EP1622459A1

EP1622459A1 - Food casing provided with an antimicrobial finish

Info

Publication number: EP1622459A1
Application number: EP04728537A
Authority: EP
Inventors: Erna Kastl
Original assignee: Kalle GmbH and Co KG
Current assignee: Kalle GmbH and Co KG
Priority date: 2003-04-25
Filing date: 2004-04-21
Publication date: 2006-02-08
Also published as: WO2004095935A1; DE10319006A1; RU2005136660A; US20060182851A1

Abstract

The invention relates to a preferred tubular-shaped food casing based on synthetic material, especially polyamide, wherein the layers and/or at least one of the layers contains at least one metal salt with antimicrobial active metal ions. The metal salt comprises, preferably, silver, copper or zinc ions. In the event of a multi-layered casing, said type of metal salt has at least one outer layer. A master batch is used, preferably, in the production of the casing, said master batch containing between 5 - 40 wt.- % metal salts. The food casing is preferably used as an artificial sausage casing.

Description

Food casing with antimicrobial finish

The invention relates to a polymer-based food casing with an antimicrobial finish and to a method for producing the casing.

Food casings, especially sausage casings, with an antimicrobial finish are already known. For example, US Pat. No. 3,864,449 discloses a sausage casing based on regenerated cellulose which contains a fat-soluble, edible anti-mycotic, in particular para-hydroxy-benzoic acid ester. In the manufacture of the sheath, the antifungal agent is dissolved in an oil (e.g. castor oil). The oil and the constituents dissolved in it are then dispersed in a viscose solution and the dispersion is then extruded through an annular die. The finely divided oil droplets are in the tubular casing after the cellulose has been regenerated and can release the active ingredient. Polymer-based casings produced by extrusion or co-extrusion from a thermoplastic melt cannot be given an antimicrobial treatment in this way.

Antibacterial impregnation can also be achieved by applying an appropriate solution or suspension to a finished tubular casing. For example, EP-A 0 384 319 discloses a composition which comprises a bacteriocin (in particular nisin or pediocin) obtainable from Pediococcus or Streptococcus species and a chelating agent. This composition can be applied to cellulose casings as well as to polymer casings (for example those based on polyolefins, polyamides, polyethylene terephthalates, polyvinylidene chloride copolymers or ethylene / vinyl acetate copolymers). Such an impregnation is naturally not very sustainable. Bacteriocins are also sensitive to heat.

Sausage casings based on polyamide are often also produced in ready-to-fill ("preconditioned") form because individual types of polyamide can absorb up to about 10% by weight of water To solve this problem, the aqueous dampening solutions were therefore treated with fungicidal and / or bactericidal granules. components. Suitable components approved under food law are in particular potassium sorbate, para-hydroxy-benzoic acid ester (PHB ester) or natamycin.

There was therefore still the task of providing shells based on thermoplastic polymers which from the beginning, i.e. are not equipped with an anti-microbial treatment only afterwards. They should also be easier to manufacture, since post-treatment with antibacterial substances is no longer necessary. Furthermore, the antimicrobial finish should be permanent, i.e. not washable, and their effectiveness does not decrease or only insignificantly even after exposure to heat. Because in the case of sausage casings, the heat can reach up to a temperature of around 95 ° C, and briefly up to around 120 ° C when sterilized. Longer storage of the food casing should not impair the antimicrobial effect.

The task was solved with the help of metal salts which are added before the extrusion of the polymer melt. In the finished casing, they release metal ions with an antimicrobial effect and thus prevent or hinder the growth of mold, bacteria, yeasts, fungi and other microorganisms.

The present invention thus relates to a single-layer or multilayer plastic food-based food casing, which is characterized in that the layer or at least one of the layers contains an antimicrobially effective amount of at least one metal salt. The metal salt preferably contains silver, copper, zinc ions and / or other metal ions with an antimicrobial, in particular antibacterial, effect.

The food casing based on plastic is preferably a casing based on polyamide and / or copolyamide (hereinafter referred to as (co) polyamide).

