METHOD AND DEVICE FOR STORING AGRICULTURAL PRODUCTS

Abstract

The present invention provides a cover for an agricultural product, said cover including a polymeric barrier material, wherein the cover is permeable or impermeable to gases, permeable to water vapour and water-resistant.

Claims

1. A cover for an agricultural product, said cover comprising a polymeric barrier material, wherein the cover is permeable or impermeable to gases, permeable to water vapour and water-resistant.

2. The cover according to claim 1, wherein the cover is characterised by one or more of the following: a water-vapour resistance (breathability) of between 0 and approximately 13 m.sup.2Pa/W according to ISO 11092; a hydrostatic resistance of between approximately 100 and approximately 275 kPa according to AS 2001.2.17; and a water repellency scale of approximately 100 according to AS 2001.2.16.

3. The cover according claim 1, wherein the polymeric barrier material includes one or more of a fluoropolymer, polyolefin, polyester, polyurethane, polyethylene, polyvinyl chloride and polyvinylidene chloride.

4. (canceled)

5. The cover according to claim 3, wherein the polymeric barrier material includes polytetrafluoroethylene.

6. The cover according to claim 1, wherein the cover comprises a laminate including the polymeric barrier material.

7. The cover according to claim 6, wherein the laminate comprises an outer layer, a layer formed from the polymeric barrier material and an inner layer, which, in use, is in contact with the agricultural product.

8. (canceled)

9. (canceled)

10. (canceled)

11. (canceled)

12. The cover according to claim 1, wherein the agricultural product is selected from any one or more of a fruit, seed, grain, nut, vegetable, flower, leaf, stem, root, woody plant, part thereof, and processed product thereof.

13. (canceled)

14. The cover according to claim 12, wherein the agricultural product is an almond.

15. The cover according to claim 1, wherein the cover is permeable to air.

16. (canceled)

17. A method for storing an agricultural product, comprising covering the agricultural product with a cover according to claim 1.

18. (canceled)

19. (canceled)

20. The method according to claim 17, wherein the cover is placed in contact with at least a portion of the agricultural product.

21. A method selected from the group consisting of: i. inhibiting spoilage of an agricultural product; ii. reducing the risk of spontaneous combustion of an agricultural product; or iii. reducing microbial levels in an agricultural product, said method comprising covering the agricultural product with a cover including a polymeric barrier material, wherein the cover is permeable or impermeable to gases, permeable to water vapour and water-resistant.

22. The method according to claim 21, wherein the covered agricultural product or an associated microenvironment is characterised by a condition which inhibits spoilage, reduces the risk of spontaneous combustion or inhibits microbial growth, wherein said condition is selected form one or more of the following: light and associated heating, moisture content; water vapour content; temperature; pH; water activity; and relative humidity.

23. The method according claim 21, wherein the spoilage is selected from one or more of rancidity and microbe proliferation.

24. (canceled)

25. The method according to claim 23, wherein the microbe is mycotoxin-producing and wherein the mycotoxins are selected from any one or more of but not limited to aflatoxins, trichothecenes, fumonisins, zearalenones and patulins.

26. (canceled)

27. A method according to claim 23, wherein the microbe is a bacterium selected from one or more of foodborne pathogens including but not limited to Escherichia coli, Salmonella spp. and Listeria spp.

28. The method according to claim 23, wherein the microbe is a fungus selected from one or more of a mould or yeast, including but not limited to Aspergillus spp., Fusarium spp., Penicillium spp, Alternaria spp., Cladisporium spp., Epiccocum spp., and Rhizopus spp.

29. (canceled)

30. (canceled)

31. (canceled)

32. The method according to claim 21, wherein the risk of spontaneous combustion is characterised by any one or more of a hydrolytic enzyme activation, an oxidative breakdown product content, a volatile gas content, a pyrophoric gas content and a low flash point chemical content.

33. (canceled)

34. (canceled)

35. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

[0088] FIG. 1 shows the effect of the protective cover, BWT, in contrast to ST, on microclimatic conditions such as relative humidity in the top layers of a nut stockpile.

[0089] FIG. 2 shows the effect of the protective covers, BWT and ST, on reducing diurnal fluctuations in relative humidity in the top layers of a nut stockpiles.

[0090] FIG. 3 shows the effect of the protective cover, BWT and ST on reducing diurnal fluctuations in temperature in the middle layers of a nut stockpiles.

[0091] FIG. 4 shows the effect of the protective covers, BWT and ST, on the moisture content of a product, e.g. nut kernels and the remaining hulls and shells (H&S).

[0092] FIG. 5 shows the difference in the growth of microbial spp. e.g. Aspergillus spp. in a product before (baseline) and after storage under the protective covers, BWT and ST.

