Fabric (woven – knitted – or nonwoven textile or cloth – etc.) – Coated or impregnated woven – knit – or nonwoven fabric which... – Coating or impregnation is water absorbency-increasing or...
Reexamination Certificate
1999-02-25
2002-02-26
Morris, Terrel (Department: 1771)
Fabric (woven, knitted, or nonwoven textile or cloth, etc.)
Coated or impregnated woven, knit, or nonwoven fabric which...
Coating or impregnation is water absorbency-increasing or...
C442S123000, C442S385000, C442S393000, C062S529000, C062S530000, C426S124000, C604S367000, C604S378000, C428S074000
Reexamination Certificate
active
06350710
ABSTRACT:
The invention relates to a new and improved absorbent insert for foodstuff packagings, especially for meat, poultry and fish. It consists of a flat pouch made of a water-permeable film and has a filling which at least in part is composed of a superabsorbent polymer having high gel stability, high retention and a low ratio of solubles. The insert is remarkable for its rapid and sustained absorption of liquid exuding from the foodstuff, and it extends the preserving period by effectively preventing microbial growth. In addition, the inserts soaked with water, when they are in the frozen state, are excellently suited as an ice substitute for refrigerating foodstuffs.
Foodstuffs are frequently presented in a prepacked form on the market. Such packagings consist predominantly of flat trays, wherein the foodstuff is covered externally by air-, water- and odorproof films. As a result, neither the aqueous constituents present in the foodstuffs nor those adhering due to previous washing can escape from the packagings. An optically quite impressive sight is the accumulation of liquid at the contact surface between the film and red meat. On the one hand, this makes the packaged foodstuffs appear unappetizing as a consequence and, because of the ingredients exuding from the foodstuffs together with the liquids, gives rise to microbial growth affecting the preserving period and, in addition, is a source of microbial infections. The high contamination of poultry with bacteria of the Salmonella class is generally familiar.
To overcome these problems, absorbent substrates for packaged foodstuffs have been developed, which are predominantly composed of multiple layers of cellulose. In practice, however, it was found that these substrates do not meet the requirements with respect to absorptive capacity and retention capability under the weight of foodstuffs resting on them.
Thus, for example, a normally six-ply layer of cellulose wadding with the dimensions 7×10 cm is capable of absorbing only about from 8 to 10 g of liquid at maximum. Now, when a piece of meat is packed in a packaging tray and kept for sale in a refrigerated display case, up to 10% of the net weight may be released as meat juice and hence, up to 50 g in the case of a 500 g piece of meat. Such a quantity surpasses by far the absorptive capacity of the absorbent layer made of cellulose fleece. As a result, there is bacterial growth on these moist, non-sterile substrates, impairing the keeping quality of the foodstuff.
Therefore, a number of efforts have been made to develop packaging systems in order to remove the liquid exuded by foodstuff from that foodstuff by absorption, so that no nutrients would be available for bacterial growth.
DE 3,034,170 C2 describes a water-adsorbing insert for foodstuff packagings, especially for meat, poultry, fish, and sausages, which contains a mixture of diatomaceous earth and aerosil in a flat pouch made of a water-permeable film. Because the inorganic filling material merely adsorbs the liquid, its absorptive capacity is low, i.e., uneconomically high amounts of adsorbent are required for sufficient liquid binding, thereby undesirably increasing the weight of the packaging. Another drawback of the inorganic adsorbers is their incapability of retaining the adsorbed liquid over a long time or under pressure load.
DE 3,034,169 C2 suggests mixtures of diatomaceous earth and an organic gel-forming agent as filling material for water-adsorbing inserts of foodstuff packagings, wherein carboxymethylcellulose, cellulose ethers, polyvinylpyrrolidone, starch, dextrose, gelatin and/or pectins are mentioned. The ratio of organic gel-forming agents is reported to be around 20 wt.-%. As a result of the high ratio of solubles and the extremely slow swelling rate of the above-mentioned compounds, the use of such adsorbing inserts for foodstuff must be regarded as critical. Solubles of the organic gel-forming agents reduce the swelling capacity thereof and may migrate out of the insert and contact the foodstuffs; slow swelling rates obstruct effective absorption of the liquid in the packaging, so that leaking of accumulated liquid may occur.
