heating water containing liquids by means of the microwaves. Cooking foodstuffs by steam is a very gentle way of cooking which is particularly popular as it tends to preserve nutritions in the food and leads to what is perceived by many as a preferable taste. In order to generate the steam in the area directly surrounding the foodstuff, some sort of enclosure must be provided in which the steam is to develop. Such enclosure should also have an opening for venting the steam, such as to prevent an excessive increase of pressure. For this purpose, plastic bags have been proposed having a closure with a vent that allows steam to escape to a certain degree. These plastic bags have to be purchased separately from the foodstuff.
A more sophisticated pressure and moisture release cooking container is described in US 7, 337, 916 B2 , comprising a tubular body having an open end and a cap for engaging the open end. The cap comprises upper and lower ends which define an intermediate region therebetween. The tubular body and the cap are at least partially sealed together by frictional forces resulting from the interference between opposing radially extending protrusions disposed on both, the tubular body and the cap. These frictional forces are opposed and eventually overcome by a steam pressure generated from within the container, whereby the cap is driven from a closed to a vented position. This pressure and moisture release cooking container is comparatively complicated in structure, and therefore rather costly for disposable food packaging. Moreover, with the container of this prior art, it is difficult to assess the status of the cooking. In particular, since the cap only moves minimally between the closed and the vented position, it will generally be difficult to discern from outside the microwave oven whether the cap has already snapped open or not. Finally, once the cap snaps open, the pressure inside the container will decrease significantly as compared to just before the frictional forces of between opposing radial extending protrusions are overcome, such that the pressure-time curve exhibits a peak rather than a single plateau, which would be more favorable for gentle cooking.
US 2016/0137379 A1 discloses an expandable package in which dough can first be sold and in which dough can then also be proofed to the correct volume by consumers. The package includes a first portion, a second portion and at least one indicator. The first portion has a first closed end, at least one first side wall surrounding the first closed end, and a first open end opposite the first closed end. The second portion has a second closed end, at least one second side wall surrounding said second closed end and a second open end opposite the second closed end. The first portion and the second portion are movably connected at the respective open ends. The at least one indicator is placed in communication with the package such that when the package is expanded to a desired inner volume, the indicator is activated. The closed end of either portion may be opened when a desired inner volume of the dough is reached. Instead of using the package for proofing dough, it may also be used for packaging and preparing popcorn, allowing for the popping of corn to a desired volume.

SUMMARY OF THE INVENTION

The problem underlying the invention is to provide a container for packaging foodstuffs and also cooking or warming up said foodstuffs, in particular instant food, which allows for a cost-efficient manufacture, good cooking behavior and at the same time gives the user visual feedback about the status of the cooking. This problem is solved by a container according to claim 1. A further aspect of the invention relates to a method of packing foodstuff using a container according to an embodiment of the invention, as set forth in claim 14. Preferable embodiments are defined in the dependent claims.
According to the invention, the container comprises a first container portion and a second container portion, each of said first and second container portions comprising a corresponding first or second end surface and a corresponding first or second wall part. Said first and second wall parts comprise first and second engaging sections, respectively, wherein said first engaging section of the first wall part is configured to engage with said second engaging section of the second wall part in a close fit that

allows a sliding movement of the first and second container portions relative to each other from a pushed-together state, in which the first and second container portions are closest together, to an extended state, in which the first and second container portions are moved away from each other while still maintaining the engagement of the engaging sections, to thereby increase the volume enclosed in the container,
provides a sufficient degree of fluid tightness to prevent leakage of foodstuffs from the container when the first and second engaging sections are engaged with each other in the pushed-together state, and
provides a predetermined degree of friction when the first and second container portions in their engaged state are moved apart from each other from the pushed-together state to the extended state, said predetermined degree of friction defining a corresponding vapor pressure to be developed inside the container upon heating in the microwave oven causing the first and second container portions to move apart,

