WO2007140303A2

WO2007140303A2 - Absorbent pad for control of food pathogens

Info

Publication number: WO2007140303A2
Application number: PCT/US2007/069746
Authority: WO
Inventors: Dianne Eastman
Original assignee: Eastman Medical Products, Inc.
Priority date: 2006-05-26
Filing date: 2007-05-25
Publication date: 2007-12-06
Also published as: WO2007140303A3

Abstract

An absorbent pad for use with food packages comprising a first layer and a second layer. The first layer is fluid impermeable and the second layer is fluid permeable. The first layer is affixed to the second layer and forms a cavity therein. An absorbent material is disposed between the first layer and the second layer. The absorbent material is at least partially formed by a cross-linked acrylic polymer.

Description

ABSORBENT PAD FOR CONTROL OF FOOD PATHOGENS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application Serial No. 60/808,824 filed May 26, 2006 and U.S. Application Serial No. [Applied For] filed May 26, 2007. The teachings of all of the foregoing are incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] This invention is directed to an absorbent pad for control of food pathogens, and in particular, an absorbent pad for use in food packaging which removes the fluids away from the food to starve the pathogens within the pad.

[0003] It has been estimated that the contamination of meat and poultry products has caused over 36 million illnesses, 325 thousand hospitalizations, and five thousand deaths in a single year in the United States. Studies have shown that Salmonella is present in 16% of market chickens and Campylobacter has been found in 60-80% of retail chickens. Other diseases such as E. coli and Listeria are also associated with consumed meats. It has been estimated that the cost of infection from these and other diseases can be as high as $37 biiiioπ per year.

[0004] It has further been found that certain variants of E. coli can grow in temperatures of up to 112°F, are resistant to drying, can survive short exposures to strong acids and resist radiation and antibiotics. As many as 40% of slaughtered animals may be infected. These levels of infection pose major health problems, especially because the common antibiotics used in the food of animals in order to keep them healthy and in the treatment of human infections are becoming more and more ineffective with prolonged usage.

[0005] It is known that these infective pathogens thrive in the fluids associated with packaged foods. Non-human fluids, near the packaged meats, provide a feeding and breeding ground for these pathogens. Furthermore, because these pathogens feed on the meat itself, they form a biofilm around the meat, spoiling the meat; decreasing shelf life. As it was known in the art, that the fluids associated with packaged meats cause spoilage, certain devices are known in the art for either draining or wicking the fluids away from the meat while the meat is contained within the package.

[0006] Generally, absorbent pads are placed beneath the food products to wick the fluids away from the food product. One such prior art package known as a CPP pad is made from recycled paper packaging material such as cigarette cartons, candy bar containers and other types of materials frequently used for display packaging. This material may contain substantia! amounts of ink and other materials used to produce easily identifiable display packages. The material is ground, bleached and formed as coarse cellulose layers. A .01 ml polyethylene sheet is placed on either side of the cellulose layer to form the pad. The polyethylene sheets are welded together by pressure perforations. One polyethylene sheet is perforated. The cellulose layer absorbs the liquid entering through the perforated layer.

[0007] The second type of absorbent type is a WFP pad, which consists of a first polyethylene .01 ml sheet and a second .01 ml sheet attached to each other at the edges. One of the polyethylene sheets is again perforated. Between the external covers is virgin wood fluff capable of absorbing the fluid.

[0008] The prior art pads have been satisfactory, however, they suffer from the disadvantage that they have limited absorption capabilities and what fluid is absorbed by the absorbent material is easily released under pressure. As a result, packaged foods such as poultry frequently drip fluid containing bacterial contaminants which although may be wicked away, are then reintroduced into the package as a result of the weight of the food pressing down upon the pad. Some absorbent materials, such as that used in the type CPP pad may return as much as 90% of the absorbed fluid.

[0009] Accordingly, an absorbent pad, which overcomes the shortcomings of the prior art, is desired. BRIEF SUMMARY OF THE INVENTION

[0010] An absorbent pad includes a first fluid impermeable layer. A porous layer is affixed to the impermeable layer. Ge! forming polymer particles of high molecular weight cross-linked acrylic polymer are disposed between the first layer and the second layer. In the preferred embodiment, the polymer particles are capable of absorbing and immobilizing fluids to form an inert environment, which is non-viable for toxic bacteria present in the fluids.

[0011] In the preferred embodiment, the pad is placed within a container, the food being supported by the impermeable layer within the container.

[0012] During use, the non-human fluids associated with the food product drain towards a bottom of the container as a result of gravity. The liquid moves through the porous layer where it is absorbed by the absorbent polymer. In a preferred embodiment, an absorbent material having a higher absorbency than the polymer material, is disposed between the impenetrable layer and the porous layer to wick liquid through the porous layer. The polymer absorbs the fluid directly as well as from the absorbent material.

