CN112931578A

CN112931578A - Preparation method of nanocellulose reinforced collagen casing

Info

Publication number: CN112931578A
Application number: CN202110164508.5A
Authority: CN
Inventors: 王稳航; 赵凯旋
Original assignee: Tianjin University of Science and Technology
Current assignee: Tianjin University of Science and Technology
Priority date: 2021-02-05
Filing date: 2021-02-05
Publication date: 2021-06-11

Abstract

The invention discloses a preparation method of a nano-cellulose reinforced collagen casing, which comprises the following steps: (1) cleaning and splitting the inner layer skin of the cowhide to obtain a second layer skin; (2) performing alkali treatment on the second layer of skin, cutting into pieces, and soaking until the pH value is neutral; (3) soaking neutral cow leather in hydrochloric acid to swell; (4) scraping the collagen fibers on the swelled cowhide, preparing into a collagen suspension and adjusting the pH; (5) preparing nano cellulose by a physical method, a chemical method or a biological method; (6) adding a nano cellulose suspension into the collagen suspension to obtain a mixed solution A; (7) adding glycerol into the mixed solution A, uniformly stirring to obtain mucilage, and refrigerating; (8) extruding the refrigerated mucilage to spray out a tubular object, drying, carrying out immobilization treatment, curing, determining nature, and packaging to obtain the sausage casing. According to the invention, the advantages of high length-diameter ratio, larger specific surface area and the like of the nano-cellulose are utilized, and the nano-cellulose is applied to preparation of the sausage casing, so that the mechanical property of the sausage casing can be improved.

Description

Preparation method of nanocellulose reinforced collagen casing

Technical Field

The invention relates to the technical field of food packaging, in particular to a preparation method of a nano-cellulose reinforced collagen casing.

Background

Currently, sausage casings play an important role in meat processing, are materials on which sausage-type products are formed, and are capable of maintaining the stability of the products for a certain period of time. The traditional meat products are all made of natural animal casings, and the development of the natural animal casings is always limited due to the limited yield and non-uniform specification of the natural animal casings. And the artificial sausage casing has uniform specification and is easier for industrial production. Therefore, nowadays more and more artificial casings have been applied in meat processing, among which the production and application of collagen based casings is particularly attractive.

The collagen has good film forming property, can be used as medical films of artificial skin and the like, can also be used as food packaging films, and is widely applied to meat products, smoked foods, fried foods, yoghourt and food ingredients. Although collagen extracted from cowhide has complete spiral structure, the mechanical strength and flexibility of the prepared collagen film and composite film can not meet the requirement of casing quality. The simple collagen material product cannot meet the requirements of the functional and high-strength application of the materials in the modern society.

CN110506778A discloses an artificial collagen ultrathin casing, which has nutritional efficacy on the basis of keeping taste, and is added with collagen, gelling agent, edible fiber and fungus substances. Because the collagen contains nutrients necessary for human skin, 17 beneficial elements can be supplemented for human body, thereby achieving the effects of moistening skin, removing wrinkles, nourishing hair and the like. Although the sausage casing has excellent functional characteristics, the formula is complex, the raw material cost is high, and the condition of mass production is difficult to meet.

CN106472648A discloses an edible collagen casing and a preparation method thereof, and the method has the characteristics of low cost and multiple purposes. The casing comprises: moisture (10-20%), chitosan (50-60%), collagen (30-35%), plasticizer (1-5%), cross-linking agent and emulsifier. The method improves the addition amount of chitosan in the casing, and the chitosan has broad-spectrum antibacterial activity, good mechanical strength and film forming property, wide source and low cost.

CN109907097A discloses an artificial sausage casing, which is prepared by mixing and pulping soybean and lotus root as reinforcing materials, taking collagen extracted from animal skin as raw materials, and adding auxiliary agents and cross-linking agents. Structural stability is maintained due to ionic interactions, dipolar interactions, hydrogen bonds, and the like among protein molecules. In addition, the lotus root slices contain lotus root silk fibers, the soybeans contain vegetable proteins, and the interaction of the lotus root slices, the soybean slices and the soybeans is promoted through the cross-linking effect of glutaraldehyde, so that the compatibility of the lotus root slices, the soybean slices and the soybeans is enhanced. The food product coated with the enteric coating can maintain intact appearance during microwaving, baking and frying.

