Abstract:
A system and method for long-term storage of a commodity in a weight range of 10-2000 kilograms includes hermetic sealing of an ultra-low permeability, easily transportable, flexible long-term storage container. The long-term storage container may also be treated using non-toxic insect repellents of botanical origin or using a synthetic pyrethroid. The long-term storage container includes a triple layer co-extruded film having an outer layer, an inner layer, and a middle layer. The middle layer is comprised of ultra-low permeability material or materials. After hermetic sealing, the long-term storage container having the commodity therein is placed into an outer container for protection during transport.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS  
       [0001]     The present application claims priority from Provisional U.S. Patent Application Ser. No. 60/658,586 filed on Mar. 7, 2005 and titled “Flexible Transport Bags,” the entire subject matter and contents of which are incorporated by reference herein in its entirety. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention is directed to a system and method of hermetic storage and easy transport of commodities. More specifically, the present invention is directed to providing an insect- and mold-resistant method for use in storage and transportation of bagged dry commodities using a hermetic, portable container. The purpose of the present invention is to combine easy transport with safe storage for dry commodities such as seeds, pulses, oil seeds, nuts, and grains normally transported either in unprotected man-portable grain or seed bags or by mechanized handling using “Big Bags.” The present invention provides a storage system having low permeability per unit area for oxygen, carbon dioxide, and water vapor. It is designed to preserve the original post-drying moisture content of the commodity, to retain beneficial volatiles of the commodity, to prevent ingress of oxygen, and to eliminate insect infestation, as well as eliminate the growth of molds during storage and transport.  
       BACKGROUND OF THE INVENTION  
       [0003]     Protected storage is required for many agricultural commodities, such as cereal grains (wheat, corn, or rice), pulses, oilseeds, dried fruits, nuts, cocoa, coffee, and spices, as well as seeds for the above, partially processed food such as flours, semolina, and others, and feed. Such commodities must be protected from the direct and indirect effects of oxygen and/or an increase in moisture, each of which permits growth of insects and/or microorganisms.  
         [0004]     It is recognized that when commodities are harvested, there is a high likelihood that insects may be present along with the harvested commodity. If left untreated, the insect population may undergo rapid growth, resulting in damage or contamination of the commodity.  
         [0005]     One approach to prevent losses from insect infestation is to use contact pesticides, or fumigants, and to prevent fungi development by the use of chemical preservatives on the commodity during storage immediately after harvest or prior to shipping. The use of these pesticides and chemicals is undesirable, as many pesticides can have an adverse effect on the health of the user, the consumer or the environment, including earth&#39;s upper atmosphere, and further may cause the development of insect resistance to the pesticide.  
         [0006]     Other solutions to the infestation problem include refrigeration or the use of large flexible, hermetically sealed enclosures during storage, referred to as Cocoons™ (GrainPro, Inc. Concord, Mass., USA). In some cases, vacuum is added for more rapid disinfestation, such as is described in U.S. Pat. No. 6,609,354 to Villers and U.S. Pat. No. 6,941,727 to Villers, all of which are incorporated by reference herein in their entireties.  
         [0007]     Specifically, a bulk commodity is hermetically sealed in a flexible container or enclosure, such as that formed from a 0.032 inch, low gas-permeability, UV resistant food grade PVC sheet material. A vacuum is established in the enclosure by using a conventional commercial vacuum pump and set point regulator. The flexible container or enclosure prevents excessive stresses when evacuated as would occur with a rigid container by conforming to the shape of the enclosed commodity. An opening, which can be opened or closed by means such as a solenoid-controlled inlet valve, is fed to an ordinary vacuum pump, with, if needed, an appropriate filter at the hermetically sealed container end to prevent clogging or damage to the pump. The vacuum pump is allowed to run for an extended period of time so that either or both Oxygen and interstitial moisture inside are substantially removed, typically down to a vacuum of 25-100 mm Hg at room temperature representing a level equivalent to, at atmospheric pressure, 0.7-2.75% oxygen. At this time the valve is closed, and the hermetically sealed container becomes a large “vacuum pack,” with periodic pumping as required to compensate for residual infiltration of air, eliminating any of the respective causes of degradation named above due either to direct or indirect effects of Oxygen. Further, any residual moisture in the absence of Oxygen will not as easily cause moisture-produced damage. Damage to the commodity can be prevented, at least in part, by restricting the metabolic activity of all biological agents, including insects, microflora, and the commodity itself.  