According to the present invention, the container hence comprises first and second container portions that are slidably connected via their respective engaging portions providing a "close fit". Herein, the "close fit" implies a certain degree of fluid tightness when the first and second engaging sections are engaged with each other in the pushed-together state, which is the state used for storage of the foodstuff in the container prior to its cooking, namely a degree of fluid tightness that prevents leakage of the foodstuff, or fluid portions thereof, under practical circumstances, such that no additional seal is needed.
When the container containing the foodstuff is placed in a microwave oven for heating or cooking the foodstuff, water or a liquid phase of the foodstuff, if present, or a water content of the foodstuff will evaporate and cause steam to develop within the container. This development of steam is desired, as the steam is used for cooking the foodstuff in the microwave oven. Due to the aforementioned degree of fluid tightness, no or only little of the steam will escape from the container, and in the course of heating, the vapor pressure of the steam will gradually increase in an initial stage of the cooking process.
Once the vapor pressure increases to a threshold that exceeds the frictional force provided by the close fit between the first and second engaging sections, the first and second container portions will start to move away from each other, thereby increasing the volume of the container. Any increase in volume in turn will lead to a drop of the vapor pressure inside the container, so it will take additional heating until the pressure overcoming the frictional force is regained. Accordingly, upon steam cooking, the first and second portions of the container move only gradually and slowly away from each other during the cooking, maintaining the pressure inside the container just at the level sufficient to overcome the frictional force.
By the time that the first and second container portions have acquired the extended state, the opening provided in one of the first and second engaging sections, which was initially covered by the other of the first and second engaging sections, is at least partially exposed, such that vapor is allowed to escape from the container, preventing an additional buildup of pressure inside the container, and bringing the relative movement of the first and second portions to an end.
The container according to the invention provides a number of advantages over the pressure and moisture release cooking container of the prior art cited above. The container according to the invention is structurally more simple, and hence less costly to manufacture. Moreover, the container according to the invention allows not only for building up a desired pressure, but also for maintaining the desired pressure. While in the prior art described above, the pressure in the container first increases until the cap snaps open, and thereafter decreases again, in the container according to the invention the pressure is always balanced with the friction associated with the close fit between the first and second engaging sections. This is true not only for the phase during which the first and second container portions gradually move from the pushed-together state to the extended state, but in the extended state as well. The reason for this is that the exposure of the opening is likewise a gradual process, which, at a certain degree of opening, prevents a further increase of pressure, and hence a further moving of the first and second portions, but does not lead to any appreciable pressure drop once the maximum extension has been reached, provided that the heating power is maintained constant, as is the case in a microwave oven. In other words, the relative motion of the first and second container portions stops automatically at a degree of exposure of the opening, where the loss of energy inside the container volume due to the escape of steam is in equilibrium with the supply of energy to the container volume by microwaves, which implies that the vapor pressure inside the container remains at least approximately constant. Notably, this vapor pressure can be controlled by designing the frictional force or tightness of the fit between the first and second engaging sections.
Moreover, in the container according to the invention, the increase in volume upon moving from the pushed-together to the extended state, is at least 10%, thereby defining a certain heating period and also giving a visual indication to the user about the state of cooking, as the user can e.g. see at a glance that the extended state has been reached. For some foods, this would indicate that the cooking is finished, for other foods, this could indicate that the desired vapor pressure has been achieved and that a final cooking period of a predetermined duration shall begin.
In preferred embodiments, the volume of the container in the extended state exceeds the volume of the container in the pushed-together state by 15 to 45 %, preferably by 20 to 35%. All of these volume increases are sufficient to give a suitable visual indication to the user. Among these ranges, the suitable volume increases can be selected depending on the foodstuff to be packaged in the container, as the volume increase is related to the cooking time until the extended state is reached.
In a preferred embodiment, an outer surface of the first engaging section of the first container portion engages with an inner surface of the second engaging section of the second container portion. In this case, the opening is preferably formed in the second engaging section of the second container portion. This means that in the pushed-together state, the opening provided in the second engaging section is separated from the foodstuff by the first engaging section, such that it will stay clean.
Preferably, the wall part of the first container portion comprises

a proximal section having an outer diameter corresponding to the outer diameter of the second engaging section of the second container portion, and
a distal section having a reduced outer diameter forming the first engaging section.

