Patent Publication Number: US-2013243912-A1

Title: Food Package

Description:
BACKGROUND OF THE DISCLOSURE 
     1. Field of Disclosure 
     The present disclosure relates to a food package that has an absorbent pad that is substantially compostable. The present disclosure further relates to a food package in which all components are substantially compostable. 
     2. Description of Related Art 
     Conventional food packages are typically composed of materials that are not compostable. Such packages typically take the form of film, sheet, and/or foam stock and are usually made from olefin-based polymers, such as polyethylene and polypropylene, or other thermoplastics, such as polyester. 
     Absorbent pads are frequently used in foods, such as meat packages, to absorb liquid leaked from the article of food. A typical absorbent pad has facing layers with a core layer in between that is made up of an absorbent or superabsorbent material. Absorbent pads are formed with the same or different materials as the remainder of a food package. For instance, the facing layers of pads are commonly formed with perforated thermoplastic films of polyethylene, polypropylene, and polyester or from paper-based and/or wood fiber materials. 
     Absorbent or superabsorbent materials most commonly employed in the absorbent pads are polyacrylic acids/acrylates. Polyacrylic acids/acrylates are very effective in absorbing liquids but commonly leave toxic residue after biodegradation, which renders them not compostable. Further, adhesives commonly employed to hold together the facing layers of absorbent pads, such as an elastomer, a thermoplastic, an emulsion, and a thermosetting material based on polyvinyl acetate, epoxy, polyurethane, and cyanoacrylate polymers, are not compostable as they likewise leave a toxic residue after biodegradation. 
     It would further be desirable to have an absorbent pad for a food package having one or more components formed with compostable materials. It would also be desirable to have a food package constructed entirely of compostable materials. 
     SUMMARY OF THE DISCLOSURE 
     According to the present disclosure, there is provided a food package. The package has a tray; an absorbent pad formed with a surface-treated carboxyalkylated polysaccharide; a wrap; and a food product. The pad is positioned flush with respect to and adjacent the tray. The food product is positioned contiguous to the pad at a first face of the pad opposite that of a second face of the pad adjacent the tray. The pad can absorb or adsorb all or a portion of any liquid that leaks from the food product. The wrap is positioned around the tray, the pad, and the food product so as to substantially seal and prevent leakage of liquid of the food product from the package. 
     Further according to the present disclosure, there is provided another embodiment of a package suitable for retaining foods. The package has a receptacle formed with one or more compostable polymers and an absorbent pad formed with a surface-treated carboxyalkylated polysaccharide; a wrap; and a food product. The pad is positioned in the receptacle and can absorb or adsorb all or a portion of any liquid leaked from an article retained within the receptacle. 
     Further according to the present disclosure, there is provided another embodiment of a food package. The package has: (i) a tray formed with one or more compostable polymers; (ii) formed with one or more compostable polymers; (iii) a wrap formed with one or more compostable polymers; and (iv) a food product. The pad is positioned flush with respect to and adjacent the tray. The article is positioned contiguous to the pad at a first face of the pad opposite that of a second face of the pad adjacent the tray. The pad can absorb or adsorb all or a portion of any liquid that leaks from the article. The wrap is positioned around the tray, the pad, and the article so as to substantially seal and prevent leakage of liquid from the package. 
     Further according to the present disclosure, there is provided another embodiment of a package suitable for retaining foods. The package has a receptacle formed with one or more compostable polymers and an absorbent pad formed with one or more compostable polymers. The pad is positioned in the receptacle and can absorb or adsorb all or a portion of any liquid leaked from an article retained within the receptacle. 
     According to the present disclosure, there is provided another embodiment of a package suitable for retaining foods. The package has a tray; an absorbent pad formed with layers or a pouch of a cellulose tissue having a basis weight range of about 12 pounds to about 16.5 pounds and a wet strength of about 2.5 pounds/ton to about 3.8 pounds/ton; a wrap; and a food product. The pad is positioned flush with respect to and adjacent the tray. The food product is positioned contiguous to the pad at a first face of the pad opposite that of a second face of the pad adjacent the tray. The pad can absorb or adsorb all or a portion of any liquid that leaks from the food product. The wrap is positioned around the tray, the pad, and the food product so as to substantially seal and prevent leakage of liquid of the food product from the package. 
     Further according to the present disclosure, there is provided another embodiment of a package suitable for retaining foods. The package has a receptacle formed with one or more compostable polymers and an absorbent pad formed with layers or a pouch of a cellulose tissue having a basis weight range of about 12 pounds to about 16.5 pounds and a wet strength of about 2.5 pounds/ton to about 3.8 pounds/ton. The pad is positioned in the receptacle and can absorb or adsorb all or a portion of any liquid leaked from an article retained within the receptacle. 
     Further according to the present disclosure, there is provided another embodiment of a food package. The package has: (i) a tray; (ii) an absorbent pad formed with one or more compostable polymers; (iii) a wrap; and (iv) a food product. The pad is positioned flush with respect to and adjacent the tray. The article is positioned contiguous to the pad at a first face of the pad opposite that of a second face of the pad adjacent the tray. The pad can absorb or adsorb all or a portion of any liquid that leaks from the article. The wrap is positioned around the tray, the pad, and the article so as to substantially seal and prevent leakage of liquid from the package. 
     Further according to the present disclosure, there is provided another embodiment of a package suitable for retaining foods. The package has a receptacle and an absorbent pad formed with one or more compostable polymers. The pad is positioned in the receptacle and can absorb or adsorb all or a portion of any liquid leaked from an article retained within the receptacle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a food package of the present disclosure having the food product therein. 