[0013] In another preferred embodiment, the polymer material forms honeycomb structures, the polymer particles being capable of absorbing at least 500 times their weight of fluid to form expanded gel particles for encapsulation and immobilization of the toxic bacteria. The pad including a quantity of polymer particles in a ratio of 1 gram per 100 ml of fluid entering the interior compartment.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In the drawing figures, which are not to scale, which are merely illustrative:

[0015] FIG. 1 is a schematic sectional diagram illustrating the absorbent pad constructed in accordance with the invention; and [0016] F!G. 2 is a graph showing the pathogen destroying effects of the pad constructed in accordance with the invention for three particular pathogens;

[0017] FIG. 3 is a graphical representation of the effect an absorbent pad constructed in accordance with the invention has on the shelf life of a food product in the presence of Campylobacter;

[0018] FiG. 4 is a graphical representation of the effect an absorbent pad constructed in accordance with the invention has on the shelf life of a food product in the presence of E. coli; and

[0019] FIG. 5 is a graphical representation of the effect an absorbent pad constructed in accordance with the invention has on the shelf life of a food product in the presence of Salmonella.

DETAILED DESCRIPTION OF THE INVENTION

[0020] Pad 10, as seen in Fig. 1 , includes a first layer 12 formed of a fluid impermeable sheet. A second layer 14 is formed of a porous material and is affixed to the impermeable layer to form a pouch or cavity 16 therebetween. A fill layer 18, formed of fluid absorbent materia!, is disposed within the cavity between porous layer 14 and impermeable layer 12.

[0021] Impermeable layer 12 may be formed of a polyethylene sheet. In a preferred embodiment, the impermeable layer 12 is .01 ml thick. Porous sheet 14 is preferably formed of a perforated layer or non-woven layer of polyethylene and is about .01 mi thick. Sheet 14 and sheet 12 are attached at the edges. It should be noted that any water impermeable, non-toxic or FDA approved material may be used.

[0022] In a preferred embodiment, the absorbent layer is formed of an acrylic cross-linked polymer. The polymer is capable of absorbing and retaining large amounts of fluid under high-pressure levels. In a preferred embodiment, the polymer is capable of absorbing at least 95-500 times its weight in fluid and capable of maintaining its absorption across a range of temperatures, from room temperature to about freezing.

[0023] In an exemplary non-limiting embodiment, the polymer is non-toxic and has substantially less than .01% of its molecular weight below 1000 Daltons. In a preferred embodiment, a polymer pad 18 is formed of a very high molecular weight anionic polymer produced by the reaction of a 2-propenamide (acrylamide) and 2- propeπoic acid (acrylic acid) plus a small portion of a bifunctional viny! cross-linking monomer to form an anionic acrylic cross-linked polymer. The result is a super absorbent polymer.

[0024] As discussed above, in a non-limiting preferred embodiment, the polymer-forming pad 18 is a high molecular weight polymer using the methylene bis- acrylamide cross-linked anionic polyacrylamide-copolymer. As a result of the cross- linker, the polymer forms a honeycomb structure of water absorbing, water swellable, and water insolubic gel-forming particles when it absorbs fluid. Walls are created surrounding each particle of free flowing, water absorbing, water-swellable, and water- insolubic gel. Individual particles are formed resulting in a tight honeycombed configuration. As a result, the retention properties of the polymer are substantial such that the polymer is capable of absorbing and retaining at least 500 times its weight of fluid.

[0025] Although the anionic polymer is much better than the prior art absorbent materials at retaining fluid, it is not as efficient in absorbing or wicking the fluid. Therefore, in a preferred embodiment, the absorbent layer is made of a combination of an anionic polymer and a material having a higher absorbent property than the anionic polymer. In a preferred embodiment, wood fluff fill is utilized but any absorbent material may be used.

[0026] By combining the two absorptive media in a single pad, the beneficial properties of both substances are employed to optimize pad performance. The wood fluff pulp in the pad acts to rapidly absorb and transport excess fluid into pad 10 while the super absorbent polymer retains this excess fluid even given external pressure.

[0027] The ratio of anionic polymer to super absorbent polymer to absorbing faster absorbing material, i.e., in this non-limiting preferred embodiment, anionic polymer to wood fluff fill, is governed by two factors: the minimum performance requirements of the pad (fluid absorption and retention) and the cost of construction (the cost of one material relative to the other). In the preferred embodiment, the pad will consist of the super absorbent polymer in amounts of 0.25 grams to 1.5 grams by weight. In one embodiment, 70% wood fluff fill and 30% polymer by weight was used.

