CA2167036A1 - Breathing gas flushed pack - Google Patents
Breathing gas flushed packInfo
- Publication number
- CA2167036A1 CA2167036A1 CA002167036A CA2167036A CA2167036A1 CA 2167036 A1 CA2167036 A1 CA 2167036A1 CA 002167036 A CA002167036 A CA 002167036A CA 2167036 A CA2167036 A CA 2167036A CA 2167036 A1 CA2167036 A1 CA 2167036A1
- Authority
- CA
- Canada
- Prior art keywords
- pack
- food product
- envelope
- film
- oxygen
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65B—MACHINES, APPARATUS OR DEVICES FOR, OR METHODS OF, PACKAGING ARTICLES OR MATERIALS; UNPACKING
- B65B53/00—Shrinking wrappers, containers, or container covers during or after packaging
- B65B53/02—Shrinking wrappers, containers, or container covers during or after packaging by heat
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65B—MACHINES, APPARATUS OR DEVICES FOR, OR METHODS OF, PACKAGING ARTICLES OR MATERIALS; UNPACKING
- B65B25/00—Packaging other articles presenting special problems
- B65B25/06—Packaging slices or specially-shaped pieces of meat, cheese, or other plastic or tacky products
- B65B25/065—Packaging slices or specially-shaped pieces of meat, cheese, or other plastic or tacky products of meat
- B65B25/067—Packaging slices or specially-shaped pieces of meat, cheese, or other plastic or tacky products of meat combined with its conservation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65B—MACHINES, APPARATUS OR DEVICES FOR, OR METHODS OF, PACKAGING ARTICLES OR MATERIALS; UNPACKING
- B65B31/00—Packaging articles or materials under special atmospheric or gaseous conditions; Adding propellants to aerosol containers
- B65B31/04—Evacuating, pressurising or gasifying filled containers or wrappers by means of nozzles through which air or other gas, e.g. an inert gas, is withdrawn or supplied
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65B—MACHINES, APPARATUS OR DEVICES FOR, OR METHODS OF, PACKAGING ARTICLES OR MATERIALS; UNPACKING
- B65B9/00—Enclosing successive articles, or quantities of material, e.g. liquids or semiliquids, in flat, folded, or tubular webs of flexible sheet material; Subdividing filled flexible tubes to form packages
- B65B9/06—Enclosing successive articles, or quantities of material, in a longitudinally-folded web, or in a web folded into a tube about the articles or quantities of material placed upon it
- B65B9/067—Enclosing successive articles, or quantities of material, in a longitudinally-folded web, or in a web folded into a tube about the articles or quantities of material placed upon it the web advancing continuously
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
- B65D81/00—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents
- B65D81/24—Adaptations for preventing deterioration or decay of contents; Applications to the container or packaging material of food preservatives, fungicides, pesticides or animal repellants
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Food Science & Technology (AREA)
- Chemical & Material Sciences (AREA)
- Dispersion Chemistry (AREA)
- Packages (AREA)
- Vacuum Packaging (AREA)
Abstract
A food product package (1) comprising a cut (5) of red meat on a tray (3) and enclosed within an envelope (7) of gas permeable film sealed at its ends (9 and 11) close to the ends of the food product and tray combination (3, 5).
The film envelope (7) is then shrunk into contact with the meat and the tray.
The film envelope (7) is then shrunk into contact with the meat and the tray.
Description
p~ TNG
The present invention relates to a food package, in particular to a pack which is known to allow a food product to be displayed with minimum change in appearance and with 5 resi6tance to bacterial activity during an extended 6helf life in a display cabinet. One example of a product to be packed in this way is a cut of fre~h red meat.
The invention also relates to a method of forming a food package.
10 In the past, fresh red meat has been stored by placing it in a gas permeable inner pack which is then stored within an outer envelope which is filled with a modified gas atmosphere, (i.e. gas-flushed to remove air and to introduce the modified atmosphere of, for example, 2~ N2 or CO2). The 15 outer envelope is of a high gas barrier material 80 that one or more of the inner per~hle packs may be stored in the high barrier outer envelope until di~play is required, and at that stage the outer envelope i~ opened and the or each pack within it is then placed in the di~play cabinet exposed to 20 the atmosphere. Thereafter the permeability of the pack allows the atmosphere within the pack to exch~nge with the environment at a controlled rate during the shelf life of the product. Fresh red meat is known to retain its red colour for over a week when stored in a cool cabinet at temperatures 25 of from 2C to 6C.
One example of a prior art specification disclosing such a double pack is US-A-5226531 (Garwood) in which the modified atmosphere within the pack is disclosed as being of 2~ N2 or CO2, or mixtures thereof. Until opening of the outer 30 container by removal of the outer cover, no extensive migration of gas from within the inner pack under the inner lid is possible, but once the outer cover has been removed ~167036 the gas permeable inner lid is communicated on its exterior to atmosphere and gas exchange can take place at a controlled rate between the interior and exterior of the pack bounded by the inner lid.
