WO1999025625A1

WO1999025625A1 - Odour-proof package

Info

Publication number: WO1999025625A1
Application number: PCT/AU1998/000928
Authority: WO
Inventors: Stephen C. Morris
Original assignee: Morris Stephen C
Priority date: 1997-11-13
Filing date: 1998-11-06
Publication date: 1999-05-27
Also published as: MY127843A; AUPP036697A0

Abstract

An odour-proof package comprising a sealable container (22) formed from substantially odour-impermeable material, the container having a gas-permeable port (24) including an odour-absorbing material (26) the arrangement being such that when the container is sealed, gas may move into and out of the container through the port, wherein any gaseous odour entering the port is absorbed by the odour-absorbing material during passage of gas such that substantially no odour emits form or enters into the container.

Description

Odour-Proof Package

Technical Field

This invention relates to an odour-proof package particularly suitable for the transport and storage of fresh food produce. Background Art

The storage and transport of fresh agricultural produce is often hampered by the problem of keeping the produce relatively fresh but preventing or minimising odours emitting from them. A fresh commodity with probably the greatest odour problem is the durian. This fruit is mainly produced in South East Asia and is highly prized for its exceptional flavour. Unfortunately, it has a most offensive odour which has resulted in it being banned by all international airlines, international hotels and virtually all mixed storerooms for fresh produce. The odour produced has a strong sulphurous component, giving the offensive 'rotten' smell and also very strong 'fruity' components. Since durian is a living fruit, it requires oxygen for its respiration, which can be high at the ambient temperatures of 30°C+ in South East Asia.

There are lucrative export markets in Hong Kong, Taiwan and Japan for this crop which is primarily serviced by exporting frozen or unripe fruit. Besides the main production areas of Thailand, Malaysia and Indonesia, there is a small production of durians in Australia around Cairns and Darwin. The development of this industry, however, suffers, as does the development of exports for South East Asia, from problems with transport due to the offensive smell of the fruit. The present inventor has developed an odour-proof package for commodities that are alive in the sense they require some exchange of gases like oxygen for maintaining their quality. The package functions by allowing movement of gases such as oxygen and carbon dioxide into and out of the package, but prevents movement of offensive gaseous odours from the package.

Disclosure of Invention

In a first aspect, the present invention consists in an odour-proof package comprising a sealable container formed from substantially odour- impermeable material, the container having a gas-permeable port including an odour-absorbing material, the arrangement being such that when the container is sealed, gas may move into and out of the container through the port, wherein any gaseous odour entering the port is absorbed by the odour- absorbing material during passage of gas such that substantially no odour emits from or enters into the container.

Typical gases that move into and out of the package would be respiratory gases oxygen and carbon dioxide required by living agricultural or fresh food produce. It will be appreciated that other gases in air will also be able to move into and out of the package via the port.

The package can be flexible and made of plastics such as polyethylene terepthalate (PET), plastic laminates including a strong odour barrier layer such as aluminium or nylon, or any other odour-impermeable package material. It has been found that PET having a thickness of about 250 μm or greater is impermeable to typical odours produced by agricultural produce. One suitable PET plastic has a thickness of about 840 μm. The package can also be a rigid box made of material such as polyethylene, preferably >0.75 mm, of any size suitable for the material to be placed therein. It will be appreciated, however, that the package may be made out of any substantially odour-impermeable material.

The container of the package is preferably closed or sealed by heat sealing or fastened with a reliable clip lock fastener or the like. It will be appreciated, however, that any form of closing or sealing would be suitable such that when the package is closed any movement of gas in and out of the package is only possible via the port. In some situations, it may be desirable to provide means for opening and resealing the odour-proof package for customs or quarantine inspection, for example. A suitable means in this regard would be a resealable fastener system such as a "cliplock" arrangement together with sealing tape. It will be appreciated, however, that any other suitable sealing means would be applicable.