However, in the above patents and other prior arts, there is no compromise between production cost, ease of processing and desired properties, such as, for example, conveniently obtaining a casing of high mechanical strength to prevent cracking during cooking; the surface roughness of the casing causes the problems of poor water resistance and air barrier property, etc.

With the development of nanotechnology, the development and application of nanomaterials are receiving more and more attention and research. The nano-cellulose has the advantages of high length-diameter ratio, larger specific surface area and the like, and provides a new direction for improving the performance of the collagen fibrous membrane.

Therefore, the problem to be solved by the skilled person is how to provide a method for enhancing the mechanical properties of collagen fiber casings with nanocellulose.

Disclosure of Invention

In view of the above, the invention provides a preparation method of a nanocellulose reinforced collagen casing.

In order to achieve the purpose, the invention adopts the following technical scheme: a preparation method of a nano-cellulose reinforced collagen casing comprises the following steps:

(1) cleaning and splitting the inner layer skin of the cowhide to obtain a second layer skin;

(2) performing alkali treatment on the second layer of skin, cutting into pieces, and soaking in distilled water until the pH value is neutral to obtain neutral cowhide;

(3) soaking neutral cowhide in hydrochloric acid, and swelling at 20-30 deg.C to obtain swelling cowhide;

(4) scraping the collagen fibers on the swollen cowhide by using a pair of tweezers, preparing into a collagen suspension, adjusting the pH value by using hydrochloric acid, and storing at a low temperature for later use; and preparing nano-cellulose;

(5) adding the collagen suspension into the nano-cellulose suspension according to a certain proportion, continuously stirring, and standing for 3-6h at room temperature to obtain a mixed solution A;

(6) adding 6-10% glycerol into the mixed solution A, uniformly stirring to obtain mucilage, and refrigerating for later use;

(7) extruding and spraying the refrigerated mucilage out of a tubular object, drying and carrying out immobilization treatment to obtain a casing semi-finished product;

(8) and curing and qualifying the semi-finished product of the casing, and packaging the semi-finished product of the casing in a winding or shrinking manner in sections to obtain a finished product of the casing.

The invention has the beneficial effects that: according to the invention, the advantages of high length-diameter ratio, larger specific surface area and the like of the nano-cellulose are utilized, and the nano-cellulose is applied to preparation of the sausage casing, so that the mechanical property of the sausage casing can be improved. Moreover, the preparation method is simple, easy to operate and more suitable for large-scale industrial production.

Preferably, in the above method for preparing a collagen casing, the collagen includes, but is not limited to, cow hide, sheep hide, chicken hide, rabbit and fish scale. The nano-cellulose raw material includes, but is not limited to, plant fiber (cotton, beet, birch, potato tuber, flax, etc.), bacterial fiber (acetobacter xylinum, etc.).

Preferably, in the step (2), the alkali treatment is specifically performed by: soaking the second layer of skin by using soda lime water with the mass fraction of 4-6%, and adjusting the pH value to 11-12; the treatment time is 1-4 h.

Preferably, in step (2), the shearing is to 10 x 10 cm;

the distilled water is replaced once at intervals of 2h during the soaking period of the distilled water.

Preferably, in the step (3), the concentration of the hydrochloric acid is 0.01-0.05mol/L, and the mass-to-volume ratio of the cow leather to the hydrochloric acid is 1 g: (3-5) mL;

the swelling time is 24-36h, so that the material is swelled to 3-4 times of the original volume.

Preferably, in the step (4), the concentration of the collagen suspension is 0.5-1.0%;

the specific operation of adjusting the pH is to adjust the pH of the collagen suspension to 1.5-2.0 with hydrochloric acid.

