CN110938241A

CN110938241A - Preparation method and application of sodium alginate/chitosan/glucosyl- β -cyclodextrin composite membrane

Info

Publication number: CN110938241A
Application number: CN201910961322.5A
Authority: CN
Inventors: 李妍; 李艳; 俞雅文; 曹珂珂; 李慧; 韩卓
Original assignee: Bengbu College
Current assignee: Bengbu College
Priority date: 2019-10-11
Filing date: 2019-10-11
Publication date: 2020-03-31

Abstract

The invention discloses a preparation method and application of a sodium alginate/chitosan/glucosyl- β -cyclodextrin composite film, wherein the composite film is applied to fresh food preservation, and the components and concentration of a blending film-forming liquid for film preparation are SA 1.5-3.5%, CS 0.3-0.7%, Glc- β -CD 0.3-0.7% and GL 0.4-0.8%Blending and modifying chitosan and sodium alginate under the electrostatic action and the hydrogen bond action of the chitosan and glucosyl- β -cyclodextrin, and then utilizing CaCl₂The cross-linking reaction between the solution and the polysaccharide composite film carries out chemical modification, thus obviously improving the comprehensive performance of the polysaccharide film and improving the application prospect of the polysaccharide film.

Description

Preparation method and application of sodium alginate/chitosan/glucosyl- β -cyclodextrin composite membrane

Technical Field

The invention belongs to the technical field of high polymer material films, and particularly relates to a preparation method and application of a sodium alginate/chitosan/glucosyl- β -cyclodextrin composite film.

Background

The high polymer material film is a film prepared by taking a high polymer compound as a substrate through the processes of mixing, tape casting, crosslinking and the like; or the film liquid can be dispersed on the outer surface of an object in a direct contact mode such as spraying, dipping or coating, and the like, and dried to form a film at room temperature. The high polymer material film mainly comprises a protein high polymer material film and a polysaccharide high polymer material film, wherein the polysaccharide high polymer material film has the advantages of strong film forming property and excellent oxygen resistance, and some polysaccharide substances also have certain antibacterial activity, so that the polysaccharide high polymer material film becomes one of hot spot materials for preparing edible food packaging, can prevent food from contacting with the external environment, inhibit microbial pollution and prolong the shelf life of the food. Most of single polysaccharide material films have the defects of insufficient mechanical strength, poor water resistance and the like, and the comprehensive performance needs to be further improved.

The invention utilizes the electrostatic action of chitosan and sodium alginate and the hydrogen bond action of glucosyl- β -cyclodextrin to carry out blending modification, and utilizes CaCl₂The cross-linking reaction between the solution and the polysaccharide composite film carries out chemical modification, thus obviously improving the comprehensive performance of the polysaccharide film and improving the application prospect of the polysaccharide film.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a preparation method and application of a sodium alginate/chitosan/glucosyl- β -cyclodextrin composite membrane.

The technical scheme of the invention is summarized as follows:

a preparation method of a sodium alginate/chitosan/glucose- β -cyclodextrin composite film comprises the following steps of preparing a blending film-forming solution with the components and concentration of SA 1.5-3.5%, CS 0.3-0.7%, Glc- β -CD 0.3-0.7% and GL 0.4-0.8%, and specifically comprises the following steps:

s1: adding sodium alginate into distilled water, stirring in a constant-temperature water bath at 60 ℃, standing and defoaming to obtain SA membrane liquid;

s2, sequentially adding chitosan, glucosyl- β -cyclodextrin and glycerol into a 2% acetic acid solution, stirring in a constant-temperature water bath at 60 ℃, standing and defoaming to obtain a CS/Glc- β -CD/GL blending membrane solution;

s3, mixing the SA membrane liquid with the CS/Glc- β -CD/GL blended membrane liquid, magnetically stirring for 120min, and removing bubbles by ultrasonic waves;

and S4, drying at 25 ℃ by adopting a tape casting method to form a composite membrane, then placing the composite membrane into a saturated CaCl2 solution for crosslinking for 15min, and airing to obtain the SA/CS/Glc- β -CD composite membrane.

A preparation method of sodium alginate/chitosan/glucosyl- β -cyclodextrin composite membrane comprises the components and concentration of SA 2.5%, CS 0.4%, Glc- β -CD 0.6%, and GL 0.5%.