The port can comprise the odour-absorbing material incorporated directly within its opening or can be covered by some form of enclosure containing the material. One suitable arrangement is a sachet containing the odour-absorbing material placed over the port. Such a sachet requires a permeable cover, such as woven polyethylene (Tyvek) that allows passage of gas but contains the material in position. A further suitable arrangement is a port with solid sides and permeable covering positioned at the ends and containing the odour-absorbing material. The odour-absorbing material may be any material that will absorb gaseous odours, particularly volatile organic odours. Preferably the odour- absorbing material is activated charcoal, powdered nickel or other compounds capable of absorbing volatile organic odours including palladium, Tenax® and platinum. It will be appreciated that the odour- absorbing material may comprise a mixture of materials to maximise efficiency. For example, activated charcoal and nickel can be used for odorous produce like durian.

Preferably the odour-absorbing material is a combination of activated charcoal and powdered nickel. More preferably the mixture is 90% charcoal/10% nickel or 75% charcoal/25% nickel (w/w). It will be appreciated that the amount of material used will depend on the volume and type of produce in the package.

In order to prevent the build-up of moisture in the package, moisture absorbing material may be optionally placed in the package.

In a second aspect, the present invention consists in a method of package produce comprising placing the produce in an odour-proof package according to the first aspect of the present invention and closing the produce therein. In a third aspect, the present invention consists in a method of storing or transporting produce comprising placing the produce in an odour-proof package according to the first aspect of the present invention and storing or transporting the produce, wherein substantially no odour is emitted from the container. The odour-proof package can be either for an individual item of produce, placed around a larger container such as a carton containing one or multiple items, or around a whole pallet. The package can be designed for each application bearing in mind the oxygen requirements of the material placed therein and the amount of produce packaged. When an aluminium/plastic laminate is used, care should be taken to prevent tearing or puncturing by, for example, any sharp thorns of the produce. A convenient solution to this is to secure the produce within a wrap of woven polyethylene or Tyvek of a grade of 75g/m² or greater. Care should also be taken to ensure that the package is protected from tearing or damage during handling and transport. In some situations, a protective covering in the form of an outer carton, for example, would be suitable. The package according to the present invention is particularly suitable for the durian, the most extreme fresh food product with an odour problem. The package, however, has applicability to any situation where odours given off by fresh produce must be contained and movement of fresh air into the container is also required. Such situations may occur in any mixed load situation - either during transport, such as by air, in commercial coolrooms, food preparation areas, or in domestic situations in the kitchen or domestic fridge. The odour producing commodities are not necessarily durians but can be any commodity producing offensive or troublesome odours (examples include onions or potatoes in mixed loads). Furthermore, the packages can be used to store commodities that are very sensitive to contamination by odours (such as apples mixed with onions or potatoes), in order to prevent odour contamination occurring during storage.

Uses of the odour package according to the present invention include firstly package the produce to prevent offensive odours emitting during transport such as by air or storage. Secondly, package the produce during mixed transport or storage to prevent contamination of other produce nearby as may occur in commercial coolrooms. Thirdly, package the produce or part of the produce for short term storage during domestic consumption in a domestic or small scale refrigerator.

Throughout this specification, unless the context requires otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element or integer or group of elements or integers but not the exclusion of any other element or integer or group of elements or integers.

In order that the present invention may be more clearly understood, preferred forms will be described with reference to the following examples and accompanying drawings. Brief Description of Drawings Figure 1 shows the effect of absorbents on durian volatiles (ethyl disulphide, propanethiol and methyl-methlbutyrate each at 10,000 mg/L). Legend indicates powder in 10x10 cm sachet.

Figure 2 shows the effect of absorbents on ethyl disulphide at 1,000 mg/L. Legend indicates powder in 10x10 cm sachet. Figure 3 shows the effects of absorbents on propanethiol at 1,000 mg/L.

Legend indicates powder in 10x10 cm sachet. Figure 4 shows the effects of absorbents on methyl-methylbutyrate at 1,000 mg/L. Legend indicates powder in 10x10 cm sachet.

Figure 5 shows performance of a range of packages and odour- absorbing sachets with fresh durian. Figure 6 shows performance of a range of packages and odour- absorbing compounds with fresh durians - Bangkok 2.

Figure 7 shows performance of a range of packages and odour- absorbing compounds with fresh durians - Bangkok 3.

Figure 8 shows performance of a range of packages and odour- absorbing powders for thawed whole durians - Sydney 1.

Figure 9 shows performance of a range of plastic boxes and sachets for absorbing odours from thawed frozen durians - Sydney 2.

Figure 10 is a diagram of a flexible odour-proof package.