5 An alternative system for packaging of red meat using this twin pack concept is one in which cuts of meat, each overwrapped in a respective sheet of PVC film whose overlapping portions are caused to a&ere to one another by the application of low temperature heat on a sealing plate 10 (and which is therefore essentially an air-permeable film pack), are placed in a single outer container in the form of a bag of high gas barrier material filled with modified gas atmosphere which may include 2, N2 or C02, or any mixture thereof.
15 Surprisingly we have now found that, by forming a pack of a material which is less permeable to oxygen than the conventional polyvinyl chloride (PVC) overwrapped pack and filling that pack with a modified atmosphere by gas flushing, the shelf life can be extended by an appreciable period and 20 no 1088 of shelf life is detected when the individual packs are stored in atmosphere rather than within the modified atmosphere of an outer barrier container.
Accordingly, one aspect of the present invention provides a method of packaging food products comprising enveloping the 25 food product in a film which is not a gas-barrier and flushing air from between the food product and the film and replacing it with a modified atmosphere of oxygen-rich 02/C02 mixture.
Preferably the pack is formed by introducing the food product 30 into a tube of the film material and heat-sealing the ends of a cut section of tube enclosing the food product. More preferably the food product is placed on a tray when 21~ s ~6 introduced into the tube of film.
The gas flushing operation may be carried out by a gas fll-Qhing lance exten~;ng into one end of the tube after the other end has already been sealed, to flush the air from 5 within the open-ended tube and to introduce the modified atmosphere after which the second end of the film tube is sealed.
Although it is possible for one or several such packs to be stored within a gas barrier outer container filled with 10 modified atmosphere, it is particularly preferred for the gas permeable film of said pack to be in direct contact with atmospheric air without the need for such an outer barrier film.
A second aspect of the present invention provideæ a food pack 15 comprising a food product enclosed within a sealed envelope of gas-permeable film, the space around the food product and within the envelope having been gas flushed to remove atmospheric air and to introduce a modified atmosphere of an oxygen-rich mixture of oxygen and carbon dioxide.
20 In order that the present invention may more readily be understood, the following description is given, merely by way of example, with reference to the accompanying drawings in which:-Figure 1 is a side elevational view of a pack in accordance 25 with the present invention, after sealing;
Figure 2 i8 a side elevational view of the pack of Figure 1,after a subsequent shr; nk; ng operation to improve the appearance of the pack; and Figure 3 is a side elevational view, in rchematic form, ~1670:~
showing an embodiment of apparatus for forming the pack in accordance with the invention.
Figure 1 shows the pack 1 as comprising a tray 3, (which may be of solid or foamed plastic, such as polypropylene, 5 polyvinyl chloride or polystyrene), supporting a product 5 in the form of a cut of red meat, for example pork having generally pink colour. The combination of tray and pork meat is enclosed within a film envelope 7 in the form of a tube having its lefthand end sealed at 9 and its righthand end 10 sealed at 11.
The ~pace 13 within the film tube 7 and around the pork joint 5 is occupied by a modified atmosphere of an oxygen-rich mixture of oxygen (2) and carbon dioxide (C02). In the preferred case the proportions are 75% by volume 2 and 25% by 15 volume of C02. Preferably the oxygen content may be at least 60%, and it i~ conceivable for it to be higher than 75%, for example 80% is one preferred choice.
As will be evident from Figure 3, the creation of a modified atmosphere conditions within the 6pace 13 is preferably 20 achieved by fir t hermetically sealing one end, of the film tube 7, say at ~eal 9, while leaving the other end (say 6eal 11) open and introducing a hollow gas flushing lance into the pack through the open end. The modified atmo~phere ga~ i~
then discharged from the lance into the interior of the film 25 tube 7 at a location well along the pack toward~ the end seal 9, and the rate of introduction of gas is such that all of the initially pre~ent air i~ expelled and the space is entirely occupied by the modified atmosphere. At this point there is relative separating movement between the tray and 30 the lance, and the hermetic seal 11 is made 80 as to form the closed pack shown in Figure 1.
The pack shown in Figure 1 is subjected to the shrink-tidying ~16703~
operation, preferably by placing it in a shrink tl~nnel in which hot air is blown over the surface of the film. The heat exchange medium for the shrink operation may instead be steam, or equally the shrink-tidying operation may be 5 effected by dipping the pack of Figure 1 into a bath of hot water.
If desired, the pack of Figure 2, or preferably a plurality of such packs, i8 placed into an outer oxygen-impermeable or barrier envelope such as a bag of barrier film, for example 10 that marketed by W.R. Grace & Co.-Conn under the Registered Trade Mark CL ~OV~C Barrier Bag. Again the interior of the bag is subjected to a gas-flushing operation similar to that described with reference to Figures 1 and 2, and the bag is sealed. Such an arrangement allows the bag to be transported 15 from the butchering area to the point of sale, whereupon the outer bag is opened and the individual packs are put on display. While in the bag the various packs 1 will be in a condition in which atmospheric air is excluded because of the barrier function of the bag material, but once they have been 20 removed from the bag the individual packs 1 are subject to a condition in which there is an eYch~nge of atmosphere between the modified atmosphere in the space 13 in the pack and the atmospheric air out~ide the pack. In practice, as a result of the shr;nk; ng operation, the pressure within the pack will 25 be higher than atmospheric so the general migration of gas will be emigration of the modified atmosphere out through the film material 7.
