JP2017093328A - Artificial casing, and food product using the casing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an artificial casing for a food product, which is improved in sufficient strength and texture, and a food product using the casing.SOLUTION: An artificial casing for a food product containing cellulose nano-fibers, and the food product using the artificial casing. Especially by using oxidized cellulose nano-fibers or carboxy-methylated cellulose nano-fibers, the tensile strength of an artificial casing obtained can be improved, and the texture (crispy palate feeling, hardness) of the food product can be improved.SELECTED DRAWING: None

Description

  The present invention relates to an artificial casing (hereinafter sometimes referred to as a casing) for processed foods such as sausages and a processed food using the same. More specifically, the present invention relates to an artificial casing made of collagen or the like and a processed food using the same.

  Since ancient times, in processed meat products such as ham and sausage, natural collagen such as the intestines and bladder membranes of animals such as sheep, pigs, cows, and horses as a coating composition for covering the surface of meat ingredients, ie, casings Natural casings such as membranes have been used. However, although these have a good texture and appearance, they lack stability in terms of size, supply amount, hygiene, etc., and artificial casings that are superior in these respects have been used. The quality required for these artificial casings is that they adhere to the ingredients, are not easily torn when filled with ingredients, that is, have a high tensile strength, and if smoked, permeable to smoke and edible casings. Is that the food containing the casing has a good texture such as crispness and hardness. On the other hand, from the viewpoint of manufacturing cost reduction, weight reduction, that is, thinning is also required at the same time, but among the above qualities, tensile strength and texture are contrary to thinning, and these are compatible at a high level. It is difficult to do.

  As a method for improving this, Patent Document 1 exemplifies a method for improving the texture of sausage using a collagen casing by mixing egg-derived protein or the like with collagen. Moreover, in patent document 2, the method of improving the tensile strength of the film (casing) obtained by adding powdered cellulose to collagen, a plastics, and regenerated cellulose is illustrated.

Japanese Patent No. 3408870 Japanese Patent Laying-Open No. 2015-183021

  However, although the method of Patent Document 1 has a certain improvement effect on the texture, it cannot be said that it is sufficient, and there is no description about improvement of tensile strength. Further, the method of Patent Document 2 has a certain improvement effect on the tensile strength, but it is not sufficient, and there is a problem that there is a feeling of roughness when ingested. Therefore, an object of the present invention is to provide an artificial casing for processed food that improves tensile strength and texture, and particularly maintains sufficient strength even when thinned, and a processed food using the same.

The present invention provides the following.
[1] An artificial casing comprising cellulose nanofibers.
[2] The artificial casing according to [1], wherein the cellulose nanofiber according to [1] is a chemically modified cellulose nanofiber.
[3] The chemically modified cellulose nanofiber is an oxidized cellulose nanofiber having an amount of carboxyl groups of 0.5 mmol / g to 3.0 mmol / g with respect to the dry weight of the chemically modified cellulose nanofiber. The artificial casing according to [2], which is characterized.
[4] The chemically modified cellulose nanofiber is a carboxymethylated cellulose nanofiber having a degree of carboxymethyl substitution per glucose unit of the chemically modified cellulose nanofiber of 0.01 to 0.50, [ The artificial casing according to 2].
[5] The artificial casing according to any one of [1] to [4], further comprising collagen.
[6] A processed food using the artificial casing according to any one of [1] to [5].

  According to the present invention, the texture can be improved and sufficient strength can be maintained even when the film is thinned.

  Hereinafter, the artificial casing of the present invention and the processed food using the same will be described in detail.

<Processed food>
The processed foods applied to the present invention are sausages (Bologna, Frankfurt, Wiener, Chorizo, Taiwan sausage, salsiccia, lingissa, weiss burst, beer shinken, riona sausage, krakou, mortadella, bia brusto, brat brusto, thuringer, and undui. Typified by sausages, Jagdbrust, Boudin Blanc, BockBurst, etc.), ham (loin ham, prosciutto, boneless ham, shoulder ham, ham with bone, pork ham, berry ham, fillet ham, etc.), salami (selberato, pepperoni, carpas, etc.) Thus, the manufacturing process of filling the casing with seasoned ground meat or minced meat as ingredients is included. In addition to livestock such as pigs, cows, birds, horses, etc., fish meat may be used, such as fish sausage, and vegetables that have been crushed into a paste like vegetable sausage may be used as ingredients. . In any case, it is preferable that the casing and the material are in close contact with each other, and therefore the material preferably has a certain degree of fluidity.