Figure 11 is a diagram of a rigid odour-proof package. Modes for Carrying Out the Invention

EXPERIMENTAL RESULTS Trapping Organic Volatiles

The principal odour components of durian according to Baldry, Dougan & Howard (1972) are ethanol, propanethiol, ethyl-methylbutyrate, methyl-methylbutyrate, ethyl acetate and ethyldisulphide. In order to test the effectiveness of various materials as odour barriers, three components of this volatile profile were selected, two offensive sulphurous compounds - propanethiol and ethyl disulphide and one strong fruity compound methyl- methylbutyrate. These classes of compounds are generally typical representatives of problem volatiles that can occur in other fresh produce.

The initial experiment system was a tall 10 L glass jar with internal dimensions of approximately 36x17x17 cm. This jar was held in a fume hood in a room at 20-25°C. A 10 mm thick sheet of perspex was sealed on the top with silicone sealant and a square hole with the dimensions 6x6 cm cut into the top. At the bottom of the jar was a 50 mL beaker into which solutions of volatiles could be placed. During experiments the 6x6 cm opening was covered with a 10x10 cm sachet made from two sheets of woven polyethylene or Tyvek, with an internally sealed area of 8x8 cm made by heat sealing. Into the sachet was placed various potential absorbents of organic volatiles for testing. The sachets were fixed over the hole in the perspex with double sided adhesive tape and the edges sealed down with flexible PVC tape.

The volatile solutions used were at concentrations of 1,000 or 10,000 mg/L in water and for each experiment a 2 mL aliquot was placed into the beaker at the bottom of the jar. This concentration is many times greater than the levels of 2.5 mg/L propanethiol and 20 mg/L ethyl-methylbutyrate stated as produced by durians (Baldry et al, 1972). The very high levels tested enabled experiments to proceed rapidly and gave increased levels of confidence in the viability of the system using actual fruit. Typically after adding the volatile solution, the sachet was fixed into place and then the fume hood operated on high for ten minutes. The passage of volatiles across the sachet was then determined by periodically by sniffing the air immediately above the sachet and recording the intensity of odour present. Prior to sniffing to assess volatiles, 2-5 minutes was spent in a volatile-free environment. Fresh volatile solutions were used each day.

The relative odour strength was assessed using a severity scale of:

0-Nil; 1 - very faint; 2 - faint; 3 - faint/moderate; 4 - moderate;

5 - moderate; 6 - strong; 7 - very strong; 8 - extremely

Durian Volatiles

Mixed Volatiles

Several absorbent powders were tested in the 10x10 cm sachets against three of the major durian volatiles. In the first experiment (Fig. 1, Table 1), the odour quickly travelled through the empty Tyvek sachet within about 20 minutes. Nickel at a loading of lg allowed odour through at about the same rate as with no powder, however, the odour had a strong fruity smell indicating that methyl-methylbutyrate was travelling through the nickel.

Charcoal at 1 g was only partly effective. While loadings of 2.5 g charcoal and 2.5 g 90% charcoal/10% nickel were equally effective, permitting only a faint odour at this very high volatile concentration. It seemed that at least

2.5 g of powder must be used for this area of sachet. Table 1: Effects of absorbents on durian volatiles (ethyl disulphide, propanethiol and methyl-methybutyrate each at 10,000 mg/L). Powder in 10x10 cm Tyvek sachet.

Odour- Absorbing Material

Time ( Min) None i g i g 2.5 g 2.5 g

Charcoal Nickel Charcoal 90%Ch/ 10%Ni

0 0 0 0 0 0

10 3 2 3 0 0

20 2 5 0 1

30 3 5 0 1

40 3 0 1

50 4 1 1

60 5 1 1

75 5 2 1

90 2 2

105 2 2

120 2

Individual Volatiles

The sulphurous volatile ethyl disulphide (Fig. 2, Table 2) was examined at a lower concentration of 1,000 mg/L. With no powder, the odour movement through the sachet was essentially maximum after 1 hour building up to a level of 5 or moderate/strong. While at loadings of 2.5 g both charcoal nickel were equally effective. The mixtures of 75/25 and 90/10 (%charcoal/%nickel) were slightly more effective than the individual components. Table 2: Effects of absorbents on ethyl disulphide at 1.000 mg/L. Powder in 10x10 cm sachet.

