CN118436071B

CN118436071B - A hydrogel for controlling diet and inducing satiety, and preparation method and application thereof

Info

Publication number: CN118436071B
Application number: CN202410904259.2A
Authority: CN
Inventors: 史慧茹; 郑雅丹
Original assignee: Zhejiang Hengmei Health Technology Co ltd
Current assignee: Zhejiang Hengmei Health Technology Co ltd
Priority date: 2024-07-08
Filing date: 2024-07-08
Publication date: 2024-11-12
Anticipated expiration: 2044-07-08
Also published as: CN118436071A

Abstract

The invention provides hydrogel for controlling diet and inducing satiety, and a preparation method and application thereof, and relates to the technical field of foods. The prepared hydrogel is a double-crosslinked satiety hydrogel, and comprises the following components: sodium carboxymethyl cellulose, acetic acid, chitosan and malic acid; the preparation method comprises the following steps: the physical crosslinking system is constructed by using sodium carboxymethyl cellulose, acetic acid and chitosan as raw materials under ultrasonic treatment, and then the chemical crosslinking saturated hydrogel with a double crosslinking structure is further prepared by using malic acid as a crosslinking agent and the obtained physical crosslinking system. The satiety hydrogel obtained by the preparation method provided by the invention has the advantages of high swelling ratio, good satiety effect, safety and no toxicity; and the method has wide applicability, and can be applied to the preparation of different types of foods in the form of raw materials so as to meet the application requirements of various foods.

Description

Hydrogel for controlling diet and inducing satiety as well as preparation method and application thereof

Technical Field

The invention belongs to the technical field of foods, and particularly relates to a hydrogel for controlling diet and inducing satiety, and a preparation method and application thereof.

Background

Obesity is a nutritional metabolic disease caused by a variety of factors, usually caused by an imbalance between energy expenditure, energy intake and energy storage. A large number of researches show that obesity can cause hypertension, dyslipidemia and endocrine and metabolic disorders, and meanwhile, obesity is also a causative factor of cancers, kidney diseases and the like, thus the obesity is a great threat to the health and life of people. Among the many causes of obesity, changes in dietary structure and lifestyle have gradually become the main factors causing obesity.

Currently, most people select diet drugs and even fat-reducing surgery to control obesity, but diet can damage cognition; the chemical weight-losing medicines have a plurality of side effects, and can cause pulmonary arterial hypertension, apoplexy, cardiovascular diseases, neuropsychiatric diseases and the like; although the effect of the weight-losing operation is remarkable, the diseases and death caused by the weight-losing medicine can be reduced, but the risk caused by the operation cannot be ignored. Thus, there is a need to find a green, natural, safe, efficient food product for weight loss or obesity prevention.

Hydrogels are three-dimensional network structures formed by the polymerization or cross-linking of hydrophilic or water-soluble polymers that swell in water and maintain structural integrity with some moisture in the structure. Hydrogels have many advantages such as biocompatibility, biodegradability, etc. In addition, hydrogels have certain mechanical properties, the surface of which resembles biological soft tissue. Hydrogels are receiving a great deal of attention in the fields of food, biomedicine and the like due to the wide physicochemical properties and biological properties of hydrogels. Among them, cellulose gel has natural non-toxic effect, high water absorption, high viscosity and water swelling effect, and is widely studied and applied to diet food.

The Chinese patent CN116162289A discloses a multi-crosslinking sodium carboxymethyl cellulose edible gel, which takes sodium carboxymethyl cellulose as a raw material and forms a stable three-dimensional crosslinking structure by triple crosslinking with various multi-polyuronic acids; the first heavy citric acid is crosslinked to form a network structure capable of absorbing water, the second heavy succinic acid is crosslinked to solidify a three-dimensional structure, water is prevented from overflowing, and the third heavy malic acid is crosslinked to increase the water absorbing groups on the three-dimensional structure, so that the water absorbing performance of the whole gel is improved. However, the method has the problems of complicated process and long time consumption. Moreover, the degree of the esterification crosslinking reaction has a great influence on the water absorption performance of the formed gel, and when the esterification reaction is sufficiently carried out by the addition amount of the acid, the water absorption performance of the gel is improved only by controlling the type and the addition amount of the acid.

Chinese patent No. 115429815A discloses a long-acting satiety composition, which is prepared by taking hypromellose or hydroxymethyl cellulose as a framework material, taking croscarmellose sodium as a disintegrating agent, and then adding a stabilizer, a glidant and the like. After the food is ingested by a human body, the food intake and excessive caloric intake are reduced by absorbing water in the stomach cellulose gel to swell and induce satiety. However, due to the high tablet compactness, the tablet swells on the outside by absorbing water to form a viscous gel which adheres to the esophagus and prevents the tablet from entering the stomach. In addition, the small quality of the tablet can meet the functional requirement by taking a large amount of tablet.

Therefore, there is a need to develop a hydrogel product that is more satiety, safer, and less costly to manufacture, and is capable of controlling diet and inducing satiety.