The (co) polyamide is generally an aliphatic (co) polyamide, such as PA 6

(Poly (ε-caprolactam) = polyamide from ε-caprolactam or 6-amino-hexanoic acid), PA 6.6 (polyhexamethylene adipamide = polyamide from hexamethylene diamide and Adipic acid), PA 6 / 6.6 (copolyamide from ε-caprolactam, hexamethylene diamine and adipic acid), PA 6 / 66.9 (copolyamide from e-caprolactam, hexamethylene diamine, adipic acid and azelaic acid), PA 6 / 66.12 (copolyamide from e-Caprolactam, hexamethylene diamine, adipic acid and laurolactam), PA 6.9 (polyamide from hexamethylene diamine and azelaic acid), PA 6.10 (polyhexamethylene sebacinamide = polyamide from hexamethylene diamine and sebacic acid), PA 6.12 (polyhexamethylene dodecanamide =) Copolyamide from ε-caprolactam and ω-aminolauric acid lactam), PA 4.6 (polytetramethylene adipinamide = polyamide from tetramethylene diamine and adipic acid) or PA 12 (poly (ε-lauric lactam)). The aliphatic (co) polyamide can be mixed with partially aromatic (co) polyamides, in particular amorphous partially aromatic (co) polyamides such as PA 6I / 6T (a copolyamide with units of hexamethylenediamine, isophthalic acid and terephthalic acid). The proportion of partially aromatic (co) polyamide is preferably not more than 50% by weight, particularly preferably not more than 30% by weight, in each case based on the total weight of all (co) polyamides. The

(Co) polyamide can also be blended with other polymers, in particular olefinic polymers, especially those that also act as adhesion promoters. Examples include ethylene / (meth) acrylic acid copolymers. Other polymers can also get into the shell material through a masterbatch containing a corresponding metal salt. This applies, for example, when a masterbatch based on polyethylene or polyester is incorporated into a polyamide layer.

The proportion of metal salt (s) in the single-layer shell or in a correspondingly equipped layer of the multi-layer shell is generally approximately

0.005 to 4.0% by weight, preferably about 0.01 to 2.0% by weight. The proportion of metal ions is accordingly about 0.0025 to 2% by weight, preferably 0.005 to 1.0% by weight, based on the total weight of the shell or a layer of the shell. In the multilayer casings, at least the outer layer preferably contains antimicrobial metal salt (s).

In addition, the casing can contain generally customary additives, such as dyes or color pigments, UV stabilizers or the like. It is generally tubular, preferably also seamless. It can be undrawn or stretched. The shell can be stretched in a blow molding process or by biaxial orientation in a so-called double-bubble process. In the latter method, a primary tube is first produced by extrusion or coextrusion, which is cooled, then heated to the stretching temperature and stretched by an internal gas pressure. A heat shrinkage suitable for sausage casings can then be set by heat setting. This residual shrinkage is generally no more than 20% in the longitudinal and transverse directions (determined by soaking in water at 90 ° C. for 5 minutes). The metal salt may also be contained in the inner layer in the multilayered shell.

In a preferred embodiment, the metal salt is applied to a carrier. The carrier can be, for example, an aluminum silicate, especially a natural or synthetic zeolite or a similar absorbent substance. Through ion exchange processes, the aluminum silicate releases antimicrobial metal ions (for example silver ions) and binds cations of the

Environment, such as sodium, potassium or calcium ions. This enables a particularly long-lasting effect to be achieved. The aluminum silicate particles generally have an average diameter of 1 to 15 μm, preferably 2 to 10 μm. They can contain up to about 40% by weight of metal ions. Suitable aluminum silicates containing metal ions are described, for example, in JP-A 02-

153723. Their use in sponge cloths is disclosed there.

A masterbatch which contains up to about 5 to 40% by weight, preferably 10 to 25% by weight, of at least one metal salt is preferably used in the production of the casing according to the invention Polyethylene, a polypropylene, a copolymer with ethylene and propylene units, an ethylene / (C ₄ - C ₈ ) α-olefin copolymer, a propylene / (C ₄ - C _a ) α-olefin copolymer or an ethyl len / propylene / (C ₄ - C ₈ ) α-olefin copolymer) or a polyamide. The masterbatch is mixed with the other constituents of the casing or the relevant layer of the multilayer casing and then extruded or coextruded.

The further layers in the multilayer embodiment are, in particular, layers based on polyolefins (especially polyethylene, polypropylene, ethylene / propylene copolymers or block copolymers, polybutylene, etc.) Polyesters, polyvinylidene chloride (PVDC), poly (ethylene-co-vinyl acetate) and / or poly (ethylene-co-methyl methacrylate). Adhesive layers, which contain or consist of polyolefins modified with functional groups, for example, can also be arranged between the individual layers, preferably relatively thin (approximately 2 to 8 μm). Including such adhesive layers, the casing according to the invention should not comprise more than 5 layers for practical reasons. In order to reduce the number of extruders required, a symmetrical structure also makes sense. For example, the composition of the inner layer is then identical to that of the outer layer.

