Net for packaging a food portion and method for packaging a food portion

Abstract

The invention relates to a net comprising fold lines (6a, 6b, 6c, 6d, 6e, 6f, 6g, 6h, 6i, 6j, 6k) that define: a triangular bottom panel (4); two quadrilateral side panels (5); two triangular top panels (8); a back panel (10) and a border that has two outer strips (12) to form a sealed back and two front strips (25) that are arranged so as to form, as an extension from the back, a sealing tab, a tear line (30) being arranged so that manually pulling on the tab causes the net to tear from the apex of the bottom panel (4) to the top panel (8) and then on either side of the top panel.

Description

[0001] BLANK FOR PACKAGING A FOOD PORTION AND METHOD FOR PACKAGING A FOOD PORTION

[0002] The invention relates to a blank for packaging a food portion, as well as to a method of packaging a food portion using such a blank.

[0003] It applies in particular to the packaging of individual food portions of fresh dairy products, such as, for example, fresh and / or processed cheese, which are packaged in a prismatic envelope with a triangular base formed by folding a blank.

[0004] To benefit from an ecologically designed packaging, the blank according to the invention is preferably formed from a complex comprising an outer layer based on cellulose fibers and an inner sealing layer.

[0005] To obtain a prismatic envelope with a triangular base, blanks are known which are provided with folding lines which are arranged so as to define:

[0006] - a lower panel having a triangular geometry, and intended to form a lower wall of the envelope;

[0007] - two side panels of quadrilateral geometry each having an internal edge which is connected by a fold line to a large external side of the lower panel, said side panels being intended to form a side wall of the envelope;

[0008] - two upper panels each having a triangular geometry presenting a large internal edge which is connected by a fold line to respectively an external side of a side panel, said upper panels being intended to form together an upper wall of the envelope;

[0009] - a rear panel having an inner edge which is connected by a fold line to a rear edge of the lower, side and upper panels, said rear panel being intended to form a rear wall of the envelope. The blank also comprises a border having two outer strips each having an inner edge which is connected by a fold line to respectively a large outer edge of an upper panel, said outer strips being arranged to be sealed to each other to form a sealing backing of the upper wall of the envelope.

[0010] The backing ensures the packaging is watertight but, particularly in relation to a flan comprising a cellulose layer, the problem arises of the ease of opening the packaging to be able to consume the portion, particularly by young children and / or for soft portions.

[0011] In particular, opening and / or tearing the backing requires handling of the packaging which, in addition to complex ergonomics, proves too restrictive for preserving the integrity of the portion.

[0012] The invention aims to improve the prior art by proposing a blank, in particular comprising a cellulose layer, for packaging a food portion, said blank making it possible to combine optimal sealing with good opening ergonomics, in particular in relation to ease of opening for young children and / or the packaging of a soft portion.

[0013] To this end, according to a first aspect, the invention proposes a blank for packaging a food portion comprising folding lines allowing the shaping of said blank into a prismatic envelope with a triangular base in which said portion can be packaged before closing said envelope, said folding lines defining a blank having:

[0014] - a lower panel having a triangular geometry intended to form a lower wall of the envelope;

[0015] - two side panels of quadrilateral geometry each having an internal edge which is connected by a fold line to a large external side of the lower panel, said side panels being intended to form a side wall of the envelope respectively; - two upper panels each having a triangular geometry having a large internal edge which is connected by a fold line to a large external side of a side panel respectively, said upper panels being intended to form together an upper wall of the envelope;

[0016] - a rear panel having an internal edge which is connected by a fold line to a rear edge of the lower, side and upper panels, said rear panel being intended to form a rear wall of the envelope;

