Cross-linked composite gels of sugar beet pectin and gelatin and methods of making and uses thereof

Abstract

The present application relates to the field of novel pectin, in particular to a crosslinked composite gel of sugar beet pectin and gelatin and a preparation method and application thereof. The preparation method of the composite gel comprises the following steps: (1) dissolving sugar beet pectin powder in deionized water to obtain a sugar beet pectin solution; (2) dissolving gelatin in deionized water to obtain a gelatin solution; (3) mixing and stirring the sugar beet pectin solution and the gelatin solution to obtain a sugar beet pectin-gelatin mixed solution; (4) adjusting the pH of the sugar beet pectin-gelatin mixed solution, adding a crosslinking agent and stirring to obtain a composite solution; (5) cooling the composite solution after heat treatment to obtain a crosslinked composite gel of sugar beet pectin and gelatin. The composite gel of sugar beet pectin prepared by the method has a good network structure and good properties, widens the application of sugar beet pectin in the food and medicine fields, and is conducive to the development of the pectin polysaccharide and sugar beet pectin industries.

Description

Technical Field

[0001] This invention relates to the field of functional food and pharmaceutical technology, and in particular to cross-linked composite gels of beet pectin and gelatin, their preparation methods and uses. Background Technology

[0002] Beet pectin is a byproduct of beet sugar production. As an acidic heteropolysaccharide, it is mainly composed of homogalacturonic acid polysaccharide (HG), rhamnose-galacturonic acid polysaccharide type I (RG-I), and rhamnose-galacturonic acid polysaccharide type II (RG-II). In recent years, it has been widely used in the food, health, pharmaceutical, and cosmetic industries. Studies have shown that beet pectin has extremely poor physical gelling properties and is almost impossible to gel via calcium ion cross-linking; therefore, its use in the pharmaceutical and cosmetic industries is somewhat limited. However, the ferulicoyl groups present on the RG-I region of beet pectin provide a pathway for cross-linking and gel formation.

[0003] Gelatin, a biopolymer, is produced through the partial hydrolysis of collagen. Studies have shown that it possesses excellent thermal reversibility, forming an ordered and compact network. However, the resulting gel structure has poor mechanical properties and the network has certain defects, which limits its application in the food industry.

[0004] A search was conducted in the China Patent Publication Database using "beet pectin and gelatin" as the abstract keywords on January 1, 2024. Two documents were found: CN106120477A A method for preparing a sustained-release drug-loaded paper base film and CN104957487A A peanut milk-flavored dumpling skin and its preparation method; neither of these is related to this patent. Summary of the Invention

[0005] Purpose of the invention: To provide a better cross-linked composite gel of beet pectin and gelatin, its preparation method and uses, the specific purpose of which is described in the detailed embodiments section for several substantial technical effects.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A beet pectin and gelatin composite crosslinked gel and its preparation method, characterized by comprising the following steps:

[0009] (1) Dissolve beet pectin powder in deionized water, stir magnetically and let stand to hydrate to obtain beet pectin solution;

[0010] (2) Dissolve gelatin in deionized water and heat and stir to obtain a gelatin solution;

[0011] (3) Mix and stir the beet pectin solution and gelatin solution to obtain a beet pectin-gelatin mixed solution;

[0012] (4) Adjust the pH of the beet pectin-gelatin mixed solution, add cross-linking agent and stir to obtain a composite solution;

[0013] (5) After heat treatment, the composite solution is cooled (time) to obtain the cross-linked composite gel of beet pectin and gelatin.

[0014] Further, in step (1), the mass fraction of the beet pectin is 5-30%.

[0015] g / L.

[0016] Furthermore, in step (1), the magnetic stirring time is 8-12 hours.

[0017] Furthermore, in step (1), the settling temperature is 0-4℃ and the time is 8-12 hours.

[0018] Furthermore, in step (2), the mass fraction of the gelatin is 20-40 g / L.

[0019] Furthermore, in step (2), the gelatin is heated at a temperature of 70-90°C for 0.5-1 hour.

[0020] Further, in step (3), the volume ratio of the beet pectin solution to the gelatin solution is 1:1.

[0021] Further, in step (4), the pH of the beet pectin solution-gelatin mixed solution is adjusted to 3.0, 4.0, 5.0, 6.0 or 7.0, preferably 4.0, and the mass concentration of beet pectin in the composite solution is 15 g / L, and the mass concentration of gelatin is 10-20 g / L. Preferably, the mass ratio of beet pectin to gelatin is 15:20.

