A self-crosslinking sugar beet pectin and a method for its preparation

Abstract

The application discloses a kind of self-crosslinking sugar beet pectin and preparation method thereof, it is related to food and cosmetic technical field.The preparation method includes the following steps: S1, sugar beet pectin solution and 4-(4, 6-dimethoxytriazine-2-yl)-4-methyl morpholinium hydrochloride solution are mixed, stirring is uniform, and mixed liquor is obtained;S2, in mixed liquor, mass concentration is 95% ethanol solution is added, and first centrifugal treatment is carried out, and first precipitate is collected;S3, first precipitate is dissolved in deionized water, and after impurity removal, concentrated solution is obtained;S4, concentrated solution is mixed with ethanol, second centrifugal treatment is carried out, and second precipitate is obtained, and second precipitate is dried, and self-crosslinking sugar beet pectin is obtained.The preparation method of the application is simple, and the surface hydrophobicity and emulsification stability of sugar beet pectin can be significantly improved without introducing exogenous protein and other components.

Description

Technical Field

[0001] This invention relates to the fields of food and cosmetic technology, and in particular to a self-crosslinking beet pectin and its preparation method. Background Technology

[0002] Pectin prepared from beet pulp has excellent emulsifying properties and is widely used in the food industry. However, compared with natural polymeric emulsifiers such as gum arabic, although beet pectin has higher emulsifying activity, it lags significantly in emulsifying stability. This insufficient emulsifying stability limits the application of beet pectin in the food industry. To improve the limitations of beet pectin's emulsifying stability, a domestic invention patent (ZL201910791536.2) proposes a method for improving the emulsifying performance of beet pectin using genipin, but the genipin-modified beet pectin has a blue color, limiting its use in food. A domestic invention patent (CN201610096124.3) proposes a method for preparing a beet pectin and protein composite emulsifier using a covalent cross-linking method, but byproducts may be generated during the covalent grafting reaction of polysaccharides and proteins, posing certain safety risks. Therefore, there is a need for a method that can improve the emulsifying stability of beet pectin while ensuring safety. Summary of the Invention

[0003] To address the problems existing in the prior art, the present invention aims to provide a self-crosslinking beet pectin and its preparation method. This method is simple to operate, can significantly improve the surface hydrophobicity and emulsification stability of beet pectin, and eliminates the need for introducing exogenous proteins or other components, thus avoiding potential safety hazards and demonstrating promising application prospects.

[0004] This invention provides the following technical solution:

[0005] This invention provides a method for preparing self-crosslinking beet pectin, which includes the following steps:

[0006] S1. Beet pectin (SBP) and 4-(4,6-dimethoxytriazine-2-yl)-4-methylmorpholine hydrochloride solution (MMTM solution) are mixed at a volume ratio of (1:1) to (1:10) and stirred evenly at room temperature to obtain a mixture; the pH of the beet pectin solution is 3 to 9 and the concentration is 0.5 to 3 wt%; the concentration of the 4-(4,6-dimethoxytriazine-2-yl)-4-methylmorpholine hydrochloride solution is 0.02 to 2 mol / L.

[0007] S2. Add an ethanol solution with a mass concentration of 95% to 100% to the mixture, and perform a first centrifugation treatment to collect the first precipitate;

[0008] S3. Dissolve the first precipitate in deionized water at a mass ratio of (1:10) to (1:25), remove impurities, and obtain a concentrated solution.

[0009] S4. Mix the concentrate with ethanol and perform a second centrifugation to obtain a second precipitate. Dry the second precipitate to obtain self-crosslinked beet pectin (self-crosslinked SBP).

[0010] Furthermore, the preparation method of the beet pectin solution is as follows: beet pectin is prepared into a 0.5-3 wt% beet pectin solution using deionized water, and then its pH is adjusted to 3-9 using a pH adjuster.

[0011] Preferably, the pH adjuster is 0.2 mol HCl or 0.2 mol NaOH.

[0012] Preferably, the stirring time is 0.5h to 24h.

[0013] Preferably, the first centrifugation process is carried out at a speed of 3000-10000 rpm for a time of 10-30 min.