Preferably, in the step (4), the nanocellulose is prepared by a mechanical method, a chemical method or a biological method.

Preferably, the mechanical method is to treat the fibrous material by high pressure homogenization or mechanical grinding, so as to separate out the cellulose with nanometer size range (diameter 10nm-100nm), wherein the high pressure homogenization pressure is 800-1500bar, and the homogenization times are 3-6 times.

The chemical method is to remove the amorphous area of the cellulose by using a chemical reagent to prepare the rodlike nano-cellulose (the diameter is 20-30nm, the length is 100-200 nm); the biological method mainly refers to a bacterial method, and the bacterial cellulose prepared by the method has an ultrafine reticular fiber structure, the crystallinity can reach 95%, the polymerization degree can reach 2000-8000, and the bacterial cellulose has the characteristics of strong water holding capacity, high biocompatibility and good degradability.

More preferably, the nanocellulose is prepared by a mechanical method.

Adopt above-mentioned technical scheme's beneficial effect: the preparation method is a mechanical method, does not need chemical reagents and has little influence on the environment. The cellulose source can be cotton linter, wood pulp fiber and other cellulose of different sizes of agriculture and forestry by-products.

Preferably, in the step (5), the mass concentration of the nano-cellulose suspension is 1-20%;

the mass ratio of the nano-cellulose to the collagen dry basis in the collagen suspension is 1-20: 100.

preferably, in the step (6), the mass ratio of the glycerol to the collagen dry basis in the mixed solution a is 6-10: 100.

Preferably, in the step (7), the drying temperature is 60-80 ℃ and the time is 10-30 h;

the mass concentration of the glutaraldehyde solution used in the immobilization treatment is 0.4-1.0%.

Preferably, in the step (8), the curing qualitative temperature is 70-80 ℃ and the curing time is 8-36 h.

Preferably, the shrinkage specifically is: shrinking casings into short tubular products by means of a shrinking apparatus, including but not limited to

The casing is contracted into a tubular shape of 20-25 cm;

corresponding to 19-21 cm;

corresponding to 20-25 cm;

corresponding to 20-26 cm;

corresponding to 23-27 cm;

corresponding to 24-28 cm.

The invention also provides an application of the nanocellulose reinforced collagen casing.

Preferably, the method can be applied to the production of sausage products such as sausage, boiled sausage, sausage and the like.

According to the technical scheme, compared with the prior art, the preparation method of the nanocellulose reinforced collagen casing disclosed by the invention has the following beneficial effects:

(1) on the basis of keeping the advantages of inherent taste, shrinkage and cohesiveness with meat of the sausage casing, the quality of the sausage casing is further improved by using the reinforcing material (nano-cellulose), the loss of the casing material in the preparation process is reduced, and the mechanical property of the sausage casing is improved.

(2) Compared with other preparation methods, the preparation method has the advantages of simple process and low requirement on equipment precision, the thickness of the obtained collagen film can reach micron level, an ultra-thin casing is formed, the transparency of the collagen casing is improved, and the application of the collagen in food packaging is widened.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a drawing showing the surface microscopic morphology (a) and the cross-sectional microscopic morphology (b) of a collagen casing in example 1 of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

The preparation method of the nano-cellulose reinforced collagen casing comprises the following steps:

(2) soaking the two layers of skins in alkaline lime water, and adjusting the pH value to 12 for 2 h. Cutting 5kg of double-layer leather into small blocks of 10cm multiplied by 10cm, soaking the double-layer leather in distilled water every 2 hours until the pH value is neutral, taking out the double-layer leather and draining to obtain neutral cowhide;

(3) immersing neutral cowhide blocks in 0.03mol/L hydrochloric acid, and performing sufficient acid swelling at 20 ℃ for 24 h; wherein, cow leather: hydrochloric acid 1:3 (W/V);