Disclosure of Invention

Aiming at the problems existing in the prior art, the invention provides a hydrogel for controlling diet and inducing satiety, a preparation method and application thereof, and the prepared hydrogel is a satiety hydrogel with double crosslinking, and the preparation method comprises the following steps: the physical crosslinking system is constructed by using sodium carboxymethyl cellulose, acetic acid and chitosan as raw materials under ultrasonic treatment, and malic acid is used as a crosslinking agent to perform further chemical crosslinking with the obtained physical crosslinking system, so that the hydrogel with a double crosslinking structure is obtained. Has the advantages of high swelling ratio, good satiety effect, safety and no toxicity. In addition, the hydrogel disclosed by the invention has wide applicability, and can be applied to the preparation of different types of foods in the form of raw materials so as to meet the application requirements of various foods.

In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:

First, the present invention provides a method for preparing a hydrogel for controlling diet and inducing satiety, comprising the steps of:

(1) Preparing a mixed solution of chitosan, acetic acid and sodium carboxymethyl cellulose: mixing and dissolving chitosan and acetic acid solution, then stirring and mixing the chitosan and sodium carboxymethyl cellulose, and carrying out ultrasonic treatment to obtain a mixed solution;

(2) First heavy physical crosslinking reaction: stirring the mixed solution in the step (1) under the condition of heat preservation, and performing physical crosslinking reaction to obtain physical crosslinked hydrogel;

(3) Vacuum drying: separating the chitosan/sodium carboxymethyl cellulose compound from the physically crosslinked hydrogel in the step (2), vacuum drying, crushing and sieving to obtain the chitosan/sodium carboxymethyl cellulose compound;

(4) Preparing a chitosan/sodium carboxymethyl cellulose compound and malic acid mixed solution: mixing malic acid with hot water to obtain a malic acid solution, and then mixing the malic acid solution with the chitosan/sodium carboxymethyl cellulose compound obtained in the step (3), and carrying out ultrasonic treatment to obtain a chitosan/sodium carboxymethyl cellulose compound and malic acid mixed solution;

(5) Vacuum drying: vacuum drying the chitosan/sodium carboxymethyl cellulose compound and malic acid mixed solution obtained in the step (4);

(6) Second chemical crosslinking reaction: and (3) heating the hydrogel after the step (5) to perform chemical crosslinking reaction to obtain the hydrogel.

Preferably, in the step (1), the mass concentration of the acetic acid solution is 0.5-2%.

Further preferably, the mass concentration of the acetic acid solution is 1%.

Preferably, in the step (1), the mass ratio of chitosan to sodium carboxymethyl cellulose is 1-3:7-10; further preferably, the mass ratio of the chitosan to the sodium carboxymethyl cellulose is 1-2:8-9; still more preferably, the mass ratio of chitosan to sodium carboxymethyl cellulose is 2:8.

Preferably, in the step (1), the total mass of the chitosan and the sodium carboxymethyl cellulose is 2-7% of the total mass of the mixed solution, namely, the mass concentration is 2-7%.

Further preferably, the total mass of the chitosan and the sodium carboxymethyl cellulose is 5% of the total mass of the mixed solution, i.e. the mass concentration is 5%.

Preferably, in step (1), the ultrasonic treatment is specifically: stirring in ultrasonic water bath with ultrasonic power of 500-700w; stirring time is 1-3h.

Further preferably, the ultrasonic treatment is carried out with an ultrasonic power of 600w and a stirring time of 2h.

Preferably, in step (1), the molecular weight of sodium carboxymethylcellulose is 50-75kDa and the molecular weight of chitosan is 50-90kDa.

Preferably, in the step (2), stirring is performed under the heat-preserving condition, specifically: the temperature is kept at 50-65 ℃ and the stirring time is 1-3h.

Further preferably, stirring is performed under the condition of heat preservation, specifically: the temperature is kept at 60 ℃ and the stirring time is 2 hours.

Preferably, in the step (3), the vacuum drying is performed at a temperature of 60-70 ℃ for 8-24 hours.

Further preferably, the vacuum drying is carried out at 65 ℃ for 12-24 hours.

Preferably, in step (3), the sieving is through a 60-100 mesh sieve; further preferably through an 80 mesh screen.

Preferably, in the step (4), the temperature of the hot water is 55-65 ℃; the temperature is more preferably 60 ℃.

Preferably, in step (4), the ultrasonic treatment is specifically: stirring in ultrasonic water bath with ultrasonic power of 500-700w; stirring time is 1-3h.

Further preferably, the ultrasonic treatment is carried out with ultrasonic power of 600w and stirring time of 2h until the ultrasonic treatment is dissolved into a transparent mixed solution.

Preferably, in step (4), the mass of malic acid is 0.3-0.7%, preferably 0.6% of the mass of the chitosan/sodium carboxymethyl cellulose complex.

Preferably, in the step (4), the mass ratio of the chitosan/sodium carboxymethyl cellulose compound to the water is 8-12:180-200; the mass ratio is further preferably 9-10:190.