Preferably, the molecular weight of the chitosan is less than or equal to 15kDa, and the deacetylation degree is more than or equal to 85 percent.

Preferably, the magnetic stirring speed is 500 rpm.

Preferably, the ultrasonic wave has a frequency of 20KHz and a power of 300W.

An application of a sodium alginate/chitosan/glucosyl- β -cyclodextrin composite film in fresh food preservation.

The invention has the beneficial effects that:

1. the invention utilizes the electrostatic action of chitosan and sodium alginate and the hydrogen bond action of glucosyl- β -cyclodextrin to carry out blending modification, and utilizes CaCl₂The cross-linking reaction between the solution and the polysaccharide composite film carries out chemical modification, thus obviously improving the comprehensive performance of the polysaccharide film and improving the application prospect of the polysaccharide film. The Chitosan (CS) is a derivative generated by deacetylation of chitin, is a few basic aminopolysaccharide existing in nature at present, has excellent mechanical property, antibacterial property, selective air permeability and water resistance, can reduce the WVP of the composite membrane, and obviously blocks foodSA is natural biomass polysaccharide formed by different MM, GM and GG chain segments connected by β -1, 4-glycosidic bond, has the properties of no toxicity, harmlessness and biodegradability, is green and environment-friendly, and Na on SA⁺(on the carboxyl unit) with Ca²⁺The Glc- β -CD has good film-forming property, and has a large amount of hydroxyl groups with CS molecules, so that the compatibility is good, and the crystallinity of the composite film can be compounded by adding the Glc- β -CD, and the flexibility of the film is improved.

2. The invention optimizes the film-making process to obtain the optimal concentration parameters of each component of SA 2.5%, CS 0.4%, Glc- β -CD 0.6% and GL 0.5%, and the actual water vapor transmission coefficient of the composite film prepared under the condition is 1.02 multiplied by 10^-10g/pas · m, a degree of swelling of 1.13, a tensile strength of 14.83MPa, and an elongation at break of 3.23%.

Drawings

FIG. 1 is a flow chart of a method for preparing a SA/CS/Glc- β -CD composite film according to the present invention;

FIG. 2 is a graph of the effect of Chitosan (CS) concentration on the actual water vapor transmission coefficient (WVP) of the composite membrane;

FIG. 3 is a graph showing the effect of Chitosan (CS) concentration on the swelling degree (S) of a composite membrane;

FIG. 4 is a graph of the effect of Chitosan (CS) concentration on the tensile strength (T) of a composite film;

FIG. 5 is a graph of the effect of Chitosan (CS) concentration on the elongation at break (E) of a composite membrane;

FIG. 6 is a graph showing the effect of Sodium Alginate (SA) concentration on the actual water vapor transmission coefficient (WVP) of the composite membrane;

FIG. 7 is a graph showing the effect of Sodium Alginate (SA) concentration on the swelling degree (S) of a composite membrane;

FIG. 8 is a graph showing the effect of Sodium Alginate (SA) concentration on the tensile strength (T) of a composite film;

FIG. 9 is a graph showing the effect of Sodium Alginate (SA) concentration on the elongation at break (E) of a composite membrane;

FIG. 10 is a graph of the effect of glucose- β -cyclodextrin (Glc- β -CD) concentration on the actual water vapor transmission coefficient (WVP) of a composite membrane;

FIG. 11 is a graph of the effect of glucose- β -cyclodextrin (Glc- β -CD) concentration on the swelling degree (S) of composite membranes;

FIG. 12 is a graph of the effect of glucose- β -cyclodextrin (Glc- β -CD) concentration on composite film tensile strength (T);

FIG. 13 is a graph of the effect of glucose- β -cyclodextrin (Glc- β -CD) concentration on the elongation at break (E) of a composite membrane;

FIG. 14 is a graph showing the effect of Glycerol (GL) concentration on the actual water vapor transmission coefficient (WVP) of a composite membrane;

FIG. 15 is a graph showing the effect of Glycerol (GL) concentration on the swelling degree (S) of a composite membrane;

FIG. 16 is a graph showing the effect of Glycerol (GL) concentration on the tensile strength (T) of a composite film;

FIG. 17 is a graph showing the effect of Glycerol (GL) concentration on the elongation at break (E) of a composite membrane;

FIG. 18 is a graph showing the effect of Chitosan (CS) concentration on the overall performance weight of a composite membrane;

FIG. 19 is a graph showing the effect of Sodium Alginate (SA) concentration on the overall performance weight of a composite membrane;

FIG. 20 is a graph showing the effect of glucose- β -cyclodextrin (Glc- β -CD) concentration on the overall performance weight of a composite membrane;

FIG. 21 is a graph showing the effect of Glycerol (GL) concentration on the overall performance weight of composite membranes.