[0014] Preferably, the second centrifugation process is carried out at a speed of 3000-10000 rpm for a time of 10-30 min.

[0015] Furthermore, in step S3, the method for removing impurities is to use a membrane filter with a molecular weight cutoff of 10 to 100 kDa.

[0016] Furthermore, the volume ratio of the mixture to the ethanol solution is 1:(2-3.5).

[0017] Furthermore, the volume ratio of the concentrate to ethanol is (1:2) to (1:5).

[0018] Preferably, the second precipitate is dried under hot air or vacuum conditions; the drying temperature is 35-50°C and the time is 6-72 hours.

[0019] The present invention also provides a self-crosslinking beet pectin prepared by the above preparation method.

[0020] This invention also provides an application of self-crosslinked beet pectin in the food or cosmetic fields.

[0021] The present invention has the following technical effects:

[0022] This invention improves the emulsification stability of beet pectin through self-crosslinking of the molecules. Using 4-(4,6-dimethoxytriazine-2-yl)-4-methylmorpholine hydrochloride solution as a carboxyl activator, self-crosslinking of beet pectin molecules is induced, significantly improving the surface hydrophobicity and emulsification stability of beet pectin. The method of this invention is simple to operate and does not require the introduction of exogenous proteins or other components, avoiding potential safety hazards and demonstrating good application prospects. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A comparison of the weight-average molecular weights of uncrosslinked beet pectin provided by the present invention and the self-crosslinked beet pectin of Example 1.

[0025] Figure 2 A comparison of the surface hydrophobicity of uncrosslinked beet pectin provided by the present invention and self-crosslinked beet pectin of Example 1.

[0026] Figure 3 A comparison diagram of the instability of emulsions prepared from uncrosslinked beet pectin provided by the present invention and from self-crosslinked beet pectin of Example 1. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] It should be understood that, when used in this specification and the appended claims, the terms “comprising” and “including” indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0029] To better understand the technical content of the present invention, the technical solution of the present invention will be further introduced and explained below with reference to specific embodiments.

[0030] Example 1

[0031] A method for preparing self-crosslinking beet pectin, comprising the following steps:

[0032] S1. Prepare a 2wt% beet pectin solution with deionized water, and adjust its pH to 3.5 using a pH adjuster.

[0033] S2. Mix the pH-adjusted beet pectin solution and the 1 mol / L 4-(4,6-dimethoxytriazine-2-yl)-4-methylmorpholine hydrochloride solution at a volume ratio of 1:5, and stir at room temperature for 12 h to obtain the mixture.

[0034] S3. Add a 95% ethanol solution to the mixture and perform a first centrifugation to obtain a first precipitate; the volume ratio of the mixture to the ethanol solution is 1:3; the centrifugation speed for the first centrifugation is 60,000 rpm and the centrifugation time is 20 min.

[0035] S4. Dissolve the first precipitate in deionized water, and filter it through a membrane with a molecular weight cutoff of 100 kDa to remove impurities and obtain a concentrated solution; the mass ratio of the first precipitate to deionized water is 1:10.

[0036] S5. The concentrate and ethanol are mixed at a volume ratio of 1:3 and then subjected to a second centrifugation to obtain a second precipitate. The second precipitate is dried under vacuum at 40°C for 36 hours to obtain self-crosslinked beet pectin. The centrifugation speed of the second centrifugation is 6000 rpm and the centrifugation time is 20 min.

[0037] Example 2

[0038] A method for preparing self-crosslinking beet pectin, comprising the following steps:

[0039] S1. Prepare a 0.5 wt% beet pectin solution with deionized water, and adjust its pH to 9 using a pH adjuster.

[0040] S2. Mix the pH-adjusted beet pectin solution and the 0.02 mol / L 4-(4,6-dimethoxytriazine-2-yl)-4-methylmorpholine hydrochloride solution at a volume ratio of 1:1 and stir at room temperature for 0.5 h to obtain the mixture.