The single-layer or multilayer, tubular casing according to the invention generally has a wall thickness of 15 to 150 μm, preferably 20 to 130 μm, particularly preferably 35 to 90 μm. Depending on the intended use, the diameter is advantageously about 20 to 200 mm, preferably 30 to 150 mm.

The casing according to the invention has the essential advantage that it is permanently antimicrobial. The term "antimicrobial effect" is understood here to mean the activity against bacteria, yeast, mold, algae, fungi and other microorganisms. Above all, the antibacterial is important

Effect, especially the effect against coli bacteria, salmonella and staphylococci. The antimicrobial component is not released from the casing by water, fat or other food components. The antibacterial effect is practically not affected by heating, UV radiation or the effects of chemicals. The antibacterial finish does not affect the taste, smell or aroma of a food contained in the casing. Subsequent antibacterial treatment, as is often described in the prior art, is no longer required. The casing according to the invention is thus largely protected against attack by microorganisms, even if it is already pre-moistened ready for filling.

The following examples illustrate the invention. "Gt" stands for "weight part (s)". Percentages are percentages by weight, unless stated otherwise or immediately apparent from the context. Example 1 (comparison): A mixture of

80 pbw of polyamide 6 (the relative viscosity of a 1% strength solution of the polyamide in 96% strength sulfuric acid at a temperature of 20 ° C. was 4), 10 pbw of amorphous polyamide 6I / 6T (®Selar PA 3426 from DuPont de Nemours Inc .; Melt index: 90 g in 10 min at 275 ° C and a load of 10 kg) and 10 pbw of ethylene / methacrylic acid copolymer (© Nucrel 0903 HC from DuPont de Nemours Inc .; Melt index: 2.5 g in 10 min at 190 ° C and 2.16 kg load)

was plasticized in a single-screw extruder at 240 ° C to a homogeneous melt. The melt was extruded through a ring die into a tube with a diameter of 18 mm. This primary tube was rapidly cooled after the extrusion, then heated to the temperature required for stretching, biaxially stretched by compressed air acting from the inside and under the action of a pair of squeeze rollers which pull in the longitudinal direction. The area stretch ratio was 9.6. The stretched casing was then heat set while the area stretch ratio remained practically unchanged. The finished casing had a diameter of 66 mm.

Example 2 (inventive single-layer casing): A mixture of

78 pbw of polyamide 6 (as in example 1),

10 pbw of amorphous polyamide 6I / 6T (as in example 1),

10 pbw of ethylene / methacrylic acid copolymer (as in Example 1) and 2 pbw of polyethylene with 20% metal oxide content (© Polybatch Abact 399 der

Schulmann AG)

was plasticized as described in Example 1 and processed into a biaxially stretched and heat-set sausage casing.

Example 3 (multilayer casing according to the invention):

The following polymer mixtures were used to produce the shell: Mixture A:

88 pbw of polyamide 6 (as in example 1),

10 pbw of amorphous polyamide 6I / 6T (as in example 1),

2 pbw of polyethylene with metal oxide content (© Polybatch Abact 400L der

Schulmann AG)

Mixture B: 70 pbw of low-density polyethylene (LDPE, Lupolen 1441 from BASF AG with an MFI of 0.2 g in 10 min at 190 ° C. and 2.16 kg load) and

30 pbw of a functional group modified low density linear polyethylene (LLDPE; the functional groups were introduced by treatment with maleic anhydride; © Escor CTR 2000 from Exxon with an MFI of 3 g in 10 min at 190 ° C. and 2.16 kg Load; the component acts as an adhesion promoter to polyamide)

Mixture C:

85 pbw of polyamide 6 (as in example 1)

15 pbw amorphous polyamide 6I / 6T (as in example 1)

The mixtures were plasticized in their own single-screw extruders at 240 ° C, the resulting homogeneous melts were brought together in a 3-layer ring die and coextruded into a tube of 18 mm diameter. The tube was then made into a biaxially stretched and heat set food casing as described. The area stretch ratio was 9.6. The finished casing had a diameter of 66 mm. The individual layers contributed to the total wall thickness of 55 μm as follows:

Outer layer (mixture A): 30 μm

Middle layer (mixture B): 20 μm

Inner layer (mixture C): 5 μm Example 4 (single-layer casing according to the invention): A mixture of

90 pbw polyamide 6.6 and

10 Gt PE with metal oxide content (© Polybatch Abact 399 the Schulmann

AG)

was plasticized in a single-screw extruder at 280 ° C. to form a homogeneous melt and, as described in Example 1, extruded into a blow tube with the aid of an annular die.