[0017] - a border having two outer strips each having an inner edge which is connected by a fold line to a large outer edge of a top panel respectively, said outer strips being arranged to be sealed to each other to form a sealing backing for the top wall of the envelope; the border further having two front strips each having a rear edge which is connected by a fold line to a front edge of respectively an outer strip and a side panel, said front strips having a common inner edge formed by a fold line extending in the extension of the top of the bottom panel, said front strips being arranged to be sealed to each other to form, in the extension of the backing, a sealing tab for the tip of the packaging,the blank comprising a tear line having two lateral segments which each extend respectively over an upper panel and along the outer edge of the adjacent side panel, each being extended by a front segment which extends, in the continuity of said lateral segment and beyond said outer edge, over the adjacent side panel and towards the top of the lower panel, said tear line being arranged so that manual pulling on the sealing tab induces a tear in said blank along its tip from the top of the lower panel to the upper panel followed by propagation of said tear on either side of the upper wall.,

[0018] According to a second aspect, the invention provides a method of packaging a food portion using such a blank, said method providing for: - folding the blank along its fold lines to form a prismatic envelope with a triangular base having a lower wall, two side walls, an upper wall and an open rear mouth;

[0019] - seal the outer and front strips of the edge to form a sealing backing for the top wall of the envelope and a sealing tab for the tip of the packaging;

[0020] - pack the portion in the packaging through the rear mouth;

[0021] - close the said mouth tightly.

[0022] Other features and advantages of the invention will appear in the following description, given with reference to the appended figures, in which:

[0023] - figure 1 schematically represents, in front and interior view, a blank according to one embodiment before its folding;

[0024] - figures 2a to 2f represent in perspective in different orientations the blank of figure 1 during different stages of its folding to form a package;

[0025] - figures 3a to 3e represent in perspective, in different orientations, different stages of opening the packaging of figure 2f;

[0026] - figures 4a and 4b schematically represent, in a view similar to figure 1, a blank according to a variant of the embodiment of the preceding figures.

[0027] In connection with these figures, a blank for packaging a food portion 1 is described below, as well as a method of packaging a food portion 1 using such a blank.

[0028] The flan is particularly suitable for packaging an individual portion of fresh dairy product, for example fresh and / or processed cheese.

[0029] The blank is formed from a complex 2 which has a sealing layer 2a with barrier properties to oxygen and / or water vapor, in order to guarantee the preservation of the packaged food portion 1. The sealing layer 2a may be made of a food-grade plastic material, in particular in the case where it is intended to be in contact with the food portion 1 packaged in the packaging. To do this, the sealing layer 2a may be made from polyethylene (PE) and / or polyethylene terephthalate (PET), or from other types of known food plastics, such as a polyamide (PA), a polypropylene (PP) or a polylactic acid (PLA).

[0030] Advantageously, the complex 2 comprises an inner sealing layer 2a as described above, as well as an outer layer 2b based on cellulose fibers. In particular, the cellulose fibers may be derived from wood and be shaped by the papermaking process to form a layer of paper or cardboard, or be in the form of a non-woven fabric.

[0031] Such an arrangement allows for environmentally friendly packaging design. In particular, the outer layer 2b can be made from recycled cellulose fibers.

[0032] According to an exemplary embodiment, the outer layer 2b has a surface mass of between 30 g / m 2 and 150 g / m 2 , in particular between 50 g / m 2 and 110 g / m 2 , and more particularly of the order of 80 g / m 2 .

[0033] Advantageously, the complex 2 comprises between 60% and 90% by weight of cellulose fibers. For this purpose, the outer layer 2b may have a thickness of the order of 60 μm, and the inner layer 2a a thickness of between 4 μm and 20 μm.

[0034] To improve the overall sealing properties of the packaging, the complex 2 may comprise at least one additional layer of film and / or varnish having suitable properties, in particular a barrier to oxygen and / or water vapor. In particular, the outer face of the outer layer 2b may be coated with an additional layer of varnish with anti-condensation properties. The complex 2 may have decorations and / or markings, for example patterns and / or inscriptions of an aesthetic and / or commercial nature linked to the food portion 1. These elements may be formed by printing and / or embossing directly on the outer layer 2b made of cellulosic fibers.

[0035] A method of packaging a food portion 1 in a blank formed in a complex 2 as described above is now described.