         [0008]     In a particular implementation, a vacuum in the range of 25-100 mm H g  is established in the enclosure at 20° C. or higher. The appropriate minimum temperature is based on the particular infesting biological contaminant(s) and the desired kill time of the biological contaminant(s). The commodity can have a weight in the range of one-half to two hundred metric tons.  
         [0009]     However, the Cocoons™ are restricted by the requirement that they be sufficiently hermetic to allow a low oxygen atmosphere to develop due to insect and/or commodity respiration and to prevent significant moisture ingress in humid atmospheres. The use of large bags provides more volume/surface area and as such, lowers permeability per ton. Thus, the smallest feasible Cocoons™ are limited by permeability considerations of available robust and moderately priced materials to a minimum capacity of about 7.5 cubic meters in bags with approximate dimensions of 2 m×3m×1.5m. Alternatively, flexible enclosures may be constructed somewhat smaller with a minimum volume of 0.7 m 3 , such as the product GrainSafes™ (GrainPro, Inc. Concord, Mass., USA), as described more fully in Israeli Patent Number 122456, incorporated herein by reference in its entirety. However, this size involves compromises in the degree of permeability and therefore the ability to kill insects based on their, and the commodity&#39;s, respiration rates versus infiltration rates of oxygen from the outside. Thus, these enclosures are too large and too unstable to be readily transportable when full.  
         [0010]     Bags which are easily human-portable are generally comprised of (high permeability) jute or woven polypropylene bags, and are typically in the 25 to 100 kg capacity. Machine transportable bags, known as “Big Bags,” are generally in the 500 to 1000 kg capacity. Although flexible, such bags alone do not afford sufficient protection from infestation or molds, do not result in a low oxygen atmosphere, or prevent the effects of absorbing moisture from the atmosphere.  
         [0011]     The material used for the Cocoons™ described above is a food grade flexible PVC plastic typically 0.83 mm thick, sold commercially by GrainPro under the trade name of Cocoon™ and for the smaller container, GrainSafe™. This PVC material is not suitable for long-term storage of small quantities; it is relatively too permeable, expensive and too stiff to be used in individual bags below five ton size without significantly compromising performance. Alternatively, semi-rigid aluminum bags, commonly known as “Joseph” bags, have long been available, and are comprised of relatively rigid aluminum coated plastic. These “Joseph” bags, however, are expensive, easily punctured, difficult to close, and do not protect against insect penetration, making them a less than optimal choice. Other forms of hermetic enclosure include amphores (large earthenware containers) as used in ancient times, lined underground pits sealed with a variety of substances, and metal or plastic drums. None are lightweight, flexible, inexpensive and easily transportable.  
       SUMMARY OF THE INVENTION  
       [0012]     According to one aspect of the invention, there is provided a system for storage and transport of a commodity. The system includes a commodity for long-term storage having a weight of 10-2000 kg, a long-term storage container for containment and hermetic sealing of the commodity therein, the long-term storage container having at least one outer layer, at least one inner layer, and a middle layer comprised of an ultra-low permeability material, and an outer container for containment of the long-term storage container, wherein the outer container is configured to protect the long-term storage container during transport.  
         [0013]     The long-term storage may include a storage period of at least four months or up to several years if the commodity is sufficiently dry. According to further features, the outer layer and inner layer are made of a flexible material, such as a polymeric material, for example, polyethylene. The middle layer may be comprised of nylon, EVOH, or any other suitable ultra-low permeability material or materials. According to further features, the commodity can have a weight of 10-100 kg, or of 250-2000 kg, for example. The outer container may be, for example, a jute bag, a polypropylene bag, or other commonly used bag for transport.  