         FIG. 2  is a cross-section of the food package of  FIG. 1  having the food product therein. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     A food package in accordance with the present disclosure is generally referenced herein by the numeral  10  and is shown in  FIG. 1 . Package  10  has a tray  12 , an absorbent pad  14 , and a wrap  16 . Package  10  is can display and store a food product  18 , such as meat, as shown in  FIG. 1 . Pad  14  has a core layer  20  and facing layers  22  and  24  as shown in  FIG. 2 . Core layer  20  is made up of a superabsorbent material, preferably a powdered or granulated material. Facing layers  22  and  24  substantially envelop core  20  to provide for retention of the superabsorbent material in pad  14 . 
     A compostable polymer is one that capable of undergoing biological decomposition in a compost site such that the polymer is not visually distinguishable and breaks down to carbon dioxide, water, inorganic compounds, and biomass, at a rate not substantially greater than that of known compostable materials (e.g., cellulose) and leaves substantially no toxic residue. Biological decomposition can occur as the result of the action of naturally occurring microorganisms, such as bacteria, and fungi. Most preferably, the compostable polymer breaks down at substantially the same rate as cellulose (paper), is ultimately not visible, does not need to be screened out, and can support plant growth. Compostability can be determined according to ASTM D6400 and D6868. 
     Compostability differs from biodegradability in that biodegradability does not have a decomposition time requirement or a requirement of leaving no toxic residue. Degradation requires that a polymer undergo a significant change in chemical structure under specific environmental conditions resulting in loss of some properties. Compostability differs from degradation in that degradation does not require that the polymer degrade from the action of naturally occurring microorganisms. 
     Compostable polymers are useful in forming the package of the present disclosure. Compostable polymers can be obtained from natural sources or manufactured synthetically. Useful natural sources include sugar cane, wheat grass, corn/potato starch, tapioca extract, and baggase. 
     Useful compostable polymers include the following: poly(hydroxyalkanoic acids) (alternately referred to as poly(hydroxyalkanoates and abbreviated as PHA); a poly(lactic acid) (PLA); a polyesteramide (PEA); polycaprolactone; a biodegradable aliphatic copolyester; a biodegradable aromatic copolyester; and a natural polymer. 
     Useful poly(hydroxyalkanoic acids) may be a homopolymer or copolymer having at least one comonomer derived from a hydroxyalkanoic acid or a derivative thereof. A derivative is a hydroxyalkanoate or a cyclic dimer (e.g., a lactide dimer) derived from the reaction between two hydroxyalkanoic acids. Blends of such polymers are also useful. 
     For example, the poly(hydroxyalkanoic acid) polymer may be a blend of copolymers of such as poly(hydroxybutyric acid-hydroxyvaleric acid) copolymers and poly(glycolic acid-lactic acid) copolymers. Such copolymers can be prepared by catalyzed copolymerization of a poly(hydroxyalkanoic acid) or derivative with one or more comonomers derived from cyclic esters and/or dimeric cyclic esters. Such esters may include glycolide (1,4-dioxane-2,5-dione); the dimeric cyclic ester of glycolic acid; lactide (3,6-dimethyl-1,4-dioxane-2,5-dione); α,α-dimethyl-β-propiolactone; the cyclic ester of 2,2-dimethyl-3-hydroxy-propanoic acid; β-butyrolactone; the cyclic ester of 3-hydroxybutyric acid; δ-valerolactone; the cyclic ester of 5-hydroxypentanoic acid; ε-capro-lactone; the cyclic ester of 6-hydroxyhexanoic acid; the lactone of the methyl substituted derivatives of 6-hydroxyhexanoic acid (such as 2-methyl-6-hydroxyhexanoic acid, 3-methyl-6-hydroxyhexanoic acid, 4-methyl-6-hydroxyhexanoic acid, 3,3,5-trimethyl-6-hydroxyhexanoic acid, and etc.); the cyclic ester of 12-hydroxy-dodecanoic acid and 2-p-dioxanone; and the cyclic ester of 2-(2-hydroxyethyl)-glycolic acid. 
     The poly(hydroxyalkanoic acid) polymers may also be copolymers of one or more hydroxyalkanoic acid monomers or derivatives with other comonomers, such as aliphatic and aromatic diacid and diol monomers (e.g., succinic acid, adipic acid, terephthalic acid, ethylene glycol, 1,3-propanediol, and 1,4-butanediol). 
     Preferably, the poly(hydroxyalkanoic acid) is a poly(glycolic acid), a poly(lactic acid) (PLA), a poly(hydroxybutyrate) or combinations of two or more of these polymers. More preferably, the poly(hydroxyalkanoic acid) is a poly(lactic acid) having a number average molecular weight (M n ) of about 3,000 to about 1,000,000. Preferably, M n  is about 10,000 to about 700,000 and more preferably about 20,000 to about 600,000. 
     The poly(lactic acid) may be a homopolymer or a copolymer containing at least about 50 mol % or at least about 70 mol %, of copolymerized units derived from lactic acid or derivatives thereof. The poly(lactic acid) homopolymers or copolymers can be prepared from the two optical monomers D-lactic acid and L-lactic acid, or a mixture thereof (including a racemic mixture thereof). The poly(lactic acid) copolymer may be a random copolymer or a block copolymer or a stereo block copolymer or a stereo complex between optical blocks. For example, the poly(lactic acid) copolymer may be the stereo complex of about 50% of poly(D-lactic acid) and about 50% of poly(L-lactic acid). 
     Useful natural polymers include thermoplastic starch, cellulose, polysaccharide gums, and protein. 
     Examples of starches and starch derivatives include modified starches, cationic and anionic starches; starch esters such as starch acetate; starch hydroxyethyl ether; alkyl starches; dextrins; amine starches; phosphates starches; and dialdehyde starches. 
     Preferred starch-based materials are surface-treated carboxyalkylated polysaccharides, interchangeably referred herein to as surface-treated carboxyalkylated starches. Such surface-treated carboxyalkylated polysaccharides are generally prepared by carboxyalkylating a starch-based material or feedstock followed by purification and surface treatment. Surface treatment refers to chemical or physical modification. 
     To improve absorption under load (AUL) characteristics, the surface-treated carboxyalkylated polysaccharides are chemically modified by reaction with a carboxyalkylating agent. The carboxyalkylating agent is preferably a carboxymethylating agent. The carboxyalkyl groups may be either in their neutral carboxylic form or in the form of carboxylate ions. 
     A typical carboxyalkylation reaction is as follows: 
       Starch-(OH) 3   +m X—(CH 2 ) y —CO 2 Z+WHO→Starch-[(O(CH 2 ) y —CO 2 Z) m ][OH] 3-m   +m WX
 