[0028] During use, pad 10 is placed in a tray 22 as is known in the art. Generally, the trays are shallow, Styrofoam trays. The pad 10 is placed with the porous layer in facing relationship with tray 22. Food 24 is supported on impermeable layer 12. Liquids 20 naturally drain towards porous layer 14. The entire assembly may then be wrapped in a liquid barrier such as plastic wrap as known in the art. The wicking properties of the wicking material (wood fluff fill in a non-limiting example) and the super absorbent polymer draw liquid 20 through porous layer 14 to be absorbed and retained by the super absorbent polymer.

[0029] Because the water and the pathogens are maintained in the honeycomb celis of the polymer, the moisture-containing bacteria are stuck in the cells. The bacteria cannot migrate to find additional nutrition. As a result, whatever substance is trapped within the honeycombed walls of the polymer starve to death. Therefore, bacteriastic agents or deodorization are not required because the polymer, by trapping and killing the bacteria, prevents formation of the biofilm and provides the bacteriastic agent.

[0030] By trapping and killing the pathogens, the shelf life of the product utilizing the absorbent pad constructed in accordance with the invention is greatly extended. Reference is now made to Figs. 2-5. As can be seen from Fig. 2, the absorbent pad, constructed in accordance with the invention (indicated as Eastman Polymer) in an embodiment utilizing 1 gram of polymer as part of the absorbent material, significantly reduces the presence the E. coli, Salmonella and Campylobacter as compared to the pads as constructed in accordance with the prior art. As seen from Fig, 2, the median number of pathogen colonies found at the food after 11 days at 8° C was almost negligible for E. coli and Campylobacter, and insignificant as compared to the amount of colonies found with the food stored with the prior art pads in the case of Salmonella. As a result, the shelf life of the packaged food is greatly extended.

[0031] Reference is now made to Figs. 3-5 in which the time period for which the number of pathogens present in the food remains at an ineffective dose is provided. As can be seen, in Fig. 2, the shelf life for food with respect to Campylobacter is extended from just over 9 days to more than 13 days, utilizing the absorbent pad constructed in accordance with the invention. Similarly, shelf life of food with respect to the presence of E. coli is extended from 11 days to about 13 days and Salmonella is also extended.

[0032] It should be noted, that the gel matrix encapsulates, immobilizes toxic viruses and fungi within the inert environment as well as bacteria. Therefore, fungi and viruses are unable to multiply or obtain nutrition from the inert environment within the gel matrix. They die as well.

[^QQ33] !t should be noted that the effective polymers for the present invention are cross-linked anionic poryacrylamides. As used herein, the term "polyacrylamide" includes polymers and copolymers of acrylamide. The copolymers include acrylamide-potassium acrylate and acrylamide acrylate. Other polymers may be employed such as potassium propenoatepropenamide copolymer and various grafted copolymers. It is preferable that polymer particles be formed of a material, which is capable of absorbing at least ten times and preferably over 100 to 500 times or more of their own weight in water. It is also preferable that these polymers maintain their integrity so as not to release fluids contained therein, even under pressure.

[0034] It should become readily apparent, that it is well within the scope of the invention to provide the polymer in container 22, i.e., integrated into the materials of the container, whether it be Styrofoam, cardboard, plastic, cellophane, polyurethane, or any other material capable of maintaining a food product therein. Furthermore, the food is wrapped, normally with a film wrap. This wrap may also contain the polymer to provide further pathogen-isolating activity within the container.

[0035] Thus, while there have been shown, described and pointed out novel features of the present invention as applied to preferred embodiments thereof, it will be understood that various omissions and substitutions and changes in the form and detail are contemplated so that the disclosed invention may be made by those skilled in the art without departing from the spirit and scope of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto. It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention, which, as a matter of language, might be said to fall therebetween. In particular, the invention should not be construed as being limited to the use of specific steps, or structures, as disclosed herein.

Claims

CLAIMSWhat is claimed as new and desired to be protected by Letters Patent of the United States is:

1. An absorbent pad for use with food packages comprising: a first layer; a second layer, said first layer being fluid impermeable and the second layer being fluid permeable, said first layer being affixed to said second layer to form a cavity therein; an absorbent material disposed between said first layer and said second layer, said absorbent material being at least partially formed by a cross- linked acrylic polymer.

2. The absorbent pad of claim 1 , wherein said fluid permeable layer is formed of a fluid impermeable material having perforations therein.

3. The absorbent pad of claim 1 , wherein said fluid permeable layer is formed of a non-woven fluid impervious material.

4. The absorbent pad of claim 1 , wherein said absorbent material further includes a second material having a higher absorbency than the poiymer.

5. The absorbent pad of claim 1 , wherein said polymer particles are capable of absorbing at least 500 times their weight of fluid.

6. The absorbent pad of claim 1 , wherein the polymer is formed of particles, the particles forming a honeycombed structure upon absorption of water.