[0022] Further, in step (4), the crosslinking agent 1 is laccase (500 U / g) added to the mixed solution at a ratio of 8-12 U / g pectin. Preferably, it is 12 U / g pectin. The crosslinking agent 2 is eugenol (99%) added to the mixed solution at a volume ratio of 0.1-5:1000, preferably 0.5:1000.

[0023] Furthermore, in step (5), the heat treatment conditions are: 30-90℃, 0.5-2.5 hours.

[0024] Furthermore, in step (5), the cooling conditions are: 0-4℃, 8-12 hours.

[0025] The present invention, which adopts the above technical solution, has the following beneficial effects compared with the prior art: (1) The beet pectin and gelatin of the present invention have natural sources, the extraction process is non-toxic and harmless, and the gel made by the combination of the two has a good gel network and thermal stability, and can be used as a gel matrix for drug delivery.

[0026] (2) The method of adjusting pH value used in this invention is safe and the cross-linking agent is of natural origin. By adjusting the pH value to make the gelatin solution have an isoelectric point, and by adding the cross-linking agent to promote cross-linking, both can promote the compounding of beet pectin and gelatin to form a gel at a lower mass, thus saving costs.

[0027] (3) The method of the present invention can expand the application scenarios of beet pectin gel, and provide new ideas for the application of beet pectin, gelatin and cross-linked modified gels in food and medicine.

[0028] Invention principle: Pectin gel has certain physiological properties. Using pectin hydrogel carriers to encapsulate and deliver drug components can be widely used in the pharmaceutical field and plays an extremely important role in food, medicine, and cosmetics.

[0029] Beet pectin (SBP) is a novel pectin extracted from leftover beet pulp. It is mainly composed of homogalacturonic acid polysaccharide (HG), rhamnose-galacturonic acid polysaccharide type I (RG-I), and rhamnose-galacturonic acid polysaccharide type II (RG-II). Compared to other pectins, SBP contains a high proportion of neutral branched chains, acetyl groups, and phenolic esters. Gelatin is a water-soluble protein. In this invention, under different pH conditions, the conformation and charge of the protein molecules in gelatin differ. Beet pectin, under the action of a cross-linking agent, interacts with the protein through electrostatic, hydrogen bonding, and ester bonding to form a pectin-protein complex with a special structure. This promotes the formation of a continuous, dense network gel structure, enhancing the gel structure.

[0030] This invention describes a beet pectin-gelatin composite crosslinked gel and its preparation method. The beet pectin solution and gelatin solution are mixed in a specific ratio, the pH is adjusted, a crosslinking agent is added, and the mixture is heated to form a crosslinked composite gel. Compared to single beet pectin gels or gelatin gels, the beet pectin-gelatin crosslinked composite gel forms a more complete gel network with dense gel pores, which is beneficial for subsequent applications. Attached Figure Description

[0031] To further illustrate the present invention, the following description is provided in conjunction with the accompanying drawings:

[0032] Figure 1 The images show the zeta potential-particle size distributions of mixed solutions of beet pectin and gelatin at different concentrations in Examples 1-6 of this invention.

[0033] Figure 2These are morphological images of gels prepared with different concentrations of beet pectin solution and gelatin solution in Examples 1-6 of the present invention.

[0034] Figure 3 The infrared spectra of gels prepared from beet pectin solution and gelatin solution under different cross-linking effects in Examples 1, 11 and Comparative Examples 1-2 of the present invention are shown.

[0035] Figure 4 Differential scanning calorimetry (DSC) spectra of gels prepared from beet pectin solution and gelatin solution under different cross-linking processes in Examples 1, 11 and Comparative Examples 1-2 of the present invention.

[0036] Figure 5 , Figure 6 , Figure 7 and Figure 8 The images are scanning electron microscope images of gels prepared from beet pectin solution and gelatin solution under different cross-linking effects in Examples 1, 11 and Comparative Examples 1-2 of the present invention.

[0037] Figure 9 This is a table of abbreviations. Detailed Implementation

[0038] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0039] Example 1: The preparation method of the cross-linked composite gel of beet pectin and gelatin of the present invention includes the following steps:

[0040] (1) Dissolve 3g of beet pectin powder in 100mL of deionized water, stir for 8 hours, and place in a 4℃ refrigerator for 12 hours to ensure that the beet pectin is fully hydrated, so as to obtain a beet pectin solution with a mass concentration of 30g / L.

[0041] (2) Dissolve 4g of gelatin powder in 100mL of deionized water and stir at 90℃ for 0.5 hours to ensure that the gelatin is fully dissolved, so as to obtain a gelatin solution with a mass fraction of 40g / L.

