WO1992021588A1 - Emballage a atmosphere modifiee - Google Patents

Emballage a atmosphere modifiee Download PDF

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Publication number
WO1992021588A1
WO1992021588A1 PCT/AU1992/000267 AU9200267W WO9221588A1 WO 1992021588 A1 WO1992021588 A1 WO 1992021588A1 AU 9200267 W AU9200267 W AU 9200267W WO 9221588 A1 WO9221588 A1 WO 9221588A1
Authority
WO
WIPO (PCT)
Prior art keywords
holes
hole
substance
packaging material
predetermined temperature
Prior art date
Application number
PCT/AU1992/000267
Other languages
English (en)
Inventor
Brian David Patterson
Arthur Cameron
Original Assignee
Commonwealth Scientific And Industrial Research Organisation
Michigan State University
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Commonwealth Scientific And Industrial Research Organisation, Michigan State University filed Critical Commonwealth Scientific And Industrial Research Organisation
Publication of WO1992021588A1 publication Critical patent/WO1992021588A1/fr

Links

Classifications

    • 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
    • B65D81/18—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 providing specific environment for contents, e.g. temperature above or below ambient
    • B65D81/20—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 providing specific environment for contents, e.g. temperature above or below ambient under vacuum or superatmospheric pressure, or in a special atmosphere, e.g. of inert gas
    • B65D81/2069—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 providing specific environment for contents, e.g. temperature above or below ambient under vacuum or superatmospheric pressure, or in a special atmosphere, e.g. of inert gas in a special atmosphere
    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
    • A23L3/00—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs
    • A23L3/34—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals
    • A23L3/3409—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals in the form of gases, e.g. fumigation; Compositions or apparatus therefor
    • A23L3/3418—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals in the form of gases, e.g. fumigation; Compositions or apparatus therefor in a controlled atmosphere, e.g. partial vacuum, comprising only CO2, N2, O2 or H2O
    • A23L3/3427—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals in the form of gases, e.g. fumigation; Compositions or apparatus therefor in a controlled atmosphere, e.g. partial vacuum, comprising only CO2, N2, O2 or H2O in which an absorbent is placed or used
    • 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
    • B65D2565/00—Wrappers or flexible covers; Packaging materials of special type or form
    • B65D2565/38—Packaging materials of special type or form
    • B65D2565/381—Details of packaging materials of special type or form
    • B65D2565/388—Materials used for their gas-permeability