Figure 3 shows an apparatus 20 as comprising an infeed belt conveyor 26 and an outfeed belt conveyor 28 to define a path 30 for the trays 3 and products 5. The packaging film 7 from supply roll 27 passes over a deflector roll 30, and then descends over a forming shoe 32 where the flat film 7 is converted into a tube whose seam is underneath and is sealed by heated film sealing nip rolls 34 rotating about vertical ~6703v axes and p;nch;ng between them the edges of the film web 7 to seal them together by virtue of the action of heat applied conductively by means of the rolls 34. The rolls 34 are positioned to either side of a longit~ n~l slit in a product 5 support plate 29 along which the trays 3 in the tube of film slide.
The thus formed tube then passes leftwardly to a sealing station 36 where a reciprocating upper sealing bar moves between a lowered or advanced sealing position 38a and a 10 raised or retracted position 38b and a vertically reciprocating lower sealing bar moves between an upper or advanced position 40a and a lower or retracted position 40b.
The vertical movements of the upper and lower sealing bars are represented by the arrows 42 and 44, respectively, and 15 the retracted positions are in each case shown in dotted line form.
Flushing gas iB introduced continuously into the tube of film material 7 by way of an infeed pipe 46 and passes into a fl--~h;ng lance 48 which passes through the film forming shoe 20 32 and terminates well to the lefthand side of the film-forming shoe 32 80 as to ensure that the modified atmosphere gas is released close to the location of the sealing station 36 and hence achieves the expulsion of substantially all of the residual air within the tube and around the individual 25 tray/product combinations 3-5 passing along the support plate 29.
In operation, a continuous supply of tray/product combinations 3-5 enters the infeed conveyor 26 and passes leftwardly through the forming shoe 32 around which the film 30 web is passing 80 as to form the tube (by means of the sealing rolls 34) from which any residual gas i8 flushed by the flushing lance 48.
- ~16703~
The movement of the film tube at the point of sealing at the sealing station 36 is permitted by virtue of the fact that the outfeed conveyor belt is mounted on stationary axis rollers 50, 52 and 54 and on horizontally moving rollers 56, 5 58, 60 and 62 whose mo~. -nt is represented by the arrows 64.
The upper and lower sealing bar also move horizontally in synchronism with the rollers 56, 58, 60 and 62. The leftmost position of the rollers 58 and 60 is shown at 58a and 60a in Figure 3.
10 The sealing station 36 thus operates in a manner which allows the film tube to be in continuous leftward movement (by virtue of simultaneous circulation of the upper and lower sealing bars around respective rectangular paths to accommodate the leftward movement at the point of sealing 15 when they are in their advanced positions 38a and 40a respectively and rightward movement when in their retracted positions 38b and 40b respectively).
Sealing of the trailing end of the just finished pack occurs simultaneously with closing the leading end of the tube of 20 sealing film 7.
Comparative tests were carried out on (i) the packs of Figures 1 and 2 and (ii) PVC overwrapped packs (in which a sheet of PVC is wrapped around the product about the longit~; n~l axis of the tray and then caused to seal against 25 itself by pressing the ~6~036 underside of the tray against a low temperature heating plate following which the loose surplus PVC film material at each end of the pack is tucked under and again 6ealed using the low heat ~ealing plate). In these test~ the PVC overwrapped 5 packages formed in air, and hence cont~; n; n9- air between the product and the PVC film, were placed within an outer barrier bag which was gas-flushed with a 75/25% oxygen-rich mixture of 02/C02 and gave a shelf life of 8 to 9 days. Using the same modified atmosphere and the same meat cuts, the pack of 10 Figures 1 and 2 gave a shelf life of a sirloin steak in the pack of the order of 9 days, measured in terms of retention of meat colour. It was also found that well into the shelf life the total viable count (TVC) of bacteria is lower with the pack of Figures 1 and 2 than with the non-flushed 15 overwrapped PVC pack.
For the purposes of this comparison test, the PVC overwrapped packs were kept in cold store conditions in their outer bag for 2 to 4 days and then removed, some on the second day, some on the third day, and some of the fourth day, and placed 20 on display in a refrigerated cabinet at between 2 and 3C.
The packs with the modified atmosphere within the shrunk sealed tube were stored in air in cold store for two days and then put on immediate display. Between 8 and 10 days from the date of packaging the coloration of the beef in the PVC
25 overwrapped packs became such that they were considered no longer saleable. The same change occurred in the packs of Figures 1 and 2 at between 8 and 10 days from packaging without the use of an outer bag containing modified atmosphere.
30 In this test the meat was sirloin ~teak having a thickness of 15 to 20 millimetres as steaks cut from several strip sirloins which had then matured for six days in vacuum bags available from the Cryovac Division of Grace.