[0042] (3) Mix a beet pectin solution with a mass fraction of 30 g / L and a gelatin solution with a mass fraction of 40 g / L at a volume ratio of 1:1 and stir magnetically for 2 hours to obtain a beet pectin-gelatin mixed solution.

[0043] (4) Adjust the pH of the beet pectin-gelatin mixed solution to 4.0, add 0.072g of laccase to obtain a composite solution. The mass concentration of beet pectin in the composite solution is 15g / L, and the mass concentration of gelatin solution is 20g / L.

[0044] (5) The composite solution is heat-treated at 40°C for 2 hours and then cooled at 4°C for 12 hours to obtain cross-linked gelatin of beet pectin and gelatin.

[0045] Example 2: The difference from Example 1 is that in step (1), the mass fraction of beet pectin is 25 g / L.

[0046] Example 3: The difference from Example 1 is that in step (1), the mass fraction of beet pectin is 20 g / L.

[0047] Example 4: The difference from Example 1 is that in step (1), the mass fraction of beet pectin is 15 g / L.

[0048] Example 5: The difference from Example 1 is that in step (1), the mass fraction of beet pectin is 10 g / L.

[0049] Example 6: The difference from Example 1 is that in step (1), the mass fraction of beet pectin is 5 g / L.

[0050] Example 7: The preparation method of the beet pectin and gelatin crosslinked composite gel of the present invention includes the following steps:

[0051] (1) Dissolve 3g of beet pectin powder in 100mL of deionized water, stir for 8 hours, and place in a 4℃ refrigerator for 12 hours to ensure that the beet pectin is fully hydrated, so as to obtain a beet pectin solution with a mass concentration of 30g / L.

[0052] (2) Dissolve 4g of gelatin powder in 100mL of deionized water and stir at 90℃ for 0.5 hours to ensure that the gelatin is fully dissolved, so as to obtain a gelatin solution with a mass fraction of 40g / L.

[0053] (3) Mix a beet pectin solution with a mass fraction of 30 g / L and a gelatin solution with a mass fraction of 40 g / L at a volume ratio of 1:1 and stir magnetically for 2 hours to obtain a beet pectin-gelatin mixed solution.

[0054] (4) Adjust the pH of the beet pectin-gelatin mixed solution to 3.0, add 0.072g of laccase to prepare a composite solution. The mass concentration of beet pectin in the composite solution is 15g / L, and the mass concentration of gelatin solution is 20g / L.

[0055] (5) The composite solution is heat-treated at 40°C for 2 hours and then cooled at 4°C for 12 hours to obtain cross-linked gelatin of beet pectin and gelatin.

[0056] Example 8: The difference from Example 7 is that in step (4), the pH is 5.0.

[0057] Example 9: The difference from Example 7 is that in step (4), the pH is 6.0.

[0058] Example 10: The difference from Example 7 is that in step (4), the pH is 7.0.

[0059] Example 11: The preparation method of the beet pectin and gelatin crosslinked composite gel of the present invention includes the following steps:

[0060] (1) Dissolve 3g of beet pectin powder in 100mL of deionized water, stir magnetically for 8 hours, and place in a 4℃ refrigerator for 12 hours to ensure that the beet pectin is fully hydrated, and obtain a beet pectin solution with a mass concentration of 30g / L.

[0061] (2) Dissolve 4g of gelatin powder in 100mL of deionized water and stir at 90℃ for 0.5 hours to ensure that the gelatin is fully dissolved, so as to obtain a gelatin solution with a mass fraction of 40g / L.

[0062] (3) Mix a beet pectin solution with a mass fraction of 30 g / L and a gelatin solution with a mass fraction of 40 g / L at a volume ratio of 1:1 and stir magnetically for 2 hours to obtain a beet pectin-gelatin mixed solution.

[0063] (4) Adjust the pH of the beet pectin-gelatin mixed solution to 4.0, add 0.072g laccase and 1mL eugenol to obtain a composite solution. The mass concentration of beet pectin in the composite solution is 15g / L and the mass concentration of gelatin solution is 20g / L.

[0064] (5) The composite solution is heat-treated at 40°C for 2 hours and then cooled at 4°C for 12 hours to obtain cross-linked gelatin of beet pectin and gelatin.

[0065] Comparative Example 1: The preparation method of the beet pectin gel of the present invention includes the following steps:

[0066] (1) Dissolve 15g of beet pectin powder in 100mL of deionized water, stir for 8 hours, and place in a 4℃ refrigerator for 12 hours to ensure that the beet pectin is fully hydrated, and obtain a beet pectin solution with a mass concentration of 15g / L.