(4) gently scraping the collagen fibers of the swelled cowhide blocks by using forceps, preparing a 0.5 wt% collagen fiber suspension by using distilled water, and then adjusting the pH of the suspension to 2 by using hydrochloric acid;

(5) simultaneously, adding the purified cotton linter into NaOH solution, alkalizing for 2h at room temperature, adding anhydrous ethanol and 35.5% of sodium monochloroacetate, uniformly mixing, placing in a water bath at 70 ℃ for reaction for 5h, washing to be neutral by using distilled water after the reaction is finished, dispersing to 1% concentration, and then carrying out high-pressure homogenization on the mixture, wherein the high-pressure homogenization pressure is set to be 1500bar, and the homogenization times are 2 times.

(6) Placing 1 wt% of nano-cellulose suspension into a magnetic stirrer at room temperature, stirring for 20min, slowly adding the nano-cellulose suspension into 0.5 wt% of collagen suspension according to the addition of 5 wt% (based on collagen fiber dry matter) to prepare a mixed membrane solution, continuously stirring by using a glass rod in the adding process, and placing for 4h at room temperature to fully react the nano-cellulose suspension and the collagen suspension to obtain a mixed solution A;

(7) adding 10 wt% of glycerol (based on collagen dry matter) into the mixed solution A, stirring for 5min, adjusting pH to 3, stirring to obtain mucilage, and refrigerating to 10 deg.C for use; wherein the mass ratio of the glycerol to the collagen dry matter in the mixed solution A is 10: 100;

(8) and putting the refrigerated adhesive cement into an extruder, spraying the refrigerated adhesive cement into a tubular object through a phi 13-20mm direct-injection nozzle, then drying the tubular object in a drying tunnel, continuously spraying a glutaraldehyde (with the mass percentage concentration of 0.5%) aqueous solution in the drying process, compressing and rolling the tubular object after drying, performing segmented packaging through shrinkage equipment, and then curing the tubular object for 24 hours at 70 ℃ in a curing cabinet to obtain a finished product.

Example 2

Cleaning ox second layer skin 50kg in water tank, dividing into 10 x 10cm pieces, soaking in 90kg soda lime for 1d, and adding 50kg water after cleaning. The reaction solution is treated at room temperature for 6h to be neutral. Cleaning, adding into 0.03mmol/L hydrochloric acid, acidifying for 24h, and chopping with chopper.

Simultaneously, adding the purified cotton linter into NaOH solution, alkalizing for 2h at room temperature, adding anhydrous ethanol and 35.5% of sodium monochloroacetate, uniformly mixing, placing in a water bath at 70 ℃ for reaction for 5h, washing to be neutral by using distilled water after the reaction is finished, dispersing to 1% concentration, and then carrying out high-pressure homogenization on the mixture, wherein the high-pressure homogenization pressure is set to be 1500bar, and the homogenization times are 4 times.

The 1 wt% CNF suspension was then stirred in a magnetic stirrer and added to the 1 wt% collagen suspension in a 10 wt% addition (based on collagen fibre dry matter) with stirring. And 10 wt% glycerol (based on collagen dry matter) was added and mixing was continued for 5min with stirring to form a mixed collagen.

Freezing collagen to below 5 deg.C, spraying into tubular object with a nozzle of phi 20-25mm by an extruder, drying in a drying tunnel, continuously spraying 1% glutaraldehyde solution, drying, rolling and packaging with shrinking equipment, and aging in an aging cabinet of 80 deg.C for 36 h.

Comparative example 1

The difference from the embodiment 1 is that the homogenization times in the cellulose preparation process are 1 time, the obtained nano-cellulose has wide length-diameter ratio size distribution, and the corresponding collagen casing is rough and has poor light transmittance; the glutaraldehyde solution is 3%, the maximum tensile value born by the obtained collagen is lower and is 50-75% of the maximum tensile value in the embodiment; and the aging time is 48h, the pressure value of the obtained collagen casing is reduced, and is about 30 percent lower than the value obtained in the example.