<Artificial casing>
The artificial casing in the present invention is edible and can be suitably used for, for example, a collagen casing, and can improve the tensile strength and texture of the casing. The thickness of a casing is about 0.01-1.0 mm normally, and the casing of this invention can be used conveniently in a normal range. In particular, even in the case of a relatively thin thickness of 0.5 mm or less, it is possible to maintain a sufficient tensile strength for processing.

  The reason why the tensile strength and texture of the casing are improved by the present invention is not clear, but is presumed as follows. First, regarding the tensile strength, the cellulose nanofibers contained in the casing have a three-dimensional structure due to the presence in the casing, and by acting as a skeleton, the elastic modulus of the casing increases, and the cellulose nanofibers become uniform. It is estimated that the tensile strength is improved by the dispersion. Next, with regard to the texture, it is assumed that the cellulose nanofiber has a so-called thixotropic property that the viscosity gradually decreases as it is subjected to shear stress, which has a good effect on the texture. Is done.

<Cellulose nanofiber>
The artificial casing for processed food of the present invention is characterized by containing cellulose nanofibers. Cellulose nanofiber is a material produced by loosening plant fibers to the nano level, and is generally a fine fiber having an average fiber diameter of about 3 to 500 nm and an average aspect ratio of 50 or more. The upper limit of the aspect ratio is not particularly limited, but is usually 1000 or less. The average fiber diameter and average fiber length of cellulose nanofibers can be obtained by averaging the fiber diameter and fiber length obtained from the results of observing each fiber using a field emission scanning electron microscope (FE-SEM). it can. Also, the aspect ratio can be calculated by the following formula:
Aspect ratio = average fiber length / average fiber diameter

  Cellulose nanofibers can be produced by applying a strong shearing force after the cellulose raw material is left unmodified or chemically modified.

<Cellulose raw material>
In the present invention, cellulose raw materials for producing cellulose nanofibers include plants (for example, wood, bamboo, hemp, jute, kenaf, farmland residue, cloth, pulp (conifer unbleached kraft pulp (NUKP), conifer bleach). Kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), hardwood bleached kraft pulp (LBKP), softwood unbleached sulfite pulp (NUSP), softwood bleached sulfite pulp (NBSP) thermomechanical pulp (TMP), regenerated pulp , Waste paper, etc.), animals (for example, ascidians), algae, microorganisms (for example, acetic acid bacteria (Acetobacter)), microbial products and the like are known, and any of them can be used in the present invention. Is a cellulose fiber derived from a plant or a microorganism, more preferably a plant Is a cellulose fiber of come.

  The fiber diameter of the cellulose fiber raw material used in the present invention is not particularly limited, and is about 30 to 60 μm in the case of softwood kraft pulp which is a general pulp, and about 10 to 30 μm in the case of hardwood kraft pulp. In the case of other pulps, those that have undergone general refining are about 50 μm. For example, when a chip or the like having a size of several centimeters is refined, it is preferable to perform a mechanical treatment with a disintegrator such as a refiner or a beater to make it about 50 μm.

<Chemical modification>
In the present invention, the cellulose raw material may be unmodified or chemically modified, but is more preferably chemically modified. Cellulose nanofibers manufactured using chemically modified cellulose raw materials have a uniform fiber length and fiber diameter compared to cellulose nanofibers manufactured using unmodified cellulose raw materials. It is assumed that it is stable and exhibits a superior effect. Although the method of chemical modification is not particularly limited, for example, oxidation, etherification, phosphorylation, esterification, phosphate esterification, silane coupling, fluorination, cationization and the like can be performed. Among these, any of oxidation, carboxymethylation, and cationization using an N-oxyl compound is preferable, and carboxymethylation or oxidation is particularly preferable because it is used for food.

<Oxidation>
In the present invention, the oxidation of the cellulose raw material can be performed using a known method, and is not particularly limited, but the amount of carboxyl groups is 0.5 mmol / g with respect to the absolute dry weight of the cellulose nanofiber. It is preferable to adjust so that it may be -3.0 mmol / g.

  As an example, it can be obtained by oxidizing cellulose in water using an oxidizing agent in the presence of a compound selected from the group consisting of an N-oxyl compound and a bromide, iodide or a mixture thereof. By this oxidation reaction, the primary hydroxyl group at the C6 position of the glucopyranose ring on the cellulose surface is selectively oxidized, and a cellulose fiber having an aldehyde group and a carboxyl group or a carboxylate group on the surface can be obtained. The concentration of cellulose during the reaction is not particularly limited, but is preferably 5% by weight or less. The N-oxyl compound refers to a compound that can generate a nitroxy radical. As the N-oxyl compound, any compound can be used as long as it promotes the target oxidation reaction.