         [0014]     According to further features of the present invention, the long-term storage container may further include a compound of botanic origin, such as an essential oil, or a synthetic pesticide, to provide an insect repellent barrier to further prevent the possibility for insect infestation and/or penetration. The commodity can be seeds, cereals, oilseeds, coffee, cocoa, dry granular agricultural products, flours, or any other typically stored dry food or feed commodity.  
         [0015]     According to another aspect of the present invention, there is provided a method for storage and transport of a commodity. The method includes placing the commodity in a long-term storage container having an outer layer, an inner layer, and a middle layer comprised of an ultra-low permeability material or materials, hermetically sealing the long-term storage container, and placing the long-term storage container in an outer container.  
         [0016]     According to further features of the present invention, the method may further include transporting the commodity in the long-term storage container and the outer container using conventional bag handling methodologies. In one embodiment, the outer container is placed into an unaltered standard shipping container. The hermetic sealing can be done by twisting or rolling an open end of the long-term storage container and clamping the twisted end to maintain hermeticity, or by heat sealing an open end of the container.  
         [0017]     Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]     The invention is herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of various embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice.  
         [0019]     In the drawings:  
         [0020]      FIG. 1A  is an illustration of a large storage container for storing of a commodity;  
         [0021]      FIG. 1B  is an illustration of multiple small storage containers, for alternative storing of the commodity of  FIG. 1A ;  
         [0022]      FIG. 2  is a cross-sectional illustration showing the layers of a material for use as a storage container;  
         [0023]      FIG. 3  is a cross sectional illustration of a long-term storage container placed inside a protective outer container; and  
         [0024]      FIG. 4  is a flow chart illustration of the steps of a method for storage and transport of commodities, in accordance with one embodiment of the present invention. 
     
    
       [0025]     It will be appreciated that for simplicity and clarity of illustration, elements shown in the drawings have not necessarily been drawn accurately or to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity or several physical components may be included in one functional block or element. Further, where considered appropriate, reference numerals may be repeated among the drawings to indicate corresponding or analogous elements. Moreover, some of the blocks depicted in the drawings may be combined into a single function.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0026]     In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be understood by those of ordinary skill in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components and structures may not have been described in detail so as not to obscure the present invention.  
         [0027]     The present invention relates to flexible reusable portable storage containers which have very low permeability to air, CO 2  and water vapor as described below, and which can be used for both short or long term storage and subsequent transportation of dry commodities. Such containers are referred to hereinbelow as “long-term storage containers” since they are capable of storing commodities for at least four months. However, it should be readily apparent that the “long-term storage containers” are not limited to long-term storage, and may be used for storage of commodities for any suitable period of time.  
         [0028]     Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.  
         [0029]     Reference is now made to  FIGS. 1A and 1B , which are illustrations of storage containers for a commodity, showing the relative permeability per volume for a single large bag versus multiple small bags. As shown in  FIG. 1A , a large storage container  10 , which can hold a particular volume V of commodity, will have a certain permeability per unit area, depicted by arrows  12 . As shown in  FIG. 1B , the same volume of commodity can be split up into several small bags  14 , wherein a fraction of the overall volume is present in each of small bags  14 . For the purpose of illustration, six small bags  14  are shown, each having a volume of V/6. The total permeability, as depicted by arrows  16 , will be greater for the six small bags  14  than for the large storage container  10 , since the overall surface area is greater. Thus, in order to enable use of smaller bags, overall permeability characteristics of the material must be decreased. For the purposes of the present invention, permeability refers to permeability to O 2 , CO 2  and water vapor. However, it should be readily apparent that overall permeability to other substances would similarly vary with bag size.  
         [0030]     In order to solve the problem of higher permeability associated with small storage containers, the present invention is directed to the use of an ultra-low permeability packaging material for purposes of long-term storage and transport of commodities. Although such materials are commonly used in the retail food industry, the low-permeability requirements of the materials used for retail packaging are much less demanding than long-term storage requirements. Thus, very small packages, on the order of less than 5 kg, are feasible for retail food packaging and are commonly used. However, the use of ultra-low permeability packaging materials for long-term storage and transport necessitates the use of storage containers which are significantly larger than retail food packages, but can be much smaller than the currently used long-term storage containers such as Cocoons™. These types of materials have not previously been used for long-term storage and transport.  