Accordingly, in the pushed-together state, the outer surface of the proximal section of the first container portion is flush with the outer surface of the second engaging section, allowing for an easier handling and a better optical appearance.
In a preferred embodiment, one of or both of the end surfaces is/are flat. A flat surface allows for placing the container thereon, facilitating storage, transportation and the cooking in the microwave oven. Note, however, that a flat surface is not mandatory, and that at least one of the end surfaces may be spherical or dome-shaped, in particular since the container will only need to have one end surface to stand on.
In a preferred embodiment, the end surface of the first container portion forms a base surface on which the container can stand in an upright position. The container preferably further comprises a visual indication indicating the upright position to a user of the container.
In a preferred embodiment, the container has the shape of a cylinder having a circular, a square, a rectangular, a hexagonal or an octagonal cross-section. Note that the cylinder does not necessarily have to be a perpendicular cylinder, i.e. with the cylinder axis perpendicular to the end surfaces, however, in preferred embodiments, this is the case.
In a preferred embodiment, the container comprises a tape covering the opening, wherein said tape preferably also fixes the first and second container portions in the pushed-together state, said tape being releasable prior to cooking or heating the foodstuffs in the microwave oven. In this embodiment, the tape protects the opening from dust and dirt, but also prevents the first and second portions of the container from being separated. The tape also indicates to the user that the package has not been opened yet. Upon preparing the foodstuff for cooking, the user may simply pull the tape off the package.
In a preferred embodiment, the first and second container portions are made from paper or cardboard, in particular from recycled paper or cardboard. This reduces the manufacturing costs of the container and is also environmentally friendly. In a preferred embodiment, at least the portions of inner surface of the first and second container portions that are exposed to the foodstuffs when the container portions are in the pushed-together state are covered by a water and/or grease resistant coating or liner. Water and grease resistant papers which can be recycled to 100% are known in the art and commercially available e. g. under the product name "Echo Natur" from SPO, Spezialpapierfabrik Oberschmitten.
Preferably, at least portions of the outer surface of one or both of the first and second container portions are covered or treated such as to allow for printing thereon. For example, the outer surface may be covered by an additional paper layer of sufficient quality to print on. In addition or alternatively, a suitable sizing, comprising a binder and filler particles, may be provided, which improves the printability of the outer surface.
A further aspect of the invention relates to a method of packaging foodstuffs, in particular instant food, using a container according to one of the embodiments recited above. Herein, the method according to the invention comprises the following steps:

filling the foodstuffs into one of the first and second container portions,
bringing said one of the first and second container portions into engagement with the other of the first and second container portions, and
pushing the first and second container portions together into the pushed-together state.

In a preferred embodiment, the method may further comprise a step of covering the opening with a tape, said tape also connecting the first and second container portions such as to fix them in the pushed-together state.

SHORT DESCRIPTION OF THE FIGURES

Fig. 1: is a front view of a container according to the invention in the pushed-together state.
Fig. 2: is a side view of the container of Fig. 1 in the pushed-together state.
Fig. 3: is a front view of the container of Fig. 1 in the extended state.
Fig. 4: is a side view of the container of Fig. 1 in the extended state.
Fig. 5: is a top view of the container of Fig. 1.
Fig. 6: is a sectional view of the container of Fig. 1 in the pushed-together state along the line A-A shown in Fig. 5.
Fig. 7: is the same sectional view as in Fig. 6 with the container in the extended state.
Fig. 8: is an enlarged view of the encircled portion of Fig. 7, showing the layer structure of the container wall part.
Fig. 9: and 10 show perspective views of containers according to the invention in the pushed-together and extended state, respectively.
Fig. 11, 12 and 13: show three perspective views showing the transition of a container according to the invention from the pushed-together to the extended state.