     wherein:
 
Y is an integer ranging from 1 to 4; X is selected from the group consisting of Cl, Br and I; W is an alkali metal; m is a numerical value ranging from 0.3 to 1.5; and Z is selected from the group consisting of H, alkali metal, ammonium and organic ammonium.
 
     Useful carboxyalkylating agents include biobased and/or non-biobased haloacids and/or salts thereof. A useful acid is monochloroacetic acid. 
     Optionally, carboxyalkylated polysaccharides are cross-linked. Cross-linking may be performed before, during, or after the carboxyalkylation step. In cross-linking, the surface of the carboxyalkylated polysaccharides is treated with a cross-linking agent. Non-limiting examples of cross-linking agents include citric acid, aluminum ions (Al 3+ ), and epichlorohydrin. 
     The carboxylated polysaccharides are then surface treated. Examples of surface treatment agents include cross-linkers, non-cross-linking acids and combinations thereof. Examples of non-crosslinking acids include monovalent acids, such as hydrochloric acid, acetic acid, glycolic acid and stearic acid. Surface treatment is performed by treating the surface of the carboxyalkylated polysaccharides with a solution having the surface treatment agent. Examples of such solvent systems include hydrophilic organic solvents and hydrophilic organic solvent/water mixtures. Most surface treatments are carried out in conjunction with a heating step. 
     A particularly useful starch-based material is BioSAP™ (Archer-Daniels Midland, Decatur, Ill.), which is biodegradable and compostable. Additional teachings to the surface-treated, carboxyalkylated polysaccharides are disclosed in U.S. Published Patent Application No. 2008/0177057 A1, which is incorporated herein by reference in its entirety. 
     Examples of derivatives of cellulose include a cellulosic ester (e.g., cellulose formate, cellulose acetate, cellulose diacetate, cellulose propionate, cellulose butyrate, cellulose valerate, mixed esters, and mixtures thereof) and cellulosic ethers (e.g., methylhydroxyethylcellulose, hydroxymethylethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxyethylpropylcellulose, or any combinations thereof). 
     Other useful polysaccharide-based polymers include an alginic acid, alginate, phycocolloid, agar, gum arabic, guar gum, acacia gum, carrageenan gum, furcellaran gum, ghatti gum, psyllium gum, quince gum, tamarind gum, locust bean gum, gum karaya, xanthan gum, and gum tragacanth, or any combination or derivative thereof. 
     Suitable protein-based polymers include Zein (prolamines derived from corn), collagen (extracted from animal connective tissue and bones) and derivatives thereof such as gelatin, glue, casein (the principle protein in cow milk), sunflower protein, egg protein, soybean protein, vegetable gelatin, gluten, or any combination or derivative thereof. 
     An embodiment of the package of the present disclosure is made up of entirely of compostable, biodegradable materials. 
     The absorbent pad takes the general form of a pouch or facing layers with one or more sealed edges. If desired, one or more edges of the pouch or facing layers can be left open so long as there is sufficient physical integrity to maintain the pouch or facing layers. The pad has one or more absorbent core layers that are made up of absorbent and/or superabsorbent materials. The superabsorbent materials can take the form of any of the aforementioned compostable polymers. A preferred material for the core layer is the BioSAP™ starch-based polymer. Preferably, the absorbent/superabsorbent material takes the form of a powder and/or granules to enhance absorption and particle/liquid interfacial contact within the absorbent pad. The compostable material used in the pouch or facing layers may be the same or different than the material used in the absorbent core. 
     Facing layers may take the form of one or more film or tissue layers. The facing layers may be composed of compostable polymers disclosed herein or compostable polymers derived from cellulose or paper-based materials originating from wood fiber, such as cellulose. Facing layers may take the form of a tissue or sheet. Tissue may be of woven or non-woven fibers. Tissue may be bleached or natural (unbleached). Processed tissues such as coffee filter tissue (CFT) may also be used. When compostable polymers are used in facing layers in the form of a film, the film may be perforated or unperforated. Perforated films are preferred. Pouches may be formed of the same materials as facing layers. 
     While tissue formed with cellulose is inherently biodegradable and compostable, it must have the strength to withstand tensions and stresses induced during manufacture and conditions of use. The tissue must also have the strength to allow moisture to pass through it and be held inside the pad without breaking down during the time the pad is in the food package. Additionally, some consumers may freeze the food package without opening it, which means the pad will remain in contact with food and moisture for long periods of time. Further, the tissue must be able to decompose in the period specified by compostability regulations. 
     For tissue, two primary physical characteristics are typically balanced: basis weight and wet strength. Basis weight corresponds to the weight (or thickness) of the tissue sheet. Wet strength corresponds to the strength of the tissue when wet. The physical characteristics must be balanced against the need for compostability. For instance, a heavy sheet may be a good choice for ease of manufacture, but its mass may be large enough that it may not decompose in sufficient time to be considered compostable. 