Detailed Description

The present invention is further described in detail below with reference to examples so that those skilled in the art can practice the invention with reference to the description.

The scheme provides a preparation method and application of a sodium alginate/chitosan/glucose- β -cyclodextrin composite membrane of an embodiment, and the preparation method comprises the following steps:

s1: adding 1.5-3.5 g of sodium alginate into 46.5-48.5 ml of distilled water, stirring in a constant-temperature water bath at 60 ℃, standing and defoaming to obtain an SA membrane solution;

s2, weighing 0.3-0.7 g of chitosan with the molecular weight of 10kDa and the deacetylation degree of 85%, 0.3-0.7 g of glucosyl- β -cyclodextrin and 0.4-0.8 g of glycerol, sequentially adding the weighed materials into 47.8-49 g of 2% acetic acid solution, stirring in a constant-temperature water bath at 60 ℃, standing and defoaming to obtain CS/Glc- β -CD/GL blended membrane liquid;

s3, mixing the SA membrane liquid with the CS/Glc- β -CD/GL blending membrane liquid, magnetically stirring at 500rpm for 120min, and removing bubbles by using ultrasonic waves with the frequency of 20KHz and the power of 300W to obtain the SA/CS/Glc- β -CD/GL blending membrane liquid, wherein the SA concentration, the CS concentration, the Glc- β -CD concentration and the GL concentration are respectively 1.5-3.5%, 0.3-0.7% and 0.4-0.8%;

s4: drying at 25 deg.C by tape casting method (placing the mixed membrane solution into an extruder, extruding through a head, cooling and shaping by a cooling roller, measuring the thickness of the membrane, corona treating, cutting, and rolling to form a composite membrane), adding saturated CaCl₂Crosslinking for 15min in the solution, and airing to obtain the SA/CS/Glc- β -CD composite film, wherein the obtained composite film is applied to fresh keeping of fresh food.

The performance of the prepared composite membrane is tested according to the comprehensive evaluation indexes and standards of the composite membrane in table 1, and the actual water vapor transmission coefficient (WVP), the swelling degree (S), the tensile strength (T) and the elongation at break (E) of the composite membrane are evaluated in sequence, wherein the total weighted value is 100 points.

TABLE 1 composite film comprehensive evaluation index and Standard

Examples 1-5 study of the Effect of different concentrations of CS on the Performance of composite membranes

In the SA/CS/Glc- β -CD/GL blending film-forming solutions of examples 1-5, the CS concentrations were 0.3%, 0.4%, 0.5%, 0.6%, and 0.7% in this order, but the concentrations of the other components were kept the same, with the SA concentration being 3.0%, the Glc- β -CD concentration being 0.5%, and the GL concentration being 0.6%.

Test results and analysis

Effects of A1 and Chitosan (CS) concentration on the actual Water vapor Transmission coefficient (WVP) of the composite Membrane

FIG. 2 is a graph of Chitosan (CS) concentration versus the actual water vapor transmission coefficient (WVP) of the composite membraneAs can be seen from FIG. 2, as the CS concentration in the deposition solution increased, the WVP decreased first and then increased. As the molecular arrangement structure of the composite membrane is in a low electrostatic and hydrogen bond phase concentration range, the hydrogen bond action and electrostatic action of CS molecules, SA and HPMC are enhanced along with the increase of the concentration of CS, the membrane compactness is enhanced, and the WVP is reduced; at higher concentrations, the amino repulsion between CS molecules is significant, to a certain extent, the arrangement between CS molecules and other molecules is difficult, the compactness is reduced, and the WVP is increased. The result shows that the 0.5 percent CS solution has better membrane preparation effect, and WVP is 1.16 multiplied by 10^-10g/Pa·s·m。

Influence of A2 and Chitosan (CS) concentration on swelling degree (S) of composite membrane

FIG. 3 is a graph showing the effect of the concentration of Chitosan (CS) on the degree of swelling (S) of a composite membrane, and it can be seen from FIG. 3 that S gradually increases as the concentration of CS in the deposition solution increases. Because the CS structure contains a large number of polar hydroxyl groups, the CS structure attracts water molecules, and the water absorption swelling S of the membrane is increased. The result shows that the 0.3% CS solution has better membrane preparation effect, and S is 0.81%.