Odour-Absorbing Material

Time (Min) None 2.5 g 2.5 g 2.5 g 2.5 g Charcoal Nickel 90%Ch/ 75%Ch/

10%Ni 25%Ni

0 0 0 0 0 0

10 1 1 1 0 0

20 2 1 1 1 1

30 2 2 1 1 1

40 4 2 1 1 1

50 4 2 2 1 1

60 4 2 2 1 1

80 5 2 2 1 1

100 5 2 2 1 2

120 5 2 2 1 2

The sulphurous volatile propanethiol (Fig. 3, Table 3) was examined at a lower concentration of 1,000 mg/L. With no powder, the odour movement through the sachet was essentially maximum after 1 hour building up to a level of 5, or moderate/strong. While at loadings of 2.5g both charcoal and nickel were equally effective. The mixtures of 75/25 and 90/10 (%charcoal/%nickel) were again slightly more effective that the individual compounds. It was noticeable that the overall odour either through the empty sachet and the filled sachets were higher than for ethyl disulphide indicating that this compound is potentially more of a problem. Table 3: Effects of absorbents on propanethiol at 1,000 mg/L. Powder 10x10 cm sachet.

Odour-Absorbing Material

Time (Min) None 2.5 g 2.5 g 2.5 g 2.5 g Charcoal Nickel 90%Ch/ 75%Ch/

10%Ni 25%Ni

0 1 0 0 0 0

10 1 1 1 0 1

20 2 1 1 1 1

30 3 2 1 1 1

40 4 2 1 1 1

50 4 3 1 1 1

60 5 3 2 1 2

80 5 3 2 2 2

100 5 3 2 2 2

120 6 3 2 2 3

The fruity ester methyl-methylbutyrate (Fig. 4, Table 4) was examined at a lower concentration of 1,000 mg/L. With no powder, the odour movement through the sachet was again essentially maximum after 1 hour building up to a level of 5, or moderate/strong. Nickel on its own at 2.5 g loading seemed to be ineffective at absorbing this class of compounds. While at a loadings of 2.5 g charcoal and the mixtures of 75/25 and 90/10 (%charcoal/% nickel) seemed to be equally effective. It was noticeable that the effectiveness of odour absorbance of this class of compound by charcoal was more effective than against the sulphurous compounds of ethyl disulphide and propanethiol. Table 4: Effects of absorbents on methyl-methylbutyrate at 1,000 mg/L. Powder in 10x10 cm sachet.

Odour-Absorbing Material

Time (Min) None None 2.5 g 2.5 g 2.5 g 2.5 g

Charcoal Nickel 90%Ch/ 75%Ch/

10%Ni 25%Ni

0 1 1 0 1 0 0

10 3 3 1 2 1 0

20 3 3 1 3 1 1

30 3 3 1 3 1 1

40 4 4 2 4 1 2

50 4 4 2 4 1 2

60 5 4 2 4 2 2

80 5 5 2 5 2 2

100 5 5 2 5 2 2

120 5 5 2 5 2 2

Gas Exchange

The gas exchange properties of the odour-absorbing sachets was tested by using the 10 L glass jar used for the volatile studies. After attaching the odour-absorbing sachet, nitrogen was added to the glass jar and the expelled air vented through the sachet. Nitrogen was added until the oxygen level was below 5% (measured by GC). After 5 minutes to equilibrate, a gas sample was taken and then again after 60 minutes. This was done for a sachet filled with 7.5 g of activated charcoal (6 mm thick) and for a sachet filled with 15 g of charcoal (9 mm thick). The opening was square 6x6 cm. The results are given in the table 5 below and indicate that gas exchange across the sachets is relatively free. Table 5

Sachet Initial Final Time Total 0₂ Permeability Permeability (g Ch) Q₂ 0₂ (min) (mL/hr/atm) cm³/m²/dav/atm cm³/cm/m²/day/atm

7.5 1.38 9.39 51 1299 9020000 5410000 15 3.26 8.23 43 1060.8 6810000 6130000

There seems to be no published measurements of durian respiration, however, in the table 6 respiration is given for a range of tropical fruit as well as the very high respiring crop of broccoli. The calculated performance of these crops sealed in an impermeable bag with a 15 g sachet is also given in table 6. The results indicate that with this sachet for 2 kg of the tropical fruit (which is the average weight of durian) the oxygen level inside the bag would be essentially the same as atmospheric. Even for the extremely high respiration of broccoli the oxygen level in the bag would be 7%. This indicates the system has considerable safety margin even if durian has a much higher respiration rate or is held at higher temperatures.