     For wet strength, a synthetic substance, e.g., a resin, is added to the tissue to allow the tissue to maintain physical integrity long enough to serve its function as layers or a pouch in the pad. If there is too much resin, will the pad will not decompose in quickly enough to be considered compostable. If there is too little resin, then the pad will physically break down before it has fulfilled its function. 
     A typical wet-strength resin is a polyamide-epichlorohydrin (PAE) resin at alkaline pH. PAE resins provide specific tissue properties, have a high level of wet strength permanence, and improve machine efficiency. During the curing process, cationic functional groups on the resin react with cellulose fiber to form a covalent bond. Resin molecules also cross-link to form a network in the cellulose web that provides strength when the paper becomes wet. Additionally, resins can reinforce existing fiber-to-fiber bonds, which also enhance the strength of the paper when it is wet. 
     An embodiment of an absorbent pad is a “low wet” strength flat tissue, such as, but not limited to, coffee filter tissue and laboratory filter paper as the facing layers. Such tissue must be manufactured to degrade in the composting certification testing within defined parameters. Important parameters include porosity, particle retention, flow rate, strength, compatibility, efficiency, and capacity. A small amount of a wet strength resin may be required in the tissue to ensure the structure maintains physical integrity when wet, but the amount used will be minimal to ensure breakdown under compost conditions. Laboratory filter paper comes in various porosities and grades depending on the applications for which it is made. 
     For the absorbent pad to be truly compostable, any adhesive used to hold it together at the edges thereof must be compostable or be present in an amount so as to not render the pad non-compostable. Adhesives or glues that are petroleum-based generally are typically not compostable. Suitable adhesives and glues for use in the present disclosure include animal-based binders and glues and wax-based glues. Animal glues are adhesives created by prolonged boiling of animal connective tissue. Protein colloid glues are formed through hydrolysis of the collagen from skins, bones, tendons, and other tissue, similar to gelatin. The proteins form a molecular bond with the object. 
     Alternatively, the absorbent pad can be held together by mechanical means at the edges without any glues or adhesives. Useful mechanical means include stitching, crimping, and intermittent perforations. Mechanical means may reduce or eliminate the need to use adhesives to assemble the pad. The pad also may also be held together by bonding edges using ultrasound or thermal bonding (heat sealing). 
     Any melt processing technique known in the art can be used to fabricate the compostable polymers. Examples of such techniques include blowing, injection molding, cast extrusion, extrusion blow molding, injection stretch blow molding, calendaring, extrusion foaming, thermoforming, stamping, and spinning. It should be understood that the foregoing description is only illustrative of the present disclosure. 
     Useful product forms from which components of the package can be formed include polymer film, sheet, and foam. A wrap typically takes the form of an unfoamed film and is typically transparent or translucent to afford easy visual inspection of the food product. A tray or receptacle may be formed with foamed or unfoamed sheet and is typically thermoformed or stamped into a desired shape. 
     The food package of the present disclosure is assembled by placing an absorbent pad onto a tray, placing the food product onto the absorbent pad and the tray, and wrapping the pad, the tray, and the food product to seal them. The wrap may extend entirely or partly underneath the tray. 
     The package of the present disclosure is useful for displaying and storing conventional food products, including meat products. Suitable meat products include poultry, beef, lamb, pork, and fish. Other suitable food products include produce and fruits. 
     In embodiments of the present disclosure in which it is desired that components (e.g., tray, wrap, or pad) of a food package be formed entirely or partly with polymers that are not necessarily biodegradable of not compostable, such components can be formed with conventional plastics or polymers, such as polyethylene, polystyrene, polyester, polyvinyl chloride, polyvinylidene chloride, and copolymers of constituent monomers thereof. Conventional non-biodegradable or non-compostable adhesives may also be substituted for biodegradable or compostable adhesives in those embodiments in which biodegradability or compostability is not required for all components of the package. 
     The following are examples of the present disclosure and are not to be construed as limiting. 
     EXAMPLES 
     Cellulose tissues having different basis weights and different wet strengths were tested for runnability, performance, and compostability. The results are set forth in the Table below. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 
               