EP 302,504 B1 suggests an absorbent pad which may be arranged in a packaging under foodstuff tending to exude liquid, e.g., meat, poultry and the like. The absorbent pad is constituted of a mat of a liquid-absorbing wood flake material enveloped by paper. The paper-enveloped absorbent pad in turn is enveloped by a liquid-impermeable material such as polyethylene which, however, has a multiplicity of perforations extending in longitudinal direction of the envelope. As a result of the relatively low absorptive capacity and the low bulk density of wood flakes, a practice-oriented absorption of liquid is obtained only with an uneconomically high packaging volume.
DE 4,325,879 C2 describes molded articles made of thermoplastic foams as packaging material for goods containing moisture, wherein the cell structure of the hydrophobic foam framework is partially open, thereby being capable of absorbing liquids which, however, cannot be bound tightly. In order to absorb polar solvents such as water, the hydrophobic foams must be modified in addition, using up to 10 wt.-% of a surfactant wetting agent. To prevent compressing of the foams under the weight of the food-stuffs, foams having higher density, i.e., higher stability, are required. However, the absorptive capacity of such thermoplastic foams is reduced with increasing foam density, i.e., with increasing stability of the foam.
To improve the absorptive capacity, superabsorbent polymers have been suggested as filling materials for absorbent pads. Compared to cellulose, they are capable of storing larger amounts of aqueous liquids.
DE 4,120,319 A1 and DE 4,234,632 A1, respectively, describe tray-shaped foodstuff packaging containers having integrated a liquid absorber system. To absorb liquid released by foodstuffs, polyacrylate polymers having a moisture absorption capacity ranging from 1 to 100 ml/g are preferably used; in particular, the alkali salts of starch-modified polyacrylates are preferably used. Other statements indicate that moisture is deposited on charged goods if there is direct contact between the absorber and the charged goods. Thus, it must be concluded that the absorbers used are not capable of binding liquid from the food-stuff sufficiently tightly or retaining same under pressure, and that solubles from the absorber may possibly be passed onto the foodstuff in case of direct contact. Because close contact of these absorbent polymers with the charged goods as well as pressure load on the swollen absorber must be avoided, an expensive construction of the packaging container in the form of an additional perforated bottom plate with supporting elements is required, separating the foodstuff from the absorber.
Absorbent substrates as supporting layers in and poultry meat packagings for collecting liquid exuded from these meat products are known from EP 434,733 B1. Inside the absorbent substrate confined externally by a partially perforated plastic film, there are layers of cellulose and thermoplastic fibers, wherein superabsorbent polymer grains of carboxymethylcellulose or acrylate absorbers are fixed, thereby improving the retention properties of the absorbent substrate, so that liquid already absorbed is not re-released even under pressure load. The superabsorbers do not have to meet specific requirements with respect to absorptive capacity, gel stability and solubles. To avoid migration in case of higher load on the absorbent pad, it is recommended not to perforate the upper film adjacent to the foodstuff and allow the liquid to enter at the lateral edges of the absorbent substrate, which are not completely sealed.
U.S. Pat. No. 4,449,977 describes a flexible absorbent product containing uniformly dispersed particles of a water-insoluble, water-swellable organic polymer in a water-insoluble, non-swellable matrix of a thermoplastic polymer, namely, a polyester. Preferably, the matrix is in the form of a fi
Jonas Gerd
Klimmek Helmut
Krause Frank
Pflüger Klaus
Befumo Jenna-Leigh
Morris Terrel
Stockhausen GmbH & Co. KG
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