Table 6

Crop Temp. °C Max. Respiration Equilibrium through 15g sachet (niL/kg/hr) for 2 kg fruit (% Oxygen)

Mango 25 60 18.6

Bananas 20 43 19.2

Guavas 20 94 17.2

Pineapples 25 28 19.8

Broccoli 25 340 7

Durian Fruit

Thailand

The first series of experiments was conducted with fresh durian fruit (2 ± 0.2 kg) in Bangkok, Thailand. For these experiments bags to contain the durian fruit were used, in combination with sachets containing a variety of odour-absorbing powders. The ambient temperature were 24-30°C during these experiments. Table 7: Performance of a range of packages and odour-absorbing powders with fresh durians - Bangkok 1.

Bag Sachet Time (h) Bag Odour Sachet Odour Condensation Intensity Type Intensity Type

LDPE (40 μm) 10 g 18 SF SF Heavy* 90%Ch/10%Ni

Mylar Small Sealed 18 0 Heavy* Mylar 10 g Charcoal 18 0 Heavy* Medium Mylar Large 10 g 18 Heavy*

90%Ch/10%Ni AL Coat/LDPE 10 g Charcoal 18 SF Heaw*

*Odour strength; 0 - Nil, 1 - very faint, 2 - faint, 3 - faint/moderate, 4 - moderate, 5 - moderate/strong, 6 - strong, 7 - very strong, 8 - extremely strong ** Odour type; S - sulphurous, F- fruity

The Mylar (or PET) bags performed very well with fresh durian. The thick film used (840 μm) besides preventing the movement of odours (Fig. 5, Table 7) and also preventing puncturing of the bag by the sharp thorns of the fruit. To prevent puncturing of the LDPE bag and the aluminium coated LDPE bag, sections of cartons were placed above and below the fruit. This worked well at preventing puncturing, but the cardboard became very soft and started to break apart due to the heavy condensation inside the bag. The LDPE bag performed poorly as an odour barrier, as did the aluminium coated

LDPE ( with a protective layer over the aluminium coating). The problem with the aluminium coating was that it was very thin, and flexing of the plastic and water penetrating tiny cracks in the inside layer meant that the aluminium layer was oxidised in many small patches. This allowed the odours to cross the bag at these points.

The sachets performed well at loadings of 10 g over the 6 cm diameter hole, either as straight charcoal or 90% charcoal/10% nickel. There was a very faint fruity odour coming through the 10 g sachets over this time. It seemed that sachets had a significant odour at their exterior surface when the bag itself did not perform well as a odour barrier, these same sachets had no odour at their external surface when attached to a good odour-proof package. Condensation of large amounts of moisture on the inside of the bag is both an aesthetic problem and likely to increase rot during storage. Some method to address this problem needs to be included if it is expected to be a problem. The use of a woven polyethylene (or Tyvek) wrap around the fruit should help prevent some of the problems of condensation.

Table 8: Performance of a range of packages and odour-absorbing compounds with fresh durians - Bangkok 2.

Bag Sachet Time Bag Odour Sachet Odour Condensation (h) Intensity Type Intensity Type

LDPE (40 μm) 15 g 18 SF SF Heavy*

Charcoal

Mylar Small 5 g 18 Heavy* 20 mL

Charcoal

Mylar 30 g 18 Heavy* 30 mL

Medium Charcoal

8 cm

Mylar Large 10 g 38 Heavy*

90%Ch/

10%Ni

Al Coat/LDPE 10 g 18 SF 4 SF Heavy*

75%C/

25%Ni *Odour strength; 0 - Nil, 1 - very faint, 2 - faint, 3 - faint/moderate, 4 - moderate, 5 - moderate/strong, 6 - strong, 7 - very strong, 8 - extremely strong ** Odour type; S - sulphurous, F- fruity

The Mylar (or PET) bags performed very well (Fig. 6, Table 8). The LDPE bag again performed poorly as an odour barrier, as did the aluminium coated LDPE (with a protective layer over the aluminium coating). It seems that 5 g of charcoal in the sachets is too little to absorb the odours. Increasing the loading to 30 g and the hole opening to 8 cm seemed to make little difference compared to loadings of 10 g over the 6 cm diameter hole. Table 9: Performance of a range of packages and odour-absorbing compounds with fresh durians - Bangkok 3.