[0041] S3. Add a 100% ethanol solution (i.e., anhydrous ethanol) to the mixture and perform a first centrifugation to obtain a first precipitate; the volume ratio of the mixture to the ethanol solution is 1:2; the centrifugation speed of the first centrifugation is 3000 rpm and the centrifugation time is 30 min.

[0042] S4. Dissolve the first precipitate in deionized water, and filter it through a membrane with a molecular weight cutoff of 60 kDa to remove impurities and obtain a concentrated solution; the mass ratio of the first precipitate to deionized water is 1:15.

[0043] S5. The concentrate and ethanol are mixed at a volume ratio of 1:2 and then subjected to a second centrifugation to obtain a second precipitate. The second precipitate is dried under vacuum at 35°C for 72 hours to obtain self-crosslinked beet pectin. The centrifugation speed of the second centrifugation is 3000 rpm and the centrifugation time is 30 min.

[0044] Example 3

[0045] A method for preparing self-crosslinking beet pectin, comprising the following steps:

[0046] S1. Prepare a 3wt% beet pectin solution with deionized water, and adjust its pH to 3 using a pH adjuster.

[0047] S2. Mix the pH-adjusted beet pectin solution and the 2 mol / L 4-(4,6-dimethoxytriazine-2-yl)-4-methylmorpholine hydrochloride solution at a volume ratio of 1:10, and stir at room temperature for 24 h to obtain the mixture.

[0048] S3. Add a 98% ethanol solution to the mixture and perform a first centrifugation to obtain a first precipitate; the volume ratio of the mixture to the ethanol solution is 1:3.5; the centrifugation speed of the first centrifugation is 10000 rpm and the centrifugation time is 10 min.

[0049] S4. Dissolve the first precipitate in deionized water, and filter it through a membrane with a molecular weight cutoff of 10 kDa to remove impurities and obtain a concentrated solution; the mass ratio of the first precipitate to deionized water is 1:25.

[0050] S5. The concentrate and ethanol are mixed at a volume ratio of 1:5 and then subjected to a second centrifugation to obtain a second precipitate. The second precipitate is dried under hot air at 50°C for 6 hours to obtain self-crosslinked beet pectin. The centrifugation speed of the second centrifugation is 10,000 rpm and the centrifugation time is 10 min.

[0051] To illustrate the technical effects of this invention, the molecular weight and surface hydrophobicity of uncrosslinked beet pectin and the self-crosslinked beet pectin prepared according to this invention were tested respectively. The test results are as follows: Figure 1 and Figure 2 As shown. From Figure 1 As can be seen, after self-crosslinking treatment, the molecular weight of beet pectin can reach 1000 kDa to 2500 kDa, which is 5 to 10 times larger than that of uncrosslinked beet pectin; Figure 2 As shown, the self-crosslinking beet pectin of the present invention exhibits significantly improved hydrophobicity, with a hydrophobic index far exceeding that of conventional beet pectin. Therefore, this demonstrates that the preparation process of the present invention can effectively achieve self-crosslinking of beet pectin, thereby increasing its molecular weight and hydrophobicity.

[0052] To more intuitively illustrate the effect of self-crosslinked beet pectin as an emulsifier on the stability of emulsions, oil-in-water emulsions were prepared using the self-crosslinked beet pectin prepared in Example 1 and uncrosslinked beet pectin as emulsifiers, respectively, with 10% (w / w) of medium-chain triglycerides as the raw material. The pH of the emulsions was 3.5. The instability coefficients of the two emulsions were tested, and the results are as follows: Figure 3 As shown, the instability index of the emulsion prepared using uncrosslinked beet pectin as an emulsifier is 0.35, while the instability coefficient of the emulsion prepared using the self-crosslinked beet pectin of the present invention is reduced to 0.17. That is, the preparation process of the present invention can improve the emulsification stability of beet pectin by more than 50%, and its stability effect is significant.

[0053] To further illustrate the technical effects of the preparation process of the present invention, comparative examples 1-2 are set up based on Example 1 as follows:

[0054] Comparative Example 1

[0055] The only difference between this comparative example and Example 1 is that the concentration of the beet pectin solution is 4 wt%, the concentration of the MMTM solution is 0.01 mol / L, and the volume ratio of the beet pectin solution to the MMTM solution is 2:1.