DESCRIPTION OF THE PREFERRED EMBODIMENT

For the purposes of promoting an understanding of the principles of the invention, reference will now be made to a preferred embodiment illustrated in the drawings, and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated apparatus and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur now or in the future to one skilled in the art to which the invention relates.
With reference to figures 1 to 8, a container 10 according to an embodiment of the invention is next described Herein, Fig. 1 is a front view of the container 10 in the pushed-together state, Fig. 2 is a side view of the container 10 in the pushed-together state, Fig. 3 is a front view of the container 10 in the extended state and Fig. 4 is a side view of the container 10 in the extended state. Fig. 5 is a top view of the container 10, and figures 6 and 7 show sectional views, taken along the line A-A in Fig. 5, in the pushed-together and extended states, respectively. Figure 8 shows the layer structure of the container wall part. Figures 9 and 10 show perspective views of the container 10 in the pushed-together and extended state, respectively. Finally, Fig. 11 to 13 show three perspective views of the container 10 as shown in figures 8 and 9, but with decoration of printing provided thereon, in a sequence of transitions from the pushed-together (Fig. 11) to the extended state (Fig. 13).
As can be seen from Fig. 1 to 7, the container 10 comprises a first portion 12 comprising an end surface 14 and a wall part 16, which in the embodiment shown has a circular cylindrical shape and comprises a proximal section 18 and a distal section 20, the distal section 20 having a reduced outer diameter. The distal section 20 forms a first engaging section.
The container 10 further comprises a second portion 22 comprising an end surface 24 and a wall part 26 which in its entirety forms a second engaging section. In the second engaging section 26 (i.e. the second wall part) an opening 28 (cf. figures 1, 3, 6 and 7) is formed. The outer diameter of the second engaging section 26 corresponds to the outer diameter of the proximal section 18 of the first wall part 16, such that these outer surfaces are flush with each other when the container 10 is in the pushed-together state.
As can be seen particularly well in the sectional views of figures 6 and 7, the first engaging section 20 is configured to engage with the second engaging section 26 in a closed fit. The closed fit allows for a sliding movement of the first and second container portions 12, 22 relative to each other from a pushed-together state shown in Fig. 1 , 2 and 6, in which the first and second container portions 12, 22 are closest together, to an extended state shown in Fig. 3 , 4 and 7, in which the first and second container portions 12, 22 are moved away from each other, while still maintaining the engagement of their engaging sections 20, 26. This sliding movement hence allows for adjusting the volume enclosed by said container 10 in what could be regarded as a "telescopic" manner. As is further seen from Fig. 1 , 2 and 6, when in the pushed-together state, the opening 28 provided in the second engaging section 26 is occluded by the first engaging section 20. Conversely, when in the extended state shown in Fig. 3, 4 and 7, the opening 28 is exposed, such as to provide for a communication between the inner volume of the container 10 and the outer atmosphere. Note that for the sake of clarity, in the figures shown, the extended state is a state in which the opening 28 is fully exposed. However, in practical applications to be described in more detail below, the "most extended state" would typically be a state in which the opening 28 is only partially exposed. Note further that the volume enclosed by the container 10 in the extended state exceeds the volume of the container 10 in the pushed-together state by approximately 25%.
Fig. 8 is an enlarged view of the encircled portion of Fig. 7, showing the structure of the wall part 16. The bulk of the wall part 16 is made from recycled cardboard 30. On the inner surface of the wall part 16, a grease and water resistant coating 32 is provided. On the outer surface of the wall part 16, a thin paper layer 34 is provided, on which a decorative printing as shown in Fig. 11 to 13 is provided. However, the printing as shown in Fig. 11 to 13 does not only have an aesthetic function, but also indicates the upright position of the container 10 as a whole, i.e. in the embodiment shown, with the first container portion 12 at the bottom and the second container portion 22 at the top.
Next the use and function of the container 10 is described. The container 10 is intended for both, packaging foodstuffs as well as cooking or warming up said foodstuffs in a microwave oven. Typically, the foodstuffs would be instant food, which only needs heating/cooking in a microwave oven, possibly after adding water and mixing by means of shaking the entire container 10.
In the intended use, the container 10 is hence prefilled with foodstuffs, and is sealed by means of a tape (not shown) connecting the first and second portions 12, 22 and also covering the opening 28 in the second engaging portion 26. By means of such tape, the first and second portions 12, 22 are fixedly held together, the opening 28 is protected from dust or dirt, and it is indicated that the container 10 is "fresh", i.e. has not been opened before.