Definitions

  • the present invention relates to a packaging material and to a method of packaging produce.
  • the packaging of the present invention can provide a modified atmosphere surrounding packaged produce.
  • oxygen is depleted by the respiration of the produce and carbon dioxide increased over atmospheric levels. In this way, the atmosphere within the sealed package is modified. Modified atmospheres of this kind are useful in retarding the aging of produce. Low but sustained levels of oxygen in particular are effective in keeping produce fresh.
  • the rate at which oxygen permeates through the walls of the package is arranged to balance the consumption of oxygen by the produce.
  • the internal concentration of oxygen is arranged between 1% and 5%.
  • the respiration rate of produce such as fruit, flowers and vegetables is greatly changed by an increase in temperature.
  • existing designs for modified atmosphere packaging work properly only if the temperature is kept within a small range.
  • the package must have permeability to oxygen that balances the rate of oxygen consumption by the product at 0°C and at 2% oxygen. If the temperature of the package is now increased, the respiration rate of the produce will rise.
  • the increase in respiration will be greater than any increase in the permeability of the polymer used to make the package.
  • oxygen will be removed more quickly than it can be replaced by permeating through the walls of the package. This will cause the oxygen level to decrease below the desired level of 2%.
  • Fruit and vegetable produce maintain their normal metabolism as long as oxygen levels do not fall below a critical value, which can be from 1 to 5% oxygen, dependent on the particular commodity and the temperature. Below this critical value, there is a change to "anaerobic" metabolism, during which substances such as ethanol accumulate in the commodity. This kind of metabolism is harmful and eventually damages the commodity irreversibly. At the same time, harmful microorganisms may be encouraged by the anaerobic conditions. These have the potential to make the commodity unfit or even dangerous for consumption.
  • the present inventors have developed a novel packaging material and method of packaging which prevents the harmful effects of increased temperature on modified atmosphere packaging.
  • the present invention consists in a packaging material provided with a hole or holes, the hole or holes being blocked at a first predetermined temperature by a substance which is solid at the first predetermined temperature and the hole or holes being open at a second predetermined temperature, the substance being liquid at the second predetermined temperature, and an absorbent material being provided in association with the packaging material in a manner such that it draws the substance from the hole or holes as the substance melts.
  • the present invention consists in a method of packaging produce comprising completely enclosing the produce in a packaging material, the packaging material being provided with a hole or holes, the hole or holes being blocked at a first predetermined temperature by a substance which is solid at the first predetermined temperature and the hole or holes being open at a second predetermined temperature the substance being liquid at the second predetermined temperature, an absorbent material being provided in association with the packaging material in a manner such that it draws the substance from the hole or holes as the substance melts.
  • the term "produce” is used to mean fruit, vegetables , flowers, plants and other living organisms which respond to low oxygen partial pressure and/or high carbon dioxide partial pressure with increased life or decreased wastage.
  • the hole or holes is/are a pore or a plurality of pores.
  • pores are holes having a maximum cross-sectional dimension of 0.1mm. Normally pores will be microscopic and present in large numbers. In contrast holes will be typically 1mm or more in major cross-sectional dimension and be present in small numbers.
  • respiring produce is hermetically sealed within a barrier to the diffusion of oxygen and carbon dioxide.
  • This barrier may be in the form of a polymer container, for instance, a plastic bag, or in some other container such as one made of metal or ceramic material. Various combinations of these materials may be used.
  • part of the container is provided with a hole or a number of holes.
  • a window of porous material including a number of pores is provided in the package. The purpose of the holes or pores is to provide channels for gas exchange across the walls of the package. Gas exchange may be provided through polymer materials that make up the walls of the package.
  • Some or all of the holes or pores are blocked by a small volume of a substance that is solid at the temperature of storage, the first predetermined temperature.
  • the substance that blocks the pore or pores is selected from a number of compounds, or mixture of compounds, that liquify if the temperature of the package rises above some predetermined level.
  • the liquification may be caused by fusion at the melting point or by the melting of a gel.
  • different holes or pores may be blocked by different substances having different melting points. In this manner when the temperature reaches a first temperature some of the holes or pores will become unblocked. As the temperature rises further more holes or pores will become unblocked.
  • the size of a hole, or the sizes and number of a plurality of holes may be chosen such that the permeability of a package to oxygen upon opening of the hole or holes at the second predetermined temperature or at a number of elevated temperatures, is matched to the consumption of oxygen by produce within the package at that temperature, or those temperatures. Examples of suitable compounds that fuse at a melting point include hydrocarbons, waxes and esters that melt at some desired temperature.
  • Typical compounds of this type are paraffins, for instance, n-pentadecane (melting point 9.5°C) and n-hexadecane (melting point 18°C) and esters such as glyceryl triacetate (melting point 4.1 C) and glyceryl trilaurate (melting point 46 C) .
  • Hydrocarbons of greater chain length give correspondingly higher melting temperatures, while intermediate melting temperatures can be obtained with mixtures of compounds.
  • Natural mixtures of glyceryl esters such as coconut oil or palm oil can also be used. These can be fractionated to give particular mixtures with desired melting points.
  • the substance which is solid at the first predetermined temperature and liquid at the second predetermined temperature can be readily selected from a well known range of compounds or mixtures thereof.
  • the compound or mixture of compounds is drawn away from the pore or pores by the absorbent material so that gas exchange can take place freely. This is accomplished by the surface surrounding the holes or pores having a physical attraction for the liquified material blocking the pore.
  • a fibrous or porous material that has a strong affinity for the liquified material can be used as a wick to draw the liquid out. Suitable materials to do this include non-woven (felted) cloths and woven textiles and porous plastics.