[0093] FIG. 6 shows the difference in the growth of microbial spp. e.g. Penicillium spp. in a product before (baseline) and after storage under the protective covers, BWT and ST.

[0094] FIG. 7 shows the difference in the growth of microbial spp. e.g. Fusarium spp. in a product before (baseline) and after storage under the protective covers, BWT and ST.

[0095] FIG. 8 shows the difference in the growth of bacteria in a product before (baseline) and after storage under the protective covers, BWT and ST.

[0096] FIG. 9 shows the difference in the percentage of mouldy kernels before (baseline) and after storage under the protective covers, BWT and ST.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0097] A protective cover (BWT) made of breathable, waterproof material and a conventional polymeric cover (ST) made of polyethylene were comparatively evaluated. The BWT consisted of a three-layer laminate; a 100% polyester woven exterior, a bi-component ePTFE middle layer, and a 100% polyester knitted backing. The BWT has a hydrostatic resistance of greater than 100 (Australian Standard (AS) 2001.2.17), water repellency scale of 100 (AS 2001.2.16), and breathability of less than 13 m.sup.2Pa/W (ISO 11092). A wide-span BWT was fabricated by joining 1.4 metre width pieces of the textile laminate together. In this application, a 14 metre wide BWT was used. The seams were heat sealed so they were water proof. Tapes were attached along the perimeter of the BWT, to aid handling and fastening of the wide-span cover.

[0098] Two stockpiles each consisting of approximately 30 tonnes of soft-shelled almonds were provided. Each stockpile measured approximately 8 metres long, 8 metres wide and 4.5 metres high. As each stockpile was built, smart sensors that monitor temperature and relative humidity were implanted at three depths within each stockpile. Nut samples were collected from corresponding sensor positions for determination of baseline moisture and microbial levels. One stockpile was covered with a BWT and the other a ST for nine weeks. At the end of the storage period, the covers were removed and the stockpiles comparatively evaluated.

Example 1

[0099] This example illustrates the effect of the BWT on microclimatic conditions in a stockpile.

[0100] A modular network of smart sensors was connected to a microcontroller (Smart Logger) equipped with a solar panel, battery and modem for remote data downloading. Three smart sensors were implanted in approximately the same three positions of each stockpile to monitor continuously the microclimatic conditions, at 10 centimetres depth from the top of the stockpile (top), at 2 metres depth (mid) and at 3 metres (base) depths.

[0101] Microclimatic data was collected during the storage period. Microclimatic profiles show that the top layers of nuts in one of the positions on the ridge of the stockpile under the BWT had lower relative humidity than those covered with the ST (FIG. 1). The BWT had enabled greater evaporation of moisture than the ST. Nuts in the surface and mid layers under the ST were exposed to higher temperatures and relative humidity than those under the BWT.

[0102] In the absence of a cover, the surface and mid layers of the stockpile would have been exposed to large and also diurnal fluctuations in environmental conditions (FIGS. 2 and 3). The corresponding exposure to the rain or high relative humidity of 70-90% for 10-18 hours on a daily basis is undesirable for storage of a product.

Example 2

[0103] This example illustrates the effect of the BWT on maintaining low moisture content in a product.

[0104] Nuts were collected from approximately the same position of each stockpile at three different depths; at 0-20 centimetres from the top (top), at 2 metres (mid) and at 3 metres (base), at nine weeks after storage. Kernels were extracted and the moisture content of kernels and remaining hulls and shells (referred to as hulls/shells) were determined using the protocols outlined in ISO 665-2000.

[0105] Kernels and hulls/shells in the top layers of the stockpile under the BWT had lower moisture contents than those covered by ST (FIG. 4). Moisture content in both kernels and hulls/shells under the ST far exceeded the acceptable thresholds of 6% and 13%, respectively.

Example 3

[0106] This example illustrates the effect of the BWT on limiting fungal growth on a product.

[0107] Nuts were sampled from the stockpiles at setting up of the trial and after storage under the BWT and ST covers for nine weeks. They were collected from approximately the same three positions of each stockpile along the ridge on the top of the stockpiles, with three replicates for each position. A 20 gram sub-sample was ground in sterile peptone water. The suspension was serially diluted and plated onto a mycological culture medium. Fungal colony types and numbers were assessed after incubation at 25 C.

[0108] An illustration of the difference in the level of mycotoxic fungi, e.g. Aspergillus spp., on the product protected by BWT, is shown in FIG. 5. Aspergillus numbers were 40 times lower in nuts protected by BWT than those protected by ST.

[0109] An example of the effect of BWT on limiting spoilage and plant pathogenic fungi, e.g. Penicillium and Fusarium spp., are illustrated in FIGS. 6 and 7. Penicillium and Fusarium numbers were 36 and 8.7 times lower, respectively, in nuts protected by BWT than those protected by ST.