For preparing the food, the consumer peels of the tape (not shown) and places the container 10 including the foodstuff within a microwave oven. Depending on the foodstuff, the consumer may further add a prescribed amount of water and mix the foodstuff and the added water, by shaking the container 10 before placing it within the microwave oven. In the embodiment shown, the container is sized and dimensioned such that it can be held or grabbed with one hand, while simultaneously holding the first and second portions 12, 22 together, such as to avoid a separation of the first and second portions during shaking.
After having been placed in the microwave oven, the water containing foodstuff is heated in the usual manner. Upon heating, water vapor (steam) is generated, and the vapor pressure steadily increases. In preferred embodiments, this steam is used for cooking the foodstuff in a gentle and tasteful way. Once the vapor pressure inside the container 10 exceeds a frictional force generated by the tight fit between the first and second engaging sections 20, 26, the second portion 22 of the container will start moving upwards, thereby increasing the volume enclosed by said container 10. The increase in volume, in turn leads to a reduction in pressure, which has to be recovered by further heating. As a result of that, the first portion will not rise abruptly, but gradually during the course of heating, while the vapor pressure is balanced with the frictional force determined by the tight fit between the first and second engaging sections 20, 26. In other words, by providing for a predetermined degree of friction between the first and second engaging sections 20, 26, a desired vapor pressure upon cooking can likewise be predetermined. In preferred embodiments, the predetermined degree of friction is chosen such that a pressure difference between the inner volume of the container 10 and the outer atmosphere in the amount of between 0.2 and 2.5 bar (20 and 250 kPa), preferably between 0.5 and 1.0 bar (50 and 100 kPa) just allows for overcoming the frictional force. As the skilled person will appreciate, depending on the foodstuff, different vapor pressures may be preferred, but in each case they can be predetermined by the "predetermined degree of friction" between the first and second engaging sections 20, 26.
The gradual separation of the first and second portions 12, 22 will automatically come to an end by the time a sufficiently large fraction of the opening 28 is exposed, such that the amount of steam escaping through the opening 28 is at equilibrium with the heat generated inside the volume of container 10. In other words, this partial occlusion of the opening 28 is automatically adjusted such that the continuous heating will maintain the pressure just below the pressure needed to overcome the friction. That is to say, in the extended state shown in Fig. 13, the vapor pressure is still maintained at, or only slightly below the desired vapor pressure. Moreover, the gradual extension of the container 10 is an indication of the cooking state that can be perceived by visual inspection by the consumer easily. Depending on the foodstuff, the container 10 could for example be used together with instructions to the consumer to stop the heating by the time a certain degree of separation is reached, that could for example be marked on the outer surface of the first engaging section 20. Alternatively, the consumer can be instructed to turn off the microwave oven once it is perceived that the process of gradual separation has come to an end (i.e. the container 10 has reached the maximally extended state). For other foodstuffs, the consumer may be instructed to wait until the extended state is reached, and to then wait for another predetermined period of time (or reset the timer of the microwave for this predetermined time). However, in any of various possible embodiments, the clearly visible separation of the first and second container portions 12, 22 gives visual feedback to the consumer about the cooking state, that greatly improves the usefulness of the container according to the present invention.
The container 10 as shown in one of Fig. 1 to 13 may be used in a method of packaging foodstuffs, in particular instant food. Such method comprises the steps of: filling the foodstuffs into one of the first and second container portions 12, 22, bringing said one of the first and second container portions (12, 22) into engagement with the other of the first and second container portions 12, 22, and pushing the first and second container portions 12, 22 together into said pushed-together state. The method further comprises a step of covering said opening 28 with a tape (not shown), thereby also connecting the first and second container portions 12, 22 such as to fix them in the pushed-together state, for transportation and storage.
Although a preferred exemplary embodiment is shown and specified in detail in the drawings and the preceding specification, these should be viewed as purely exemplary and not as limiting the invention. It is noted in this regard that only the preferred exemplary embodiment is shown and specified, and all variations and modifications should be protected that presently or in the future lie within the scope of protection of the invention as defined in the claims.

