Curcumin microcapsule as well as preparation method and application thereof

Abstract

The invention discloses a curcumin microcapsule as well as a preparation method and application thereof. The curcumin microcapsule comprises curcumin, positively charged protein, negatively charged protein and edible inorganic salt, the positively charged protein is at least one of lysozyme, lactoferrin and acidic gelatin, and the negatively charged protein is at least one of whey protein, soybean protein, pea protein and ovalbumin. The curcumin microcapsule disclosed by the invention has the advantages of high curcumin load rate, good stability and the like, and the curcumin microcapsule is simple and convenient in preparation process, wide in raw material source, low in production cost, low in energy consumption and free of large-scale equipment, and has a very wide application prospect in the fields of foods and biological medicines.

Description

Technical Field

[0001] The present invention relates to the technical field of food processing, and in particular to a curcumin microcapsule and a preparation method and application thereof. Background Art

[0002] Curcumin, a polyphenolic compound found in the rhizome of turmeric (Curcuma longa), has attracted considerable attention in the food and biopharmaceutical fields for its diverse bioactivities, including antioxidant, anti-inflammatory, and anti-tumor activities. However, curcumin suffers from drawbacks such as poor water solubility, chemical instability, and low oral bioavailability, which significantly limit its application.

[0003] At present, the solubility and chemical stability of curcumin are mainly increased by constructing carriers loaded with curcumin. The constructed carriers mainly include the following categories:

[0004] 1) Emulsions and nanoemulsions: Curcumin is a lipophilic compound, and its concentration in corn oil and soybean oil can reach 7.6 mg / mL and 7.4 mg / mL after 48 hours of dissolution. Therefore, emulsions and nanoemulsions are currently widely used to encapsulate and deliver curcumin (Trends Food Sci. Technol., 2018, 71, 155-169). However, emulsion and nanoemulsion encapsulation methods have disadvantages such as high oil intake, complex preparation process, and difficulty in controlling emulsion stability, which limit their application range;

[0005] 2) Nanoparticles: Various nanoparticles constructed from biomacromolecules have been reported for curcumin loading and delivery, such as nanoscale γ-cyclodextrin-based metal-organic framework-curcumin nanoparticles and protein-curcumin nanoparticles. While nanoscale γ-cyclodextrin-based metal-organic framework-curcumin nanoparticles can achieve a curcumin loading rate of up to 300 mg / g, the complex preparation process and the use of methanol make them difficult to use in the food industry (Food Chem., 2022, 383, 132605). Protein has been shown to be the optimal curcumin loading material in the food industry. Simply mixing curcumin with amphiphilic food proteins can form protein-curcumin nanoparticles, significantly improving curcumin's water solubility, chemical stability, and oral bioavailability. The curcumin loading rate of protein-curcumin nanoparticles is approximately 100 mg / g, which can be increased to 150 mg / g with the assistance of physical fields such as ultrasound (Food Res. Int., 2015, 75, 157-165). However, due to the large surface area of the nanoparticles, their effect on improving curcumin's chemical stability is very limited.

[0006] Therefore, it is of great significance to develop a curcumin microcapsule with large curcumin loading capacity, good stability, simple preparation process, and green and non-toxicity. Summary of the Invention

[0007] One of the purposes of the present invention is to overcome the problems of existing curcumin products such as low curcumin loading, poor stability, and complex preparation process, and to provide a green and non-toxic curcumin microcapsule with large curcumin loading, good stability, simple preparation process.

[0008] The second object of the present invention is to provide a method for preparing curcumin microcapsules with a simple preparation process, a wide source of raw materials, low production cost, low energy consumption, and no need for large-scale equipment.

[0009] A third object of the present invention is to provide applications of the curcumin microcapsules in the food field or the biopharmaceutical field.

[0010] The technical solution adopted by the present invention is:

[0011] A curcumin microcapsule comprises curcumin, a positively charged protein, a negatively charged protein and an edible inorganic salt; the positively charged protein is at least one of lysozyme, lactoferrin and acidic gelatin; the negatively charged protein is at least one of whey protein, soy protein, pea protein and ovalbumin.