Bag Sachet Time Bag Odour Sachet Odour Condensation (h) Intensity* Type** Intensity Type

LDPE (40 μm) 15 g 52 SF SF Heavy

Charcoal

Mylar Small 10 g Light

Charcoal

Mylar 30 g 52 heavy 35 mL

Medium Charcoal

8 cm

Mylar Large 10 g 52 Heavy

90%Ch/

10%N

AL Coat/LDPE 10 g 52 SF SF Heavy

Charcoal

Al oil 10 g Light

Charcoal

The same bags and sachets combinations were left in place, this time for 52 hours (Fig. 7, Table 9). The performance was still the same as for 18 hours (Fig. 6, Table 8). This indicated the capacity of the Mylar bag and 10 g charcoal to cope with durian odours over this time. Also in this experiment a durian was split in half longitudinally, and half put into the small Mylar bags and half into the Al foil/PE composite; these bags were then left for 7 hours. Both these bags performed well. The relative improvement of performance over the aluminium coated bag indicates that when a thicker or stronger layer of aluminium such as foil is used, the vapour barrier is effective. Sydney

The second series of experiments was conducted with thawed durian fruit that had been imported frozen from Thailand. The size used was 2 ± 0.2 kg. For these experiments bags to contain the durian fruit were used, in combination with sachets containing a variety of odour-absorbing powders. Temperature in the laboratory was 22-26°C.

Table 10: Performance of a range of packages and odour-absorbing powders for thawed whole durians - Sydney 1.

Bag Sachet Bag Odour Intensity Sachet Odour Intensity

48h 72h 96h Type 48h 72h 96h Type

Mylar Large lO g Ch 0 0 0 1 1 1 F

LDPE 10 g Ch 5 4 4 S&F 3 3 3 S&F

PE/ALFoil/Pa 10 g Ch 0 1 F

The odour from the thawed durians was similar to that from fresh durians, particularly for the sulphurous compounds, however, the pleasant fruity components of the odour of the fresh durian seemed much weaker. To prevent the piercing of the bag by the thorns the fruit were first wrapped in Tyvek (or woven polyethylene) of 75 g/m². The Mylar (or PET) bag performed very well (Fig. 8, Table 10). The LDPE bag again performed poorly as an odour barrier. In this experiment a LDPE/aluminium foil/paper composite was used. This performed as well as the PET bag. There was no real change over the four days with the performance of the bags and sachets, except for a small loss in intensity between 48 and 96 hours. This indicates that the Mylar and aluminium foil/polyethylene laminate with their sachets has good capability at absorbing odours over this time.

This experiment used resealable plastic boxes 1) a translucent polyethylene box with a clip on lid, walls 1.25 mm thick and 190x260x85 mm in size, and 2) a white polycarbonate box with a clear lid a silicone rubber seal held in place by metal clips, walls 2 mm thick and 210x300x105 mm. Holes 6 mm in diameter were cut in the lid and the sachets attached as previously. Due to the smaller size of the boxes, only half a durian cut lengthways was placed in each box. The polyethylene box performed very well over the 4 days test with a much poorer performance of the polycarbonate box. The sachets performed as previously. At the end of the trial a strong odour was noticed in each box. Washing with hot soapy water and airing overnight largely got rid of the smell, except for a faint odour that was slightly stronger in the PE box than the polycarbonate box. Further airing for 48 hours reduced the odour to an extremely faint, almost undetectable level. The results are shown in Fig. 9, Table 11.

Table 11: Performance of a range of plastic boxes and sachets for absorbing odours from thawed frozen durians - Sydney 2.