[0036] The method firstly provides for forming on the blank fold lines 6a-6k arranged to allow the shaping of said blank into a prismatic envelope 3 with a triangular base, in which the food portion 1 can be packaged before closing said envelope to form a package.

[0037] Advantageously, these fold lines 6a-6k are formed by creasing the outer layer 2b of cellulosic fibers, which makes it easier to fold the blank while maintaining the integrity of the sealing layer 2a.

[0038] In relation to the figures, the method provides for forming fold lines 6a-6k on the blank, so as to define there:

[0039] - a lower panel 4 having a triangular geometry and intended to form a lower wall of the envelope 3;

[0040] - two side panels 5 of quadrilateral geometry, each of which has an internal edge 5a which is connected by a fold line 6a to a large external side 4b of the lower panel 4, and which are intended to form a side wall 7 of the envelope 3;

[0041] - two upper panels 8 each having a triangular geometry having a large internal edge 8a which is connected by a fold line 6b to respectively an external side 5b of a side panel 5, said upper panels being intended to form together an upper wall 9 of the envelope 3; - a rear panel 10 having an internal edge 10a which is connected by a fold line 6c to a respective rear edge 4a, 5c, 8c of the lower 4, side 5 and upper 8 panels, said rear panel being intended to form a rear wall 11 of the envelope 3; and

[0042] - a border having two outer strips 12 which each have an inner edge 12a connected by a fold line 6d to respectively a large outer edge 8b of an upper panel 8, said outer strips being arranged to be sealed to each other to form a sealing backing 13 of the upper wall 9 of the envelope 3.

[0043] The lower panel 4 has a geometry in the shape of an isosceles triangle, the base of which forms the rear edge 4a which is defined by the fold line 6c separating said lower panel from the rear panel 10.

[0044] Each upper panel 8 has a geometry in the shape of a right triangle, the hypotenuse of which forms the large internal edge 8a which defines the fold line 6b between said upper panel and the adjacent side panel 5. Similarly, for each upper panel 8:

[0045] - the large side 8b forming the right angle of said triangle is defined by the external folding line 6d relative to the adjacent external strip 12; and

[0046] - the small perpendicular side 8c is defined by the rear folding line 6c of said upper panel relative to the rear panel 10.

[0047] The outer strips 12 of the border extend to the rear edge 14 of the blank, and the border has a rear strip 15 which extends between the rear ends of said outer strips and all along the rear edge 14 of said blank, said rear strip being connected by a fold line 6e to a rear edge 10b of the rear panel 10, being arranged to be sealed on itself to form a hem 16 for sealing the rear wall 11 of the packaging.

[0048] In relation to figures 2a and 2b, the packaging method provides for folding the blank along its fold lines 6a, 6b, 6c, 6d, 6e to form a prismatic envelope 3 with a triangular base having a lower wall, two side walls, an upper wall and an open rear mouth.

[0049] To do this, the process involves successively folding:

[0050] - the lines 6a defining the large external sides 4b of the lower panel 4, so as to erect the side panels 5 to form the side walls 7 of the envelope 3 (figure 2a);

[0051] - the lines 6b defining the respective external sides 5b of the side panels 5, so as to fold the upper panels 8 above the lower panel 4 to form the upper wall 9 of the envelope 3;

[0052] - the lines 6d defining the respective large external edges 8b of the upper panels 8, so as to erect the external strips 12 of the border by arranging their respective internal faces against each other (figure 2b).

[0053] In particular, at the end of these folding steps, an envelope 3 is obtained with an open rear mouth 17 (figure 2d), and the inner face of the rear strip 15 of the border delimits an inner periphery of said rear mouth.

[0054] The method then provides for sealing the outer strips 12 of the border, so as to form a sealing backing 13 of the upper wall 9 of the envelope 3.

[0055] To do this, the method provides for depositing a layer of an adhesive on the respective inner faces of the outer strips 12, so as to form the sealing backing 13 by a “flesh-flesh” type sealing of said outer strips.