[0012] Preferably, the loading rate of curcumin in the curcumin microcapsules is greater than 400 mg / g.

[0013] Preferably, the mass ratio of the positively charged protein to the negatively charged protein is 1:0.25-4.

[0014] Preferably, the edible inorganic salt is at least one of sodium chloride and potassium chloride.

[0015] Preferably, the mass percentage of the edible inorganic salt in the curcumin microcapsules is 0.1% to 0.4%.

[0016] Preferably, the curcumin microcapsules are spherical with a diameter of 0.2 μm to 3 μm.

[0017] A method for preparing the curcumin microcapsules as described above comprises the following steps:

[0018] 1) dispersing the positively charged protein and the negatively charged protein in water respectively, adding an edible inorganic salt and adjusting the pH value to 6-7 to obtain a dispersion of the positively charged protein and a dispersion of the negatively charged protein;

[0019] 2) uniformly mixing the negatively charged protein dispersion and the curcumin solution to obtain a negatively charged protein-curcumin dispersion;

[0020] 3) mixing the positively charged protein dispersion and the negatively charged protein-curcumin dispersion and stirring until liquid-liquid phase separation occurs to obtain a curcumin microcapsule dispersion;

[0021] 4) drying the curcumin microcapsule dispersion to obtain curcumin microcapsule powder.

[0022] Preferably, the dispersion method in step 1) is mechanical stirring, the stirring rate is 200 rpm to 400 rpm, and the stirring time is 1 hour to 4 hours.

[0023] Preferably, the mass percentage of the positively charged protein in the dispersion of the positively charged protein in step 1) is 0.1% to 10%.

[0024] Preferably, the mass percentage of the negatively charged protein in the negatively charged protein dispersion in step 1) is 0.1% to 2%.

[0025] Preferably, the solvent in the curcumin solution in step 2) is ethanol.

[0026] Preferably, the concentration of the curcumin solution in step 2) is 3 mg / mL to 5 mg / mL.

[0027] Preferably, in step 2), the mass ratio of the negatively charged protein in the dispersion of the negatively charged protein to the curcumin in the curcumin solution is 1:0.5-1.

[0028] Preferably, the mixing method in step 2) is mechanical stirring.

[0029] Preferably, the mechanical stirring is carried out at a stirring rate of 200 rpm to 400 rpm and a temperature of 30° C. to 40° C., and the stirring time is 1 h to 2 h.

[0030] Preferably, the stirring in step 3) is carried out at a stirring rate of 100 rpm to 200 rpm, and the stirring time is 1 min to 3 min.

[0031] Preferably, the drying method in step 4) is freeze drying or spray drying.

[0032] Application of the curcumin microcapsules in the food field or the biomedicine field.

[0033] The beneficial effects of the present invention are as follows: the curcumin microcapsules of the present invention have the advantages of high curcumin loading rate (over 400 mg / g) and good stability, and the preparation process is simple, the raw material source is wide, the production cost is low, the energy consumption is low, and no large-scale equipment is required. Therefore, the curcumin microcapsules have very broad application prospects in the fields of food and biomedicine.

[0034] Specifically:

[0035] 1) The curcumin microcapsules of the present invention have a good curcumin loading effect, with a curcumin loading rate exceeding 400 mg / g, and can fully exert the antioxidant, anti-inflammatory and anti-tumor biological activities of curcumin;

[0036] 2) The crowded environment of the curcumin microcapsules of the present invention reduces the diffusion rate of the internal substances, and the concentration effect changes the chemical reaction equilibrium, which together inhibits the chemical degradation of curcumin;

[0037] 3) The raw materials and solvents used in the preparation of the curcumin microcapsules of the present invention are all food grade, low cost, green, non-toxic and environmentally friendly, with a simple preparation process, low energy consumption, no need for large-scale equipment, and suitable for large-scale industrial production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a microscope image of the curcumin microcapsules in Example 1.

[0039] Figure 2 This is a scanning electron microscope image of the curcumin microcapsules in Example 1.