               
                   
               
               
                 Basis 
                 Wet 
                   
                   
                   
               
               
                 Weight 
                 Strength 
                 Runnability 
                 Compostability 
                 Performance 
               
               
                   
               
             
            
               
                 18.5 
                 9.5 
                 Y 
                 N 
                 Y 
               
               
                 18.5 
                 5.6 
                 Y 
                 N 
                 Y 
               
               
                 16.5 
                 9.5 
                 Y 
                 N 
                 Y 
               
               
                 16.5 
                 5.6 
                 Y 
                 N 
                 Y 
               
               
                 16.5 
                 3.8 
                 Y 
                 Y 
                 Y 
               
               
                 14.5 
                 5.6 
                 Y 
                 N 
                 Y 
               
               
                 14.5 
                 3.8 
                 Y 
                 Y 
                 Y 
               
               
                 14.5 
                 2.5 
                 N 
                 Y 
                 N 
               
               
                   
               
            
           
         
       
     
     Based on the foregoing, a preferred cellulose tissue has a basis weight range of about 12 pounds to about 16.5 pounds and a wet strength of about 2.5 pounds/ton to about 3.8 pounds/ton. Basis weight range is the weight in pounds of a given number of sheets of a given size typically measured under ASTM D646. Wet strength is pounds of wet strength resin per ton of cellulose tissue and is determined according to Wet Tensile Breaking Strength tests set forth in ASTM D829. 
     Various alternatives and modifications can be devised by those skilled in the art without departing from the disclosure. Accordingly, the present disclosure is intended to embrace all such alternatives, modifications and variances that fall within the scope of the appended claims.