Preferably, the vacuum drying in the step (5) is carried out at a temperature of 60-70 ℃ for 8-24 hours; further preferably, the vacuum drying is carried out at 65 ℃ for 12-24 hours; still more preferably, the vacuum drying is performed at 65℃for 12 hours.

In the invention, the product obtained after the step (5) is dried in vacuum is in a fluffy and porous state.

Preferably, in the step (6), the heating is high-temperature heating, the temperature is 85-120 ℃, and the heating is carried out for 4-8 hours.

Further preferably, the heating is at a temperature of 105-120 ℃.

Still more preferably, the heating is at a temperature of 115-120℃for 6h.

Preferably, after the second chemical crosslinking reaction, the product is crushed, sieved, in particular: pulverizing into particles with high-speed pulverizer, and sieving with 50-80 mesh sieve; preferably through a 60 mesh screen to obtain a double crosslinked saturated hydrogel.

The invention further provides the hydrogel prepared by the preparation method, and the hydrogel is double-crosslinked satiety hydrogel.

Finally, the invention provides application of the hydrogel in preparing foods with effects of controlling diet, inducing satiety and losing weight.

Compared with the prior art, the invention has the following beneficial effects:

1. Compared with carboxymethyl cellulose hydrogel prepared by single physical or chemical crosslinking, the preparation method provided by the invention has the beneficial effects that: the positively charged chitosan and polyanion carboxymethyl cellulose are firstly subjected to physical crosslinking under an acidic condition to form a surface-connected compact and internal loose structure; based on physical crosslinking, malic acid is used as a crosslinking agent to crosslink sodium carboxymethyl cellulose, so that linear sodium carboxymethyl cellulose is linked into a network-shaped three-dimensional structure in a chemical bond form, and the linear sodium carboxymethyl cellulose and the physical crosslinking form the sodium carboxymethyl cellulose/chitosan double-crosslinked hydrogel. The water absorption swelling ratio of the hydrogel prepared by the invention is further improved, and the mechanical property is enhanced; on the other hand, the double cross-linking exists, and the hydrogel prepared by the method overcomes the phenomena of short occupying residence time, short collapsibility time and the like of single cross-linking in an acidic stomach environment, and has the effects of long occupying residence time, difficult collapsibility and long satiety supporting time in gastric juice and small intestine environments.

2. In the preparation method provided by the invention, vacuum drying and ultrasonic auxiliary stirring are used, so that the preparation method has the remarkable beneficial effects: before the second chemical crosslinking reaction, the traditional hot air drying is replaced by vacuum drying, and compared with the adopted hot air drying for 40-72 hours, the vacuum drying only needs 18-32 hours, so that the drying time is shortened; the prepared hydrogel is compact and hard particles with high particle density and smooth and compact surface due to inconsistent migration rate of hot air drying moisture, and the hydrogel prepared by vacuum drying is of a fluffy and porous surface structure, and forms a uniform honeycomb pore structure on microcosmic, so that the water absorption swelling performance is improved compared with that of hot air drying; compared with the traditional stirring, the ultrasonic auxiliary stirring accelerates the intermolecular movement, so that the chitosan and carboxymethyl cellulose molecules are dispersed more uniformly, the crosslinking efficiency is improved, the uncrosslinked molecular weight is reduced, and the crosslinking degree is reduced.

3. According to the preparation method of the hydrogel, the sodium carboxymethyl cellulose, the acetic acid, the chitosan and the malic acid are used as raw materials for carrying out the crosslinking reaction, so that the preparation cost is low, the production realizability is high, and the swelling rate is high; according to the invention, high-temperature drying is adopted to carry out chemical crosslinking to form an intermolecular three-dimensional network structure, and vacuum drying is adopted to increase the porous structure of the substance, so that the swelling performance is further improved.

4. The hydrogel provided by the invention is an edible satiety hydrogel, chitosan, sodium carboxymethyl cellulose, acetic acid and malic acid are all natural and safe raw materials, and compared with the hydrogel prepared by using aldehydes (such as formaldehyde and acetaldehyde) as a cross-linking agent and introducing ethanol into the raw materials in the prior art, the hydrogel prepared by the invention is safe, green, nontoxic and wide in application, and can be applied to the preparation of functional foods.

Drawings

FIG. 1 is a flow chart of the preparation of an example of a saturated hydrogel with double crosslinking.

FIG. 2 is a mechanical drawing of physical and chemical crosslinking reactions of a saturated hydrogel with dual crosslinks according to the present invention.

FIG. 3 is a graph of the swelling ratio versus the in vitro swelling test.

FIG. 4 is a scanning electron microscope contrast plot of the hydrogels of example 1 and comparative example 2.

Detailed Description

The following non-limiting examples will enable those of ordinary skill in the art to more fully understand the invention and are not intended to limit the invention in any way. The following is merely exemplary of the scope of the invention as it is claimed and many variations and modifications of the invention will be apparent to those skilled in the art in light of the disclosure, which should be considered as falling within the scope of the invention as claimed.