[0040] Figure 3 This is a microscope image of the curcumin microcapsules in Comparative Example 1.

[0041] Figure 4 Graph showing the protein recovery test results of the curcumin microcapsules in Examples 1 to 4 and Comparative Examples 1 to 2.

[0042] Figure 5 Graph showing the curcumin loading rate test results of the curcumin microcapsules in Examples 1 to 4 and Comparative Examples 1 to 2.

[0043] Figure 6 Graph showing the stability test results of the curcumin microcapsules in Examples 1 to 4 and Comparative Examples 1 to 2. DETAILED DESCRIPTION

[0044] The present invention will be further explained and illustrated below with reference to specific embodiments.

[0045] Example 1:

[0046] A curcumin microcapsule, the preparation method of which is as follows:

[0047] 1) adding lactoferrin to distilled water at a mass ratio of lactoferrin to distilled water of 0.1:99.9, then adding 0.1 wt % of sodium chloride, then stirring for 1 h at a stirring speed of 200 rpm, and then adjusting the pH value to 6 to obtain a lactoferrin dispersion; adding whey protein to distilled water at a mass ratio of whey protein to distilled water of 0.1:99.9, then adding 0.1 wt % of sodium chloride, then stirring for 1 h at a stirring speed of 200 rpm, and then adjusting the pH value to 6 to obtain a whey protein dispersion;

[0048] 2) adding curcumin to ethanol and stirring at a stirring rate of 200 rpm for 1 h to prepare a curcumin solution with a concentration of 4 mg / mL; then mixing the whey protein dispersion and the curcumin solution at a whey protein:curcumin mass ratio of 2:1; and stirring at a stirring rate of 200 rpm and a temperature of 30° C. for 1 h to obtain a whey protein-curcumin dispersion;

[0049] 3) mixing the lactoferrin dispersion and the whey protein-curcumin dispersion in a mass ratio of 1:2 between lactoferrin and whey protein, and stirring for 1 min at a stirring rate of 100 rpm until liquid-liquid phase separation occurs, to obtain a curcumin microcapsule dispersion;

[0050] 4) freeze-drying the curcumin microcapsule dispersion to obtain curcumin microcapsule powder.

[0051] The microscopic image of the curcumin microcapsules (dispersion) in this example is as follows: Figure 1 As shown, the scanning electron microscope (SEM) image of curcumin microcapsules (powder) is as follows Figure 2 shown.

[0052] Depend on Figure 1 and Figure 2 It can be seen that the curcumin microcapsules are regular spherical (the inorganic salt acts as a plasticizer for the microcapsule structure, which can make the microcapsule structure present a regular spherical shape), and are relatively uniform in size with a diameter of 0.2μm to 3μm.

[0053] Example 2:

[0054] A curcumin microcapsule, the preparation method of which is as follows:

[0055] 1) adding lysozyme to distilled water at a mass ratio of lysozyme to distilled water of 0.5:99.5, adding 0.2 wt % potassium chloride, stirring for 4 hours at a stirring rate of 400 rpm, and adjusting the pH value to 7 to obtain a lysozyme dispersion; adding soy protein to distilled water at a mass ratio of soy protein to distilled water of 0.5:99.5, adding 0.2 wt % potassium chloride, stirring for 4 hours at a stirring rate of 400 rpm, and adjusting the pH value to 7 to obtain a soy protein dispersion;

[0056] 2) adding curcumin to ethanol and stirring at a stirring rate of 400 rpm for 4 h to prepare a curcumin solution with a concentration of 4 mg / mL; then mixing the soy protein dispersion and the curcumin solution at a mass ratio of soy protein to curcumin of 1:1; and stirring at a stirring rate of 400 rpm and a temperature of 40° C. for 2 h to obtain a soy protein-curcumin dispersion;

[0057] 3) mixing the lysozyme dispersion and the soy protein-curcumin dispersion in a lysozyme:soy protein mass ratio of 1:1, and stirring for 3 minutes at a stirring rate of 200 rpm until liquid-liquid phase separation occurs, thereby obtaining a curcumin microcapsule dispersion;

[0058] 4) freeze-drying the curcumin microcapsule dispersion to obtain curcumin microcapsule powder.