  • non-woven cloths made by Dupont from polyethylene under the trade name “Tyvec”, and by Kimberley Clark from polypropylene fibres under the trade mark “EVOLUTION”. These materials are hydrophobic and suitable when hydrophobic liquids such as paraffins are used as the substance blocking the holes or pores. Hydrophilic wicks are suitable when water needs to be removed, as when polysaccharide or protein gels are used as the blocking substance.
  • the absorbent material can also act as the barrier so that the two functions can be combined. For instance, microporous "windows" of a particular area that allows just sufficient gas exchange at some temperatures are made by Fresh
  • the pores may be filled with the substance in a number of ways.
  • the substance in liquid form is applied to the packaging material including pores but without the absorbent material.
  • the substance fills the pores and is held therein by surface tension.
  • the temperature is then lowered causing the substance to solidify within the pores and the absorbent material is then included.
  • the hole or holes are blocked by the substance in a manner such that transient temperature increases do not result in the hole or holes being unblocked - only sustained temperature increases resulting in the holes or holes being unblocked. This may be achieved, for example, by increasing the viscosity of the substance such that it is only slowly withdrawn from the hole or holes by the absorbent material.
  • Figure 1 is a diagrammatic representation of a piece of packaging material according to this invention.
  • Figure 2 is a graph showing a plot of gas permeability at various temperatures of the material of Figure 1 when the pores are filled with n-pentane
  • Figure 3 is a graph showing a plot of gas permeability at various temperatures of the material of Figure 1 when the pores are filled with n-hexadecane
  • Figure 4 is a graph showing a plot of gas permeability at various temperatures of the material of Figure 1 when the pores are filled with a 50% solution of Palmolein in hexadecane;
  • Figure 5 is a diagrammatic representation of another packaging material according to the present invention
  • Figure 6 is a graph showing the oxygen content of the atmosphere surrounding blueberries packaged according to this invention as compared with those packaged in conventional packaging at 0°C and 20°C.
  • Figure 1 shows one way in which the present invention can be made to increase the oxygen permeability of polyethylene film of the type often used for modified atmosphere storage of horticultural produce.
  • a sheet 10 of polyethylene packaging film 100 micrometers thick (the barrier) was joined in supposition to a disk 11 of a non-woven fabric with a diameter of 3.2cm made from polyethylene fibres (the wick) with two heat seals 12 at right angles to each other, as shown in Figure 1.
  • the non-woven fabric used in this case was "Tyvec", made by Dupont.
  • a hole 13 for gas exchange was made with a 23-gauge hypodermic needle.
  • the holes were located in this position because this ensured close contact with the wick.
  • the film was then cooled to 0°C and each of the holes filled with about 2 microlitres of various compounds that freeze at particular temperatures, thereby blocking the holes. Gas exchange through the holes was therefore impeded as long as the temperature remained below the melting point of the compound. This was verified by microscopic examination which showed that as soon as the compound melted, the liquid was drawn out of the holes into the wick. In this way the hole was open so the gas exchange could occur freely through the hole.
  • Figure 2 shows the results of measuring the permeability of a disc of polyethylene film including a wick and holes made in the way described above. After cooling the polymer disc to 0 C, the holes were filled with two microlitres of the hydrocarbon n-pentadecane (melting point 9.5 C) . The polymer disc was then mounted in a permeability cell so that the passage of oxygen from the air through it to a container filled with nitrogen could be measured. While the measurements were being taken the temperature of the polymer film was gradually increased from 0 to 14 C. The permeability of the disc to oxygen was calculated from the rate of oxygen transfer at each temperature, so giving the values plotted against temperature in Figure 2.
  • Figure 3 shows the results of a similar test which shows the temperature at which permeability increases can be varied simply by choosing a compound with a suitably different melting point.
  • the holes in the polymer disk were filled with the hydrocarbon n-hexadecane (melting point 18 C) .
  • Figure 3 shows that permeability of the disk remained low until the temperature reached about 18.5°C. Between 18.5 and 19.5°C the permeability to oxygen increased and then stabilised at a relatively high level.
  • FIG. 4 shows the results of a similar test which shows that mixtures of compounds are useful where pure compounds of some particular melting point are not available.
  • the holes were filled with a mixture of 50% (w/w) Palmolein in n-hexadecane.
  • Palmolein is a mixture of triglycerides derived from palm oil which melts at about 12°C.
  • the permeability to oxygen increased to between 15 and 16 C, that is, at a temperature intermediate between the two constituents.
  • Figure 5 shows the invention constructed as an adhesive patch which can be applied to modified atmosphere packages.
  • a roll of adhesive electrical insulating tape was cooled in liquid nitrogen and a hole drilled of diameter 0.1 cm through the roll.
  • Discs 20 of tape of diameter 2 cm were then cut around each hole 21 from the roll.
  • a disc 22 with a diameter of 1 cm of non-woven polyethylene cloth was then stuck to the centre of the adhesive side of the insulating tape.
  • a hole was pierced in the non-woven cloth 23 with a hypodermic needle to correspond with the hole 21 in the adhesive tape 20.
  • Figure 6 shows the result of using the adhesive disc shown in Figure 5 in the modified atmosphere storage of blueberries, the freshness of which can be preserved under atmosphere of reduced oxygen at 0°C.
  • Blueberries were weighed (200 g) into plastic punnets and cooled overnight to 0°C. Each punnet was then hermetically sealed within a bag made of polyvinyl chloride film. The thickness of the film was 30 micrometers and the dimensions of the bag were 18 cm x 18 cm. Each bag had a circular hole punched in it of diameter 0.5 cm, and this hole was covered with the adhesive square of tape with the non-woven cloth wick.
  • the hole in the adhesive square was then filled with two microlitres of the hydrocarbon n-pentadecane (melting point 9.5°C), which immediately solidified and blocked the hole. Bags to which such adhesive squares were attached are hereinafter referred to as "Tempak” bags. Control bags were also prepared in which the hole was blocked with a polymerising resin (Silastic RTV 3110, made by Dow Corning) that does not melt within the range of temperature investigated. Each bag was provided with a button of modified silicone resin (silicone self-curing glass sealant, made by Dow Corning) . This formed a self-sealing port through which gasses could be sampled using a hypodermic syringe.
  • a polymerising resin Silicon RTV 3110, made by Dow Corning