- 2i67036 g The gas mixture in the individual packs was 80% 2 and 20%
CO2, by volume, and where (in the case of the PVC overwrapped comparison bags) an outer bag was used, the gas atmosphere in that bag was 65% 2 and 20% CO2 by volume. The trays used for 5 the packs of both types were type 2M foamed polystyrene trays available from Linpac Ltd, and having a depth of 16 millimetres at the rim. The PVC film used for the comparison test was a 15~m thick single layer of film whereas the film for the packs of Figures 1 and 2 were of a 15 to l9~m thick 3 10 ply film whose facing layers (both inside and outside the pack) were of a blend of ethylene vinyl acetate (EVA), linear medium density polyethylene and linear low density polyethylene, and the intervening layer was of linear low density polyethylene with antifogging agents present. Such a 15 film is disclosed in US-A-4551380.
By virtue of an irradiation dosage of 7 Megarads in the case of the film used for the packs of Figures 1 and 2, the film used for the packs of Figures 1 and 2 was capable of withstAn~;ng the levels of heat and pressure of the sealing 20 bars required to seal the ends of the tube 80 as to obtain gas-tight seals by the HFFS (horizontal-foam-fill-seal) process illustrated in Figure 3. In practice the seals occur very close to the ends of the tray 3 in Figure 1, 80 that much less film is used in the case of the packs of Figures 1 25 and 2 than in the case of the comparison overwrapped PVC film packs, and moreover the seal is much more gas-tight and drip-proof in the case of the pack of Figures 1 and 2, where a hot bar seal is formed, than in the case of the comparison PVC
overwrapped packs where the film simply adhere~ to itself by 30 virtue of mild application of heat and only low pressure.
One possible explanation for the improved shelf life of the packs of Figures 1 and 2 may be that the seal is more gastight and consequently the overall gas permeability of the pack is less than in the case of the PVC overwrapped packs.
~16~03~
As a result the CO2 in the modified atmosphere stays in contact with the meat for longer in the early stages of the storing and consequently the bacteriostatic effects are better.
5 In spite of the high gas permeabilities of the film used in the modified atmosphere pack, for some unknown reasons they behave similarly to barrier films. This may be because the gas exchange acroRs the film might be not 80 rapid as expected or there may be an absorption of the modified 10 atmosphere by the packaged food that then releases the absorbed gases more slowly.
The films themselves may have different gas permeabilities in that the film used for the packs of Figures 1 and 2 has an oxygen permeability of up to 15000 cc O2/m2/bar/24hr at 23C
15 and 0% relative humidity (RH), preferably between 6000 and 12000 cc O2/m2/bar/24hr at 23C and 0% RH whereas the PVC film has a permeability of from 14000 to 15000 cc O2/m2/bar/24hr at 23C and 0% RH. These conditions of measurement are set out in ASTM D-3985.
20 The sealing temperature of the sealing bars used on the packs of Figures 1 and 2 is of the order of 200C whereas the temperature of the hot plate against which the overwrapped PVC film is placed for a&esion purposes is of the order of 70C.
25 Although, as indicated above, the modified atmosphere used may be 2, N2, CO2 or any acceptable mixture thereof, in practice the choice of the modified atmosphere depends upon the nature of the meat. For cooked poultry it is desirable to avoid the presence Of 2 but to use a mixture of N2 and CO2, 30 whereas for red meat the presence Of 2 helps to maintain the colour and the presence of CO2 lowers bacterial activity.
The present invention relates to a food package, in particular to a pack which is known to allow a food product to be displayed with minimum change in appearance and with 5 resi6tance to bacterial activity during an extended 6helf life in a display cabinet. One example of a product to be packed in this way is a cut of fre~h red meat.
The invention also relates to a method of forming a food package.
10 In the past, fresh red meat has been stored by placing it in a gas permeable inner pack which is then stored within an outer envelope which is filled with a modified gas atmosphere, (i.e. gas-flushed to remove air and to introduce the modified atmosphere of, for example, 2~ N2 or CO2). The 15 outer envelope is of a high gas barrier material 80 that one or more of the inner per~hle packs may be stored in the high barrier outer envelope until di~play is required, and at that stage the outer envelope i~ opened and the or each pack within it is then placed in the di~play cabinet exposed to 20 the atmosphere. Thereafter the permeability of the pack allows the atmosphere within the pack to exch~nge with the environment at a controlled rate during the shelf life of the product. Fresh red meat is known to retain its red colour for over a week when stored in a cool cabinet at temperatures 25 of from 2C to 6C.
One example of a prior art specification disclosing such a double pack is US-A-5226531 (Garwood) in which the modified atmosphere within the pack is disclosed as being of 2~ N2 or CO2, or mixtures thereof. Until opening of the outer 30 container by removal of the outer cover, no extensive migration of gas from within the inner pack under the inner lid is possible, but once the outer cover has been removed ~167036 the gas permeable inner lid is communicated on its exterior to atmosphere and gas exchange can take place at a controlled rate between the interior and exterior of the pack bounded by the inner lid.