  The amount of the N-oxyl compound used is not particularly limited as long as it is a catalytic amount that can oxidize cellulose as a raw material. For example, 0.01 to 10 mmol is preferable, 0.01 to 1 mmol is more preferable, and 0.02 to 0.5 mmol is more preferable with respect to 1 g of absolutely dry cellulose. Moreover, about 0.1-4 mmol / L with respect to a reaction system is good.

  The bromide is a compound containing bromine, and examples thereof include alkali metal bromide that can be dissociated and ionized in water, such as sodium bromide. Further, an iodide is a compound containing iodine, and examples thereof include alkali metal iodide. The amount of bromide or iodide used can be selected as long as the oxidation reaction can be promoted. The total amount of bromide and iodide is, for example, preferably 0.1 to 100 mmol, more preferably 0.1 to 10 mmol, and still more preferably 0.5 to 5 mmol with respect to 1 g of absolutely dry cellulose.

  As the oxidizing agent, known ones can be used, and for example, halogen, hypohalous acid, halous acid, perhalogen acid or salts thereof, halogen oxide, peroxide and the like can be used. Of these, sodium hypochlorite is preferable because it is inexpensive and has a low environmental impact. The appropriate amount of the oxidizing agent used is, for example, preferably 0.5 to 500 mmol, more preferably 0.5 to 50 mmol, further preferably 1 to 25 mmol, and most preferably 3 to 10 mmol with respect to 1 g of absolutely dry cellulose. . For example, 1-40 mol is preferable with respect to 1 mol of N-oxyl compounds.

  The cellulose oxidation process allows the reaction to proceed efficiently even under relatively mild conditions. Therefore, the reaction temperature is preferably 4 to 40 ° C, and may be room temperature of about 15 to 30 ° C. As the reaction proceeds, a carboxyl group is generated in the cellulose, so that the pH of the reaction solution is reduced. In order to advance the oxidation reaction efficiently, an alkaline solution such as an aqueous sodium hydroxide solution is added to maintain the pH of the reaction solution at about 8 to 12, preferably about 10 to 11. The reaction medium is preferably water because it is easy to handle and hardly causes side reactions.

  The reaction time in the oxidation reaction can be appropriately set according to the degree of progress of oxidation, and is usually 0.5 to 6 hours, for example, about 0.5 to 4 hours. The oxidation reaction may be performed in two stages. For example, by oxidizing the oxidized cellulose obtained by filtration after the completion of the first-stage reaction again under the same or different reaction conditions, the efficiency is not affected by the reaction inhibition by the salt generated as a by-product in the first-stage reaction. Can be oxidized well.

  Another example of the carboxylation (oxidation) method is a method of oxidizing by contacting a gas containing ozone and a cellulose raw material. By this oxidation reaction, at least the hydroxyl groups at the 2nd and 6th positions of the glucopyranose ring are oxidized and the cellulose chain is decomposed. The ozone concentration in the gas containing ozone is preferably 50 to 250 g / m 3, and more preferably 50 to 220 g / m 3. The amount of ozone added to the cellulose raw material is preferably 0.1 to 30% by weight and more preferably 5 to 30% by weight when the solid content of the cellulose raw material is 100% by weight. The ozone treatment temperature is preferably 0 to 50 ° C, and more preferably 20 to 50 ° C. The ozone treatment time is not particularly limited, but is about 1 to 360 minutes, and preferably about 30 to 360 minutes. When the conditions for the ozone treatment are within these ranges, the cellulose can be prevented from being excessively oxidized and decomposed, and the yield of oxidized cellulose is improved. After the ozone treatment, an additional oxidation treatment may be performed using an oxidizing agent. The oxidizing agent used for the additional oxidation treatment is not particularly limited, and examples thereof include chlorine compounds such as chlorine dioxide and sodium chlorite, oxygen, hydrogen peroxide, persulfuric acid, and peracetic acid. For example, these oxidizing agents can be dissolved in a polar organic solvent such as water or alcohol to prepare an oxidizing agent solution, and a cellulose raw material can be immersed in the solution for additional oxidation treatment.