[0056] The adhesive may be a hot melt glue or a cold glue, so as to ensure a permanent and watertight seal of the backing 13. In particular, as the outer strips 12 extend to the rear edge 14 of the blank, their sealing makes it possible to obtain a sealing backing 13 which closes the periphery of the rear mouth 17.

[0057] Then, as shown in Figures 2c and 2d, the backing 13 is folded back onto the upper wall 9 of the envelope 3 after it has been sealed.

[0058] The method then provides for packaging the food portion 1 in the packaging through the rear mouth 17, then folding the rear panel 10 to close said mouth.

[0059] Thus, the method makes it possible to form a mold by means of the envelope 3, into which the food portion 1 can be poured in liquid or viscous form before closing said envelope, which makes it possible to limit production costs by avoiding an additional step of shaping said food portion before packaging in the package.

[0060] This arrangement also makes it possible to produce food portions 1 packaged more hygienically and with better storage conditions. Indeed, by pouring the food portion 1 directly into its individual packaging, its exposure to ambient air is limited, which limits the risk of contamination, particularly by germs. Furthermore, if the food portion 1 is poured at a temperature higher than the pasteurization temperature, this further improves its storage properties.

[0061] To fold the rear panel 10, the method provides for extending the fold lines 6a, 6b, 6d defining the outer 4b, 5b, 8b and inner 5a, 8a edges of the lower 4, side 5 and upper 8 panels on said rear panel so as to form lower 18, side 19 and upper 20 sectors therein, said folding being carried out by folding flat the side sectors 19 to fold down the upper 20 and lower 18 sectors, as shown in Figure 2e. To be able to close the mouth 17 tightly, the method then provides for:

[0062] - folding the rear strip 15 flat, by placing an upper portion of the inner face of said rear strip on a lower portion of said inner face;

[0063] - seal the inner face of the rear strip 15, by a “flesh-flesh” type association of its upper and lower portions, in order to form the sealing hem 16 of the rear wall 11.

[0064] This embodiment allows in particular continuous sealing of the inner face of the rear strip 15, guaranteeing optimal sealing due in particular to the absence of any excess thickness in said sealing.

[0065] To enable the rear strip 15 to be sealed, the method first provides for depositing a layer of adhesive on its inner face, in particular an adhesive similar to that placed on the outer strips 12 of the border to form the upper sealing backing 13.

[0066] In the embodiment shown, the method provides for extending the fold lines 6a, 6b, 6d of the rear panel 10 onto the rear strip 15 of the border, so as to form on said rear strip lower 21, lateral 22 and upper 23 sectors in the rear extension of the corresponding sectors 18, 19, 20 of said rear panel.

[0067] Thus, as shown in Figures 2d and 2e, the flat folding of the rear strip 15 is achieved by arranging the inner face of the upper sectors 23 on the inner face of the lower sector 21, and by folding on itself the inner face of each of the lateral sectors 22.

[0068] In particular, the different folding lines 6a, 6b, 6d are extended in a rectilinear manner, which makes it easier to manufacture the blank and fold the envelope 3. The method provides for forming, on the respective lateral sectors 19, 22 of the rear panel 10 and the rear strip 15, a pattern 6f of folding lines which is arranged to allow them to be folded flat.

[0069] In particular, as shown in Figures 1, 2a, 2b, 2c and 2d, each pattern of fold lines forms a triangle 6f extending over the lateral sector 19 of the rear panel 10, the base of the triangle 6f being formed by the front edge of the lateral sector 19 and the apex of said triangle being arranged on the rear edge of said lateral sector, said apex being extended by a fold line 6g extending over the lateral sector 22 of the rear strip 15 to the rear edge 14 of said rear strip.

[0070] The process also provides for the formation of:

[0071] - on each of the upper sectors 20, 23: a section 6h of fold line which extends from the intersection between the front edge and the internal edge of the upper sector 20 of the rear panel 10 to the rear edge 14 of the blank; and

[0072] - on the lower sectors 18, 21: two sections 6i of folding line which extend from the intersection between the front edge 10a of the rear panel 10 and respectively one of the external edges of its lower sector 18 to the rear edge 14 of the blank.