[0110] The three examples also show that through maintaining dryness in the covered nuts, BWT was effective in limiting microbial growth, as there was no increase in microbial numbers above the baseline levels. However, with the ST cover which tended to promote build-up of relative humidity, both Aspergillus, Fusarium and Penicillium levels had increased markedly above the baseline levels.

Example 4

[0111] This example illustrates the effect of the BWT on limiting bacterial growth on a product.

[0112] Nuts before and after nine weeks storage under the BWT and ST covers were collected and processed as described in Example 3. A 20 gram subsample was ground in sterile peptone water, and an aliquot spread on a bacteriological agar medium and then incubated at 35 C. Bacterial colonies were counted within 48 hours after incubation.

[0113] After nine weeks storage, the bacterial counts in nuts covered with BWT was 143 times lower than those covered by ST (FIG. 8). The data also show bacterial growth increased over time on nuts covered by the ST, whereas those under the BWT did not increase. The build-up in relative humidity and condensation under the ST was a contributing factor for the marked difference in bacterial numbers. The data also provide evidence that controlling moisture in a product is an effective measure in limiting microbial growth.

Example 5

[0114] This example illustrates the effect of a BWT on product quality.

[0115] Nuts were collected from the top, middle and basal sections of approximately the same positions of each stockpile covered with a BWT and a ST. A sub-sample of 300 nuts was assessed visually for a range of quality criteria, these included: fungal growth and rots (Penicillium, Aspergillus, Rhizopus, Fusarium spp.), and general deterioration in quality.

[0116] Nuts in the top layers of the stockpile covered by the ST were more exposed to condensation and environmental fluctuations. As a result, the nuts were poorer in quality and had a higher incidence of mould infection than those protected by the BWT (FIG. 9). The higher levels of moisture in the nuts also caused the kernels to deteriorate, which resulted in rancidity and off-flavours.

Example 6

[0117] This example illustrates the indirect effect of a BWT on minimising mycotoxin levels in a product.

[0118] Nuts were collected from approximately the same positions at the top, middle and basal sections of the stockpiles covered with a BWT and ST after storage in the field for nine weeks. Kernels were extracted from the nut samples and 80 grams of kernels were ground in a blender. A 5 gram homogenised sub-sample was extracted with 20 millilitres of acetonitrile/water (84/16) by shaking for 30 minutes. 10 millilitres of the supernatant was passed through a Mycosep cartridge (Romer labs). The eluant was collected and evaporated to dryness using rotary evaporator (40 C.). The residue was reconstituted with 1 millilitre of mobile phase (20% acetonitrile with 0.2% formic acid) and was injected (20 microlitres) in a liquid chromatography-mass spectrometer (LC-MS) for analysis.

[0119] Matrix matched calibration curves were used to determine aflatoxin levels in the nut samples. A mixed solution of aflatoxins (B1, B2, G1, G2, and acetonitrile) (Sigma-Aldrich) was used to prepare dilutions for the matrix matched calibration curves. A standard curve of the four aflatoxins was prepared by spiking blank almond (5 grams) with 0.22 to 18 parts per billion (ppb) aflatoxins.

[0120] LC-MS/MS analysis was conducted on a triple quadrupole mass spectrometer (6460A, Agilent Technologies, USA), equipped with a quaternary solvent delivery system, a column oven, a photo-diode array detector and an auto-sampler. An aliquot (20 microlitres) of each sample was injected and separated on a Hydro Synergi C18 analytical column (150 millimetres2.0 millimetres, 5 micrometre particle size, Phenomenex, NSW, Australia) at 30 C. The following solvents with a flow rate of 200 microlitres/minute were used: A0.2% formic acid solution in purified water; and B0.2% formic acid solution in acetonitrile. The elution profile was a linear gradient for B of 20% to 100% over 18 minutes in solvent A. Ions were generated using an electrospray source in the positive mode under conditions set following optimisation using a solution of aflatoxins. MS experiments in the full scan (parent and product-specific) and the selected reaction monitoring (SRM) mode were conducted.

[0121] Nut samples under the ST cover were more exposed to condensation; had a higher moisture content and Aspergillus levels, and correspondingly higher levels of aflatoxins than those under the BWT.

[0122] It is to be understood that various alterations, modifications and/or additions may be made without departing from the spirit of the present invention as outlined herein.

[0123] As used herein, except where the context requires otherwise, the term comprise and variations of the term, such as comprising, comprises and comprised, are not intended to be in any way limiting or to exclude further additives, components, integers or steps.

[0124] Reference to any prior art in the specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in Australia or any other jurisdiction or that this prior art could reasonably be expected to be ascertained, understood and/or regarded as relevant by a person skilled in the art.