Effect of A3, Chitosan (CS) concentration on tensile Strength (T) of composite films

FIG. 4 is a graph showing the influence of the concentration of Chitosan (CS) on the tensile strength (T) of a composite film, and it can be seen from FIG. 4 that T tends to increase and then decrease with the increase in the concentration of CS in the deposition solution. When the concentration is lower, the hydrogen bond effect and the electrostatic effect are enhanced along with the increase of the CS concentration, the membrane structure becomes compact, at the moment, the membrane can bear certain pressure, and the T is increased; at higher concentrations, the amino repulsion between CS molecules is significant to a certain extent, the arrangement between CS molecules and other molecules is difficult, the compactness is reduced, the T strength is reduced, and the E is increased. The result shows that the 0.5 percent CS solution has better membrane preparation effect, and the T is 8.64 Mpa.

Effect of A4, Chitosan (CS) concentration on elongation at Break (E) of composite film

FIG. 5 is a graph showing the effect of the concentration of Chitosan (CS) on the elongation at break (E) of the composite membrane, and it can be seen from FIG. 5 that E tends to decrease first and then increase as the concentration of CS in the deposition solution increases. Like the effect of CS on T, the effect of CS on the compactness of the membrane structure leads E to decrease first and then increase. The result shows that the film prepared by 0.3% CS solution has better effect, and E is 3.67.

Examples 3 and 6-10 study on the effect of different concentrations of SA on the performance of the composite membrane while maintaining the CS concentration of 0.5%, the Glc- β -CD concentration of 0.5% and the GL concentration of 0.6%, the SA concentrations in the SA/CS/Glc- β -CD/GL blending deposition solutions of examples 6-10 were 1.5%, 2.0%, 2.5% and 3.5% in this order, and the SA concentrations in the deposition solutions of example 3 were 3.0%.

Test results and analysis

B1 Effect of Sodium Alginate (SA) concentration on actual Water vapor Transmission coefficient (WVP) of composite Membrane

FIG. 6 is a graph showing the effect of Sodium Alginate (SA) concentration on the actual water vapor permeability coefficient (WVP) of the composite membrane, and it can be seen from FIG. 6 that as the SA concentration in the deposition solution increases, the WVP gradually decreases. As the SA ratio is increased, the crosslinking degree between SA molecules and CS molecules is more and more compact, so that the membrane structure is more compact, and the WVP is smaller and smaller. The results show that the 3.5% SA solution has better membrane preparation effect, and the WVP is 0.90 multiplied by 10^-10g/Pa·s·m。

Influence of B2 and Sodium Alginate (SA) concentration on swelling degree (S) of composite membrane

FIG. 7 is a graph showing the effect of Sodium Alginate (SA) concentration on the swelling degree (S) of the composite membrane, and it can be seen from FIG. 7 that S gradually decreases as the SA concentration increases. Because the volume of the polymer material in the solvent is influenced by the Tangnan potential to expand, and the quantity of ionized groups of the polymer material controls the process, SA and CS are crosslinked, so that the quantity of groups of the polymer material is reduced, and S is reduced. The results show that the 3.5% SA solution works best, with S at 1.97%.

Influence of B3 and Sodium Alginate (SA) concentration on tensile strength (T) of composite film

FIG. 8 is a graph showing the effect of Sodium Alginate (SA) concentration on the tensile strength (T) of the composite film, and it can be seen from FIG. 8 that the SA concentration increases and the T tends to decrease. Under the weak acidic condition, the CS carries positive charges and the SA with negative charges to generate intermolecular electrostatic interaction to form ionic bonds, so that the spatial structure of the composite membrane is compact. As the concentration of SA increases, the electrostatic effect gradually increases; within the proper range, the concentration increases, the SA molecules are more orderly and tightly arranged, and the T rises. The result shows that the film effect of the 3.5 percent SA solution is better, and the T is 10.8 MPa.