[0059] Example 3:

[0060] A curcumin microcapsule, the preparation method of which is as follows:

[0061] 1) adding acidic gelatin to distilled water at a mass ratio of 1:99, adding 0.3 wt % potassium chloride, stirring at a stirring rate of 300 rpm for 3 hours, and adjusting the pH value to 6.5 to obtain an acidic gelatin dispersion; adding ovalbumin to distilled water at a mass ratio of 1:99, adding 0.3 wt % potassium chloride, stirring at a stirring rate of 300 rpm for 3 hours, and adjusting the pH value to 6.5 to obtain an ovalbumin dispersion;

[0062] 2) adding curcumin to ethanol and stirring at a stirring rate of 300 rpm for 3 h to prepare a curcumin solution with a concentration of 4 mg / mL; then, mixing the ovalbumin dispersion and the curcumin solution at a mass ratio of ovalbumin to curcumin of 1.5:1; and stirring at a stirring rate of 300 rpm and a temperature of 35° C. for 1 h to obtain an ovalbumin-curcumin dispersion;

[0063] 3) mixing the acidic gelatin dispersion and the ovalbumin-curcumin dispersion in a mass ratio of 1:2 between the acidic gelatin and the ovalbumin, and stirring for 2 minutes at a stirring rate of 150 rpm until liquid-liquid phase separation occurs, thereby obtaining a curcumin microcapsule dispersion;

[0064] 4) freeze-drying the curcumin microcapsule dispersion to obtain curcumin microcapsule powder.

[0065] Example 4:

[0066] A curcumin microcapsule, the preparation method of which is as follows:

[0067] 1) adding lactoferrin to distilled water at a mass ratio of 2:98, adding 0.2 wt % sodium chloride, stirring for 4 h at a stirring speed of 200 rpm, and adjusting the pH value to 6.3 to obtain a lactoferrin dispersion; adding whey protein to distilled water at a mass ratio of 2:98, adding 0.2 wt % sodium chloride, stirring for 4 h at a stirring speed of 200 rpm, and adjusting the pH value to 6.3 to obtain a whey protein dispersion;

[0068] 2) adding curcumin to ethanol and stirring at a stirring rate of 300 rpm for 2 h to prepare a curcumin solution with a concentration of 4 mg / mL, then mixing the whey protein dispersion and the curcumin solution at a mass ratio of whey protein to curcumin of 1:1, and stirring at a stirring rate of 400 rpm and a temperature of 40° C. for 2 h to obtain a whey protein-curcumin dispersion;

[0069] 3) mixing the lactoferrin dispersion and the whey protein-curcumin dispersion in a mass ratio of 1:1 between lactoferrin and whey protein, and stirring for 2 min at a stirring speed of 200 rpm until liquid-liquid phase separation occurs, to obtain a curcumin microcapsule dispersion;

[0070] 4) freeze-drying the curcumin microcapsule dispersion to obtain curcumin microcapsule powder.

[0071] Comparative Example 1:

[0072] A curcumin microcapsule, the preparation method of which is as follows:

[0073] 1) lactoferrin was added to distilled water at a mass ratio of 0.1:99.9, the mixture was stirred for 1 h at a stirring speed of 200 rpm, and the pH value was adjusted to 6 to obtain a lactoferrin dispersion; whey protein was added to distilled water at a mass ratio of 0.1:99.9, the mixture was stirred for 1 h at a stirring speed of 200 rpm, and the pH value was adjusted to 6 to obtain a whey protein dispersion;

[0074] 2) adding curcumin to ethanol and stirring at a stirring rate of 200 rpm for 1 h to prepare a curcumin solution with a concentration of 4 mg / mL; then mixing the whey protein dispersion and the curcumin solution at a whey protein:curcumin mass ratio of 2:1; and stirring at a stirring rate of 200 rpm and a temperature of 30° C. for 1 h to obtain a whey protein-curcumin dispersion;

[0075] 3) mixing the lactoferrin dispersion and the whey protein-curcumin dispersion in a mass ratio of 1:2 between lactoferrin and whey protein, and stirring for 1 min at a stirring rate of 100 rpm until liquid-liquid phase separation occurs, to obtain a curcumin microcapsule dispersion;

[0076] 4) freeze-drying the curcumin microcapsule dispersion to obtain curcumin microcapsule powder.