Determination of the antibacterial properties of the food casings:

For this, the bacteriostatic activity S was determined using the method described in JIS Z 2801 using Staphylococcus aureus ATCC 6538 as

Test organism determined. The following results were obtained:

) * The bacteriostatic activity S was evaluated as follows: <0.0 microbial growth, insufficient antibacterial effect 0.0 to <1.0, no significant bacterial reduction, insufficient antibacterial effect

1, 0 to <2, O germ reduction, good antibacterial effect for certain applications

> 2.0 strong germ reduction, good antibacterial effect

Claims

claims

1. Single- or multi-layer food casing based on plastic, characterized in that the layer or at least one of the layers contains an antimicrobially effective amount of at least one metal salt.

2. Food casing according to claim 1, characterized in that the metal salt contains silver, copper, zinc ions and / or other metal ions with an antimicrobial, preferably antibacterial effect.

3. Food casing according to claim 1 or 2, characterized in that it is a casing based on polyamide and / or copolyamide.

4. Food casing according to one or more of claims 1 to 3, characterized in that the (co) polyamide is an aliphatic (co) polyamide.

5. Food casing according to claim 4, characterized in that the aliphatic (co) polyamide is mixed with at least one partially aromatic (co) polyamide, preferably at least one amorphous partially aromatic (co) polyamide.

6. Food casing according to claim 5, characterized in that the proportion of the at least one partially aromatic (co) polyamide is not more than 50% by weight, preferably not more than 30% by weight, in each case based on the total weight of all (Co ) polyamides.

7. Food casing according to one or more of claims 1 to 6, characterized in that the proportion of metal salt (s) in the single-layer casing or in a suitably equipped layer of the multilayer casing 0.005 to 4.0 wt .-%, preferably about 0.01 to 2.0 wt .-%, based in each case on the total weight of the shell or the layer in the shell.

8. Food casing according to one or more of claims 1 to 7, characterized in that the proportion of metal ions is 0.0025 to 2 wt .-%, preferably 0.005 to 1, 0 wt .-%, each based on the total weight of the Envelope or the relevant layer of envelope.

9. Food casing according to one or more of claims 1 to 8, characterized in that it is multilayered and that at least the outer layer contains at least one antibacterially active metal salt.

10. Food casing according to one or more of claims 1 to 9, characterized in that it is tubular, preferably also seamless.

11. Food casing according to one or more of claims 1 to

10, characterized in that it is undrawn.

12. Food casing according to one or more of claims 1 to 10, characterized in that it is biaxially stretched, preferably also heat-set.

13. Food casing according to one or more of claims 1 to 12, characterized in that it is multi-layered and the further layers based on polyolefins, polyesters, polyvinylidene chloride, poly (ethylene-co-vinyl acetate) and / or poly (ethylene-co- methyl methacrylate).

14. Food casing according to claim 13, characterized in that it has no more than 5 layers.

15. Food casing according to claim 13, characterized in that it has a symmetrical structure.

16. Food casing according to claim 13, characterized in that it has an asymmetrical structure.

17. Food casing according to one or more of claims 1 to 17, characterized in that it is pre-watered ready for filling.

18. Food casing according to one or more of claims 1 b 18, characterized in that it has a wall thickness of 15 b 150 microns, preferably from 20 to 130 m, particularly preferably from 35 b 90 microns.

19. Food casing according to one or more of claims 1 to 19, characterized in that it has a diameter of about 20 to

200 mm, preferably 30 to 150 mm.

20. A method for producing a food casing according to one or more of claims 1 to 20, characterized in that a masterbatch containing about 5 to 40 wt .-%, preferably about 10 to

Contains 25% by weight of at least one antimicrobial metal salt, mixed with the other constituents of the shell or the relevant layer of the shell and then extruded or coextruded.

21. The method according to claim 21, characterized in that the masterbatch as carrier material is a polyolefin, preferably a polyethylene, a polypropylene, a copolymer with ethylene and propylene units, an ethylene / (C ₄ -C ₈ ) α-olefin copolymer , a propylene / (C ₄ -C ₈ ) α-olefin copolymer or an ethylene / propylene / (C ₄ -C ₈ ) α-olefin copolymer, or a polyamide.