7. A food package including: a tray; an absorbent pad disposed in the tray, the absorbent pad adapted to be received by the tray and for food to be disposed thereon, the absorbent pad having a first layer, a second layer, said first layer being fluid impermeable and the second layer being fluid permeable, said first layer being affixed to said second layer to form a cavity therein, an absorbent material disposed between said first layer and said second layer, said absorbent material being at least partially formed by a cross-linked acrylic polymer; and a wrap adapted to wrap food within the tray upon the absorbent pad.

8. The food package of claim 7, wherein said fluid permeable layer is formed of a fluid impermeable material having perforations therein.

9. The food package of claim 7, wherein said fluid permeable layer is formed of a non-woven fluid impervious material.

10. The food package of claim 7, wherein said absorbent material further includes a second material having a higher absorbency than the polymer.

11. The food package of claim 7, wherein said polymer is formed of particles, said particles being capable of absorbing at least 500 times their weight of fluid.

12. The food package of claim 7, wherein the polymer forms particles, the particles forming a honeycombed structure upon absorption of water.

13. A method for extending the shelf life of a food product, the food product having non-human fluids associated therewith comprising the steps of: providing a container; providing an absorbent pad having a first layer a second layer, said first layer being fluid impermeable and the second layer being fluid permeable, said first layer being affixed to said second layer to form a cavity therein, and an absorbent material disposed between said first layer and said second layer, said absorbent material being at least partially formed by a cross-linked acrylic polymer; providing a food having associated non-human liquids on the pad; and enclosing the container.

14. The method of claim 13, wherein said fluid permeable layer is formed of a fluid impermeable materia! having perforations therein.

15. The method of claim 13, wherein said fluid permeable layer is formed of a non-woven fluid impervious material.

16. The method of claim 13, wherein said absorbent material further includes a second material having a higher absorbency than the polymer.

17. The method of claim 13, wherein said polymer is formed of particles, said particles being capable of absorbing at least 500 times their weight of fluid.

18. The method of claim 13, wherein the polymer is formed of particles, the particles forming a honeycombed structure upon absorption of water.

19. The method of claim 13, further comprising the step of enclosing said food with a wrap, wherein said wrap includes an acrylic cross-linked polymer.

20. The method of claim 13, wherein said container is formed with an acrylic cross-linked polymer.

21. The method of claim 13, wherein said polymer is an anionic acrylamide acrylate copolymer.

22. The method of claim 13, wherein the interior compartment of the container has a fluid capacity of at least 100 ml.

23. The method of claim 13, wherein said absorbent material includes a predetermined quantity of free-flowing, water absorbing, water swellable, water insoluble gel forming polymer particles of high molecular weight cross-linked anionic acrylamide polymer capable of absorbing at least 500 times its own weight of fluid.

24. A method of absorbing fluid draining from food within a package comprising the steps of: providing an absorbent pad; a first layer; a second layer, said first layer being fluid impermeable and the second layer being fluid permeable, said first layer being affixed to said second layer to form a cavity therein; an absorbent material disposed between said first layer and said second layer, said absorbent material being at least partially formed by a cross- linked acrylic polymer; and providing a food having associated non-human liquids adjacent the pad.

25. The method of claim 24, wherein said fluid permeable layer is formed of a fluid impermeable material having perforations therein.

26. The method of claim 24, wherein said fluid permeable layer is formed of a non-woven fluid impervious material.

27. The method of claim 24, wherein said absorbent material further includes a second material having a higher absorbency than the polymer.

28. The method of claim 24, wherein said polymer particles are capable of absorbing at least 500 times their weight of fluid.

29. The method of claim 24, wherein the polymer forms particles, the particles forming a honeycombed structure upon absorption of water.

30. The method of claim 24, wherein said absorbent pad is a wrapping material, the wrapping material including an acrylic cross-linked polymer.

31. The method of claim 24, wherein said container is formed with an acrylic cross-linked polymer.

32. The method of claim 24, further comprising the step of providing a container, the absorbent pad being placed in the container,

33. The method of claim 24, wherein said polymer is an anionic acrylamide acrylate copolymer.

34. The method of claim 24, wherein the interior compartment of the container has a fluid capacity of at least 100 ml.

35. The method of claim 24, wherein said absorbent material includes a predetermined quantity of free-flowing, water absorbing, water swellable, water insolubic, gel forming polymer particles of high molecular weight cross-linked anionic acrylamide polymer capable of absorbing at least 500 times its own weight of fluid.

36. A method of absorbing fluid associated with a food, comprising the step of wrapping the food, the wrap containing an anionic acrylamide polymer.

37. The method of claim 36, wherein said wrap includes a predetermined quantity of free flowing, water absorbing, water swellable, water insolubic, gel forming polymer particles of high molecular weight cross-linked polymer capable of absorbing at least 500 times its own weight of fiuid.