[0077] The microscopic image of the curcumin microcapsules (dispersion) in this comparative example is as follows: Figure 3 shown.

[0078] Depend on Figure 3 It can be seen that the curcumin microcapsules present an amorphous structure (lacking the plasticizing effect of inorganic salts on the microcapsule structure).

[0079] A curcumin microcapsule, the preparation method of which is as follows:

[0080] 1) adding whey protein to distilled water at a mass ratio of whey protein to distilled water of 2:98, and stirring for 3 h at a stirring rate of 300 rpm to obtain a whey protein dispersion;

[0081] 2) curcumin was added to ethanol, and then stirred at a stirring rate of 300 rpm for 2 h to prepare a curcumin solution with a concentration of 4 mg / mL. The whey protein dispersion and the curcumin solution were then mixed at a mass ratio of 1:1 between whey protein and curcumin, and then stirred at a stirring rate of 400 rpm for 2 h. The mixture was centrifuged for 5 min at a centrifugal force of 3000 g to remove the precipitate to obtain a whey protein-curcumin suspension.

[0082] 3) freeze-drying the whey protein-curcumin suspension dispersion to obtain curcumin microcapsule powder.

[0083] Performance testing:

[0084] 1) The curcumin microcapsules (dispersions) in Examples 1 to 4, the curcumin microcapsules (dispersions) in Comparative Example 1, and the curcumin microcapsules (whey protein-curcumin suspension) in Comparative Example 2 were centrifuged for 20 min at a centrifugal force of 3000 g. The protein concentration of the supernatant was determined using a BCA protein concentration assay kit, and the protein recovery of the curcumin microcapsules was calculated. The test results are shown in FIG. Figure 4 shown.

[0085] The protein recovery rate was calculated as follows: protein recovery rate (%) = (initial protein concentration of test sample - protein concentration of supernatant) / initial protein concentration of test sample × 100%, where the initial protein concentration of the test sample refers to the protein concentration of the curcumin microcapsule dispersion or the whey protein-curcumin suspension.

[0086] Depend on Figure 4 It can be seen that the protein recovery rate of the curcumin microcapsules in Examples 1 to 4 is slightly lower than that of the curcumin microcapsules in Comparative Examples 1 and 2. The reason is that the inorganic salt weakens the electrostatic interaction strength between proteins, thereby causing the protein recovery rate of the microcapsules to decrease.

[0087] 2) Use UV-visible spectrophotometer to measure the absorbance of 0μg / mL, 2μg / mL, 4μg / mL, 6μg / mL, 8μg / mL and 10μg / mL curcumin ethanol solution at a wavelength of 426nm, and plot the OD 426 -curcumin concentration standard curve, then the curcumin microcapsules (dispersions) in Examples 1 to 4, the curcumin microcapsules (dispersions) in Comparative Example 1 and the curcumin microcapsules (whey protein-curcumin suspension) in Comparative Example 2 were centrifuged for 20 min at a centrifugal force of 3000 g, and the absorbance of the supernatant at a wavelength of 426 nm was measured using an ultraviolet-visible spectrophotometer. The curcumin concentration of the supernatant was then compared with the standard curve, and the curcumin loading rate was calculated. The test results are shown in FIG. Figure 5 shown.

[0088] The curcumin loading rate was calculated as follows: curcumin loading rate (mg / g) = (total curcumin content - curcumin concentration of supernatant × volume of supernatant) / (total protein content × protein recovery rate).