[0073] In relation to figures 2e and 2f, the different patterns 6f and sections 6h, 6i of folding lines formed on the lateral sectors 19 of the rear panel 10 make it possible to fold said lateral sectors which forms two lateral gussets 24 of triangular geometry, which are then folded down onto a respective lateral wall 7.

[0074] In particular, after sealing the rear strip 15, the sealing hem 16 thus formed is folded over a lower portion of the rear wall 11 of the envelope 3, and the side gussets 24 are then each folded over the adjacent side wall 7. In a variant not shown, the sealing of the rear mouth 17 can be carried out by folding the side sectors 19 flat into triangular gussets 24 towards the inside of the packaging and on either side of the rear wall 11 of the envelope 3, then, after sealing the rear strip 15, by folding the sealing hem 16 over said rear wall.

[0075] To facilitate the opening of the packaging, in particular by young children and / or in relation to a soft food portion 1, the method provides for forming the fold lines so that the border further has two front strips 25, which each have a rear edge 25a connected by a fold line 6j to a front edge 12b, 5d of respectively an outer strip 12 and a side panel 5, as well as a common internal edge 26 formed by a fold line 6k extending in the extension of the top of the lower panel 4.

[0076] Advantageously, as shown in Figures 1, 4a, 4b, the blank has a symmetry with respect to the axis defined by the common internal edge 26 of the front strips 25 (vertical in Figure 1), which makes it easier to manufacture said blank and to fold the envelope 3.

[0077] Each of the fold lines 6b defining the internal edges 8a of the upper panels 8 extends to the front edge 25b of the front strip 25, forming, on either side of said line, an external sector 27 in the extension of an external strip 12 and an internal sector 28 delimited with the common internal edge 26.

[0078] Especially :

[0079] - each of the interior sectors 28 has a rear edge 28a formed by a fold line 6j and a free front edge 28b, said edges being parallel; and

[0080] - the top of each of the upper panels 8 opens at the intersection between the adjacent outer 27 and inner 28 sectors. Alternatively, as shown in Figures 4a and 4b, each of the fold lines 6a, 6d respectively defining the large outer sides 4b of the lower panel 4 and the respective large outer edges 8b of the upper panels 8 also extend to the front edge 25b of the adjacent front strip 25a, so as to form in the inner sector 28 of said front strip:

[0081] - a central triangular sub-sector 28a;

[0082] - two lateral sub-sectors 28b on either side of said central sub-sector.

[0083] In relation to figure 2b, the front strips 25 are arranged to be sealed to each other so as to form, in the extension of the backing 13, a sealing tab 29 for the tip of the packaging.

[0084] To do this, the method provides for depositing a layer of an adhesive, in particular similar to that used on the backing 13 and the rear hem 16, on the inner face of the front strips 25 of the border, so as to allow the formation of the tab 29 by “flesh-flesh” type sealing of said front strips.

[0085] As shown in Figures 2c and 2d, the method provides, after sealing the upper backing 13 and the front tab 29, to:

[0086] - fold the backing 13 onto the upper wall 9 of the envelope 3, so as to arrange the upper part of the tongue 29, formed by sealing the outer sectors 27, horizontally;

[0087] - fold down onto a side wall 7 the lower part of said tab, formed by sealing the interior sectors 28; and

[0088] - fold said upper part onto said side wall, partially covering said lower part of the tab 29.

[0089] The method further provides for forming on the blank a tear line 30 which has two lateral segments 30b which each extend respectively over an upper panel 8 and along the external edge 5b of the adjacent lateral panel 5, each being extended by a front segment 30a which extends, in the continuity of said lateral segment and beyond said external edge, over the adjacent lateral panel 5 and towards the top of the lower panel 4.

[0090] The tear line 30 is arranged so that a manual pull on the sealing tab 29 induces a tear in the blank along its tip from the top of the lower panel 4 to the upper panel 8, followed by a propagation of said tear on either side of the upper wall 9.