[0067] (2) Adjust the pH of the beet pectin solution to 4.0, mix and stir, and then sterilize at 40℃.

[0068] Heat treatment for 2 hours, followed by cooling at 4°C for 12 hours, yields beet pectin gel.

[0069] Comparative Example 2: The preparation method of the gelatin gel of the present invention includes the following steps:

[0070] (1) Dissolve 20g of gelatin powder in 100mL of deionized water, stir at 90℃ for 0.5 hours to ensure that the gelatin is fully dissolved, and obtain a gelatin solution with a mass fraction of 20g / L.

[0071] (2) Adjust the pH of the gelatin solution to 4.0, mix and stir, heat-treat at 40°C for 2 hours, and then cool at 4°C for 12 hours to obtain gelatin gel.

[0072] Example: Structural characterization was performed on the mixed solutions and gels from Examples 1-11 and Comparative Examples 1-2, including:

[0073] (1) Zeta potential-particle size determination of mixed solution: The equilibrium time was set to 60s and the measurement temperature was 25℃. To prevent multiple scattering effect, the sample was diluted to a liquid concentration of approximately 0.01g / 100ml.

[0074] (2) Determination of gel morphology: Take 5 mL of gelatin solution with a mass concentration of 40 g / L, stir at 90℃ for 0.5 hours, and then put it into a centrifuge tube with 5 mL of beet pectin solution of different mass concentrations. Heat treat at 40℃ for 2 hours, take it out and cool to room temperature, let it stand at 4℃ for 12 hours to form a gel, and then place the centrifuge tube upside down in a black background to take a picture of the vertical surface of the gel.

[0075] (3) Gel infrared spectroscopy determination: The gel was ground into powder, and 1 mg of sample was thoroughly mixed with 100 mg of pure potassium bromide (KBr) powder, with a sample / potassium bromide ratio of 1:100 (w / w). Then, a transparent and uniform thin film was prepared by pressing the film at 10 MPa. The film was detected at 4000-400 cm⁻¹ against a pure potassium bromide particle background. The spectral resolution was 2 cm⁻¹.

[0076] (4) Gel differential scanning calorimetry determination: Place the sample (5-10 mg) on ​​a standard aluminum pan, roll it up, and heat it from 25 °C to 225 °C at a heating rate of 10 °C / min, while continuously purging with nitrogen gas (50 mL / min). Use an empty sealed pan as a reference. Run all samples in triplicate.

[0077] (5) Determination of gel microstructure: The gel was cut into thin slices, pre-frozen in liquid nitrogen for 20 min, and then freeze-dried in a freeze dryer. The freeze-dried sample was attached to the sample tray with double-sided conductive adhesive, and platinum was sprayed by DC sputtering vacuum. The morphology of the sample surface was scanned and observed.

[0078] The above measurement results are as follows Figure 1-5 As shown.

[0079] like Figure 1As shown, under different beet pectin concentrations, the particle size of the mixed solution first decreases and then increases with the increase of beet pectin concentration; the potential shows a decreasing-gradual trend, and the potential decreases sharply when the beet pectin concentration is between 10g / L and 15g / L.

[0080] like Figure 2 As shown, this invention can form a complete gel under different beet pectin concentrations, which does not collapse when inverted. The resulting gels show slight differences in color but are all pale yellow. However, as the beet pectin concentration increases, the solids in the composite gel increase, and the gel appears stronger and more uniform in color.

[0081] like Figure 3 As shown, under different crosslinking conditions, the addition of a crosslinking agent leads to changes in the structure of the resulting composite gel, forming new amide bonds and ester bonds. (3448cm) -1 The absorption peak at 3600-3300 cm⁻¹ is formed by the stretching vibrations of -NH³⁺ and -OH groups in gelatin. -1 The broad peak at 1650 cm⁻¹ is due to the stretching of intramolecular and intermolecular hydrogen bonds. Compared to the infrared spectrum of gel, gelatin shows a peak at 1650 cm⁻¹. -1 -NH at the location 3+ The absorption peak disappears, and beet pectin is at 1641m. -1 The absorption peak of -COO- at m shifts to 1630m. -1 The presence of nearby structures indicates the formation of new amide bonds. Eugenol was added as a crosslinking agent, resulting in a gel thickness of 1558 cm⁻¹. -1 Corresponding to the -COO- group, 1068 cm -1 The absorption peak corresponding to the stretching vibration of COC indicates the formation of a new ester bond.