The amount of the carboxyl group, carboxylate group, and aldehyde group of the cellulose fiber can be adjusted by controlling the amount of the oxidizing agent added and the reaction time.
The carboxyl group content is measured, for example, by preparing 60 ml of a 0.5 wt% slurry (aqueous dispersion) of oxidized cellulose, adding 0.1 M hydrochloric acid aqueous solution to pH 2.5, and then adding 0.05 N sodium hydroxide. The electrical conductivity was measured by dropping the aqueous solution until the pH reached 11, and the amount was calculated from the amount of sodium hydroxide (a) consumed in the neutralization step of the weak acid where the change in electrical conductivity was slow, using the following formula: can do:
Amount of carboxyl group [mmol / g oxidized cellulose or cellulose nanofiber] = a [ml] × 0.05 / oxidized cellulose weight [g].

<Carboxymethylation>
In the present invention, the carboxymethylation of the cellulose raw material can be carried out using a known method and is not particularly limited. However, the degree of carboxymethyl group substitution per anhydroglucose unit of cellulose is 0.01-0. It is preferable to adjust to 50. As an example, the following production method can be mentioned, but it may be synthesized by a conventionally known method or a commercially available product may be used. Cellulose is used as the starting material, and water and / or lower alcohol 3 to 20 times by weight in the solvent, specifically methanol, ethanol, N-propyl alcohol, isopropyl alcohol, N-butanol, isobutanol, tertiary butanol, etc. Or a mixed medium of two or more. The mixing ratio of the lower alcohol is 60 to 95% by weight. Examples of mercerizing agents include 0.5 to 20-fold moles of alkali metal hydroxide per anhydroglucose residue of the starting material, specifically, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide. A bottoming raw material, a solvent, and a mercerizing agent are mixed, the reaction temperature is usually 0 to 70 ° C., preferably 10 to 60 ° C., and the reaction time is usually 15 minutes to 8 hours, preferably 30 minutes to 7 hours. Perform mercerization. Thereafter, a carboxymethylating agent is added in an amount of 0.05 to 10.0 times mol per glucose residue, the reaction temperature is usually 30 to 90 ° C., preferably 40 to 80 ° C., and the reaction time is usually 30 minutes to 10 hours, The etherification reaction is preferably performed in the range of 1 hour to 4 hours.

As a measuring method of the carboxymethyl substitution degree per glucose unit, it can obtain by the following method, for example. That is, 1) About 2.0 g of carboxymethylated cellulose fiber (absolutely dry) is precisely weighed and put into a 300 mL conical stoppered Erlenmeyer flask. 2) Add 100 mL of a solution of 100 mL of special concentrated nitric acid to 1000 mL of nitric acid methanol and shake for 3 hours to convert the carboxymethyl cellulose salt (CM cellulose) into hydrogenated CM cellulose. 3) Weigh accurately 1.5 to 2.0 g of hydrogenated CM-modified cellulose (absolutely dry) and put into a 300 mL conical flask with a stopper. 4) Wet the hydrogenated CM cellulose with 15 mL of 80% methanol, add 100 mL of 0.1N NaOH, and shake at room temperature for 3 hours. 5) Back titrate excess NaOH with 0.1 N H2SO4 using phenolphthalein as indicator. 6) The degree of carboxymethyl substitution (DS) is calculated by the following formula:
A = [(100 × F ′ − (0.1N H 2 SO 4) (mL) × F) × 0.1] / (absolute dry mass of hydrogenated CM-modified cellulose (g))
DS = 0.162 × A / (1−0.058 × A)
A: 1N NaOH amount (mL) required for neutralizing 1 g of hydrogenated CM-modified cellulose
F ′: factor of 0.1 N H 2 SO 4 F: factor of 0.1 N NaOH

<Cationization>
In the present invention, the cationization of the cellulose raw material can be performed using a known method, and for example, ammonium, phosphonium, sulfonium, or a group having ammonium, phosphonium or sulfonium can be contained in the cellulose molecule by cationization. A group containing ammonium is preferred, and a group containing quaternary ammonium is particularly preferred. The specific cationization method is not particularly limited, but as an example, cationization of cellulose raw material such as glycidyltrimethylammonium chloride, 3-chloro-2hydroxypropyltrialkylammonium hydride or its halohydrin type Cation having group containing quaternary ammonium by reacting agent and catalyst alkali metal hydroxide (sodium hydroxide, potassium hydroxide, etc.) in the presence of water and / or alcohol having 1 to 4 carbon atoms Modified cellulose can be obtained. The amount of the cationizing agent is preferably 5% by weight or more, more preferably 10% by weight or more with respect to 100% by weight of the cellulose fibers. The upper limit is usually 800% by weight or less, preferably 500% by weight or less. The amount of the catalyst is preferably 0.5% by weight or more, more preferably 1% by weight or more with respect to 100% by weight of the cellulose fibers. The upper limit is usually 7% by weight or less, preferably 3% by weight or less. The amount of alcohol is preferably 50% by weight or more, more preferably 100% by weight or more, based on 100% by weight of cellulose fibers. The upper limit is usually 50000% by weight or less, preferably 500% by weight or less.