Where numerical ranges are provided in the examples, it is understood that unless otherwise stated herein, both endpoints of each numerical range and any number between the two endpoints are significant both in the numerical range. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

The invention is further illustrated by means of the following specific examples. The various chemical reagents used in the examples of the present invention were obtained by conventional commercial means unless otherwise specified.

In the following examples, sodium carboxymethylcellulose was purchased from Yu environmental protection materials Co., ltd., changzhou, and had a viscosity of 600 to 1300mPa.s and a substitution degree of 0.8 to 1.0; chitosan was purchased from the biological sciences company of Mono Zhejiang, with a degree of deacetylation of 94%, a particle size of 100-200 mesh and a viscosity of 0.7-1mpa.s. Products of different manufacturers have no significant effect on the effect.

The flow chart for the preparation of a saturated hydrogel with double cross-linking is shown in fig. 1: chitosan is a polycation alkaline polysaccharide, the solubility of the chitosan in water is poor due to intermolecular hydrogen bonds in the chitosan, the polycations can be mutually repelled by static electricity and the polymer is solvated by adding dilute acetic acid in the water, when a certain amount of carboxymethyl cellulose is added, the chitosan with positive charges and anionic polysaccharide sodium carboxymethyl cellulose undergo intermolecular ion crosslinking reaction to form a surface-connected compact internal loose structure, and the chitosan is a hydrophilic polymer which can be obviously swelled in water but is insoluble in water. In the second crosslinking reaction, the sodium carboxymethyl cellulose and malic acid are subjected to esterification crosslinking reaction again; because malic acid contains two carboxyl groups, cyclic acyl can be generated under the condition of heating loss, under the high-temperature catalysis effect, two adjacent carboxyl groups in the crosslinking agent malic acid are dehydrated firstly to generate cyclic anhydride, and the anhydride reacts with-OH in sodium carboxymethyl cellulose molecules to generate the crosslinked cellulose ether with a reticular space structure. Finally, the satiety hydrogel with a three-dimensional network structure of a physical and chemical double cross-linked structure is obtained.

The mechanical and chemical crosslinking reactions of the saturated hydrogels with double crosslinking are shown in figure 2.

Example 1

A diet-controlling and satiety-inducing hydrogel, comprising the following components: sodium carboxymethyl cellulose, acetic acid, chitosan, and malic acid.

The hydrogel is double-crosslinked satiety hydrogel, and the preparation method comprises the following steps:

(1) Weighing 2g of chitosan and 8g of sodium carboxymethyl cellulose for standby, preparing 190mL of 1% mass fraction dilute acetic acid solution, adding 2g of chitosan into the dilute acetic acid solution, stirring until the chitosan and the sodium carboxymethyl cellulose are completely dissolved, adding 8g of sodium carboxymethyl cellulose, stirring for 2 hours in a 600w ultrasonic water bath, and obtaining a mixed solution of chitosan, sodium carboxymethyl cellulose and dilute acetic acid; the mass concentration of the sodium carboxymethyl cellulose is 4 percent, and the mass concentration of the chitosan is 1 percent.

(2) First heavy physical crosslinking reaction: stirring the mixed solution for 2 hours at the temperature of 60 ℃ and fully carrying out a first heavy physical crosslinking reaction to obtain the physical crosslinking hydrogel.

(3) Vacuum drying: separating chitosan/sodium carboxymethyl cellulose composite from the physical crosslinked hydrogel, vacuum drying at 65 ℃ for 12 hours, crushing and sieving with a 80-mesh sieve to obtain the chitosan/sodium carboxymethyl cellulose composite.

(4) Dissolving 0.06g malic acid in 190g purified water at 60 ℃ and stirring uniformly to obtain a malic acid solution, adding 10g of the chitosan/sodium carboxymethyl cellulose compound into the malic acid solution, and stirring in a 600w ultrasonic water bath at 65 ℃ for 2h until the solution is dissolved into a transparent mixed solution.

(5) Vacuum drying: and (3) placing the chitosan/sodium carboxymethyl cellulose compound and malic acid mixed solution obtained in the step (4) into a vacuum drying oven, and drying for 12 hours at 65 ℃ to form a fluffy and porous state.

(6) Second chemical crosslinking reaction: placing the product obtained after the vacuum drying in the step (5) in an electrothermal blowing drying oven, and heating and drying for 6 hours at 115 ℃ to carry out chemical crosslinking reaction; crushing into particles by a high-speed crusher, and sieving by a 60-mesh sieve to obtain the double-crosslinked satiety hydrogel.

Example 2

The difference from example 1 is that the amounts of chitosan and sodium carboxymethylcellulose are different, 1g of chitosan and 9g of sodium carboxymethylcellulose.

Example 3

The difference from example 1 is that the mass of malic acid used is 0.03g, i.e. the mass of malic acid is 0.3% of the mass of the chitosan/sodium carboxymethyl cellulose complex.

Example 4

The difference from example 1 is that the heat drying temperature in step (6) was 105 ℃.