[0082] like Figure 4 As shown, under different crosslinking conditions, the addition of the crosslinking agent alters the thermal stability of the resulting composite gel. Gelatin exhibits an endothermic peak at 167°C, while beet pectin shows endothermic peaks at 136°C and 147°C. The DSC diagram of the gel formed by laccase crosslinking shows endothermic peaks at 155°C and 171°C. Compared to the comparative example, the peak temperature shifts towards higher temperatures, indicating that the interaction between beet pectin and gelatin increases the thermal decomposition temperature. The beet pectin-gelatin-eugenol composite gel exhibits an exothermic peak at 163°C, with a significantly increased peak area.

[0083] like Figures 5-9 As shown, beet pectin gel does not fully form a gel structure, making it difficult to support a stable and complete gel network framework; the gelatin network exhibits a sheet-like structure, and the gel surface becomes smooth by laccase cross-linking, forming a stable and continuous network structure, but the pore size is relatively large. The laccase and eugenol cross-linked gel network structure is uniform and regular, with dense pores and smooth network walls.

[0084] This patent innovatively combines ferulic acyl groups and gelatin present on the RG-I region of beet pectin, resulting in excellent mechanical properties and a superior network structure.

[0085] In summary, this invention discloses a cross-linked composite gel of beet pectin and gelatin and its preparation method. It belongs to the field of functional food and pharmaceutical technology. The preparation method of the composite gel includes the following steps: (1) dissolving beet pectin powder in deionized water to obtain a beet pectin solution; (2) dissolving gelatin in deionized water to obtain a gelatin solution; (3) mixing and stirring the beet pectin solution and the gelatin solution to obtain a beet pectin-gelatin mixed solution; (4) adjusting the pH of the beet pectin-gelatin mixed solution, adding a cross-linking agent and stirring to obtain a composite solution; (5) cooling the composite solution after heat treatment to obtain the cross-linked composite gel of beet pectin and gelatin. The beet pectin composite gel prepared by the method of this invention has a good network structure and good properties, broadening the application of beet pectin in the food and pharmaceutical fields, and is beneficial to extending the development of the pectin polysaccharide and beet pectin industries.

[0086] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims.

Claims

1. A method for preparing a cross-linked composite gel of beet pectin and gelatin, characterized in that: Includes the following steps: (1) Dissolve beet pectin powder in deionized water, stir and let stand to hydrate to obtain beet pectin solution; (2) Dissolve gelatin in deionized water and heat and stir to obtain a gelatin solution; (3) Mix and stir the beet pectin solution and gelatin solution to obtain a beet pectin-gelatin mixed solution; (4) Adjust the pH of the beet pectin-gelatin mixed solution, add cross-linking agent and stir to obtain a composite solution; (5) After heat treatment, the composite solution is cooled to obtain a cross-linked composite gel of beet pectin and gelatin. In step (1), the mass fraction of beet pectin is 5-30 g / L; in step (2), the mass fraction of gelatin is 20-40 g / L. In step (3), the volume ratio of the beet pectin solution to the gelatin solution is 1:0.5-2; In step (4), the cross-linking agent is laccase, which is added to the mixed solution at a ratio of 8-12 U / g pectin; and / or: in step (4), the cross-linking agent is eugenol, which is added to the mixed solution at a volume ratio of 0.1-5:1000; In step (5), the heat treatment conditions are: 30-90℃, 0.5-2.5 hours; in step (5), the cooling conditions are: 0-4℃, 8-12 hours.

2. The method for preparing the cross-linked composite gel of beet pectin and gelatin as described in claim 1, characterized in that: In step (1), the stirring time is 8-12 hours; in step (1), the settling temperature is 0-4℃ and the time is 8-12 hours.

3. The method for preparing the cross-linked composite gel of beet pectin and gelatin as described in claim 1, characterized in that: In step (2), the gelatin is heated at a temperature of 70-90°C for 0.2-0.5 hours.

4. The method for preparing the cross-linked composite gel of beet pectin and gelatin as described in claim 1, characterized in that: In step (4), the pH of the beet pectin-gelatin mixed solution is adjusted to 3.0 to 7.

0.

5. A beet pectin and gelatin crosslinked composite gel prepared by the method for preparing beet pectin and gelatin crosslinked composite gel according to any one of claims 1-4.

6. The beet pectin and gelatin crosslinked composite gel prepared by the method of any one of claims 1-4 can be used as a gel matrix for drug delivery, as a food ingredient or additive, or as a cosmetic ingredient or additive.

Images