Performance testing

Table 1 shows the application test of the nanocellulose-reinforced collagen casing in example 1 of the present invention, including the test results of the finished product and the application test results. Wherein, the three tests (comparison, serial numbers 1 and 2) are products prepared by the same formula, and the used raw materials and auxiliary materials are the same batch.

Table 2 shows the number of batches, two secondary production tests were performed.

The test method comprises the following steps: testing the casing performance: the longitudinal breaking force and strength were tested according to national standard SB/T10373-2004;

TABLE 1 characterization of nanocellulose-reinforced collagen casing properties

TABLE 2 application test results

Batches of	High speed filling	Filling	Steaming and boiling
				1	Is normal	Is normal	Is normal
2	Is normal	Is normal	Is normal

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A preparation method of a nano-cellulose reinforced collagen casing comprises the following steps:

(4) scraping collagen fibers on the swollen cowhide, preparing into collagen suspension, adjusting the pH value with hydrochloric acid, and storing at low temperature for later use; and preparing nano-cellulose;

(5) adding the nano-cellulose suspension into the collagen suspension, continuously stirring, and standing at room temperature for 3-6h to obtain a mixed solution A;

(6) adding glycerol into the mixed solution A, uniformly stirring to obtain mucilage, and refrigerating for later use;

(7) extruding and spraying the refrigerated mucilage out of a tubular object, drying and carrying out immobilization treatment to obtain a semi-finished product of the casing;

(8) and curing and qualifying the semi-finished product of the sausage casing, and packaging the semi-finished product of the sausage casing in sections to obtain a finished product of the sausage casing.

2. The method for preparing a nano-cellulose reinforced collagen casing as claimed in claim 1, wherein the alkali treatment in step (2) is carried out by: soaking the second layer of leather in soda lime water with the mass fraction of 4% -6%, and adjusting the pH value to 11-12; the treatment time is 1-4 h.

3. The method for preparing a nano-cellulose reinforced collagen casing as claimed in claim 1, wherein in the step (3), the concentration of hydrochloric acid is 0.01-0.05mol/L, and the mass volume ratio of the cowhide and the hydrochloric acid is 1 g: (3-5) mL;

the swelling time is 24-36h, and the material is swelled to 3-4 times of the original volume.

4. The method for preparing a nano-cellulose reinforced collagen casing as claimed in claim 1, wherein in the step (4), the concentration of the collagen suspension is 0.5% -1.0%;

the specific operation of adjusting the pH is to adjust the pH of the collagen suspension to 1.5-2.0 by adopting hydrochloric acid.

5. The method for preparing a nano-cellulose reinforced collagen casing as claimed in claim 1, wherein in the step (4), the nano-cellulose raw material comprises plant fiber or bacterial fiber;

the nano-cellulose is prepared by a mechanical method, a chemical method or a biological method.

6. The method for preparing a nano-cellulose reinforced collagen casing as claimed in claim 1, wherein in step (5), the mass concentration of the nano-cellulose suspension is 1-20%;

the mass ratio of the nano-cellulose in the nano-cellulose suspension to the collagen dry basis in the collagen suspension is 1-20: 100.

7. the method for preparing a nano-cellulose reinforced collagen casing as claimed in claim 1, wherein in step (6), the concentration of glycerol is 6% -10%; the mass ratio of the glycerol to the collagen dry basis in the mixed solution A is 6-10: 100.

8. The method for preparing a nano-cellulose reinforced collagen casing as claimed in claim 1, wherein in the step (7), the drying temperature is 60-80 ℃ and the drying time is 10-30 h;

the fixing agent adopted in the immobilization treatment is glutaraldehyde solution, and the mass concentration is 0.4-1.0%.

9. The method for preparing a nano-cellulose reinforced collagen casing as claimed in claim 1, wherein in the step (8), the curing temperature is 70-80 ℃ and the curing time is 8-36 h.

10. Use of a nanocellulose-reinforced collagen casing prepared by the process of any one of claims 1 to 9 in an enteral product.