Abstract

Un matériau d'emballage (20), devant être utilisé pour maintenir une atmosphère régulée autour d'un produit emballé, comprend un ou plusieurs trou(s) (21) obturé(s) par une substance telle qu'un hydrocarbure, laquelle est solide à basse température et liquide à une température plus élevée. Le matériau d'emballage est utilisé avec un matériau absorbant (22) agencé pour extraire la substance liquéfiée du ou des trou(s) (21) aux températures plus élevées afin de libérer le trou et de rendre le matériau d'emballage perméable aux gaz à des températures élevées. En permettant à l'air de pénétrer dans l'emballage aux températures plus élevées, le matériau d'emballage (20) réduit les risques de dégradation anaérobie du produit à l'intérieur de l'emballage à ces températures.
PCT/AU1992/000267 1991-06-06 1992-06-05 Emballage a atmosphere modifiee WO1992021588A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AUPK6567 1991-06-06
AUPK656791 1991-06-06

Publications (1)

Publication Number Publication Date
WO1992021588A1 true WO1992021588A1 (fr) 1992-12-10

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PCT/AU1992/000267 WO1992021588A1 (fr) 1991-06-06 1992-06-05 Emballage a atmosphere modifiee

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6210724B1 (en) 1999-08-23 2001-04-03 Landec Corporation Temperature-responsive containers

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH615641A5 (en) * 1976-06-04 1980-02-15 Hag Ag Overpressure valve for packaging containers
AU5366579A (en) * 1978-12-18 1980-06-26 Safta S.p.A. + Bieffe S.p.A. Valved flexible container
DE3634791A1 (de) * 1985-10-18 1987-04-23 Bs & B Safety Systems Inc Verfahren zur freigabe eines unter druck stehenden stroemungsmediums und temperaturabhaengig ansprechende druckentlastungseinrichtung hierfuer
GB2200618A (en) * 1987-02-19 1988-08-10 Michael Greengrass Controlled ripening of produce and fruits

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH615641A5 (en) * 1976-06-04 1980-02-15 Hag Ag Overpressure valve for packaging containers
AU5366579A (en) * 1978-12-18 1980-06-26 Safta S.p.A. + Bieffe S.p.A. Valved flexible container
DE3634791A1 (de) * 1985-10-18 1987-04-23 Bs & B Safety Systems Inc Verfahren zur freigabe eines unter druck stehenden stroemungsmediums und temperaturabhaengig ansprechende druckentlastungseinrichtung hierfuer
GB2200618A (en) * 1987-02-19 1988-08-10 Michael Greengrass Controlled ripening of produce and fruits

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6210724B1 (en) 1999-08-23 2001-04-03 Landec Corporation Temperature-responsive containers

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