[0091] Thus, the blank makes it possible to provide the consumer with packaging with a rigid tab 29 whose large dimensions make it easier to grasp it with the fingers, said tab also forming a lever arm to facilitate the initiation of tearing of said packaging along the line 30 formed for this purpose in said packaging.

[0092] In Figure 1, the tear line 30 comprises a single front segment 30a which extends over the side panels 5 from the top of the bottom panel 4 to beyond the outer edge 5b of each of said side panels.

[0093] Alternatively, as shown in Figures 4a and 4b, the tear line 30 comprises two distinct front segments 30a, separated by a blank section devoid of said tear line which extends over the top of the lower panel 4. This arrangement makes it possible to avoid the presence of a tearable zone at the front point of the envelope 3 after folding, in order to limit the risks of leakage of food product 1 at the level of said point by untimely rupture of such a tearable zone.

[0094] Especially :

[0095] - The front segment(s) 30a of the tear line 30 extend(s) parallel to a rear edge 4a of the lower panel 4;

[0096] - each lateral segment 30b of the tear line 30 extends parallel to a respective outer edge 5b of the corresponding side panel 5. This arrangement allows the consumer to open the packaging on the front point and the upper wall 9 of the envelope 3, and in particular on either side of the sealing backing 13. Thus, the consumer does not need to tear the backing 13 to open the packaging, which makes it possible to guarantee the sealing of said backing during storage of the packaged food portion 1 and to facilitate access to said food portion when opening its packaging.

[0097] Advantageously, the lateral segments 30b of the tear line 30 delimit between them and on the upper wall 9 of the envelope 3 a tearable zone whose surface area is greater than at least 80%, and in particular greater than 95% of the total surface area of ​​said upper wall.

[0098] To do this, each lateral segment 30b extends in particular over more than 90% of the length of the adjacent external edge 5b, while having an intrinsic length which remains less than 100% of said external edge length, in order to guarantee the separation of the tip from the rest of the packaging when it is opened.

[0099] Thus, the tear line 30 makes it possible to form in the envelope 3 a large opening to facilitate the extraction of the food portion 1 from the packaging.

[0100] In particular, each lateral segment 30b of the tear line 30 extends along the outer edge 5b, forming a strip 31 between them, so that, after opening the packaging, each strip 31 rests on an upper wall of the food portion 1, so as to keep a lateral wall 7 of the envelope 3, to which it is attached, resting on it. This arrangement makes it possible to wedge the food portion 1 laterally on the lower wall of the envelope 3, while waiting for it to be extracted by the consumer, as shown in FIG. 3d.

[0101] Each of the strips 31 has a width which is less than 10% of the width of the adjacent side panel 5, and in particular less than 5% of said width. This arrangement makes it easier to extract the food portion.

[0102] I by the consumer, who must then simply move the side walls 7 apart (figure 3e) to be able to remove said food portion from the lower wall of the casing 3 while retaining its shape integrity, particularly in the case of a soft food portion 1.

[0103] In Figures 1 and 4a, each lateral segment 30b of the tear line 30 extends rectilinearly to the rear edge 8c of respectively an upper panel 8, and extends in particular onto the rear panel 10, preferably opening into the section 6h of the fold line of the adjacent upper sector 20.

[0104] Thus, by continuing his pulling force on the tab 29, the consumer can partially, but not completely, tear the rear wall 11 of the envelope 3, so as to hold the food portion 1 between the rear wall portion

[0105] II not torn and the side walls 7, pending the extraction of said food portion from the packaging by said consumer.

[0106] According to a variant shown in Figure 4b, the tear line 30 has two rear segments 30c which each extend a lateral segment 30b respectively, each rear segment 30c extending rectilinearly on the adjacent lateral panel 5 to an end facing the junction between the internal folding lines 6i, 6f of the corresponding rear lateral sector 19.

[0107] In particular, each lateral tear segment 30b is connected to the corresponding front segment 30a and / or rear segment 30c by an elbow 30d of curved geometry, said elbows each having a radius of curvature which is arranged to ensure tearing along said segments.