LIST OF REFERENCE SIGNS

10: container
12: first container portion
14: first end surface
16: first wall part
18: proximal section of first wall part 16
20: distal section of first wall part 16 (first engaging section)
22: second container portion
24: second end surface
26: second engaging section
28: opening
30: cardboard wall
32: inner coating of cardboard wall 30
34: outer paper layer

Claims

A container (10) for packaging foodstuffs and for cooking or warming up said foodstuffs, in particular instant food, in a microwave oven, said container (10) comprising:
a first container portion (12) and a second container portion (22), each of said first and second container portions (12, 22) comprising a corresponding first or second end surface (14, 24) and a corresponding first or second wall part (16, 26), wherein said first and second wall parts (16, 26) comprise first and second engaging sections (20, 26), respectively, wherein said first engaging section (20) of the first wall part is configured to engage with said second engaging section (26) of the second wall part in a close fit that
- allows a sliding movement of the first and second container portions (12, 22) relative to each other from a pushed-together state, in which the first and second container portions (12, 22) are closest together, to an extended state, in which the first and second container portions (12, 22) are moved away from each other while still maintaining the engagement of the engaging sections (20, 26), to thereby increase the volume enclosed in the container (10),

- provides a sufficient degree of fluid tightness to prevent leakage of foodstuffs from the container (10) when the first and second engaging sections (20, 26) are engaged with each other in the pushed-together state, and

- provides a predetermined degree of friction when the first and second container portions (12, 22) in their engaged state are moved apart from each other from the pushed-together to the extended state, said predetermined degree of friction defining a corresponding vapor pressure to be developed inside the container (10) upon heating in the microwave oven causing the first and second container portions (12, 22) to move apart,

wherein an opening (28) is provided in one of the first and second engaging sections (20, 26) , which opening is covered by the other of the first and second engaging sections (20, 26) when the first and second container portions (12, 22) are in the pushed-together state, and which is at least partially exposed when the first and second container portions (12, 22) are in the extended state, thereby allowing vapor to escape from the container (10), wherein the volume of the container (10) in the extended state exceeds the volume of the container (10) in the pushed-together state by at least 10% .
The container (10) of claim 1, wherein the volume of the container (10) in the extended state exceeds the volume of the container (10) in the pushed-together state by 15 to 45 %, preferably by 20 to 35%.
The container (10) of claim 1 or 2, wherein an outer surface of the first engaging section (20) of the first container portion (12) engages with an inner surface of the second engaging section (26) of the second container portion (22).
The container (10) of claim 3, wherein the opening (28) is formed in the second engaging section (26) of the second container portion (22).
The container (10) of claim 3 or 4, wherein the wall (16) part of the first container portion (12) comprises
- a proximal section (18) having an outer diameter corresponding to the outer diameter of the second engaging section (26) of the second container portion (22) , and

- a distal section having a reduced outer diameter forming the first engaging section (20).
The container (10) of one of the preceding claims, wherein one of or both of the end surfaces (14, 24) is/are flat.
The container (10) of one of the preceding claims, wherein the end surface of the first container portion (14) forms a base surface on which the container (14) can stand in an upright position.
The container (10) of claim 7, wherein the container (10) comprises a visual indication indicating the upright position to a user of the container (10).
The container (10) of one of the preceding claims, wherein the container (10) has the shape of a cylinder having a circular, a square, a rectangular, a hexagonal or an octagonal cross-section.
The container (10) of one of the preceding claims, further comprising a tape covering the opening (28), wherein said tape preferably also fixes the first and second container portions (12, 22) in the pushed-together state, said tape being releasable prior to cooking or heating the foodstuffs in the microwave oven.
The container (10) of one of the preceding claims, wherein the first and second container portions (12, 22) are made from cardboard, in particular from recycled cardboard.
The container (10) of one of the preceding claims, wherein at least the portions of inner surface of the first and second container portions (12, 22) that are exposed to the foodstuffs when the container portions (12, 22) are in the pushed-together state are covered by a water and/or grease resistant coating or liner.
The container (10) of one of the preceding claims, wherein at least portions of the outer surface of one or both of the first and second container portions (12, 22) are covered or treated such as to allow for printing thereon.
A method of packaging foodstuffs, in particular instant food, using a container (10) according to one of claims 1 to 13, said method comprising the following steps:
- filling the foodstuffs into one of the first and second container portions (12, 22),

- bringing said one of the first and second container portions (12, 22) into engagement with the other of the first and second container portions (12, 22), and

- pushing the first and second container portions (12, 22) together into the pushed-together state.
The method of claim 14, further comprising a step of covering the opening (28) with a tape, said tape also connecting the first and second container portions (12, 22) such as to fix them in the pushed-together state.