  The reaction temperature at the time of cationization is usually 10 ° C or higher, preferably 30 ° C or higher, and the upper limit is usually 90 ° C or lower, preferably 80 ° C or lower. The reaction time is usually 10 minutes or longer, preferably 30 minutes or longer. The upper limit is usually 10 hours or less, preferably 5 hours or less. The reaction solution may be stirred as necessary during the cationization reaction. In this method, the cation substitution degree per glucose unit of the cation-modified cellulose obtained is controlled by the amount of the cationizing agent to be reacted, the composition ratio of water and / or alcohol having 1 to 4 carbon atoms. Can be adjusted. The degree of substitution herein refers to the number of substituents introduced per unit structure (glucopyranose ring) constituting cellulose. In other words, it is defined as “a value obtained by dividing the number of moles of the introduced substituent by the total number of moles of hydroxyl groups of the glucopyranose ring”. Since pure cellulose has three substitutable hydroxyl groups per unit structure (glucopyranose ring), the theoretical maximum value of the degree of substitution of the cellulose fiber of the present invention is 3 (minimum value is 0).

In the present invention, the degree of cation substitution per glucose unit of cationized cellulose is preferably 0.01 to 0.40. By introducing a cationic substituent into cellulose, the celluloses repel each other electrically. For this reason, the cellulose which introduce | transduced the cation substituent can be nano-defibrated easily. In addition, when the cation substitution degree per glucose unit is smaller than 0.01, nano-defibration cannot be sufficiently performed. On the other hand, if the degree of cation substitution per glucose unit is larger than 0.40, the fiber form cannot be maintained because it swells or dissolves and may not be obtained as a nanofiber. The degree of cation substitution per glucose unit can be calculated from the following equation by measuring the nitrogen content with a total nitrogen analyzer TN-10 (Mitsubishi Chemical) after drying the sample (cation-modified cellulose). . The degree of substitution referred to here represents the average value of the number of moles of substituents per mole of anhydroglucose unit.
Degree of cation substitution = (162 × N) / (1-151.6 × N)
N: Nitrogen content

<Phosphate esterification>
In the present invention, phosphoric acid esterification of the cellulose raw material can be carried out using a known method. Examples of phosphoric acid used for the phosphoric acid esterification include polyphosphoric acid, orthophosphoric acid, phosphorous acid, phosphorous oxochloride and the like. Examples of the anhydride include phosphorus pentoxide which is an anhydride of orthophosphoric acid. Further, these phosphoric acids may be mixed and used. The phosphate ester may form a salt with sodium, potassium, ammonium or the like.

<Defibration>
In the present invention, an apparatus for defibrating is not particularly limited, but a strong shearing force is applied to the aqueous dispersion using an apparatus such as a high-speed rotation type, a colloid mill type, a high pressure type, a roll mill type, or an ultrasonic type. Is preferred. In particular, for efficient defibration, it is preferable to use a wet high-pressure or ultrahigh-pressure homogenizer that can apply a pressure of 50 MPa or more to the aqueous dispersion and can apply a strong shearing force. The pressure is more preferably 100 MPa or more, and further preferably 140 MPa or more. In addition, prior to defibration / dispersion treatment with a high-pressure homogenizer, the cellulose nanofibers may be pretreated using a known mixing, stirring, emulsifying, and dispersing device such as a high-speed shear mixer as necessary. Is also possible.

  In the case of defibration by the above treatment, the solid content concentration as the cellulose fiber raw material is 0.1 wt% or more, preferably 0.2 wt% or more, particularly 0.3 wt% or more, and 10 wt% or less, particularly 6 % By weight or less. When the solid content concentration is too low, the amount of liquid is too large with respect to the amount of the cellulose fiber raw material to be processed, resulting in poor efficiency, and when the solid content concentration is too high, the fluidity is deteriorated.