5 An alternative system for packaging of red meat using this twin pack concept is one in which cuts of meat, each overwrapped in a respective sheet of PVC film whose overlapping portions are caused to a&ere to one another by the application of low temperature heat on a sealing plate 10 (and which is therefore essentially an air-permeable film pack), are placed in a single outer container in the form of a bag of high gas barrier material filled with modified gas atmosphere which may include 2, N2 or C02, or any mixture thereof.
15 Surprisingly we have now found that, by forming a pack of a material which is less permeable to oxygen than the conventional polyvinyl chloride (PVC) overwrapped pack and filling that pack with a modified atmosphere by gas flushing, the shelf life can be extended by an appreciable period and 20 no 1088 of shelf life is detected when the individual packs are stored in atmosphere rather than within the modified atmosphere of an outer barrier container.
Accordingly, one aspect of the present invention provides a method of packaging food products comprising enveloping the 25 food product in a film which is not a gas-barrier and flushing air from between the food product and the film and replacing it with a modified atmosphere of oxygen-rich 02/C02 mixture.
Preferably the pack is formed by introducing the food product 30 into a tube of the film material and heat-sealing the ends of a cut section of tube enclosing the food product. More preferably the food product is placed on a tray when 21~ s ~6 introduced into the tube of film.
The gas flushing operation may be carried out by a gas fll-Qhing lance exten~;ng into one end of the tube after the other end has already been sealed, to flush the air from 5 within the open-ended tube and to introduce the modified atmosphere after which the second end of the film tube is sealed.
Although it is possible for one or several such packs to be stored within a gas barrier outer container filled with 10 modified atmosphere, it is particularly preferred for the gas permeable film of said pack to be in direct contact with atmospheric air without the need for such an outer barrier film.
A second aspect of the present invention provideæ a food pack 15 comprising a food product enclosed within a sealed envelope of gas-permeable film, the space around the food product and within the envelope having been gas flushed to remove atmospheric air and to introduce a modified atmosphere of an oxygen-rich mixture of oxygen and carbon dioxide.
20 In order that the present invention may more readily be understood, the following description is given, merely by way of example, with reference to the accompanying drawings in which:-Figure 1 is a side elevational view of a pack in accordance 25 with the present invention, after sealing;
Figure 2 i8 a side elevational view of the pack of Figure 1,after a subsequent shr; nk; ng operation to improve the appearance of the pack; and Figure 3 is a side elevational view, in rchematic form, ~1670:~
showing an embodiment of apparatus for forming the pack in accordance with the invention.
Figure 1 shows the pack 1 as comprising a tray 3, (which may be of solid or foamed plastic, such as polypropylene, 5 polyvinyl chloride or polystyrene), supporting a product 5 in the form of a cut of red meat, for example pork having generally pink colour. The combination of tray and pork meat is enclosed within a film envelope 7 in the form of a tube having its lefthand end sealed at 9 and its righthand end 10 sealed at 11.
The ~pace 13 within the film tube 7 and around the pork joint 5 is occupied by a modified atmosphere of an oxygen-rich mixture of oxygen (2) and carbon dioxide (C02). In the preferred case the proportions are 75% by volume 2 and 25% by 15 volume of C02. Preferably the oxygen content may be at least 60%, and it i~ conceivable for it to be higher than 75%, for example 80% is one preferred choice.
As will be evident from Figure 3, the creation of a modified atmosphere conditions within the 6pace 13 is preferably 20 achieved by fir t hermetically sealing one end, of the film tube 7, say at ~eal 9, while leaving the other end (say 6eal 11) open and introducing a hollow gas flushing lance into the pack through the open end. The modified atmo~phere ga~ i~
then discharged from the lance into the interior of the film 25 tube 7 at a location well along the pack toward~ the end seal 9, and the rate of introduction of gas is such that all of the initially pre~ent air i~ expelled and the space is entirely occupied by the modified atmosphere. At this point there is relative separating movement between the tray and 30 the lance, and the hermetic seal 11 is made 80 as to form the closed pack shown in Figure 1.
The pack shown in Figure 1 is subjected to the shrink-tidying ~16703~
operation, preferably by placing it in a shrink tl~nnel in which hot air is blown over the surface of the film. The heat exchange medium for the shrink operation may instead be steam, or equally the shrink-tidying operation may be 5 effected by dipping the pack of Figure 1 into a bath of hot water.
If desired, the pack of Figure 2, or preferably a plurality of such packs, i8 placed into an outer oxygen-impermeable or barrier envelope such as a bag of barrier film, for example 10 that marketed by W.R. Grace & Co.-Conn under the Registered Trade Mark CL ~OV~C Barrier Bag. Again the interior of the bag is subjected to a gas-flushing operation similar to that described with reference to Figures 1 and 2, and the bag is sealed. Such an arrangement allows the bag to be transported 15 from the butchering area to the point of sale, whereupon the outer bag is opened and the individual packs are put on display. While in the bag the various packs 1 will be in a condition in which atmospheric air is excluded because of the barrier function of the bag material, but once they have been 20 removed from the bag the individual packs 1 are subject to a condition in which there is an eYch~nge of atmosphere between the modified atmosphere in the space 13 in the pack and the atmospheric air out~ide the pack. In practice, as a result of the shr;nk; ng operation, the pressure within the pack will 25 be higher than atmospheric so the general migration of gas will be emigration of the modified atmosphere out through the film material 7.