Example 5

The difference from example 1 is that the heat drying temperature in step (6) is 120 ℃.

Example 6

The difference from example 1 is that the vacuum drying time in step (3) is 24 hours.

Example 7

The difference from example 1 is that the diluted acetic acid solution of step (1) is 240mL, i.e. the total mass of chitosan and sodium carboxymethyl cellulose in step (1) is 4% of the total mass of the mixed solution.

Comparative example 1

Unlike example 1, chitosan was replaced with sodium carboxymethyl cellulose, i.e. the hydrogel had no chitosan component.

The preparation method of the sodium cellulose hydrogel comprises the following steps:

(1) Weighing 10g of sodium carboxymethylcellulose for standby, preparing 190mL of 1% mass fraction dilute acetic acid solution, mixing 10g of sodium carboxymethylcellulose with the dilute acetic acid solution, and stirring in a 600w ultrasonic water bath for 2 hours to obtain a mixed solution of sodium carboxymethylcellulose and dilute acetic acid; the mass concentration of sodium carboxymethyl cellulose is 5%.

(2) Stirring the mixed solution for 2 hours at the temperature of 60 ℃ and fully carrying out a first heavy physical crosslinking reaction to obtain the physical crosslinking hydrogel.

(3) The physical crosslinking hydrogel is dried in vacuum for 12 hours at 65 ℃, crushed and sieved by a 80-mesh sieve, and the sodium carboxymethyl cellulose/acetic acid compound is obtained.

(4) Dissolving 0.06g malic acid in 190g purified water at 60 ℃ and stirring uniformly to obtain a malic acid solution, adding 10g of the sodium carboxymethyl cellulose/acetic acid compound into the malic acid solution, and stirring in a 600w ultrasonic water bath at 65 ℃ for 2h until the sodium carboxymethyl cellulose/acetic acid compound is dissolved into a transparent mixed solution.

(5) Vacuum drying: the mixture was placed in a vacuum oven and dried at 65℃for 12h.

(6) Placing the product obtained by vacuum drying in the step (5) in an electrothermal blowing drying oven, and heating and drying for 6 hours at 115 ℃ to carry out chemical crosslinking reaction; finally, crushing the mixture into particles by a high-speed crusher, and sieving the particles by a 60-mesh sieve to obtain the sodium cellulose hydrogel.

Comparative example 2

The difference from example 1 is that the vacuum drying in step (3) and step (5) was replaced with ordinary hot air drying, both hot air drying at 65℃for 12 hours.

Comparative example 3

The difference from example 1 is that the mass of malic acid used is 0.002g, i.e. the mass of malic acid is 0.02% of the mass of the chitosan/sodium carboxymethyl cellulose complex.

Comparative example 4

The difference from example 1 is that the heat drying temperature in step (6) is different and replaced with 80 ℃.

Comparative example 5

The difference from example 1 is that the amounts of chitosan and sodium carboxymethylcellulose are different, in this comparative example 8g of chitosan and 2g of sodium carboxymethylcellulose.

Comparative example 6

The difference from example 1 is that the mass of malic acid used is 0.2g, i.e. the mass of malic acid is 2% of the mass of the chitosan/sodium carboxymethyl cellulose complex.

Comparative example 7

The difference from example 1 is that the acetic acid of step (1) is replaced with citric acid.

Comparative example 8

The difference from example 1 is that acetic acid and malic acid are replaced with each other: malic acid (mass fraction 1%) was used in step (1), and acetic acid (mass fraction 0.6%) was used in step (4).

Comparative example 9

The difference from example 1 is that the raw materials of sodium carboxymethyl cellulose and chitosan were deleted, and carboxymethyl chitosan (CAS number 83512-85-0, available from Shanghai Seiya Biotechnology Co., ltd., product number S30948, carboxylation degree. Gtoreq.80%) was replaced as a whole, specifically:

(1) Weighing 10g of carboxymethyl chitosan for standby, preparing 190mL of 1% mass fraction diluted acetic acid solution, mixing 10g of carboxymethyl chitosan with the diluted acetic acid solution, and stirring in a 600w ultrasonic water bath for 2 hours to obtain a mixed solution of carboxymethyl chitosan and diluted acetic acid; the mass concentration of the carboxymethyl chitosan is 5%.

(3) The physical crosslinking hydrogel is dried for 12 hours in vacuum at 65 ℃, crushed and sieved by a 80-mesh sieve, and the carboxymethyl chitosan/acetic acid compound is obtained.

(4) Dissolving 0.06g malic acid in 190g purified water at 60 ℃ and stirring uniformly to obtain a malic acid solution, adding 10g of the carboxymethyl chitosan/acetic acid compound into the malic acid solution, and stirring in a 600w ultrasonic water bath at 65 ℃ for 2h until the malic acid solution is dissolved into a transparent mixed solution.