<Form of cellulose nanofiber>
In the present invention, the form of the cellulose nanofiber is not particularly limited, and may be a dispersion of cellulose nanofiber, a dry solid of cellulose nanofiber, or a wet solid in an intermediate state. In addition, in this invention, the dry solid substance of a cellulose nanofiber means what dehydrated and dried the dispersion liquid containing a cellulose nanofiber to 12% or less of moisture content. When cellulose nanofibers are used as a dry solid, examples include those obtained by drying a dispersion of cellulose nanofibers, or those obtained by drying a mixture of cellulose nanofibers and a water-soluble polymer. The latter is preferable in terms of redispersibility. Examples of the water-soluble polymer include cellulose derivatives (carboxymethylcellulose, methylcellulose, hydroxypropylcellulose, ethylcellulose), xanthan gum, xyloglucan, dextrin, dextran, carrageenan, locust bean gum, alginic acid, alginate, pullulan, starch, and hard starch. , Scrap flour, Positive starch, Phosphorylated starch, Corn starch, Gum arabic, Locust bean gum, Gellan gum, Gellan gum, Polydextrose, Pectin, Chitin, Water-soluble chitin, Chitosan, Casein, Albumin, Soy protein lysate, Peptone, Polyvinyl alcohol , Polyacrylamide, sodium polyacrylate, polyvinylpyrrolidone, polyvinyl acetate, polyamino acid, polylactic acid, polymalic acid, polyglyce Latex, rosin sizing agent, petroleum resin sizing agent, urea resin, melamine resin, epoxy resin, polyamide resin, polyamide / polyamine resin, polyethyleneimine, polyamine, plant gum, polyethylene oxide, hydrophilic cross-linked polymer, polyacrylic Refers to acid salts, starch polyacrylic acid copolymers, tamarind gum, gellan gum, pectin, guar gum and colloidal silica and mixtures of one or more thereof. Among these, it is preferable from a compatible point to use carboxymethylcellulose and its salt.

  The dry solid of the cellulose nanofiber is dehydrated and dried after adjusting the pH of the cellulose nanofiber aqueous dispersion or the mixture containing the cellulose nanofiber dispersion and the water-soluble polymer to 9-11. It is preferable from the viewpoint of redispersibility. When the water-soluble polymer is blended in the cellulose nanofiber dispersion, the amount of the water-soluble polymer is preferably 5 to 50% by weight based on the absolutely dry solid content of the cellulose nanofiber. If it is less than 5% by weight, the effect of sufficient redispersibility is not exhibited. On the other hand, when it exceeds 50% by weight, problems such as viscosity characteristics and dispersion stability, which are characteristic of cellulose nanofiber, occur.

  As the dehydration / drying method of the cellulose nanofiber dispersion or the mixture containing the cellulose nanofiber dispersion and the water-soluble polymer, any conventionally known method may be used, for example, spray drying, pressing, air drying, hot air drying, And vacuum drying. Examples of the drying apparatus specifically used in the method of the present invention are as follows. That is, continuous tunnel dryer, band dryer, vertical dryer, vertical turbo dryer, multi-stage disk dryer, aeration dryer, rotary dryer, air dryer, spray dryer dryer, spray dryer , Cylindrical dryers, drum dryers, screw conveyor dryers, rotary dryers with heating tubes, vibration transport dryers, batch-type box dryers, aeration dryers, vacuum box dryers, stirring dryers, etc. These drying apparatuses can be used alone or in combination of two or more. Among these, it is preferable to use a drum drying apparatus from the viewpoint of energy efficiency because the heat energy is uniformly supplied directly to an object to be dried. The drum drying apparatus is also preferable in that it can immediately collect a dried product without applying heat more than necessary.

  The dried solid can be pulverized and classified as necessary. In particular, dry pulverization or wet pulverization is preferable because a more refined additive can be obtained. Examples of the apparatus used in the dry pulverization include impact mills such as a hammer mill and a pin mill, medium mills such as a ball mill and a tower mill, and jet mills. Examples of the apparatus used in the wet pulverization include apparatuses such as a homogenizer, a mass collider, and a pearl mill.

<Manufacture of artificial casing and processed food>
In the present invention, cellulose nanofibers and other materials can be mixed by a known method, and an artificial casing can be produced by a known method. From the viewpoint of uniformly dispersing the components of the casing containing cellulose nanofibers, a method of stirring the dispersion containing the components of the casing and the aqueous dispersion of cellulose nanofibers with a mixer or the like is preferable.