[0056] Comparative Example 2

[0057] The only difference between this comparative example and Example 1 is that the concentration of the beet pectin solution is 0.4 wt%, the concentration of the MMTM solution is 2 mol / L, and the volume ratio of the beet pectin solution to the MMTM solution is 1:15.

[0058] The weight-average molecular weight and hydrophobicity index of the self-crosslinked beet pectin prepared in Comparative Example 1 and Comparative Example 2 were tested. Water-in-oil emulsions were prepared using the self-crosslinked beet pectin prepared in Comparative Example 1 and Comparative Example 2 as emulsifiers, with 10% (w / w) of medium-chain triglycerides as raw materials, and their instability index was tested. The test results are shown in Table 1 below:

[0059] Table 1 Comparative test results

[0060] Weight-average molecular weight Hydrophobicity Index Instability Index Comparative Example 1 254kDa 7.6 0.29 Comparative Example 2 3108kDa 24.3 0.52

[0061] As shown in Table 1, after changing the ratio of beet pectin solution and MMTM solution in this application, the instability coefficient of the self-crosslinked beet pectin prepared as an emulsifier was increased and the stability was decreased, which further illustrates that the preparation process of this invention can effectively improve the emulsification stability of beet pectin.

[0062] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing self-crosslinking beet pectin, characterized in that, Includes the following steps: S1. A beet pectin solution and a 4-(4,6-dimethoxytriazine-2-yl)-4-methylmorpholine hydrochloride solution are mixed at a volume ratio of (1:1) to (1:10) and stirred evenly at room temperature to obtain a mixed solution; the beet pectin solution has a pH of 3 to 9 and a concentration of 0.5 to 3 wt%; the 4-(4,6-dimethoxytriazine-2-yl)-4-methylmorpholine hydrochloride solution has a concentration of 0.02 to 2 mol / L. S2. Add an ethanol solution with a mass concentration of 95% to 100% to the mixture, and perform a first centrifugation treatment to collect the first precipitate; S3. Dissolve the first precipitate in deionized water at a mass ratio of (1:10) to (1:25), remove impurities, and obtain a concentrated solution. S4. Mix the concentrate with anhydrous ethanol and perform a second centrifugation to obtain a second precipitate. Dry the second precipitate to obtain self-crosslinked beet pectin.

2. The method for preparing self-crosslinking beet pectin as described in claim 1, characterized in that, The beet pectin solution is prepared as follows: beet pectin is prepared into a 0.5-3 wt% beet pectin solution using deionized water, and then the pH is adjusted to 3-9 using a pH adjuster.

3. The method for preparing self-crosslinking beet pectin as described in claim 1, characterized in that, In step S1, the stirring time is 0.5h to 24h.

4. The method for preparing self-crosslinking beet pectin as described in claim 1, characterized in that, The first centrifugation process is carried out at a speed of 3000–10000 rpm for a time of 10–30 min.

5. The method for preparing self-crosslinking beet pectin as described in claim 1, characterized in that, The second centrifugation process is carried out at a speed of 3000–10000 rpm for a time of 10–30 min.

6. The method for preparing self-crosslinking beet pectin as described in claim 1, characterized in that, In step S3, the method for removing impurities is to use a membrane filter with a molecular weight cutoff of 10 to 100 kDa.

7. The method for preparing self-crosslinking beet pectin as described in claim 1, characterized in that, The volume ratio of the mixture to the ethanol solution is 1:(2-3.5).

8. The method for preparing self-crosslinking beet pectin as described in claim 1, characterized in that, The volume ratio of the concentrate to ethanol is (1:2) to (1:5).

9. The method for preparing self-crosslinking beet pectin as described in claim 1, characterized in that, The second precipitate is dried under hot air or vacuum conditions; the drying temperature is 35-50°C and the time is 6-72 hours.

10. A self-crosslinking beet pectin, characterized in that, It is prepared by the method for preparing self-crosslinking beet pectin according to any one of claims 1-9.

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