         [0031]     Reference is now made to  FIG. 2 , which is a cross-sectional illustration of a material  20  for use in accordance with one embodiment of the present invention. Material  20  includes an outer layer  22  and an inner layer  24 , with a middle layer  26  sandwiched between outer and inner layers  22  and  24 . In accordance with embodiments of the present invention, outer layer  22  and inner layer  24  are co-extruded with middle layer  26 . The purpose of middle layer  26  is to provide low permeability, while the outer and inner layers  22  and  24  are designed to add strength to middle layer  26 .  
         [0032]     In one embodiment, co-extruded plastic outer layer  22  and inner layer  24  are comprised of polymeric material, such as polyethylene, while middle layer  26  is comprised of a very low permeability material, such as, for example, nylon. An example of such a co-extruded material is Plastobarr N 80, manufactured and sold by Plastopil Ltd., Hazorea, Israel, originally designed for chemical and bacteriological warfare protection and now also used in retail vacuum packaging of meats, fish, or cheese (“vacuum pouches”) to preserve freshness, and also used in retail packaging for preserving freshness of fresh vegetables. This material includes a thin co-extruded flexible triple-layer material (PE/PA/PE), including an outer layer and an inner layer of one polymeric material (polyethylene), and a very low permeability middle layer sandwiched between the two outer layers.  
         [0033]     In some embodiments, any one or several of outer layer  22 , inner layer  24  and middle layer  26  may include multiple layers of material. In one embodiment, inner layer  24  is nylon. In another embodiment, inner layer  24  is EVOH. In yet another embodiment, middle layer  24  is comprised of a combination of two or more materials. For example, a material which has low permeability to oxygen, but not to moisture may be combined with a material which has low permeability to water but not to oxygen. It should be readily apparent that middle layer  24  may be comprised of any low permeability barrier material suitable for sandwiching between an outer layer and an inner layer.  
         [0034]     In one embodiment, material  20  may additionally include a coating or impregnation of a compound of botanic origin to improve resistance to insect penetration. An example of a natural pesticide suitable for impregnation or coating is an essential oil such as produced by Biopack, Ltd. (Caesaria, Israel) and described more fully in U.S. Patent Publication US2005-0208157, filed 5 Apr. 2004, Ser. No. 10/816,861 and Israel Patent Application Number 160950, both of which are incorporated herein by reference in their entireties. This insect repellent material is intended to further prevent possible insect penetration of the liner.  
         [0035]     Methods for impregnating plastic films with essential oils are known in the art, and are described in, for example, U.S. Patent Publication Number US-2005-0208157-A1. Specifically, a composition of matter suitable for fabricating polymer-based packaging materials can be generated by mixing ar-trumerone sesquiterpene alcohols and/or turmeric oleoresin solid residue with polymers as a melt, by solvent compounding, or by immobilization or covalently linking of these compounds to the polymers. A composition of matter suitable for fabricating paper based packaging materials can be generated by adding ar-turmerone sesquiterpene alcohols and/or turmeric oleoresin solid residue to a paper pulp emulsion or impregnating paper, paperboard or textile substances with these compounds using methods well known in the art (e.g. spraying, dipping). A composition-of-matter suitable for fabricating flexible packaging materials, composed mainly of laminates, can be generated by adding ar-turmerone, sesquiterpene alcohols and/or turmeric oleoresin solid residue to any adhesive or ink or lacquer or any other additive between the laminate layers or to any coating on the laminate.  
         [0036]     For non-food or feed products, such as seeds, a synthetic pesticide may be used, such as, for example, Deltamethrin (commercially available from Sumitomo Chemical Company, Tokyo, Japan), but with greater precautions and limitations because of potential toxicity.  