(6) Placing the product obtained by vacuum drying in the step (5) in an electrothermal blowing drying oven, and heating and drying for 6 hours at 115 ℃ to carry out chemical crosslinking reaction; and finally, crushing the mixture into particles by a high-speed crusher, and sieving the particles by a 60-mesh sieve to obtain the carboxymethyl chitosan hydrogel.

Comparative test 1 determination of swelling Rate

1.00G of a sample is accurately sampled and is marked as W ₁, the sample is placed in a 500mL beaker, 300mL of purified water is added into the beaker, swelling is carried out for 20min at the temperature of 20+/-2 ℃ and then suction filtration is carried out, and the solid matters obtained by suction filtration are placed on clean weighing paper to weigh the mass of the solid matters and are marked as W ₂.

Swelling ratio= (W ₂-W₁）/W₁.

The swelling ratio results of the hydrogels prepared in each of the examples and comparative examples are shown in Table 1.

TABLE 1

As can be seen from table 1, the comparison results of example 1, example 3, comparative example 3 and comparative example 6 show that: in the esterification and crosslinking reaction process of sodium carboxymethyl cellulose and the crosslinking agent, the adding amount of the crosslinking agent has a great influence on the swelling effect of the composition. When the adding amount of the cross-linking agent is in a proper range, the sodium carboxymethylcellulose in the system can carry out full cross-linking reaction with malic acid, the formed hydrogel has an optimal three-dimensional network structure of gel, the water absorption swelling ratio is optimal, and the satiety can be induced, so that the effects of diet control and weight losing are achieved.

The mass ratio of chitosan to sodium carboxymethyl cellulose has a larger influence on the swelling rate of the gel, and the results of example 1, example 2, comparative example 1 and comparative example 5 show that: when the mass ratio of the two is 1-3:7-10, the water absorption rate of the obtained hydrogel is ideal; when the mass of the chitosan is relatively large, the gel formed by excessive cationic polysaccharide is mainly physically crosslinked, the chitosan exists in a dispersed particle form after water absorption, and cannot form an integral gel with the sodium carboxymethyl cellulose polymer, and the physical crosslinking reversibility is relatively strong, so that the water absorption rate of the gel is relatively small; in the case of sodium carboxymethylcellulose, the gel formed is mainly formed by crosslinking sodium carboxymethylcellulose and malic acid, and compared with the double-crosslinked gel, the three-dimensional structure is reduced, so that the swelling rate is reduced.

As can be seen from comparison of example 1, example 4, comparative example 2 and comparative example 4: the crosslinking temperature and the drying mode are one of the important factors affecting the gel swelling rate. The cross-linking reaction between carboxymethyl cellulose and malic acid is essentially an esterification reaction that causes cross-linking between sodium carboxymethyl cellulose, which requires a suitable temperature to promote the reaction. Within a suitable crosslinking temperature range, malic acid and sodium carboxymethylcellulose can be crosslinked sufficiently to optimize the swelling rate. In addition, the physical crosslinked composite gel prepared by different drying modes is also relatively high in swelling rate before chemical crosslinking. When the gel is physically crosslinked in comparative example 2, the gel obtained by chemical crosslinking after hot air drying instead of vacuum drying is compact and smooth sheet, and the hydrogel obtained by chemical crosslinking after vacuum drying is porous and fluffy sheet. Further verification of microstructure shows that the hydrogel prepared by vacuum drying and chemical crosslinking has a loose and porous structure, the wall thickness of the bracket is Bao Junyi, all the chambers in the bracket are mutually communicated, and compared with the hydrogel obtained by hot air drying, the swelling rate of the hydrogel sample is further improved.

Comparative test 2 in vitro swelling Effect test

In-vitro swelling test reference 2015 edition of Chinese pharmacopoeia, the specific preparation methods of artificial gastric juice, artificial intestinal juice and artificial colon juice are as follows:

(1) Preparing artificial gastric juice:

Taking 16.4mL of diluted hydrochloric acid with the concentration of 1mol/L, adding about 800mL of water and 10g of pepsin, shaking uniformly, adding water to dilute to 1000mL, and placing in a refrigerator with the temperature of 4 ℃ for standby.

(2) Preparing artificial intestinal juice:

① Taking 6.8g of monopotassium phosphate, adding 500mL of water, and adjusting the pH value to 6.8 by using 0.1mol/L NaOH solution;

② Taking 10g of trypsin, and adding a proper amount of water to dissolve the trypsin;

after mixing ① and ② above, water was added to dilute to 1000mL.

(3) Preparation of artificial colon fluid

5.59G of dipotassium hydrogen phosphate and 0.41g of potassium dihydrogen phosphate are taken, dissolved by adding water, and the volume is fixed to 1000mL, and the pH value is regulated to 8.4 by 0.1mol/L sodium hydroxide solution.

(4) Simulated in vitro swelling Effect test

Accurately weighing 0.5000+/-0.05 g of dry hydrogel particles, which is marked as W _Dry, putting the hydrogel particles into a flask filled with 25mL of artificial gastric juice, heating in a water bath at 37 ℃ and continuously stirring, swelling the hydrogel for 90min, and obtaining a hydrogel sample swelled in the artificial gastric juice through suction filtration, wherein the accurate weighing is marked as W _Stomach.