Figure 3 shows an apparatus 20 as comprising an infeed belt conveyor 26 and an outfeed belt conveyor 28 to define a path 30 for the trays 3 and products 5. The packaging film 7 from supply roll 27 passes over a deflector roll 30, and then descends over a forming shoe 32 where the flat film 7 is converted into a tube whose seam is underneath and is sealed by heated film sealing nip rolls 34 rotating about vertical ~6703v axes and p;nch;ng between them the edges of the film web 7 to seal them together by virtue of the action of heat applied conductively by means of the rolls 34. The rolls 34 are positioned to either side of a longit~ n~l slit in a product 5 support plate 29 along which the trays 3 in the tube of film slide.
The thus formed tube then passes leftwardly to a sealing station 36 where a reciprocating upper sealing bar moves between a lowered or advanced sealing position 38a and a 10 raised or retracted position 38b and a vertically reciprocating lower sealing bar moves between an upper or advanced position 40a and a lower or retracted position 40b.
The vertical movements of the upper and lower sealing bars are represented by the arrows 42 and 44, respectively, and 15 the retracted positions are in each case shown in dotted line form.
Flushing gas iB introduced continuously into the tube of film material 7 by way of an infeed pipe 46 and passes into a fl--~h;ng lance 48 which passes through the film forming shoe 20 32 and terminates well to the lefthand side of the film-forming shoe 32 80 as to ensure that the modified atmosphere gas is released close to the location of the sealing station 36 and hence achieves the expulsion of substantially all of the residual air within the tube and around the individual 25 tray/product combinations 3-5 passing along the support plate 29.
In operation, a continuous supply of tray/product combinations 3-5 enters the infeed conveyor 26 and passes leftwardly through the forming shoe 32 around which the film 30 web is passing 80 as to form the tube (by means of the sealing rolls 34) from which any residual gas i8 flushed by the flushing lance 48.
- ~16703~
The movement of the film tube at the point of sealing at the sealing station 36 is permitted by virtue of the fact that the outfeed conveyor belt is mounted on stationary axis rollers 50, 52 and 54 and on horizontally moving rollers 56, 5 58, 60 and 62 whose mo~. -nt is represented by the arrows 64.
The upper and lower sealing bar also move horizontally in synchronism with the rollers 56, 58, 60 and 62. The leftmost position of the rollers 58 and 60 is shown at 58a and 60a in Figure 3.
10 The sealing station 36 thus operates in a manner which allows the film tube to be in continuous leftward movement (by virtue of simultaneous circulation of the upper and lower sealing bars around respective rectangular paths to accommodate the leftward movement at the point of sealing 15 when they are in their advanced positions 38a and 40a respectively and rightward movement when in their retracted positions 38b and 40b respectively).
Sealing of the trailing end of the just finished pack occurs simultaneously with closing the leading end of the tube of 20 sealing film 7.
Comparative tests were carried out on (i) the packs of Figures 1 and 2 and (ii) PVC overwrapped packs (in which a sheet of PVC is wrapped around the product about the longit~; n~l axis of the tray and then caused to seal against 25 itself by pressing the ~6~036 underside of the tray against a low temperature heating plate following which the loose surplus PVC film material at each end of the pack is tucked under and again 6ealed using the low heat ~ealing plate). In these test~ the PVC overwrapped 5 packages formed in air, and hence cont~; n; n9- air between the product and the PVC film, were placed within an outer barrier bag which was gas-flushed with a 75/25% oxygen-rich mixture of 02/C02 and gave a shelf life of 8 to 9 days. Using the same modified atmosphere and the same meat cuts, the pack of 10 Figures 1 and 2 gave a shelf life of a sirloin steak in the pack of the order of 9 days, measured in terms of retention of meat colour. It was also found that well into the shelf life the total viable count (TVC) of bacteria is lower with the pack of Figures 1 and 2 than with the non-flushed 15 overwrapped PVC pack.
For the purposes of this comparison test, the PVC overwrapped packs were kept in cold store conditions in their outer bag for 2 to 4 days and then removed, some on the second day, some on the third day, and some of the fourth day, and placed 20 on display in a refrigerated cabinet at between 2 and 3C.
The packs with the modified atmosphere within the shrunk sealed tube were stored in air in cold store for two days and then put on immediate display. Between 8 and 10 days from the date of packaging the coloration of the beef in the PVC
25 overwrapped packs became such that they were considered no longer saleable. The same change occurred in the packs of Figures 1 and 2 at between 8 and 10 days from packaging without the use of an outer bag containing modified atmosphere.
30 In this test the meat was sirloin ~teak having a thickness of 15 to 20 millimetres as steaks cut from several strip sirloins which had then matured for six days in vacuum bags available from the Cryovac Division of Grace.