Box Sachet Box Odour Intensity Sachet Odour Intensity 48h 96h Type** 48h 96h Type

PE De lO g Ch 0 0 1 1 F

Polycarbonate 10 g Ch 4 3 S&F l 1 F

*Odour strength; 0 - Nil, 1 - very faint, 2 - faint, 3 - faint/moderate, 4 - moderate, 5 - moderate/strong, 6 - strong, 7 - very strong, 8 - extremely strong

** Odour type; S - sulphurous, F- fruity

Examples of a flexible and a rigid odour-proof package are shown in Fig. 10 and Fig. 11, respectively. The flexible package 10 comprises a closable end 12 that can be closed after the produce has been added. The end 12 may be closed by heat sealing or by a flexible seal. A port 14 is positioned in the package 10 and is covered by a sachet 16 containing odour- absorbing material. In use, gases may enter and leave the package 10 via the port 14 such that any gaseous odour passing through the port 14 is absorbed by the odour-absorbing material before reaching the immediate environment of the package.

The rigid package 20 comprises a base container 22 and a closable lid 23 that can be closed after the produce has been added. A port 24 is positioned in the lid 23 and is covered by a sachet 26 containing odour- absorbing material. In use, gases may enter and leave the package 20 via the port 24 such that any gaseous odour passing through the port 24 is absorbed by the odour-absorbing material before reaching the immediate environment of the package. This form of package 20 has the benefit of being re-useable. After use, the package 20 can be washed and the odour-absorbing material can be replenished or treated to remove the absorbed odours.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

REFERENCES

Baldry, J., Dougan, J. and Howard, G.E. (1972) Volatile flavouring constituents of durian. Phytochemistry 11:2081-2084.

Claims

CLAIMS:

1. An odour-proof package comprising a sealable container formed from substantially odour-impermeable material, the container having a gas- permeable port including an odour-absorbing material, the arrangement being such that when the container is sealed, gas may move into and out of the container through the port, wherein any gaseous odour entering the port is absorbed by the odour-absorbing material during passage of gas such that substantially no odour emits from or enters into the container.

2. The package according to claim 1 wherein the odour-impermeable material is a plastic.

3. The package according to claim 2 wherein the plastic is selected from the group consisting of polyethylene terepthalate (PET), polyethylene, plastic laminates including a strong odour barrier layer such as aluminium or nylon, and other odour-impermeable materials.

4. The package according to claim 3 wherein the plastic is PET having a thickness of about 250 ╬╝m or greater, preferably about 840 ╬╝m.

5. The package according to claim 1 wherein the material is impermeable to odours produced by agricultural produce.

6. The package according to claim 3 wherein the plastic is polyethylene, preferably having a thickness of >0.75 mm.

7. The package according to any one of claims 1 to 6 sealed by heat sealing or sealed with a re-useable sealing means.

8. The package according to any one of claims 1 to 7 wherein the port comprises the odour-absorbing material incorporated therein, or the port is covered by an enclosure containing the material.

9. The package according to claim 8 wherein the port has an inner and outer opening separated by a cavity, each opening having a gas-permeable covering and the odour-absorbing material positioned within the cavity.

10. The package according to claim 8 wherein the enclosure is a sachet containing the odour-absorbing material positioned over the port.

11. The package according to claim 10 wherein the sachet includes a gas- permeable cover, such as woven polyethylene, that allows passage of gas.

12. The package according to any one of claims 1 to 11 wherein the odour- absorbing material is selected from the group consisting of activated charcoal, powdered nickel, and other compounds capable of absorbing volatile organic odours including palladium and platinum, and mixtures thereof.

13. The package according to claim 12 wherein the odour-absorbing material is a combination of activated charcoal and powdered nickel.

14. The package according to claim 13 wherein the mixture is 90% charcoal/10% nickel, or 75% charcoal/25% nickel [w/w).

15. The package according to any one of claims 1 to 14 further including a moisture-absorbing material.

16. A method of package produce, the method comprising placing the produce in an odour-proof package according to any one of claims 1 to 15 and sealing the produce therein, wherein substantially no odour is emitted from or enters into the container.

17. A method of storing or transporting produce, the method comprising placing the produce in an odour-proof package according to any one of claims 1 to 15, sealing the produce therein and storing or transporting the produce, wherein substantially no odour is emitted from or enters into the container.

18. The method according to claim 16 or 17 wherein the produce is a fresh food produce.

19. The method according to claim 18 wherein the fresh food produce is durian.

20. Use of the odour-proof package according to any one of claims 1 to 15 to prevent offensive odours emitting from or into produce packaged in the container of the packaging.