Stock material or miscellaneous articles – Hollow or container type article – Flexible food casing
Reexamination Certificate
2000-03-17
2002-11-26
Beck, Shrive P. (Department: 1762)
Stock material or miscellaneous articles
Hollow or container type article
Flexible food casing
C428S034300, C426S105000, C426S129000
Reexamination Certificate
active
06485802
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a seamless, tubular sausage casing based on cellulose hydrate having a continuous coating made of a polymeric material on its outer surface. The casing is particularly useful for liver sausage.
2. Description of Related Art
Coated tubular cellulose hydrate sausage casings are generally known. For example a casing according to DE-A 32 40 847 is furnished on the outside with a fungicidal coat. It includes the reaction product of a cationic polymer based on polyamine, polyamide and epichlorohydrin with an alkali metal salt, alkaline earth metal salt or ammonium salt of propionic acid, sorbic acid, ascorbic acid, benzoic acid, 4-hydroxybenzoic acid, 4-chlorobenzoic acid or 4-methoxybenzoic acid. A seamless, tubular casing based on cellulose hydrate having a coating on the outside and on the inside is disclosed, for example in EP-A 001 545 and U.S. Pat. No. 4,287,217. The inner coating includes a thermoplastic material and is virtually impermeable to water and water vapor. The outer coating, in contrast, is permeable to water and water vapor and comprises an elastic copolymer, preferably an acrylate or methacrylate copolymer or a butadiene, isoprene or chloroprene copolymer. It does not form a closed coat and therefore has no barrier action either. It is produced by applying an emulsion which comprises the copolymer in the form of particles having a diameter of up to 0.08 &mgr;m and is subsequently dried. The weight of the outer coating is generally from 0.5 to 8.0 g/m
2
. Because the impermeable inner coating the casing is not smoke-permeable, a sausage produced using such a casing cannot be smoked.
A sausage casing that has an oxygen barrier layer and water vapor barrier layer on its outside or inside is described in EP-A 457 178. The barrier layer consists essentially of a copolymer based on monomers of the formula H
2
C═CR
1
—X, where R
1
is a hydrogen atom or a methyl group and X is O—CO—(C
1
-C
20
)alkyl or CO—O—(C
1
-C
20
)alkyl. The copolymer, moreover, can further contain units of (meth)acrylic acid or (meth)acrylonitrile. Particular preference is given to copolymers of butyl acrylate, methyl methacrylate and acrylic acid. The barrier layer forms a closed coat and has a weight per unit area of at least 12 g/m
2
, preferably at least 14 gm
2
. The barrier properties or such a casing virtually approach those of a polyvinylidene chloride (PVDC) layer. This casing is also impermeable to smoke.
For unsmoked liver sausage, customarily casings having a high barrier action to oxygen and water vapor are used, since the liver sausage emulsion is particularly sensitive to atmospheric oxygen and dries out relatively easily. Oxidation is recognizable by a green discoloration of the emulsion surface, while drying out is recognizable by a brown discoloration. When casings having particularly effective barrier layers are used (in particular those having PVDC layers), there is generally only a low risk of discoloration and loss of weight by drying out.
Previously, fiber-reinforced cellulose hydrate casings have generally been used for smoked liver sausage. In addition, collagen casings or natural casings have also been used. Liver sausage casings made of acrylate-coated fabric which are sewn up to make tubes are also known. All of these casings are permeable to smoke, but also to oxygen and water vapor. As a consequence, the liver sausage emulsion in these casings becomes discolored, even after only a few days and thus loses quality.
SUMMARY OF THE INVENTION
An object of the present invention was therefore to provide a seamless, tubular casing for smoked liver sausage.
The present application thus relates to a seamless, tubular sausage casing comprising cellulose hydrate, wherein the casing has a continuous coating of a polymeric material on its outer surface, and wherein the coating is permeable to hot smoke and cold smoke and the coating preferably has a thickness of from 3 to 10 &mgr;m.
Additional advantages, features and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, and representative devices, shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
A casing according to the present invention should generally be resistant to boiling water and hot steam, permeable to hot smoke and cold smoke, and sufficiently impermeable to oxygen and water vapor so that the sausage can be stored for at least 3 to 5 days in a cold room before it is enclosed by a second packaging. In addition a casing of the instant invention should generally reduce or prevent as far as possible the sausage from drying out. In addition, a casing of the present invention should generally protect liver sausage emulsion (or other contents therein) against the action of light and should preferably not affect the fat/protein equilibrium, so that substantially no fat separates out from the emulsion. Not least, the casing should advantageously fit tightly and without creasing and should be able to be peeled off readily without tearing or having a tendency toward tear propagation. For ecological reasons, the casing should in addition also be substantially or completely free from chlorine-containing compounds, such as PVDC. The simultaneous solution of all these objects has previously been thought to be impossible. However, it has now been found that many or all of the above may be solved by employing a thin outer coating made of a synthetic polymer or copolymer.
The coating preferably comprises a homopolymer or copolymer consisting of or comprising units of monomers of the formula H
2
C═CR
1
—X, where R
1
is a hydrogen atom or a methyl group and X is O—CO—R
2
or CO—O—R
2
, where R
2
is (C
1
-C
10
)alkyl, preferably (C
1
-C
5
)alkyl.
In addition, units of other vinyl monomers may be present in the polymer coating if desired for any reason. The content of these other units, if included, is generally up to 45% by weight, preferably up to 30% by weight, in each case based on the total weight of the polymer. The other vinyl monomers are preferably those of the formula H
2
C═CR
1
—X, where X is OH, CO
2
H, CO—NH—(C
1
-C
10
)alkyl or CN. The content of (meth)acrylic acid units and of (meth)acrylonitrile units is generally relatively small. For example, in the case of (meth)acrylic acid units, the content is preferably from 0.1 to 20% by weight, more preferably from 0.5 to 10% by weight, and in the case of (meth)acrylonitrile units, preferably from 0.1 to 35% by weight, more preferably from 1.0 to 20% by weight, in each case based on the total weight of the polymer. Other suitable vinyl monomers include unsubstituted or substituted styrenes, (C
2
-C
8
)alkenes (especially ethylene or propylene) and/or conjugated (C
4
-C
10
)alkadienes (especially butadiene or isoprene). Using polyfunctional compounds, in particular polyfunctional aziridines, the (meth)acrylate polymers may be crosslinked and/or otherwise linked to the cellulose surface. The term “(meth)acrylate” in this context means “acrylate and/or methacrylate”. The same applies to “(meth)acrylic acid”, “(meth)acrylamide”, “(meth)acrylonitrile” etc.
The polymer is preferably hydrophilic. Its mean molecular weight M
w
is preferably relatively large, i.e. advantageously greater than 200,000, preferably greater than 500,000. Polyesterurethanes are also suitable, and may be prepared for example from a polyesterdiol, a chain extender and a diisocyanate or triisocyanate. The polyesterdiols are preferably formed in this case from an unbranched (C
3
-C
10
) diol (especially butane-1,4-diol or hexane-1,6-diol) and a (C
3
-C
8
) dicarboxylic acid, (especially adipic acid). Suitable chain extenders can comprise, inter alia, diols and diamines, such as hexamethylenediamine. The diisocyanate or
Grolig Gerhard
Hammer Klaus-Dieter
Lang Bernd-Adolf
Seelgen Hans-Werner
Beck Shrive P.
Connolly Bove & Lodge & Hutz LLP
Kalle Nalo GmbH & Co.KG
Tsoy Elena
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