Manually stuffed polyamide sausage casing

The present invention relates to a polyamide casing for foodstuffs, especially sausages. It is particularly suitable for the production of sausages on a smaller scale, in which they are filled not automatically, but manually. It is especially suitable for boiled and steamed sausages.

Fiber-reinforced cellulose casings produced by the viscose process and provided with a water-impermeable inner coating have the largest share in the production of cooked and scalded sausages. In second place are casings made of thermoplastics, especially polyamides or copolymers of vinylidene chloride. For the production of commercial scale sausages, internally coated, fiber-reinforced cellulose casings are much better suited than thermoplastic casings.

After filling, boiled and steamed sausages are steamed in water or steam at a temperature of around 80 ° C, and sometimes also at a temperature of 110 ° C to 130 ° C. The filling volume of the sausages also increases. During cooling, the volume decreases markedly again. The sausage casing must adapt to the varying volume of sausage stuffing. In particular, the sausage casing should shrink during cooling so that no wrinkles are formed. Sausages with a wrinkled casing are considered no longer fresh. ' Moreover, the casing should be stretched so that no liquid collects underneath it after brewing. This "jelly build-up" between casing and stuffing is also considered a quality defect.

The said internally coated cellulose casings are usually softened prior to filling. The highly hygroscopic cellulose is thereby saturated with water. The water absorption is generally from 110 to 140% by weight. At the same time, the casing expands ("swell") and becomes very stretchy. In this condition, it is filled with stuffing. After brewing and cooling, the sausage is dried. After that, the casing again reflects the majority of the absorbed water. However, due to the water-impermeable inner coating, practically no moisture can escape from the sausage stuffing. During drying, the cellulose layer strongly shrinks and thus stiffly hugs the cooled sausage stuffing. This prevents a fold4

185 The filling and deposition of the jelly, even when the stuffing - as is usual during manual filling, was filled without additional pressure or only under slight pressure.

Due to their functional properties, the internally coated cellulose casings are perfect for manual filling. However, the disadvantage of these casings is their cumbersome and expensive production by the viscose method. In this case, a cellulose xanthate solution is first applied to the hose-shaped fibrous reinforcement. The cellulose xanthate is then precipitated in a dilute solution of sulfuric acid and regenerated as cellulose hydrate. After washing and drying the casing, a polymer dispersion is applied to the inside of the casing, which then forms a water-impermeable coating.

On the other hand, it is much simpler and cheaper to produce thermoplastic shells for boiled and scalded sausages by extrusion blow molding. In this respect, casings made of biaxially oriented polyamide have gained some importance. DE-A 2 850 182 (= GB-A 2 035 198) describes a single-ply, biaxially oriented casing made of aliphatic polyamide, the glass transition temperature of which when dry is at least 48 ° C and can drop to at least 3 ° C after water absorption. ° C, preferably down to -5 ° C. Specifically, polyamide-6 (= polycaprolactam), polyamide-7, polyamide-6,6 (= polyamide with hexamethylenediamine and adipic acid) and polyamide-6.10 (= polyamide with hexamethylenediamine and sebacic acid) are disclosed. According to DE-A 2 850 181, the casing also contains, inter alia, an ionomer resin, a modified ethylene vinyl acetate copolymer and / or a quaternary copolymer of ethylene, butylene, aliphatic ethylenically unsaturated carboxylic acid units with 3 to 5 carbon atoms and an ester of this carboxylic acid with an alcohol containing from 1 to 8 carbon atoms. This casing is less prone to tear when the sausages are cut. The polyamide casing according to DE-A 3 227 945 (US-A 4 560 520 and US-A4 601 929) should have the same advantage.

In order that the finished cooked and scalded sausages lose as little weight as possible during storage, even in the case of thermoplastic casings, it is desirable to have as little water and water vapor permeability as possible. However, many polyamides can absorb up to 10% by weight of water. For this reason, pure polyamide casings are of little use. In order to overcome this drawback, multi-layer casings have been developed which additionally contain (at least) one layer of a water-impermeable polymer. The bidirectionally oriented casing according to EP-A 573 306 consists of a middle polyamide layer as well as an inner and an outer layer of a water-retaining polymer, for example a polyolefin. DE-A 4 017 046 also discloses a three-layer, biaxially oriented and thermally set casing. In this case, the outer layer consists of an aliphatic polyamide and / or copolyamide, the intermediate layer of a polyolefin and an adhesive component, and the inner layer of an aliphatic and / or partially aromatic (co) polyamide.