The hydrogel sample swelled in the artificial gastric juice is respectively put into a flask filled with 25mL of artificial intestinal juice, the mixture is continuously stirred under the water bath heating at 37 ℃, after the hydrogel swells for 90min, the hydrogel sample swelled in the artificial intestinal juice is obtained through suction filtration, and the accurate weighing is recorded as W _{Small intestine}.

The swelling hydrogel samples in the artificial intestinal juice are respectively put into a flask filled with 25mL of the artificial intestinal juice, the mixture is continuously stirred under the water bath heating at 37 ℃, after the hydrogel swells for 90min, the swelling hydrogel samples in the artificial intestinal juice are obtained through suction filtration, and the accurate weighing is recorded as W _Colon.

Calculate the swelling ratio (swelling multiple) of the hydrogel:

Swelling ratio of hydrogel in artificial gastric juice Q _Stomach=W_Stomach/W_Dry.

Swelling ratio of hydrogel in artificial intestinal fluid Q _{Small intestine}=W_{Small intestine}/W_Dry.

Swelling ratio of hydrogel in artificial intestinal juice Q _Colon=W_Colon/W_Dry.

The swelling times of the hydrogels prepared in each of the examples and comparative examples, which were tested for swelling in vitro, are shown in FIG. 3.

As can be seen from fig. 3, each hydrogel sample had a swelling effect in gastric juice that was tested in water. The swelling ratio in the small intestine is reduced because the gel has a physically crosslinked portion, and when the gel having physical crosslinking enters the small intestine in a neutral environment, the physically crosslinked structure portion fails, resulting in collapse of the three-dimensional structure portion, thereby affecting the swelling ratio.

When the prepared double-crosslinked satiety hydrogel enters gastric juice, the three-dimensional network structure of the hydrogel is supported by physical crosslinking and chemical crosslinking, so that the hydrogel can still absorb a large amount of water in the gastric juice to form the hydrogel with higher swelling ratio, and the swelling effect is not reduced due to the collapse of the gel structure in a longer time; in the neutral small intestine structure, physical crosslinking points formed by ionic bonds still exist, and a hydrogel three-dimensional network is formed together with chemical crosslinking points and a high swelling state is maintained; the hydrogel enters an alkaline colon environment, and the anion is reduced to cause the ion crosslinking of chitosan and sodium carboxymethyl cellulose to break, and the alkaline environment is favorable for the hydrolysis of ester groups, so that the hydrogel loses chemical crosslinking points, and is smoothly discharged out of the body.

Comparative test 3 scanning electron microscope analysis

Scanning Electron Microscope (SEM) analysis: the hydrogels of example 1 and comparative example 2 were subjected to sem analysis of microstructure, and the sem image is shown in fig. 4. As can be seen from the results in fig. 4, the saturated gel prepared by vacuum drying and chemical crosslinking in example 1 has a loose porous structure compared with the hot air drying in comparative example 2, the wall thickness Bao Junyi of the scaffold, and the internal chambers are mutually communicated, and the swelling rate of the sample obtained by hot air drying is further improved compared with that of the sample obtained by hot air drying.

Comparative experiment 4 animal experiment

(1) Animal feeding conditions and groupings: preparing 6-week-old clean-class male C57 mice, weighing (20+/-2) g, adaptively feeding for 7 days, and dividing the mice into 15 groups according to a random grouping method, wherein 5 mice are in each group; blank control group (gastric lavage saline+low fat feed), experimental group (gastric lavage hydrogel solution+high fat feed), negative control group (gastric lavage saline+high fat feed), positive control group (gastric lavage orlistat solution+high fat feed). The gastric lavage dose was 0.2 mL/dose. The experimental period is 8 weeks, mice are fed in separate cages in the same room, 5 mice are fed in each cage, the mice can drink water and eat freely, the mice are alternated for 12 hours in day and night, the temperature is controlled at (23+/-2) DEG C, and the humidity is 60%.

(2) Determination of mouse body mass and abdominal fat mass: mice mass was measured weekly during the experiment. The mice were dissected and abdominal fat was removed and weighed. The results are shown in Table 2.

TABLE 2

Letter a, b, c, d, e in table 2 represents the result of the significant difference: the same letters between different rows in the same column indicate that the difference is not significant (P > 0.05), and the different letters indicate that the difference is significant (P < 0.05).

The body mass and the abdominal fat mass can intuitively show the weight losing and weight controlling effects. At the beginning of the experiment, the weights of the mice in each group were not statistically different (P > 0.05), and after 8 weeks of feeding, the mass of the mice and the mass of abdominal fat at the time of dissection showed a certain difference due to individual differences. As shown in table 2, the weight of the blank control group is significantly lower than that of the other groups after 8 weeks, and the weight of the negative control group is significantly higher than that of the other groups, which indicates that the mice not taking the high-fat feed are healthy. In addition, the positive control group and the example 1 have no significant difference (P > 0.05), and the body weight and the abdominal fat are significantly lower than those of other experimental groups, which shows that the satiety hydrogel in the example 1 has no significant difference from the effect of the weight-losing medicament, and has good body weight control effect.