[0108] Furthermore, the lower panel 4 is devoid of a tear line, in order to remain attached to the envelope 3 after opening the packaging, thus forming a tray on which the food portion 1 can be held while waiting to be taken by the consumer.

[0109] According to one embodiment, the tear line 30 is obtained by partial pre-cutting of the thickness of the blank, in particular by ablation of material, to a sufficient depth to form a weakening line allowing the tearing of said blank to be guided along said line. Advantageously, the line 30 can be formed by laser cutting with different parameters at the elbows 30d connecting the segments 30a, 30b and / or 30c, in order to facilitate the tearing along said elbows.

[0110] To preserve the integrity of the inner layer 2a, and therefore the sealing of the packaging, the tear line 30 is formed by at least partial removal of only the outer layer 2b.

[0111] Advantageously, the tear line 30 is formed, for example by laser cutting or by mechanical cutting, over approximately 4 / 5 of the total thickness of the outer layer 2b, which allows a good compromise between preserving the sealing of the packaging and the ease of its opening by tearing along said line.

[0112] According to another embodiment, the tear line 30 allows the tearing of the blank to be guided without prior pre-cutting of said blank, for example by means of a folding or grooving line of the blank, and / or a particular orientation of the fibers of the outer layer 2b along said line.

Claims

CLAIMS 1. Blank for packaging a food portion (1) comprising folding lines (6a, 6b, 6c, 6d, 6e, 6f, 6g, 6h, 6i, 6j, 6k) allowing the shaping of said blank into a prismatic envelope (3) with a triangular base in which said portion can be packaged before closing said envelope, said folding lines defining a blank having: - a lower panel (4) having a triangular geometry intended to form a lower wall of the envelope (3); - two side panels (5) of quadrilateral geometry each having an internal edge (5a) which is connected by a fold line (6a) to respectively a large external side (4b) of the lower panel (4), said side panels being intended to form respectively a side wall (7) of the envelope (3); - two upper panels (8) each having a triangular geometry presenting a large internal edge (8a) which is connected by a fold line (6b) to respectively an external side (5b) of a side panel (5), said upper panels being intended to form together an upper wall (9) of the envelope (3); - a rear panel (10) having an internal edge (10a) which is connected by a fold line (6c) to a rear edge (4a, 5c, 8c) of the lower (4), side (5) and upper (8) panels, said rear panel being intended to form a rear wall (11) of the envelope (3); - a border having two outer strips (12) each having an inner edge (12a) which is connected by a fold line (6d) to a large outer edge (8b) of a top panel (8) respectively, said outer strips being arranged to be sealed to each other to form a sealing backing (13) of the top wall (9) of the envelope (3); said blank being characterized in that the border further has two front strips (25) each having a rear edge (25a) which is connected by a fold line (6j) to a front edge (12b, 5d) of respectively an outer strip (12) and a side panel (5), said front strips having an inner edge (26) common formed by a fold line (6k) extending in the extension of the top of the lower panel (4), said front strips being arranged to be sealed to each other to form, in the extension of the backing (13), a sealing tab (29) of the tip of the packaging, and in that the blank comprises a tear line (30) having two lateral segments (30) which each extend respectively on an upper panel (8) and along the external edge (5b) of the adjacent side panel (5), each being extended by a front segment (30a) which extends, in the continuity of said lateral segment and beyond said external edge, on the adjacent side panel (5) and in the direction of the top of the lower panel (4),said tear line being arranged so that a manual pull on the sealing tab (29) induces a tear in said blank along its tip from the top of the lower panel (4) to the upper panel (8) followed by a propagation of said tear on either side of the upper wall (9)., 2. Blank for packaging a food portion (1) according to claim 1, characterized in that the tear line (30) comprises a single front segment (30a) which extends over the side panels (5) from the top of the bottom panel (4) to beyond the outer edge (5b) of each of said side panels.