When heated to a temperature of about 80 ° C or more, the casings begin to shrink when the sausages are brewed. As a result of this thermal shrinkage, the circumference of the casing is usually reduced by about 5 to 20%. The amount of shrinkage also depends on the conditions of prior heat setting. Typically, during heat setting, a transverse shrinkage of up to 40% occurs. At the same time, the diameter of the hose becomes more even.

When the sausages are brewed, thermal shrinkage occurs almost immediately. As a result, the stress on the casing is greatest at the beginning of the brewing, when the stuffing is still expanding in this phase. As a result, the casing may expand permanently, with the result that the tension of the cooled sausage is no longer sufficient. In addition, the oriented polyamide layers have only a relatively low residual elasticity.

When producing sausages on an industrial scale, this difficulty was solved by filling the stuffing under high pressure. Typically, depending on the diameter of the sausage casing, a filling pressure of 20 to 40 kPa is used. However, for this purpose specially constructed filling machines are needed. In this way, a first (partially flexible) extension of the casing is achieved. The resulting restoring force is similar to that of contraction

185 306 thermal stress is partially leveled. The remaining force, as a rule, is simply sufficient to ensure a rigid and taut fit of the casing without wrinkles.

However, without special filling machines, a high filling pressure cannot be achieved. Manually filled polyamide casings are therefore mostly wrinkled and have an unsightly appearance. Therefore, in artisanal applications, the internally coated cellulose casings described in the introduction are still used.

For this reason, the task arose to develop a cooked and scalded sausage casing made of thermoplastic plastics by extrusion blow molding, which casing does not wrinkle even when the stuffing is filled without pressure or under slight pressure, i.e. by hand and without the use of special filling machines. .

This task has been solved by developing a bidirectionally oriented and thermally fixed, hose-shaped, seamless, single or multi-layer casing of foodstuffs, especially sausages, in which the layer, and in the case of multilayer layers, at least one of the layers, contains a block copolymer with "hard" aliphatic polyamide blocks and with "soft" aliphatic polyether blocks, which copolymer corresponds to one of formulas 1 to 3:

Ea- (NH- [CH₂]_x-WHAT)_m-X_and- (AO) nAX_and- (CO- [CH₂]_x-NH)_m-E_and (1) in which they mean:

And the alkanediyl residue of the formula -CH₂-CH₂- (= eta.no-1,2-diyl).

-CH₂-CH (CH 3) - (= propane-1,2-diyl) or

- (CH2) 4- (= butanediyl),

X_and -O- or -NHE_and H, (C₂-Cs) alkanoyl, benzosoyl or phenylacetyl,

CO-N ([CH2]_x., -CH 3) -CO- (C 1 -C ₄) alkyl,

CO-N ([CH2]_x_1-CH 3) -CO-C 6H 5 or

CO-N ([CH2] x-1-CH 3) -CO-CH 2-C 6H5, x integer from 5 to 11, m integer from 30 to 200, and n integer from 4 to 60; a group of formula 2, (2) in which are:

Xb an alkanediyl residue of the formula - [CH2]_with- where z is an integer from 4 to 10, meta- or para-phenylene,

-NH- (C1-C6) alkyl-NH-,

-NH-C 6H 3- (CH 3) -NH-,> N- [CH2] x -, - CH3, - [CH2]_with-CO-N ([CH2] x. - CH3) - or

-C 6H4-CO-N - ([CH 2] x-1-CH3) where C6H4 is meta- or para-phenylene,

Eb -OH, -O- (C1-C7) alkyl, -O-phenyl or the group of formula 4, and A, m and n are as defined above;

- [X- (CO) - [CH2] x-NH) oYX- (AO) pA] - (3) where they are:

Y -CO-, -CO- [CH2]_with-CO- or -CO-C6H4CO- where C6H4 is meta- or para-phenylene, or -CO-N ([CH ₂] x., - CH3) -CO-,

-CO-N ([CH2] x-1-CH3) -CO- [CH2]_with-CO-N ([CH₂] xi-CH₃) -CO- or

-CO-N ([CH2] x-1-CH 3) -CO-C 6H4-CO-N ([CH₂] x-1-CH 3) -CO-, wherein C6H4 is as defined, by an integer with a value from 10 to 150 and p an integer with a value from 4 to 100 and A, x and z are as defined above.