- 2i67036 g The gas mixture in the individual packs was 80% 2 and 20%
CO2, by volume, and where (in the case of the PVC overwrapped comparison bags) an outer bag was used, the gas atmosphere in that bag was 65% 2 and 20% CO2 by volume. The trays used for 5 the packs of both types were type 2M foamed polystyrene trays available from Linpac Ltd, and having a depth of 16 millimetres at the rim. The PVC film used for the comparison test was a 15~m thick single layer of film whereas the film for the packs of Figures 1 and 2 were of a 15 to l9~m thick 3 10 ply film whose facing layers (both inside and outside the pack) were of a blend of ethylene vinyl acetate (EVA), linear medium density polyethylene and linear low density polyethylene, and the intervening layer was of linear low density polyethylene with antifogging agents present. Such a 15 film is disclosed in US-A-4551380.
By virtue of an irradiation dosage of 7 Megarads in the case of the film used for the packs of Figures 1 and 2, the film used for the packs of Figures 1 and 2 was capable of withstAn~;ng the levels of heat and pressure of the sealing 20 bars required to seal the ends of the tube 80 as to obtain gas-tight seals by the HFFS (horizontal-foam-fill-seal) process illustrated in Figure 3. In practice the seals occur very close to the ends of the tray 3 in Figure 1, 80 that much less film is used in the case of the packs of Figures 1 25 and 2 than in the case of the comparison overwrapped PVC film packs, and moreover the seal is much more gas-tight and drip-proof in the case of the pack of Figures 1 and 2, where a hot bar seal is formed, than in the case of the comparison PVC
overwrapped packs where the film simply adhere~ to itself by 30 virtue of mild application of heat and only low pressure.
One possible explanation for the improved shelf life of the packs of Figures 1 and 2 may be that the seal is more gastight and consequently the overall gas permeability of the pack is less than in the case of the PVC overwrapped packs.
~16~03~
As a result the CO2 in the modified atmosphere stays in contact with the meat for longer in the early stages of the storing and consequently the bacteriostatic effects are better.
5 In spite of the high gas permeabilities of the film used in the modified atmosphere pack, for some unknown reasons they behave similarly to barrier films. This may be because the gas exchange acroRs the film might be not 80 rapid as expected or there may be an absorption of the modified 10 atmosphere by the packaged food that then releases the absorbed gases more slowly.
The films themselves may have different gas permeabilities in that the film used for the packs of Figures 1 and 2 has an oxygen permeability of up to 15000 cc O2/m2/bar/24hr at 23C
15 and 0% relative humidity (RH), preferably between 6000 and 12000 cc O2/m2/bar/24hr at 23C and 0% RH whereas the PVC film has a permeability of from 14000 to 15000 cc O2/m2/bar/24hr at 23C and 0% RH. These conditions of measurement are set out in ASTM D-3985.
20 The sealing temperature of the sealing bars used on the packs of Figures 1 and 2 is of the order of 200C whereas the temperature of the hot plate against which the overwrapped PVC film is placed for a&esion purposes is of the order of 70C.
25 Although, as indicated above, the modified atmosphere used may be 2, N2, CO2 or any acceptable mixture thereof, in practice the choice of the modified atmosphere depends upon the nature of the meat. For cooked poultry it is desirable to avoid the presence Of 2 but to use a mixture of N2 and CO2, 30 whereas for red meat the presence Of 2 helps to maintain the colour and the presence of CO2 lowers bacterial activity.
Claims (18)
1. A method of packaging food products comprising enveloping the food product in a film which is not a gas-barrier and flushing air from between the food product and the film and replacing it with a modified atmosphere of oxygen-rich O2/CO2 mixture.
2. A method according to claim 1, wherein the exterior of said pack is in direct contact with atmosphere.
3. A method according to either of the preceding claims, wherein the food product is standing on a tray within the envelope.
4. A method according to any one of the preceding claims, wherein the envelope is formed as a tube which is just large enough in cross-section to receive the food product, and the length is just in excess of the inserted goods; and wherein the ends of the tube are heat-sealed by welding bars.
5. A method according to any one of the preceding claims, wherein the film used for the envelope has an oxygen permeability of up to 15000 cc O2/m2/bar/24hr at 23°C and 0%
relative humidity.
relative humidity.
6. A method according to claim 5, wherein the oxygen permeability is from 6000 to 12000 cc O2/m2/bar/24hr at 23°C
and 0% relative humidity.
and 0% relative humidity.
7. A method according to any one of the preceding claims, wherein the percentage of oxygen present in the modified atmosphere is at least 60% by volume.
8. A method according to claim 7, wherein the oxygen content is over 70% by volume, preferably 80% by volume.
9. A method according to any one of the preceding claims, wherein the food product is a cut of red meat.
10. A method according to any one of claims 1 to 9, including the step of heat shrinking the envelope into contact with the food product.
11. A method of packaging a food product, substantially as hereinbefore described, with reference to and as illustrated in the accompanying drawings.