Influence of B4 and Sodium Alginate (SA) concentration on elongation at break (E) of composite film

FIG. 9 is a graph showing the effect of Sodium Alginate (SA) concentration on the elongation at break (E) of the composite membrane, and it can be seen from FIG. 9 that the concentration of SA in the membrane-forming solution is increased and E is also gradually increased. The increase in the SA ratio leads to an increase in the number of hydrogen bonds in the spatial network structure of the composite membrane, and thus to an increasing E. The results show that the 3.5% SA solution has better membrane preparation effect, and the E is 3.76%.

Examples 3, 11-14 study on the effect of different concentrations of Glc- β -CD on the performance of composite films

The concentrations of Glc- β -CD in the SA/CS/Glc- β -CD/GL blend film-forming solutions of examples 11-14 were 0.3%, 0.4%, 0.6%, 0.7% in this order, and the film-forming solution of example 3 corresponded to a concentration of Glc- β -CD of 0.5% while keeping the concentrations of CS, SA, and GL, 0.5% unchanged.

Test results and analysis

Effect of C1, Glucosyl- β -Cyclodextrin (Glc- β -CD) concentration on the actual Water vapor Transmission coefficient (WVP) of the composite Membrane

FIG. 10 is a graph showing the effect of glucose- β -cyclodextrin (Glc- β -CD) concentration on the actual water vapor transmission coefficient (WVP) of the composite membrane, and it can be seen from FIG. 10 that as the concentration of Glc- β -CD increases, the WVP tends to decrease and then increase, because the WVP is affected by the membrane tightness, when the ratio of Glc- β -CD is low, unsaturated hydrogen bonds are generated between molecules, the compactness gradually increases, and the WVP gradually decreases, and when the ratio of Glc- β -CD is high, intra-molecular hydrogen bonds are generated, the hydrogen bonding between molecules is weakened, the membrane compactness decreases, and the WVP increases, the result shows that the membrane preparation effect of 0.6% Glc- β -CD solution is good, and the WVP is 1.03 × 10^-10g/Pa·s·m。

Effect of C2, Glucosyl- β -Cyclodextrin (Glc- β -CD) concentration on composite film tensile Strength (T)

FIG. 11 is a graph showing the effect of the concentration of glucose- β -cyclodextrin (Glc- β -CD) on the swelling degree (S) of the composite membrane, and it can be seen from FIG. 11 that as the concentration of Glc- β -CD increases, S gradually increases, and a large amount of polar hydroxyl groups exist in the Glc- β -CD structure, which increases the water absorption of the membrane, causes a large amount of water vapor to migrate on the surface of the membrane, and S gradually increases.

Effect of C3, Glucosyl- β -Cyclodextrin (Glc- β -CD) concentration on composite film tensile Strength (T)

FIG. 12 is a graph showing the effect of the concentration of glucose- β -cyclodextrin (Glc- β -CD) on the tensile strength (T) of the composite membrane, and it can be seen from FIG. 12 that when the ratio of Glc- β -CD is increased, T is increased and then decreased, and the difference in the concentration of Glc- β -CD causes the effect on intermolecular and intramolecular hydrogen bonds, which leads to the increase and decrease of the membrane structure density and the increase and decrease of T, and the results show that the effect of preparing the membrane from the 0.6% Glc- β -CD solution is better, and T is 12.50 MPa.

Effect of C4, Glucosyl- β -Cyclodextrin (Glc- β -CD) concentration on elongation at break (E) of composite Membrane

FIG. 13 is a graph showing the effect of the concentration of glucose- β -cyclodextrin (Glc- β -CD) on the elongation at break (E) of the composite membrane, and it can be seen from FIG. 13 that the E increases and then decreases with the increase of the concentration of Glc- β -CD, but the reason for this is that the added Glc- β -CD increases the distance between CS molecules and increases the flexibility of the membrane, thus increasing the E of the composite membrane, and when the concentration of Glc- β -CD increases, the acting force between membrane structures is reduced, and the E decreases, and the result shows that the 0.5% Glc- β -CD solution has a better effect of preparing the membrane, and the E is 2.14%.