The body weights and abdominal fats of examples 2, 3, 4,6 and 7 have no significant difference (P > 0.05), and the body weight significance (P < 0.05) is superior to that of comparative examples 1, 3, 6, 8 and 9, indicating that the body weight control effect of the hydrogels prepared in examples is better than that of the hydrogels prepared in comparative examples, and the weight loss effect is remarkable.

As can be seen from the data in table 2, the body weight and abdominal fat of the experimental group are significantly lower than those of the negative control group (P < 0.05), which indicates that the body weight and fat content of the mice can be significantly improved under the action of the satiety hydrogel, and a better body weight control effect is shown, because the satiety hydrogel particles are swelled after entering the digestive system, form gel masses in the stomach and the small intestine, have long-term satiety after eating, and reduce the intake energy, and the hydrogel can absorb fat and reduce the body weight and fat quality.

Finally, it should be noted that the above description is only for illustrating the technical solution of the present invention, and not for limiting the scope of the present invention, and that the simple modification and equivalent substitution of the technical solution of the present invention can be made by those skilled in the art without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for preparing a hydrogel for controlling diet and inducing satiety, comprising the steps of:

(1) preparing a mixed solution of chitosan, acetic acid and sodium carboxymethyl cellulose: mixing and dissolving chitosan with an acetic acid solution, and then stirring and mixing with sodium carboxymethyl cellulose, and ultrasonically treating to obtain a mixed solution; in step (1), the mass concentration of the acetic acid solution is 0.5-2%; the mass ratio of chitosan to sodium carboxymethyl cellulose is 1-3:7-10; the total mass of chitosan and sodium carboxymethyl cellulose is 2-7% of the total mass of the mixed solution;

(2) First physical cross-linking reaction: stirring the mixed solution in step (1) under heat preservation conditions to perform a physical cross-linking reaction to obtain a physically cross-linked hydrogel;

(3) vacuum drying: separating the chitosan/sodium carboxymethyl cellulose complex from the physically cross-linked hydrogel of step (2), vacuum drying, crushing and sieving to obtain the chitosan/sodium carboxymethyl cellulose complex;

(4) preparing a chitosan/sodium carboxymethyl cellulose complex and a malic acid mixture: mixing malic acid with hot water to obtain a malic acid solution, and then mixing the solution with the chitosan/sodium carboxymethyl cellulose complex of step (3), and ultrasonically treating the solution to obtain a chitosan/sodium carboxymethyl cellulose complex and a malic acid mixture; in step (4), the mass of the malic acid is 0.3-0.7% of the mass of the chitosan/sodium carboxymethyl cellulose complex; and the mass ratio of the chitosan/sodium carboxymethyl cellulose complex to water is 8-12:180-200;

(5) vacuum drying: vacuum drying the chitosan/sodium carboxymethyl cellulose complex and malic acid mixture obtained in step (4);

(6) Second chemical cross-linking reaction: heating after step (5) to carry out a chemical cross-linking reaction to obtain a hydrogel.

2. The preparation method according to claim 1, characterized in that:

The ultrasonic treatment in step (1) is specifically: ultrasonic water bath stirring treatment, ultrasonic power 500-700w, stirring time 1-3h;

The mass concentration of the acetic acid solution is 1%; the mass ratio of chitosan to sodium carboxymethyl cellulose is 1-2:8-9; the total mass of chitosan and sodium carboxymethyl cellulose is 5% of the total mass of the mixed solution.

3. The preparation method according to claim 2, characterized in that in step (1), the ultrasonic treatment has an ultrasonic power of 600w and a stirring time of 2h.

4. The preparation method according to claim 2, characterized in that in step (1), the mass ratio of chitosan to sodium carboxymethyl cellulose is 2:8.

5. The preparation method according to claim 1, characterized in that, in step (2), the stirring under insulation conditions is specifically: insulation temperature is 50-65°C, and stirring time is 1-3h.

6. The preparation method according to claim 1, characterized in that in step (3), the vacuum drying is carried out at a temperature of 60-70°C and a drying time of 8-24 hours; and the sieving is carried out through a 60-100 mesh sieve.

7. The preparation method according to claim 1, characterized in that in step (4), the hot water has a temperature of 55-65°C; and the ultrasonic treatment is specifically: ultrasonic water bath stirring treatment, ultrasonic power 500-700w, stirring time 1-3h.

8. The preparation method according to claim 1, characterized in that:

In step (5), the vacuum drying is carried out at a temperature of 60-70°C and a drying time of 8-24 hours;

In step (6), the heating is specifically high-temperature heating at a temperature of 85-120° C. for 4-8 hours.

9. The hydrogel prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the hydrogel according to claim 9 in preparing food having the effects of controlling diet, inducing satiety and reducing weight.