12. A food pack comprising a food product enclosed within a sealed envelope of oxygen-permeable film, the space around the food product and within the envelope being occupied by a modified atmosphere of an oxygen-rich mixture of O2/CO2.
13. A pack according to claim 12, wherein the food product is standing on a tray enclosed in the envelope.
14. A pack according to either of claims 13 and 14, wherein the oxygen permeability of the envelope is up to 15000 cc O2/m2/bar/24hr measured at 23°C and 0% relative humidity.
15. A pack according to claim 14, wherein the oxygen permeability is from 6000 to 12000 cc O2/m2/bar/24hr at 23°C
and 0% relative humidity.
and 0% relative humidity.
16. A pack according to any one of claims 12 to 15, wherein the envelope is of tubular form with the ends of the tubular portion heat sealed by welding bar seals close to the ends of the food product.
17. A pack according to claim 16, wherein the envelope has been heat shrunk after sealing.
18. A pack substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9500566A GB2296905A (en) | 1995-01-12 | 1995-01-12 | Package with modified atmosphere |
| GB9500566.6 | 1995-01-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2167036A1 true CA2167036A1 (en) | 1996-07-13 |
Family
ID=10767920
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002167036A Abandoned CA2167036A1 (en) | 1995-01-12 | 1996-01-11 | Breathing gas flushed pack |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP0721887A1 (en) |
| JP (1) | JPH08244723A (en) |
| AU (1) | AU4096296A (en) |
| CA (1) | CA2167036A1 (en) |
| GB (1) | GB2296905A (en) |
| NZ (1) | NZ280820A (en) |
| ZA (1) | ZA96180B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH11255270A (en) * | 1998-03-10 | 1999-09-21 | Okura Ind Co Ltd | Method for sealed-stretch-shrink-packaging for fresh meat with filled gas |
| US7776416B2 (en) * | 2001-08-20 | 2010-08-17 | Cryovac, Inc. | Case-ready package having absorbent pad |
| NL1019367C2 (en) * | 2001-11-14 | 2003-01-17 | Langeveld & Sleegers B V Fa | Packaging assembly as well as method and device for manufacturing such a packaging assembly. |
| ITRM20040319A1 (en) | 2004-06-30 | 2004-09-30 | Micromec S R L Unipersonale | APPARATUS AND METHOD OF PACKAGING IN FILM. |
| FR2929595B1 (en) * | 2008-04-04 | 2010-07-30 | Doux Frais | PROCESS FOR PACKAGING POULTRY |
| US9955703B2 (en) | 2013-11-25 | 2018-05-01 | Jbs Usa, Llc | Method and system for processing meat products in a modified atmosphere |
| FR3075763B1 (en) * | 2017-12-22 | 2019-12-20 | C.E.R.M.E.X. Constructions Etudes Et Recherches De Materiels Pour L'emballage D'expedition | WELDING DEVICE AND METHOD FOR WELDING HEAT-SHRINKABLE FILMS COATING LOTS OF OBJECTS IN A SHRINKING MACHINE |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1692190A1 (en) * | 1967-11-14 | 1971-07-08 | Kalle Ag | Method of making a durable portion pack of fresh meat |
| GB1199998A (en) * | 1968-04-03 | 1970-07-22 | Unilever Ltd | Food Package |
| FR2290153A1 (en) * | 1974-11-08 | 1976-06-04 | Soplaril Sa | Film and dish food pack with an oxygenated atmosphere - for conserving chilled meat without discolouration or taint |
| US3958390A (en) * | 1975-01-02 | 1976-05-25 | Hayssen Manufacturing Co. | Packaging |
| US4642239A (en) * | 1984-01-09 | 1987-02-10 | Transparent Paper Plc | Packaging of fresh meat |
| GB8606223D0 (en) * | 1986-03-13 | 1986-04-16 | Ives D C A | Food packaging |
| JPH02501918A (en) * | 1987-10-29 | 1990-06-28 | ガーウッド・リミテッド | improved packaging |
-
1995
- 1995-01-12 GB GB9500566A patent/GB2296905A/en not_active Withdrawn
-
1996
- 1996-01-10 ZA ZA96180A patent/ZA96180B/en unknown
- 1996-01-11 CA CA002167036A patent/CA2167036A1/en not_active Abandoned
- 1996-01-11 EP EP96300228A patent/EP0721887A1/en not_active Withdrawn
- 1996-01-12 JP JP8004352A patent/JPH08244723A/en active Pending
- 1996-01-12 AU AU40962/96A patent/AU4096296A/en not_active Abandoned
- 1996-01-12 NZ NZ280820A patent/NZ280820A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| JPH08244723A (en) | 1996-09-24 |
| GB2296905A (en) | 1996-07-17 |
| AU4096296A (en) | 1996-07-18 |
| EP0721887A1 (en) | 1996-07-17 |
| ZA96180B (en) | 1996-08-22 |
| GB9500566D0 (en) | 1995-03-01 |
| NZ280820A (en) | 1998-04-27 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued | ||
| FZDE | Discontinued |
Effective date: 20000111 |