185 306 "Hard" polyamide blocks in the Formulas 1 to 3 block copolymer generally have a glass transition temperature (Tg) of 20 to 80 ° C, while the "soft" polyether blocks have a Tg of -100 to -20 ° C. The sequence x is preferably 5, i.e. the polyamide blocks are preferably polycaprolactam blocks, while A is preferably ethane-1,2-diyl or butane-1,4-diyl, i.e. the polyether blocks are preferably polyether blocks. (ethylene glycol) or poly (butylene glycol) blocks. The block copolymer of formula III, in which hard and soft blocks alternate, generally have an average molecular weight of M_in in the range of 20,000 to 70,000.

Of the block copolymers of the formulas 1 and 2, copolymers with a value of m from 40 to 100 and with a value of n from 10 to 40 are preferred. Of the block copolymers of formula III, on the other hand, copolymers with a value of from 10 to 60 and a p value of 20 to 40 are preferred. .

Block copolymers of formula I where Xa = -NH- and block copolymers of formula 3 where X = -O- and Y = -CO- [CH2] 4-CO- or -CO- [CH2] are particularly preferred. i0-CO-.

Block copolymers of formulas 1, 2 and 3 are known per se and are described in US-A 4,501,861.

In a particular embodiment of the present invention, this layer further comprises at least one aliphatic and / or partially aromatic (co) polyamide in a mixture with the block copolymers. Preferred (co) polyamides of this type are polyamide-6 (PA-6), polyamide-6 / 6.6 (= copolyamide with ε-caprolactam, hexamethylenediamine and adipic acid), PA-6/12 (copolyamide with ε-caprolactam and ω-lactam of aminolauric acid). PA-12 (= poly (ω-lactam of amiyo-auryic acid) and PA-61/6 T (copohamide with heasamethylenediamine, isophthalic acid and terephthalic acid). The content of additional polymers in this layer is up to 85% by weight, based on the total layer weight.

The layer of block copolymers of the formulas 1, 2 and / or 3 can also be colored by the addition of inorganic and organic pigments. Finally, other additives may also be present, in particular anti-sticking agents and processing improvers.

The casing of the foodstuffs is made by extrusion blow molding. Corresponding methods are known to the person skilled in the art. Generally, the polymer (polymer mixture) is first plasticized to a homogeneous melt and then extruded through a heated annular die. In this way, a seamless casing is obtained. The relatively thick hose obtained during extrusion is cooled quickly in order to keep the polymers in an amorphous state. It is then heated to the temperature required for stretching and stretched by blowing it in a mold, the hose being stretched as a result of the pressure of the gas inside it (usually air). The stretched hose is then partially heat set so that the residual shrinkage at 80 ° C remains in the range of 5 to 20%. At the same time, the stretching ratio is slightly reduced. The area stretch ratio of the heat-set sheath is generally in the range of from about 6 to about 10.

A casing with slightly less favorable shrink properties is obtained by blowing the hose immediately after it exits the annular nozzle and then also (partially) thermally setting it. After cooling, the casings are placed flat and rolled up.

For special applications, for example when casings with lower water vapor permeability are desired, multi-purpose casings are preferred. The additional layers preferably consist of polyamides (e.g. PA-6) or polyolefin (e.g. polyethylene or polypropylene). The polyolefins may also contain adhesion-promoting functional groups. The additional layers may also consist of (copolymers with ethylenically unsaturated monomer units (for example vinyl acetate, vinyl alcohol or (meth) acrylic acid), vinylidene chloride copolymers or acrylonitrile copolymers, ionomer resins or mixtures of said (co) polymers.

In the case of a two-layer casing according to the present invention, the additional layer is preferably inside the casing. When the casing according to the invention is a three-layer casing, the outer layer preferably comprises block copolymers of the formulas 1, 2 and / or 3. The multi-layer casing according to the invention usually comprises no more than 5 layers.

185 306

Multilayer casings are generally made by coextrusion. Co-extrusion nozzles, with the increase in the number of extruded layers, are becoming technically more complicated and more expensive, which reduces the number of layers. This is followed by blow molding and (partial) heat setting as described above.

The casing according to the invention shows a high shrinkage under conditions which are usually achieved during boiling and scalded sausage. It has approximately the "rubber" properties of returning to the original state. Sausages produced without the use of filling machines after steaming and cooling are flexible and wrinkle-free.

In the following examples, the abbreviation Gt stands for parts by weight. Unless otherwise stated, the percentages are by weight.

Example I.

A mixture containing

Gt of polyamide 6 (relative viscosity of a 1% solution of polyamide in sulfuric acid with 96% vaxial 4) and

The Gt block copolymer with poly (propylene glycol) blocks and polycaprolactam blocks (®Orilon EXL 2112 from Ems-Chemie AG) with a melting point of 209 ° C (determined by the DSC method = differential scanning calorimetry) was plasticized in a single screw extruder at 240 ° C to form homogeneous melt and extruded through an annular hose die with a diameter of 18 mm. The hose was cooled rapidly, then brought to the temperature required for stretching, stretched by blowing in a mold, and finally thermally set, with the stretch ratio in the transverse direction reduced by 5%, while the stretch ratio in the longitudinal direction remained unchanged. The area stretching ratio was 8.7. The finished casing had a diameter of 60 mm.

Example II

A mixture containing

Polyamide 6 Gt (as in example I)

Gt of block copolymer with poly (butane-1.4-diio) blocks and polycaprolactam blocks (®Pebax 5533 SN01 by Elf Atochem SA), which had a melt index of 5 g / 10 minutes at 235 ° C and 1 kg load, and

The Gt of polyamide 6/12 (®Grilon Cf6S from Ems Chemie AG), which had a melt index of 50 g / 10 minutes at 190 ° C and a load of 10 kg, was extruded as described in Example 1 in the form of a 19 mm diameter hose. mm, stretched and heat set. The area stretching ratio was 8.3. The finished casing again had a diameter of 60 mm.

Example III

The following mixtures were prepared for the production of the three-layered sausage casing: Mixture A:

Polyamide 6 Gt (as in Example I) and

Gt of the block copolymer used in Example 1;

Mixture B:

Gt LDPE (low-density polyethylene), with a melt index of 0.2 g / 10 minutes at 190 ° C and a load of 2.16 kg (®Lupolen 2) 4ID from BasF AG) and

Gt LLDPE (linear low density polyethylene), modified with maleic anhydride to adhere to the polyamide, with a melt index of 3 g / 10 minutes at 190 ° C and 2.16 kg load (®Escor CTR 2000 from Exxon) .

Mixture C:

Polyamide 6 Gt (as in Example I) and

Gt of amorphous polyamide 61 / 6T, which had a melt index of 90 g / 10 min at 275 ° C and 10 kg vacuum (®Sela.r PA 3426 from Du Pont de Nemours Inc.).

The mixtures were extruded in three single-screw extruders, always at a temperature of 240 ° C, as a homogeneous melt, then fed together into a three-layer annular die and co-extruded in the form of a three-layer hose with a diameter of 29 mm. Next snake and how to opśsanoi oozciiyaano and thermally fixed. During the tempers

185 306 fixation, the transverse stretch ratio was reduced by 20%. The area stretching ratio was then 8.7. The diameter of the finished sausage casing was 80 mm. The total wall thickness of the sheath was 54 µm. Its outer layer (from mixture A) was 34 µm thick, the middle layer (from mixture B) was 16 µm thick, and the inner layer (from mixture C) was 4 µm thick.