Example 3, 15-18 study on the influence of different concentrations of GL on the performance of composite membranes

While the CS concentration was maintained at 0.5%, the SA concentration was maintained at 3.0%, and the Glc- β -CD concentration was maintained at 0.5%, the GL concentrations in the SA/CS/Glc- β -CD/GL blending film-forming solutions of examples 15 to 18 were 0.4%, 0.5%, 0.7%, and 0.8%, respectively, and the film-forming solution of example 3 corresponded to the case where the GL concentration was 0.6%.

Test results and analysis

Effect of D1 and Glycerol (GL) concentration on actual Water vapor Transmission coefficient (WVP) of composite Membrane

FIG. 14 is a graph showing the effect of Glycerol (GL) concentration on the actual water vapor transmission coefficient (WVP) of the composite membrane, and it can be seen from FIG. 14 that as GL concentration gradually increases, WVP first decreases and then increases. The reason may be that at low concentrations, GL increases the water binding capacity of the composite membrane and WVP decreases; at high concentrations, too many hydrogen bonds are formed in GL, which increases the composite membrane gap and WVP. The results show that the film prepared from 0.5% GL solution has good effect, and the WVP is 0.87 multiplied by 10^-10g/Pa·s·m。

Effect of D2 and Glycerol (GL) concentration on swelling degree (S) of composite film

FIG. 15 is a graph showing the effect of Glycerol (GL) concentration on the swelling degree (S) of a composite membrane, and it can be seen from FIG. 15 that S increases first and then decreases as the GL concentration increases. The same effect of GL in D1 on the water retention and the membrane gap of the composite membrane resulted in the increase of S after the decrease. The result shows that the membrane preparation effect of the 0.7 percent GL solution is better, and the S content is 2.62 percent

Effect of D3 and Glycerol (GL) concentration on tensile Strength (T) of composite films

FIG. 16 is a graph showing the effect of the concentration of Glycerol (GL) on the tensile strength (T) of the composite film, and it can be seen from FIG. 16 that T gradually decreases as the concentration of GL increases. GL is used as a plasticizer to weaken the hydrogen bond effect among the molecules of the composite membrane, increase the molecular distance, destroy the crystallization area of SA, increase the molecular chain fluidity, and reduce T. The result shows that the film prepared by 0.4 percent GL solution has better effect, and the T is 15.77 MPa.

Effect of D4 and Glycerol (GL) concentration on elongation at Break (E) of composite film

FIG. 17 is a graph showing the effect of the concentration of Glycerol (GL) on the elongation at break (E) of the composite membrane, and it can be seen from FIG. 17 that E tends to increase as the concentration of GL increases. The same effect of GL in D3 on the membrane molecular distance and molecular chain fluidity leads to an increase in E. Experiments show that the 0.8 percent GL solution has better membrane preparation effect, and the E is 3.08 percent

According to the test results and analysis of the embodiments 1-18, the influence of different CS, SA, Glc- β -CD and GL concentrations on the comprehensive performance weight value of the composite membrane is researched, and the optimal process parameters for preparing the composite membrane are obtained.

A. FIG. 18 is a graph showing the effect of different concentrations of Chitosan (CS) on the overall performance weight of the composite membrane, in which SA concentration gradually increases and the weight gradually increases. Because CS and SA produce the electrostatic interaction, make the complex film structure inseparable gradually, ionized group quantity reduces, and the hydrogen bond effect is strengthened, so WVP, S, T and E weighted value increase gradually to make the weighted value rise gradually. When the SA is 3.5%, the weight value is 75.7 at most, and the film performance is best; however, too high concentration of SA causes the composite membrane solution to be too viscous and difficult to form. Therefore, the optimum concentration of SA is 2.5%.

B. FIG. 19 is a graph showing the effect of different Sodium Alginate (SA) concentrations on the overall performance weight of the composite membrane, and it can be seen that the weight value increases first and then decreases as the SA concentration increases. With the increase of the concentration of SA, the hydrogen bond action and the electrostatic action with CS are enhanced under low concentration, the membrane structure is more compact, and the weight values of WVP, S and T are increased; at high concentrations, the repulsive force of the amino groups on the CS increases, hydrogen bonds are not expected to form, the compactness decreases, the weight values of WVP and T decrease, and the total weight value increases first and then decreases. When CS is 0.4%, the weight is 66.2 at the highest, and the membrane performance is optimal.

C. FIG. 20 is a graph showing the effect of different concentrations of glucose- β -cyclodextrin (Glc- β -CD) on the overall performance weights of the composite membrane, wherein the weights increase and decrease with the increase of the concentration of Glc- β -CD, and at low concentrations, Glc- β -CD forms intermolecular hydrogen bonds with SA and CS, resulting in tight arrangement of membrane structures, which leads to an increase in WVP, T and E weights, and at high concentrations, Glc- β -CD forms intramolecular hydrogen bonds, which reduces the compactness of the membrane, while the weights of WVP, S, T and E decrease, and the total weights increase and decrease, and when Glc- β -CD is 0.6%, the weight is 60.4 at the highest, resulting in optimal membrane performance.

D. FIG. 21 is a graph showing the influence of Glycerol (GL) concentration on the overall performance weight of a composite membrane, and it can be seen that the weight value increases and then decreases as the GL concentration increases. GL is used as a hydrophilic plasticizer, the intermolecular and intramolecular hydrogen bonding effect is increased at low concentration, the molecular chain distance between HPMC, CS and SA and the intramolecular fluidity are reduced, and the weight values of WVP and E are increased; high concentrations increase intermolecular spacing, decrease water binding, and decrease the weight values of WVP and T. The total weight value rises first and then falls. When the GL concentration is 0.5%, the weight value is 57.4 at the highest, and the membrane performance is optimal.

In summary, the optimal parameters for preparing the composite membrane are CS concentration of 0.4%, SA concentration of 2.5%, Glc- β -CD concentration of 0.6%, and GL concentration of 0.5%.

Preparing the film according to the optimal process parameters, namely preparing the blend film-forming solution for film, wherein the components and the concentration of the blend film-forming solution are 0.4 percent of CS, 2.5 percent of SA, 0.6 percent of Glc- β -CD and 0.5 percent of GL, and performing verification tests in parallel for three times, wherein the verification test results are shown in Table 2:

table 2 shows the results of the test

As is clear from Table 2, the actual water vapor transmission coefficient of the composite membrane prepared under the process conditions of 0.4% CS concentration, 2.5% SA concentration, 0.6% Glc- β -CD concentration and 0.5% GL concentration was 1.02X 10^-10g/pas · m, a degree of swelling of 1.13, a tensile strength of 14.83MPa, and an elongation at break of 3.23%.

While embodiments of the invention have been disclosed above, it is not limited to the applications listed in the description and the embodiments, which are fully applicable in all kinds of fields of application of the invention, and further modifications may readily be effected by those skilled in the art, so that the invention is not limited to the specific details without departing from the general concept defined by the claims and the scope of equivalents.

Claims

1. A preparation method of a sodium alginate/chitosan/glucose- β -cyclodextrin composite film is characterized in that a blending film-forming solution for film making comprises the following components and concentrations of SA 1.5-3.5%, CS 0.3-0.7%, Glc- β -CD 0.3-0.7%, and GL 0.4-0.8%, and specifically comprises the following steps:

s4: drying at 25 deg.C by tape casting to form composite membrane, and adding saturated CaCl₂Crosslinking for 15min in the solution, and airing to obtain the SA/CS/Glc- β -CD composite membrane.

2. A preparation method of a sodium alginate/chitosan/glucosyl- β -cyclodextrin composite membrane is characterized in that the components and the concentration of a blending membrane-forming solution for preparing the membrane are SA 2.5%, CS 0.4%, Glc- β -CD 0.6% and GL 0.5%.

3. The preparation method of the sodium alginate/chitosan/glucosyl- β -cyclodextrin composite membrane as claimed in any one of claims 1 or 2, wherein the molecular weight of chitosan is less than or equal to 15kDa, and the degree of deacetylation is greater than or equal to 85%.

4. The preparation method of sodium alginate/chitosan/glucose- β -cyclodextrin composite membrane according to claim 1, wherein the magnetic stirring speed is 500 rpm.

5. The preparation method of sodium alginate/chitosan/glucose- β -cyclodextrin composite membrane according to claim 1, wherein the ultrasonic frequency is 20KHz, and the power is 300W.

6. The use of the sodium alginate/chitosan/glucosyl- β -cyclodextrin composite film as claimed in any one of claims 1 or 2 in fresh food preservation.