  In the present invention, the amount of cellulose nanofiber added in the casing is preferably 0.05% by weight or more and 50% by weight or less, and 0.1% by weight or more and 30% by weight or less based on the total dry weight of the casing. The following is more preferable. If the content is less than 0.05% by weight, sufficient effects are not exhibited. If it exceeds 50% by weight, the coupling between the main components of the casing is weakened, and the strength of the entire casing is lowered.

  As an example of a method for producing a casing, a dispersion containing casing components is extruded into a coagulation bath such as a saturated saline solution from a double cylindrical nozzle that rotates in reverse to each other, washed with water, and then dried with air. Can be obtained.

  The method of filling the casing with the ingredients can be performed using a known method, for example, a commercially available filling machine (stuffer). Here, the filling machine includes an extruder and a filling nozzle. As a usage method, the casing is loaded into the filling nozzle, the end of the casing is closed, and then the ingredients are extruded to fill the casing with the ingredients. After filling the casing, it can be ligated by twisting both ends with an appropriate length.

  As another method, the material is extruded from the inside of the double-structure nozzle of the filling machine, and at the same time, a dispersion containing the components of the casing is extruded from the periphery (protecon system), and a coagulating liquid such as a coagulating circle aqueous solution. There are also methods of drying after dipping inside or drying as it is. The present invention can be suitably used for this method. After filling by the above method, the processed food of the present invention can be obtained by heating, drying, smoking, boiling in water, and cooling by a known method, if necessary.

  Hereinafter, although an example is given and the present invention is explained still in detail, the present invention is not limited to these.

<Manufacture of oxidized cellulose nanofiber>
Bleached unbeaten kraft pulp derived from coniferous trees (whiteness 85%) 5.0 g (absolutely dry) 39 mg (0.05 mmol for 1 g of absolute dry cellulose) TEMPO (0.05 mmol for absolute dry cellulose) and 514 mg (absolutely dry) The solution was added to 500 ml of an aqueous solution in which 1.0 mmol) was dissolved in 1 g of cellulose, and stirred until the pulp was uniformly dispersed. An aqueous sodium hypochlorite solution was added to the reaction system so that sodium hypochlorite was 5.5 mmol / g, and the oxidation reaction was started at room temperature. During the reaction, the pH in the system was lowered, but a 3M sodium hydroxide aqueous solution was sequentially added to adjust the pH to 10. The reaction was terminated when sodium hypochlorite was consumed and the pH in the system no longer changed. The reaction mixture was filtered through a glass filter to separate the pulp, and the pulp was sufficiently washed with water to obtain oxidized pulp (carboxylated cellulose). The pulp yield at this time was 90%, the time required for the oxidation reaction was 90 minutes, and the amount of carboxyl groups was 1.6 mmol / g. This was adjusted to 1.0% (w / v) with water and treated with an ultra-high pressure homogenizer (20 ° C., 150 Mpa) three times to obtain an oxidized cellulose nanofiber dispersion. The obtained fiber had an average fiber diameter of 3 nm and an aspect ratio of 250.

<Production of carboxymethylated cellulose nanofiber>
In a stirrer that can mix pulp, 200 g dry pulp (NBKP (conifer bleached kraft pulp), Nippon Paper Industries Co., Ltd.) and 111 g sodium hydroxide dry mass (per anhydroglucose residue of the bottom material) 2.25 moles) and water was added so that the pulp solid content was 20% (w / v). Thereafter, after stirring at 30 ° C. for 30 minutes, 216 g of sodium monochloroacetate (in terms of active ingredient, 1.5 times mol per glucose residue of pulp) was added. After stirring for 30 minutes, the temperature was raised to 70 ° C. and stirred for 1 hour. Thereafter, the reaction product was taken out, neutralized and washed to obtain a carboxymethylated pulp having a carboxymethyl substitution degree of 0.25 per glucose unit. Thereafter, the carboxymethylated pulp was made 1% solids with water, and fibrillated by treating it with a high-pressure homogenizer 5 times at 20 ° C. and 150 MPa to obtain carboxymethylated cellulose fibers. The obtained fiber had an average fiber diameter of 15 nm and an aspect ratio of 50.

  In addition, the amount of carboxyl groups and the degree of carboxymethyl substitution in the above production examples were measured by the method described above.