         [0037]     Bags manufactured from this or similar material will have a very low permeability to Oxygen, Carbon Dioxide, and water vapor, even when the total thickness is under 0.1 mm. Thus, the permeability per unit area for Oxygen is reduced 8 to 10 fold or more over the permeability per unit area of the Cocoons™ typically from 400 cc/m 2 /day to 50 cc/m 2 /day or less for oxygen, while maintaining water vapor permeability of 9 grams/m 2 /day or less. The term “ultra low permeability” for purposes of the present invention thus refers to permeability to Oxygen of less than 100 cc/m 2 /day and to water vapor less of than 15 g/m 2 /day. A container with ultra low permeability can have capacities ranging from 10 kg to 2,000 kg and preferably in a range of 20 kg to 1000 kg. The use of ultra low permeability containers enables the use of relatively small portable bags for hermetic storage and transport, which enhances portability, flexibility, and practicality as compared to hermetic storage and transport using Cocoons™.  
         [0038]     To compensate for the relative mechanical fragility of containers or bags such as the ones of the present invention, these containers may be used as liners inside protective outer containers for transport and handling, as illustrated in  FIG. 3  in cross section. As shown in  FIG. 3 , a commodity  30  is placed inside a long-term storage container  32 , comprised of ultra-low permeability material  20 . In one embodiment, long-term storage container  32  is capable of holding commodities within a range of 10-2000 kg. In one embodiment, long-term storage container  32  is capable of holding commodities within a range of 10-100 kg. In another embodiment, long-term storage container  32  is capable of holding commodities within a range of 250-2000 kg. Long-term storage container  32  is then placed in an outer container  34 , which is used for transport.  
         [0039]     Alternatively, material  20  is used to line outer container  34  prior to introduction of commodity  30  therein. Outer container  34  may be, for example, comprised of Jute (burlap) or woven polypropylene as conventionally used in the grain trade, typically containing around 50 kg of commodity, such as those commercially available from NYP Corp, Elizabeth, N.J., USA. Alternatively, outer container  34  may be a “Big Bag” designed for mechanized-handling typically up to 1000 kg capacity (commercially available from Palrig Plastic Industries, Kibbutz Naot Mordechai, Israel or B.A.G. Corp., Dallas, Tex., USA) or a similar bag designed for greater capacities. Any other suitable flexible transport bag, or a bin or box may be used as outer container  34 . In an alternative embodiment, multiple long-term storage containers  32  may be placed into one outer container  34 .  
         [0040]     Reference is now made to  FIG. 4 , which is a flowchart illustration of the steps of a method for storage and transport of commodities, in accordance with one embodiment of the present invention. First, the commodity is placed (step  101 ) into long-term storage container  32 , in one embodiment comprised of a triple layer co-extruded film, as described above. In another embodiment, the long-term storage container  32  additionally includes impregnated or coated insecticide. Next, long-term storage container  32  is hermetically sealed (step  102 ). The sealing can be done by twisting an open end of the container and clamping the twisted end. Alternatively, sealing can be done by rolling an open end of the container and clamping the rolled end. Hermetic sealing can also be accomplished by heat sealing an open end of the container. The steps of placing and sealing are repeated until the entire commodity is in a storage container  32 . Each of the long-term storage containers  32  is then placed (step  103 ) in one or more conventional protective outer containers  34  for protection in handling and transport. Infesting insects including eggs, larva, pupae, and adult insects at room temperature or above consume the available oxygen in a period of days to a few weeks and die in the same manner as in the previously referenced Cocoons™. The moisture level of the commodity remains substantially constant regardless of exterior humidity levels. Thus, commodities are hermetically enclosed in flexible portable containers which are insect-free and in which mold and fungus growth is inhibited due to maintaining sufficiently low moisture level and/or low Oxygen level as well as, in some cases, the protective effect of out-gassing of the commodity and the generation of CO 2  from the commodity and/or insects, while suitable for transport. Lastly, commodities which are inside storage containers  32  and further inside protective outer container  34  may be transported (step  104 ) by hand or by mechanized means. The transporting can be done by conventional bag handling methodologies, and may be done by placing the outer container into an unaltered standard shipping container.  
         [0041]     Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims. All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention.