US3645760A

US3645760A - Dry sausage casing

Info

Publication number: US3645760A
Application number: US7297A
Authority: US
Inventors: Merril N O'brien; Albin F Turbak
Original assignee: Individual
Current assignee: Continental Group Inc; Teepak Investments Inc
Priority date: 1970-01-05
Filing date: 1970-01-05
Publication date: 1972-02-29
Anticipated expiration: 1989-02-28
Also published as: SE371084B; FR2075215A5; NL7100007A; GB1287997A; DE2100210A1; CA927190A

Abstract

A synthetic tubular sausage casing for processing dry sausages is prepared by impregnating or coating a reinforcing paper, preferably a saturating tissue, with a solution or dispersion of a water-soluble or dispersible protein, having a molecular weight above about 10,000 and an isoelectric point in the range from pH 2 to pH 6. The solution or dispersion is of a concentration such that the protein is impregnated in or coated on the paper at a concentration of about 0.1 percent -6.0 percent based on dry weight of the paper. The paper coated or impregnated with protein is cross linked by reaction with a nontoxic cross-linking agent (nontoxic in the resulting product). The coated or impregnated paper is then formed into a tubular casing and impregnated with viscose or other suitable material which is hardened or regenerated in and upon the protein saturated or coated paper reinforcement.

Description

United States Patent OBrien et all.

[ Feb. 29, 1972 22 VISOQSE WASHING Primary Examiner-Frank W. Lutter Assistant Examiner-Robert Halper Attorney-Neal J. Mosely and David V. Munnis [57} ABSTRACT A synthetic tubular sausage casing for processing dry sausages is prepared by impregnating or coating a reinforcing paper, preferably a saturating tissue, with a solution or dispersion of a water-soluble or dispersible protein, having a molecular weight above about 10,000 and an isoelectric point in the range from pH 2 to pH 6. The solution or dispersion is of a concentration such that the protein is impregnated in or coated on the paper at a concentration of about 0.1 percent -6.0 percent based on dry weight of the paper. The paper coated or impregnated with protein is cross linked by reaction with a nontoxic cross-linking agent (nontoxic in the resulting product). The coated or impregnated paper is then formed intoa tubular casing and impregnated with viscose or other suitable material which is hardened or regenerated in and upon the protein saturated or coated paper reinforcement.

9 Claims, 5 Drawing Figures PRODUCT REELING AND STORAGE DRY SAUSAGE CASING BACKGROUND OF THE INVENTION l Field of the Invention Dry sausage, of which the various salami and cervelats are prime examples, is conventionally processed by drying rather than by cooking, hence the name. Dry sausage is ordinarily served cold, without further cooking by the housewife.

The manufacture of dry sausage customarily involves mixing desired proportions of fat and lean means,'beef or pork, with selected spices, seasonings and curing materials to form an emulsion which is initially cured at a few degrees above freezing (36 to 38 F.), for two or three days depending upon the size of the meat particles so that they will be preserved sufficiently to be smoked and dried.

The chill cured meat emulsion is then firmly packed into casings of suitable size and shape, and the ends of the casing are tied ready for delivery to the drying room or Smokehouse,v

dependent upon the type of sausage. The smoked dry sausage is smoked and then dried, while unsmoked dry sausage is dried only. The drying or curing time will vary with the particular type of sausage being processed and to some extent with the processing conditions. However, 60 to 90 days is usually considered a minimum time and periodsof 120 to 180 days or more are used under some circumstances.

The prrocessing of dry sausage is described fully in Sausage and Ready-to-Serve Meats, published by the American Meat Institute. The term dry sausage" as used herein includes the entire range of dry and semidry sausages. The semidry sausages include the thuringer cervelates which are dried for about days (other semidry sausages may be dried as short a time as 2 to 6 days). Dry sausage is usually sold in three different forms; first, new sausage or semidry sausage, about 10 to 25 days after smoking (having about percent shrinkage); second, medium dry sausage, about 30 to 60 days after smoking (having about 32 percent shrinkage); and dry sausage, about 60 to 90 days or more after smoking (having about 40 percent shrinkage).

Previously, the sausage meat emulsions were stuffed into casings formed of natural materials or animal products such as sewn beef middles and hog casings. More recently, considerable interest has been developed in utilizing certain synthetic materials out of which casings could be formed. Particularly, the industry has turned to the use of casings formed of regenerated cellulose per se or of the product known in the art as fibrous casing and which is composed of cellulosic fibers impregnated and held together by regenerated cellulose.

The use of such synthetic materials is not only desirable because of the greater control over the supply that can be exercised in keeping with the rapid growth and demand of the various packaged and/or cased meat products, but also the materials can be conventionally synchronized and extruded into seamless tubular form of preselected diameter. Most importantly, casings formed of the aforesaid fibrous materials, unlike the natural product can be made sufficiently flexible as well as durable to be advantageously used in the stuffing step, while also being sufficiently nonelastic that they will not stretch out of shape during or subsequent to stuffing, but will retain a more constant shape and size corresponding to that to which it was initially fabricated.

This, of course, permits a definite relation to be established between the number of slices of the sausage and weight which may be assembled as a unit, and is obviously a highly desirable characteristic in the mechanical high-speed packaging methods employed today. In addition, the cellulosic casings which there is a tendency for mold and/or so called "brown ring" to develop. This trouble is not encountered where natural casings are used since natural casings tend to expand and contract with the sausage during curing.

2. Description of the Prior Art The coating or impregnation of cellulosic casings to improve the adhesion of the casing to dry sausages is well known in the prior art.

Voss et al. U.S. Pat. No. 1,978,744 discloses a cellulosic casing having an internal coating of gelatin to improve adhesion toward dry sausages. Bose] U.S. Pat. No. 2,802,745 discloses a casing formed of regenerated cellulose in which gelatin particles of a size less than 0.1 mm. were dispersed in the viscose from which the casing was formed so that the casing has gelatin particles dispersed throughout the wall thereof.

Firth U.S. Pat. No. 3,158,488 discloses the use of monoglycerides or acetylated monoglycerides, either along or in combination with gelatin, as internal coatings for casings to be used for the processing of dry sausages. Rose et al. U.S. Pat. No. 3,360,383 disclose the internal coating of a cellulosic casing with a mixture of a protein, such as gelatin, and liquid smoke. The protein is hardened by the liquid smoke during the drying process. Rose U.S. Pat. No. 3,367,786 discloses the coating of a cellulosic casing internally with a coating mixture of a soluble protein, such as gelatin, and piperazine as a hardening agent for the protein. Shiner et al. U.S. Pat. No. 3,378,379 discloses a fibrous cellulosic casing coated internally with a water soluble cationic thermosetting resin which is subsequently cured. Rose U.S. Pat. No. 3,383,223 disclose the internal coating of a fibrous cellulosic casing with a mixture of a soluble protein and glutaraldehyde.

The prior art is generally subject to the objection that the various coating processes involve the use of an internal coating slug which is introduced into the casing after formation of the casing prior to drying. This coating technique is expensive and uncertain in operation since the depletion of the slug or coating solutions often results in erratic nonuniform coating.

SUMMARY OF THE INVENTION In recent years, regenerated cellulose casings, primarily of the fibrous paper-reinforced-type, have been made and sold commercially for use inthe manufacture of dry sausages. These casings have generally been coated on their inner surfaces with a thin layer of gelatin or other materials which is effective in causing the casing to adhere to a dry sausage emulsion and follow the shrinkage of the casing during curing. Gelatin coated casings of this type, however, are subject to the disadvantage that they must be soaked in water prior to use and this soaking generally results in a very substantial loss of the gelatin coating. As a result, there has been a substantial failure of adhesion of casings to dry sausages during processing which has resulted in the production of unsatisfactory sausage products. The loss of gelatin during the soaking step can be offset by some extent by application of a heavier gelatin coating. The thickness of the gelatine coating however is determined largely by the concentration of gelatin in the solution used to coat the casing and the coatings which have been used commercially are at a maximum practical thickness. Certain of the prior art patents, mentioned above, are concerned with the treatment of gelatin coating solutions with various hardening agents, e.g., glutaraldehyde, liquid smoke, piperazine, etc., which insure that the coating provided on the inner surface of the casing is sufficiently insoluble to prevent leaching out during the presoak operation while allowing the coating sufficient adhesion toward the dry sausage to perform its desired function of causing the casing to shrink with the sausage during processing. A further problem in the preparation of dry sausage casings is the manner of application of the adhesive coating to the inner surface of the casing. The most common and most economical mode of application of the internal adherent coating has been the slug coating technique. A solution of the coating material is introduced into the casing in the form of a liquid slug. The opening in the casing is closed and the casing moves past the sluginto the casing dryer. The internal surface of the casing is continuously coated and dried along with the casing in the dryer. This procedure has had the disadvantage that the depletion rate of the coating solution is uncertain and erratic coverage of the internal coating may result.

This invention is based on our discovery that fibrous reinforced casing suitable for use in the preparation of dry sausages may be prepared by impregnating a fibrous reinforcing paper, preferably a long fiber hemp-saturating tissue, with an aqueous solution or dispersion of a water-soluble or waterdispersible swollen protein. The protein used-may be any of the soluble or dispersible proteins having molecular weights above 10,000 and an isoelectric point in the range from about pH 2 to pH 6. These soluble proteins include (but are not limited to) the albumins, globulins, glutenins, prolamines, prolines, hydroxy prolines, histones, elastins, and protamines. Typical examples are egg albumin, edestin, glutenin, procollagen, gelatin, gliadin, etc. The solution is impregnated in or coated upon the saturating tissue. In the case of the more soluble proteins solution is dispersed relatively uniformly through the saturating tissue, although there tends to be a higher concentration on the surface at which the coating solution is applied. In the case of the water-dispersible proteins the coating forms primarily on the surface of the saturating tissue. The coated or impregnated saturating tissue is hardened or cross linked with a suitable cross-linking agent which is nontoxic under conditions of ultimate use. The cross-linking agent used must either be nontoxic per se or must be chemically combined in a form which is totally nontoxic in the finished product. Suitable cross-linking agents include formaldehyde (used at very low levels), glutaraldehyde, liquid smoke, etc. The hardening or cross-linking agent is preferably added in admixture with the solution or dispersion or the protein under conditions of temperature insufficient to effect the cross linking. During the drying operation the coating is heated to a high enough temperature to effect the desired hardening of cross linking.

The coated or impregnated paper is used in the formation of a fibrous casing by forming a continuous elongated tube and saturating the tube externally with a solution of the desired casing forming material, which is subsequently hardening or regenerated. Typically, the tubular casing would be impregnated with viscose which would be subsequently coagulated and regenerated to form a regenerated cellulose paperreinforced casing. Alternatively, the tubular casing paper could be impregnated with collagen, polyvinyl alcohol, amylose, alginates, dextran, etc., to form a suitable reinforced casing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic view illustrating the formation of fibrous casing in accordance with a more or less standard commercial procedure.

FIG. 2 is a detail cross section of a portion of uncoated fibrous casing showing the relative position of the supporting fibrous paper and the regenerated cellulose thereon.

FIG. 3 is a sectional view of a portion of fibrous casing as shown in FIG. 2 but provided with a hardened protein coating as taught be the prior art.

FIG. 4 is a diagrammatic view of the impregnation or coating of fibrous paper with a protein solution or dispersion in accordance with a preliminary step in this invention.

FIG. 5 is a view in cross section of the wall of a fibrous casing having protein hardened and incorporated therein in accordance with this invention.

PRIOR ART PREPARATION OF FIBROUS CASING Referring to the drawing, there is shown a somewhat diagrammatic view of the process and apparatus used in the preparation of fibrous casing in accordance with the prior art.

In the drawing, a ribbon of paper 11, which is formed of natural cellulosic fibers, and which is preferably a long fiber, hemp paper weighting 10-20 pounds per ream, passes from roll 12 over rollers 13 and 14 and around guides 15 and 16 which form the paper into tubular form.

The paper then proceeds downwardly over mandrel 17 which may be a steel pipe having an outside diameter of two to seven inches, more or less, depending upon the size of the tube or casing which is to be produced. The mandrel 17 may be of a suitable length, conveniently 7 about 30 feet long, and, as shown, can be suspended from a suitable support such as 'an I- beam 18 or the like. The paper ribbon 11, now shaped in the form of a tube, passes downwardly over the mandrel 17, through a forming ring 19 which is a metallic ring having an in: side diameter slightly larger than the diameter of the paper tube passing through it. The forming ring 19 functions to maintain the paper in the form of a tube until it reaches the coating die 21.

Coating die 21 is a hollow annular structure of metal or the like and contains an annular opening 22, circumferentially of its inner face, through which viscose is applied to the outer surface of the downwardly paper tube. Viscose is supplied under positive pressure from the chamber of die 21 through the annular slit 22 to thoroughly impregnate and coat the paper tube which is moving downwardly through the die.

The sleeve 33, formed of metal or the like, which is shrunk onto the mandrel 17, functions to effect more uniform application or viscose through the orifice 22 as the paper tube 11 passes downwardly thereover. A number of slip rings 220 are positioned on mandrel 17- at preselected intervals. The slip rings 22a are preferably shrunk onto the mandrel at about 3- foot intervals and function to keep the inside wall of the viscose-impregnated, paper tube from scraping against the outside wall of mandrel 17 as the tube moves downwardly.

Continuing in its downward movement, the viscose-impregnated, paper tube 11 enters coagulating bath 23 contained in vessel 24. Coagulating bath 23 contains about 5 percent sulfuric acid and various salts. On contact with the acid bath, the viscose impregnated in and coated upon paper tube 11 is coagulated and regenerated. The conversion of viscose to regenerated cellulose begins and continues within the bath as the tube moves around roller 25 and continues as the tube moves over and under

wiper rods

26 and 27, rollers 28, and then through washing baths and drying tunnels not shown here, but being substantially the same as those used in the art of making regenerated cellulose casings, as exemplified in US. Pat. No. 1,937,225 and related patents. For convenience in understanding the overall intention, the steps of washing, drying and reeling and storage of the produce casing are shown diagrammatically without reference to any particular apparatus for accomplishing those steps.

In carrying out the acid regeneration of cellulose in the paper tubing, acid for the bath 23 is supplied through pipe 29. The same kind and concentration of acid is supplied to the interior of the casing through the mandrel 17 through a pipe 31. Spent acid from within the casing is withdrawn through pipe 32 at a rate which is balanced by the incoming acid, as shown. In the preparation of casing in accordance with this process, the speed of the casing in its downward movement is approximately 2050 feet per minute, more or less, and the contact time in the acid bath 23 is of the order of 10-40 seconds.

The fibrous casing which is produced in this process is a tough, strong casing useful in the preparation of large sausages such as bolognas and the like. The same general process and apparatus is used in the production of other types of fibrous casing. For example, other soluble impregnating materials, such as alginates, dextran derivatives, amylose, polyvinyl alcohol, collagen, etc., may be substituted for viscose to produce a fibrous casing made from the hardened or regenerated material derived from the coating or impregnating solution.

A cross section of a portion of the wall of a cellulosic fibrous casing is shown in FIG. 2. The reinforcing paper is thoroughly saturated and coated with viscose during the process of manufacture and cellulose is regenerated therefrom. The cross section shown in FIG. 2 shows the reinforcing paper and regenerated cellulose impregnated therein and the regenerated cellulose coating as distinct layers. This structure of the fibrous casing is clearly shown when the casing is sectioned and stained and observed under a microscope.

In the manufacture of fibrous dry sausage casings in accordance with the prior art, a fibrous casing prepared as described above is coated internally with a proteinaceous or other adherent coating which is hardened thereon as a distinct layer provided an adhesive bond between the casing and the dry sausage processed therein. The cross section of a prior art fibrous day sausage casing is shown in FIG. 3. In this cross section it is seen that the paper and impregnated regenerated cellulose and cellulose coating appear as distinct layers, as shown in FIG. 2, while the adherent hardened protein coating appears as a distinct layer on the paper portion of the casing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS in Fig. 4 there is shown a diagrammatic view of the process of coating fibrous paper in preparation for the formation of dry sausage casing in accordance with this invention. A roll of fibrous paper (preferably a long fiber hemp-saturating paper) is unwound with the paper web 51 passing between a coating roller 52 and press roller 53.

Rollers

52 and 53 are positioned in a coating tank 54 containing a solution 55 of protein such as gelatin or the like. Alternatively, the coating bath 55 may be a dispersion of a water dispersible (but insoluble) protein such as a dilute slurry of collagen. The coated or impregnated web of paper which leaves the

rolls

52 and 53 passes through dryer 56 where the coating solution is thotoughly dried. The coating solution in tank 54 includes a chemical hardening or crosslinking agent which is relatively inactive at room temperature but which is reacted with the protein when heated to a higher temperature in the dryer to harden the protein coating. The dried coated or impregnated paper web is then rewound on windup roll 57.

In carrying out this invention, the coated or impregnated paper from roll 57 is passed through the apparatus as shown in FIG. 1 to form the paper into a continuous tubular fibrous casing and impregnate or coat the paper with viscose (or other casing forming solution), the impregnated paper being passed through a coagulating and regenerating bath as described in connection with FIG. 1.

A cross section of a portion of the wall of the casing thus prepared is shown in FIG. 5. The casing wall comprises a regenerated cellulose layer 58 secured on an integral with a layer 59 comprising paper admixed with hardened protein and regenerated cellulose. This casing differs from that shown in FIG. 3 in that the hardened protein is not present as a distinct layer on the inner surface of the casing but rather is dispersed throughout the paper and the regenerated cellulose is admixed therewith. The amount of protein added to the paper in the treating step shown diagrammatically in FIG. 4 is in the range from about 0.1 to 6.0 percent based on the dry weight of the paper. At protein addons less than 0.1 percent the resulting product is ineffective as a dry sausage casing, i.e., it does not adhere to and follow the surface of the meat during processing. At protein addons greater than 6.0 percent the paper is blinded and nonporous to the extent that the viscose will not penetrate adequately to form a properly reinforced casing. At higher protein content, the cellulose is coated on the outside of the paper rather than impregnated throughout the paper and is not given the added strength and resistance against stretch which is produced in a typical fibrous casing where the viscose thoroughly impregnates the reinforcing paper.

The following nonlimiting examples are illustrative of the scope of this invention.

EXAMPLE 1 A gelatin-coating solution was prepared by dissolving 2 pounds gelatin in 50 pounds water and heating to F. with stirring. To this mixture there was added 11 pounds glycerin with 30 minutes additional stirring. The solution was diluted with 16.5 pounds additional water and cc. ofa 25 percent aqueous solution of glutaraldehyde added. The solution was further diluted to 1 percent gelatin content and then cooled in preparation for coating fibrous casing paper.

A l4-pound hemp fiber-saturating tissue was coated with the gelatin coating solution at 80 ft./min. using the apparatus described in FIG. 43 above. The paper picked up about 200 percent wt. of the solution which represented a 2 percent gelatin content on the finished dried paper.

Next, the gelatin impregnated paper was slit to size and used in the preparation of fibrous casing. The gelatin-impregnated paper was passed through the casing manufacturing operation as shown in FIG. 1 and as described above. The casing produced is substantially as shown in FIG. 5 cross section.

' Portions of the casing prepared in accordance with this example were used in the preparation and processing of a variety of dry and semidry sausages including hard salami, Genoa salami, and summer sausage. The casings were prepared with untreated controls and control casings having gelatin coatings inside prepared by a liquid slug-coating technique as used in the prior art. The untreated control casings separated from the sausage during processing. The casings produced in accordance with this example and the casings provided with an internal gelatin coating as taught by the prior art adhered adequatelyto the dry sausage compositions throughout their processing.

EXAMPLE 2 A gelatin-coating composition was prepared as described in Example 1 and diluted 50 percent with additional water. A 14- pound hemp paper was impregnated with the solution and dried as described in Example 1. The paper had a gelatin content of 1 percent wt.

The gelatin impregnated paper was formed into fibrous casing as described in Example 1 and the casing used in the preparation of a variety of dry and semidry sausages. The casing performed well and adhered to dry sausage and semidry sausage throughout the processing thereof. There was no substantial loss of gelatin from the casing during the presoak operation prior to stuffing with the sausage paste or emulsion.

EXAMPLE 3 A coating solution was prepared as described in Example 1 and diluted to 0.05 percent gelatin content. When this solution is used to coat hemp-saturating tissue as described in Example 1 there is a 0.1 percent addon of gelatin in the finished paper.

The gelatin-treated paper is used in the formation of fibrous casing which is subsequently used in the preparation of a variety of dry and semidry sausages. The casing adheres well to dry and semidry sausages during all phases of the processing thereof. However, at this level of gelatin addon there are a few cases of casing separation from the sausage. It would appear therefore that a 0.1 percent gelatin addon represents about the minimum gelatin content for a dry sausage casing.

EXAMPLE 4 A casing treating solution was prepared as described in Example l and diluted to a 2 percent gelatin content.

A long fiber hemp-saturating tissue was coated with this gelatin solution as described in Example 1 with a percent solution pickup. The paper was dried and found to have a 3.6 percent gelatin addon.

The gelatin impregnated paper was used in the preparation of fibrous casing as described in Example 1 and the casing used in the preparation of a variety of dry and semidry sausages. The casing adhered to the sausages with greater uniformity than casing coated internally with gelatin in accordance with prior art techniques. There was no substantial loss of gelatin from the casing during the presoak operation prior to stuffing with sausage paste or emulsion.

EXAMPLE A gelatin-coating solution was prepared as described in Example l and sufficient gelatin added to produce a 4 percent wt. concentration of gelatin. The coating solution is used to coat a long fiber hemp-saturating tissue as described in Example 1. There is about a 200 percent liquid pickup. This produces a gelatin addon of about 8 percent wt. on the paper.

When this paper is used in the preparation of fibrous casing it is found that the viscose solution does not penetrate adequately. The high gelatin content almost totally blinds the saturating tissue so that the viscose only coats the exterior of the treated paper and is not able to penetrate the paper adequately. It is not possible to produce a satisfactory fibrous casing from paper having this high gelatin addon. When the gelatin addon is reduced to about 6 percent the paper is only partially blinded and viscose penetration is poor but adequate to produce a fibrous casing giving moderately good performance.

EXAMPLE 6 A gelatin-treating solution is prepared as described in Example 4 containing 2 percent gelatin and substituting about 0.2 percent formaldehyde, based on the weight of gelatin used, for glutaraldehyde as the hardening or cross-linking agent for the gelatin. Solution is used in impregnation of a long fiber hemp-saturated tissue with about 18 percent liquid pickup. The treated casing, after drying, has about a 3.6 percent wt. gelatin addon.

When this casing paper is made into fibrous casing in ac cordance with the process described in Example 1 and used in the processing of dry of semidry sausages the casings are found to function satisfactorily in comparison with commercial dry sausage casing prepared in accordance with the prior art internal coating techniques.

EXAMPLE 7 The process of coating fibrous paper was repeated as described in Example 6 with 1.0 percent wt. liquid smoke (Char-Sol), based on the weight of gelatin, substituted for formaldehyde as the hardening or cross-linking agent. The coating solution was used to coat a long fiber hemp-saturating tissue to a 3.6 percent wt. gelatin addon.

The coated paper is used to manufacture a fibrous casing which is in turn used in the processing of dry and semidry sausage casing with satisfactory results, equivalent to those obtained in Examples 4 and 6.

EXAMPLE 8 A collagen-coated solution (or slurry) is prepared by diluting a 4.2 percent collagen slurry, produced in accordance with Talty et al. US. Pat. No. 3,408,918, to a. content of 0.40 percent collagen. A long fiber hemp saturating tissue was passed through the coater, as shown in FIG. 4, to coat the collagen slurry onto the paper. The collagen slurry included about 0.05 percent wt. glutaraldehyde based on the weight of collagen. The hemp-saturating tissue was coated on one side rather than being thoroughly impregnated as in the case of a gelatin solution. The collagen slurry is coated on the paper and only partially impregnated into the porous structure of the paper. There is approximately 200 percent takeup of the slurry with the result that the paper has a collagen addon of about 0.8 percent wt.

The collagen-coated paper, after drying, was used in the preparation of fibrous casing in accordance with the process described in connection with the apparatus shown schematically in FIG. 1. In preparing fibrous casing from collagen coated paper it is necessary that the collagen coating be turned to the inside of the tube and the viscose added to the untreated side of the paper.

The casing prepared in this manner, having a 0.8 percent wt. addon of collagen, based on the paper weight, was used in the processing of a variety of dry and semidry sausages and gave excellent results as compared to prior art internally coated fibrous casing used commercially for the preparation of dry and semidry sausages.

EXAMPLE 9 of dry sausages and semidry sausages with entirely satisfactory results as compared to prior art and dry sausage casings having internal coatings of gelatin.

EXAMPLE 10 The process described in Example 4 is repeated with wheat gluten being substituted for gelatin as the protein coating or impregnant for fibrous casing paper. A coating solution is prepared containing 2 percent wheat gluten in place of the 2 percent gelatin solution used in Example 4. When a fibrous casing paper is coated with the solution and dried (the gluten being hardened or cross linked by reaction with a glutaraldehyde) the paper is found to have a 3.6 percent wt. addon of gluten.

The gluten-impregnated casing paper is used in the preparation of fibrous casing using the process as described in Example 14. The casing is used in the preparation and processing of dry sausages and semidry sausages with satisfactory results. The casing adheres to and follows or shrinks with the sausage during processing.

We claim:

1. A method of preparing tubular artificial casings for the processing of dry sausages which comprises,

a. impregnating or coating a saturating tissue paper with a solution or dispersion of a water-soluble or dispersible protein having a molecular weight greater than about 10,000 and an isoelectric point in the range from pH 2 to pH 6,

b. drying the impregnated or coated paper and hardening the protein therein,

c. forming the dried paper into a continuous tube,

d. impregnating and coating the outer surface of said tube with a solution of a film-forming material, and

e. setting said film forming material to produce a paperreinforced tubular film having the inner surface thereof containing hardened protein uniformly dispersed therein.

2. A method of preparing tubular artificial casings according to claim 1 in which said solution of film-fanning material is viscose which is set by acid regeneration.

3. A method of preparing tubular artificial casings according to claim 2 in which a hardening agent is added to the paper to harden the protein therein.

inner surface thereof with a chemically hardened protein having a molecular weight greater than about l0,000 and an isoelectric point in the range of from pH 2 to pH 6 and impregnated thoroughly with a film-forming material over the protein-impregnated fibers of the paper and coated on the outer surface of said tube with a coating of substantial thickness of said film-forming material.

Claims

2. A method of preparing tubular artificial casings according to claim 1 in which said solution of film-forming material is viscose which is set by acid regeneration.
3. A method of preparing tubular artificial casings according to claim 2 in which a hardening agent is added to the paper to harden the protein therein.
4. A method of preparing tubular artificial casings according to claim 2 in which a hardening agent is added to the paper in admixture with the protein dispersion or solution to harden the protein on the paper during drying.
5. A method of preparing tubular artificial casings according to claim 2 in which the protein is applied to the paper in a concentration of 0.1-6.0 percent wt. based on dry weight of the paper.
6. A method of preparing tubular artificial casings according to claim 2 in which the protein is gelatin.
7. A method of preparing tubular artificial casings according to claim 2 in which the protein is collagen.
8. A method of preparing tubular artificial casings according to claim 2 in which the protein is gluten.
9. A tubular artificial food casing comprising a tube of a saturating tissue paper impregnated or coated on at least the inner surface thereof with a chemically hardened protein having a molecular weight greater than about 10,000 and an isoelectric point in the range of from pH 2 to pH 6 and impregnated thoroughly with a film-forming material over the protein-impregnated fibers of the paper and coated on the outer surface of said tube with a coating of substantial thickness of said film-forming material.