<Example 1>
After the hair removal treatment was completed, the cow skin bed was lightly washed with water, 3% by weight of 2% lime aqueous solution was added to 1% by weight of the skin, and lime treatment was performed at 20 ° C. for 10 days. After washing with water, it was immersed in a 1% aqueous solution of sulfuric acid to neutralize and remove excess lime, and further washed with water and then immersed in a 1% aqueous lactic acid solution at 15 ° C. for 3 days to swell the skin. This was crushed by a meat grinder equipped with a plate having a hole with a diameter of 12 mm, further processed by a roll defibrator, mixed with 1% by weight of this leather and 1% by weight of water, and refined by passing 5 times through a refiner. A collagen fiber dispersion having a pH of 3.0 and a concentration of 9% was obtained. 100 g of the above-mentioned aqueous dispersion of cellulose nanofibers for addition and 1100 g of the above collagen fiber dispersion (1.0% by weight of the dryness of the cellulose nanofibers in the total dryness of the mixed dispersion) are mixed, and a mixer For 10 minutes to obtain a mixed dispersion of cellulose nanofibers and collagen. The solid content concentration of the mixed dispersion was 8.3%.
Using this mixed dispersion, tests on tensile strength and texture were conducted by the following method.

<Tensile strength>
A collagen film having a thickness of 1.0 mm was prepared from the above mixed dispersion, the film was cut to a width of 1.5 mm, and the tensile strength was measured using a tensile tester (manufactured by Toyo Seiki Co., Ltd.).

<Food texture>
Sausage was prepared according to a conventional method. First, as a material, 500 g of a meat emulsion of minced meat was prepared by cutting and mixing minced pork urine with ice water, salt, color former, seasoning and the like.

Next, extrude the ingredients from the inside of the double-structure nozzle of the filling machine, and at the same time, extrude the mixed dispersion of cellulose nanofiber and collagen from its surroundings, dry the surface, and then heat, dry and smoke. Then, it was cooled to make sausage. The weight per sausage was about 40 g. The thickness of the casing was 0.5 mm. The sausage was immersed in a warm water bath kept at about 70 ° C. for 20 minutes, and the sausage whose product temperature was warmed to about 70 ° C. was sampled by 10 panelists, and the texture of the skin (breaking and firmness) ) Was evaluated by the following 5-point method, and the average score was taken as the evaluation score.
(1) Chopping 5 It has elasticity and is crisp and easy to bite.
4 Slightly good.
3 No change.
2 Somewhat bad.
1 There is no elasticity, the crispness is bad and the bite is not crisp.
(2) Hardness 5 When chewing, no skin remains in the mouth.
4 When chewing, almost no skin remains in the mouth.
3 When chewing, a slight skin remains in the mouth.
2 When chewing, some skin remains in the mouth.
1 A large amount of skin remains in the mouth when chewing.

<Example 2>
The same procedure as in Example 1 was conducted except that the cellulose nanofibers of Example 1 were changed to carboxymethylated cellulose nanofibers produced by the above method.

<Comparative Example 1>
The same procedure as in Example 1 was performed except that cellulose nanofibers were not used in Example 1.

<Comparative example 2>
The same procedure as in Example 1 was conducted except that cellulose nanofibers were changed to powdered cellulose (KC Flock W-400G, manufactured by Nippon Paper Industries Co., Ltd.) in Example 1.

  As is apparent from the results in Table 1, in Examples 1 and 2 containing cellulose nanofibers, it was tensile compared to Comparative Example 1 containing no cellulose nanofibers and Comparative Example 2 containing powdered cellulose. It can be seen that both strength and texture are good.

Claims (6)

  An artificial casing comprising cellulose nanofibers.   The artificial casing according to claim 1, wherein the cellulose nanofiber according to claim 1 is a chemically modified cellulose nanofiber.   The chemically modified cellulose nanofiber is an oxidized cellulose nanofiber having an amount of carboxyl groups of 0.5 mmol / g to 3.0 mmol / g with respect to the absolutely dry weight of the chemically modified cellulose nanofiber. The artificial casing according to claim 2.   3. The chemically modified cellulose nanofiber according to claim 2, wherein the chemically modified cellulose nanofiber is a carboxymethylated cellulose nanofiber having a degree of carboxymethyl substitution per glucose unit of 0.01 to 0.50. The artificial casing as described.   The artificial casing according to any one of claims 1 to 4, further comprising collagen.   Processed food using the artificial casing according to any one of claims 1 to 5.