3. Blank for packaging a food portion (1) according to one of claims 1 or 2, characterized in that each lateral segment (30b) of the tear line (30) extends parallel to a respective outer edge (5b).

4. Blank for packaging a food portion (1) according to any one of claims 1 to 3, characterized in that each lateral segment (30b) of the tear line (30) extends along the external edge (5b) forming a strip (31) between them.

5. Blank for packaging a food portion (1) according to any one of claims 1 to 4, characterized in that each lateral segment (30b) of the tear line (30) extends to the rear edge (8c) of a top panel (8) respectively.

6. Blank for packaging a food portion (1) according to claim 5, characterized in that each lateral segment (30b) of the tear line (30) extends onto the rear panel (10).

7. Blank for packaging a food portion (1) according to any one of claims 1 to 6, characterized in that each of the fold lines (6b) defining the internal edges (8a) of the upper panels (8) extends to the front edge (25b) of the front strip (25) forming, on either side of said line, an external sector (27) in the extension of an external strip (12) and an internal sector (28) delimited with the common internal edge (26).

8. Blank for packaging a food portion (1) according to claim 7, characterized in that each of the interior sectors (28) has a rear edge (28a) formed by a folding line (6j) and a free front edge (28b), said edges being parallel.

9. Blank for packaging a food portion (1) according to any one of claims 1 to 8, characterized in that the fold lines (6a, 6b, 6d) defining the external (4b, 5b, 8b) and internal (5a, 8a) edges of the lower (4), side (5) and upper (8) panels extend, in particular in a rectilinear manner, on the rear panel (10) to form lower (18), side (19) and upper (20) sectors on said rear panel.

10. Blank for packaging a food portion (1) according to any one of claims 1 to 9, characterized in that the border has a rear strip (15) which is connected by a fold line (6e) to a rear edge (10b) of the rear panel (10), said rear strip being arranged to be sealed on itself to form a sealing hem (16) of the rear wall (11) of the packaging.

11. Blank for packaging a food portion (1) according to claims 9 and 10, characterized in that the rear strip (15) has lower (21), lateral (22) and upper (23) sectors in the rear extension of the corresponding sectors (18, 19, 20) of the rear panel (10), the lateral sectors (19, 22) of the rear panel (10) and of the rear strip (15) each having a pattern (6f, 6g) of fold lines which is arranged to allow the flat sealing of the rear strip (15).

12. Blank for packaging a food portion (1) according to any one of claims 9 to 11, characterized in that each of the upper sectors (20, 23) has a section (6h) of folding line extending from the intersection between the front edge and the internal edge of the upper sector (20) of the rear panel (10) to the rear edge (14) of the blank.

13. Blank for packaging a food portion (1) according to claim 12, characterized in that each of the lateral segments (30b) of the tear line (30) opens into the corresponding section (6h) of the folding line.

14. Blank for packaging a food portion (1) according to any one of claims 1 to 13, characterized in that it is formed from a complex (2) comprising an outer layer (2b) based on cellulose fibers and an inner sealing layer (2a).

15. Blank for packaging a food portion (1) according to claim 14, characterized in that the tear line (30) is formed by at least partial removal of only the outer layer (2b).

16. Blank for packaging a food portion (1) according to one of claims 14 or 15, characterized in that the folding lines (6a, 6b, 6c, 6d, 6e, 6f, 6g, 6h, 6i, 6j, 6k) are formed by creasing the outer layer (2b).

17. Method for packaging a food portion (1) using a blank according to any one of claims 1 to 16, said method providing: - folding the blank along its folding lines (6a, 6b, 6c, 6d, 6e, 6f, 6g, 6h, 6i, 6j, 6k) to form a prismatic envelope (3) with a triangular base having a lower wall, two side walls (7), an upper wall (9) and an open rear mouth (17); - seal the outer (12) and front (25) strips of the border to form a sealing backing (13) of the upper wall (9) of the envelope (3) and a sealing tab (29) of the tip of the packaging; - package the portion (1) in the packaging through the rear mouth (17); - close the said mouth tightly.

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