[0089] Depend on Figure 5 It can be seen that due to the occurrence of liquid-liquid phase separation, the curcumin loading rate of the curcumin microcapsules in Examples 1 to 4 and Comparative Example 1 is higher than 400 mg / g, which is much higher than the curcumin microcapsules in Comparative Example 2 (protein encapsulating curcumin alone), indicating that the reduction of the protein recovery rate of the microcapsules is conducive to increasing the curcumin loading rate.

[0090] 3) The curcumin microcapsules (dispersion) in Examples 1 to 4, the curcumin microcapsules (dispersion) in Comparative Example 1, and the curcumin microcapsules (whey protein-curcumin suspension) in Comparative Example 2 were stored in the dark at 4° C. for 14 days, and samples were taken on the 1st, 3rd, 5th, 7th, 10th, and 14th days, mixed with 5 volumes of anhydrous ethanol, vortexed for 30 seconds, centrifuged for 15 minutes, and the centrifugal force was 3000 g. The supernatant was taken to determine the content of curcumin, and the curcumin retention rate was calculated. The test results are as follows: Figure 6 shown.

[0091] The curcumin retention rate was calculated as follows: curcumin retention rate (%) = remaining curcumin content / curcumin content before storage × 100%.

[0092] Depend on Figure 6 It can be seen that the curcumin retention rate of the curcumin microcapsules in Examples 1 to 4 after storage for 14 days is very high (greater than 95%), while the retention rate of the curcumin microcapsules in Comparative Examples 1 and 2 is low (less than 75%), indicating that the spherical domains formed by liquid-liquid phase separation in Examples 1 to 4 can have a good stabilizing effect on curcumin, while the irregular complex formed by the lack of inorganic salt plasticization in Comparative Example 1 has the same stabilizing effect on curcumin as the protein in Comparative Example 2, that is, the lack of stabilizing effect of the domain.

[0093] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A curcumin microcapsule, characterized in that The composition includes curcumin, positively charged protein, negatively charged protein and edible inorganic salt; the positively charged protein is at least one of lysozyme, lactoferrin and acid gelatin; the negatively charged protein is at least one of whey protein, soy protein, pea protein and ovalbumin.

2. The curcumin microcapsule according to claim 1, wherein: The loading rate of curcumin in the curcumin microcapsules is greater than 400 mg / g.

3. The curcumin microcapsule according to claim 1 or 2, wherein: The mass ratio of the positively charged protein to the negatively charged protein is 1:0.25-4.

4. The curcumin microcapsule according to claim 1 or 2, wherein: The edible inorganic salt is at least one of sodium chloride and potassium chloride.

5. The curcumin microcapsule according to claim 1 or 2, wherein: The mass percentage of the edible inorganic salt in the curcumin microcapsules is 0.1% to 0.4%.

6. The curcumin microcapsule according to claim 1 or 2, wherein: The curcumin microcapsules are spherical and have a diameter of 0.2 μm to 3 μm.

7. A method for preparing curcumin microcapsules according to any one of claims 1 to 6, characterized in that: The following steps are involved: 1) dispersing the positively charged protein and the negatively charged protein in water respectively, adding an edible inorganic salt and adjusting the pH value to 6-7 to obtain a dispersion of the positively charged protein and a dispersion of the negatively charged protein; 2) uniformly mixing the negatively charged protein dispersion and the curcumin solution to obtain a negatively charged protein-curcumin dispersion; 3) mixing the positively charged protein dispersion and the negatively charged protein-curcumin dispersion and stirring until liquid-liquid phase separation occurs, thereby obtaining a curcumin microcapsule dispersion; 4) drying the curcumin microcapsule dispersion to obtain curcumin microcapsule powder.

8. The preparation method according to claim 7, characterized in that: The mass percentage of positively charged protein in the positively charged protein dispersion in step 1) is 0.1% to 10%; the mass percentage of negatively charged protein in the negatively charged protein dispersion in step 1) is 0.1% to 2%.

9. The preparation method according to claim 7 or 8, characterized in that: Step 3) The stirring is carried out at a stirring rate of 100 rpm to 200 rpm, and the stirring time is 1 min to 3 min.

10. Use of the curcumin microcapsule according to any one of claims 1 to 6 in the food field or biomedicine field.

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