Example IV

Example III was repeated with the only change that instead of the mixture A used therein, mixture A consisting of

Polyamide 6 Gt (as in Example I) and

Gt of the block copolymer according to Example 1

As described in Example 1, a 28 mm diameter three layer hose was coextruded, stretched and heat set. The area stretching ratio was 9. The diameter of the finished sausage casing was 80 mm. The total wall thickness of the sheath was 51 µm, with the outer layer (from mixture A) 30 µm thick, the middle layer (from mixture B) 15 µm thick and the inner layer (from mixture C) 6 µm thick.

Example V

Example III was repeated with the only change that instead of the mixture A used therein, mixture A consisting of

Polyamide 6 Gt (as in Example I) and

Gt of the block copolymer also used in Example 2 and

Polyamide 6/12 Gt (as in Example 2).

The finished casing had a diameter of 80 mm and its surface stretch ratio was 7.9. The total wall thickness of the sheath was 56 µm, with the outer layer (from mixture A) 35 µm thick, the middle layer (from mixture B) 15 µm thick. and inner layer (from mixture C) - thickness 6 µm.

Example VI

Example III was repeated with the only change that instead of the mixture A used therein, mixture A consisting of

Polyamide 6 Gt (as in Example I) and

Gt of the block copolymer also used in Example 2 and

Polyamide 6/12 Gt (as in Example 2).

The diameter of the finished casing was 80 mm. The area stretching ratio was 9.0. The total wall thickness of the sheath was 52 µm, with the outer layer (mixture A) 32 µm thick, the middle layer (mixture B) 14 µm thick and the inner layer (mixture C) 6 µm thick.

Comparative example I.

According to DE-A 2 850 182, the polyamide 6, also used in Example 1, was extruded by the method described therein in the form of a 19 mm diameter hose, which was then stretched as described and thermally fixed. The stretching ratio of the area was 8.3, its diameter was 60 mm.

Comparative example II

According to DE-A 4 017 046 as described therein, component A: polyamide 6 (as in example 1), mixture B: identical to mixture B in example 3 and mixture C: identical to mixture C in example 3, were coextruded as 29 mm diameter hose, stretched and thermally fixed. During thermal setting, the transverse stretching ratio decreased by 20%. The finished casing had a stretching ratio of 7.9 and a diameter of 52 mm. The total wall thickness of the sheath was 52 µm, with the outer layer (from component A) having a thickness of 31 µm, the middle layer (from mixture B) - thickness of 13 µm, and the inner layer (from mixture C) - thickness of 8 µm.

The measured values ​​in the table below show the advantages of the casing according to the present invention over the prior art casing.

485 306

1) measurement according to DIN 53 455 on a 15 mm wide strip kept in water for 30 minutes, with a distance of 50 mm between the handles of the testing machine;

2) denotes the tensile stress that must be applied during the test according to DIN 53 455 in order to stretch a 15 mm wide strip in water for 30 minutes by 5% with a distance between the handles of the testing machine equal to 50 mm and a tensile speed of 50 mm / minute ;

3) the percent increase in the outer circumference of the hose pieces that had previously been stored in water for 30 minutes and then inflated until the specified internal pressure was reached;

4) after storage for 15 minutes in water at 80 ° C;

5), the casing was exposed on one side to air with relative humidity of 85% at 20 ° C. Water vapor permeability was measured according to DIN 53 122;

6) subjective evaluation of the casing stored in water for 30 minutes. The numbers have the following meanings: 1 extremely soft; 2 - very soft; 3 - soft and 4 medium soft.

7) the casing was manually filled with fine-grained sausage stuffing under constant slight pressure and closed with metal clips. The sausages were then cooked for 60 minutes in a brewing cabinet at 78 ° C and 100% relative humidity. After cooling to 7 ° C, the appearance and consistency of the casings were assessed.

185 306

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185 306

185 306

CO-X_b- CO - (NH - [CI - ^ - CO ^ -Eb 1

ABOUT

And (AO) nA-O-CO-X_b-CO- (NH- [CH2kCQsE_b

PATTERN 2

-N — C = O [^CH2] x

PATTERN 4

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