Preparation method of high all-trans beta-carotene microcapsule

Abstract

The invention provides a preparation method of a high all-trans beta-carotene microcapsule, which comprises the following steps: a) mixing and dissolving beta-carotene crystals, vegetable oil, an antioxidant and an organic solvent to obtain a beta-carotene solution, the mass ratio of beta-carotene to fatty glyceride being (0.1-5): 1; b) mixing and emulsifying the beta-carotene solution and the protective colloid aqueous solution, and evaporating to remove the organic solvent to obtain a beta-carotene emulsion; and c) carrying out spray granulation on the beta-carotene emulsion to obtain the low-trans-content beta-carotene microcapsule. And d) isomerizing the low-trans-content beta-carotene microcapsule at 70-90 DEG C under the protection of nitrogen for 1-5 hours to obtain the high-all-trans-content beta-carotene microcapsule. The preparation method is simple in process and convenient to operate, and the obtained product is high and controllable in trans content, small in color difference and high in bioavailability.

Description

Technical Field

[0001] The invention belongs to the technical field of preparations, and in particular relates to a method for preparing high all-trans beta-carotene microcapsules. Background Art

[0002] β-Carotene is an orange-yellow fat-soluble compound, a natural organic pigment, and one of the most common and stable natural pigments in nature. It is widely found in many plant foods such as green vegetables, carrots, pumpkins, and mangoes. β-Carotene is not only an important source of vitamin A in the body, but also has important physiological functions for the human body. It can quench free radicals, reduce the damage of free radicals to cells, and improve the body's immune function. It also helps maintain the normal structure and function of the skin and protect the skin from damage by ultraviolet rays.

[0003] The molecular formula of β-carotene is C 40 H 56 , molecular weight of 536.88, melting point of 184°C, about 20 isomers, insoluble in water, methanol, ethanol, propylene glycol, glycerin, acid or alkali, slightly soluble in vegetable oil, moderately soluble in aliphatic and aromatic olefins, and easily soluble in chlorinated hydrocarbons; due to the multiple double bond structure, its chemical properties are very unstable and it is easily oxidized and destroyed under the conditions of light and oxygen.

[0004] The limited solubility and extreme sensitivity to oxygen of β-carotene hinder its direct application in food, feed, etc. Using microencapsulation technology, water-soluble macromolecules such as gelatin and octenyl succinate starch can be used to encapsulate β-carotene to improve its activity and bioavailability.

[0005] Patent US3886294 introduces the use of vegetable oil to melt β-carotene at high temperature, emulsify it, and dry it to make a water-dispersible carotenoid powder, but its trans content is low and the particle size is large.

[0006] US4693892 describes the use of a colloid mill to grind β-carotene into microparticles, which are then dried to form water-dispersible carotenoid powder. However, the grinding method has low efficiency, high energy consumption, and it is difficult to achieve a carotenoid powder particle size below 1 μm.

[0007] US3998753 describes a method for preparing water-dispersible carotenoids, wherein the particle size of the carotenoids is less than 1 μm. The method first prepares the carotenoids and other additives into a solution of an organic solvent, then adds the solution to an aqueous solution containing gelatin, a dispersant, and a stabilizer, and forms an emulsion through high-speed shearing; removes the organic solvent, and spray-dries to obtain the desired powder. However, due to the long time and high temperature for evaporating the solvent, the trans content of the powder is usually low.

[0008] The method for preparing water-dispersible carotenoid powder described in EP0065193 (or US4522743) is to dissolve carotenoid in a volatile water-miscible solvent at 50-200°C within 10 seconds, and then quickly mix with an aqueous solution containing a protective colloid at 10-50°C, so that the carotenoid is dispersed in the protective colloid with a size of <0.5 μm, remove the solvent, and dry to obtain the carotenoid powder. This process needs to be carried out under high pressure equipment (pressure at 3.0-6.0 MPa) and high temperature (170-200°C), which has high requirements on equipment and is difficult to operate and control.

[0009] CN101016259 A introduces a method for preparing a high all-trans β-carotene preparation, wherein β-carotene, a combined antioxidant, and a solvent containing an emulsifier are mixed and dissolved at 30 to 60°C to form a solution, and then added to ethanol or isopropanol stirred at high speed in the form of a spray, so that β-carotene is precipitated in the form of an amorphous powder of <2μm, and after filtering, the filter cake is added to water pre-dissolved with auxiliary materials such as protective colloids, and subsequent preparation operations such as emulsification, removal of residual solvents, and spray drying are performed to finally obtain a high all-trans β-carotene preparation, wherein the combined antioxidant is composed of a class A antioxidant and a class B antioxidant. This method requires the use of a large amount of solvent and a large amount of antioxidant, and the particle size of the β-carotene microcapsules is large, and the process is relatively cumbersome.

[0010] Although the above processes have been applied in actual production, it is found that during the preparation process, operations such as dissolution, desolventization, heating, and pressurization will produce a considerable amount of cis isomers, resulting in a low content of all-trans β-carotene in the final preparation product and a large variation. This problem has always troubled researchers around the world.

[0011] Since the chemical properties of the all-trans isomer are more stable than other isomers and its potency in the organism is the highest, increasing the content of all-trans β-carotene in the preparation means effectively improving its nutritional value in the organism.

[0012] Unfortunately, apart from the conventional mention of adding certain antioxidants, there are very few reports on increasing the content of the all-trans isomer in β-carotene preparations. Summary of the invention

[0013] The purpose of the present invention is to solve the above problems and to provide a method for preparing high all-trans β-carotene microcapsules. The preparation method is simple to operate and the obtained product has a high and controllable all-trans β-carotene content and high bioavailability.

[0014] The technical solution of the present invention is as follows:

[0015] A method for preparing high all-trans β-carotene microcapsules comprises the following steps:

[0016] a) mixing and dissolving β-carotene crystals, vegetable oil, an antioxidant and an organic solvent to obtain a β-carotene solution;

[0017] b) mixing and emulsifying the β-carotene solution and the protective colloid aqueous solution, and evaporating the organic solvent to obtain a β-carotene emulsion;

[0018] c) spray granulating the β-carotene emulsion to obtain low all-trans content β-carotene microcapsules;

[0019] d) heating the low trans-content β-carotene microcapsules for isomerization to obtain high all-trans β-carotene microcapsules;

[0020] In step a), the vegetable oil contains 40-60 wt% of long-chain saturated fatty acids, and the number of carbon atoms in the long-chain saturated fatty acids is 12-16.

[0021] Preferably, the vegetable oil in step a) contains 40-60 wt% of lauric acid, preferably coconut oil, palm kernel oil or babassu oil, more preferably coconut oil;

[0022] The mass ratio of beta-carotene to vegetable oil is (0.1-5):1, preferably 0.5:1.

[0023] Preferably, the organic solvent in step a) is one or more of dichloromethane, chloroform, ethyl acetate and propyl acetate.

[0024] Preferably, the antioxidant in step a) is selected from one or more of TBHQ, VC palmitate, tocopherol, BHT, and ethoxyquinoline, preferably dl-α-tocopherol;

[0025] The amount of the antioxidant used is 0.1 to 5 times the mass of β-carotene, and most preferably 0.1 to 0.2 times.

[0026] Preferably, the emulsification method in step b) is one or more of high-pressure homogenization emulsification, online pipeline high-shear emulsification, and ultra-gravity emulsification.

[0027] Preferably, the protective colloid in step b) is selected from one or more of octenyl succinate starch, gum arabic, sodium lignin sulfonate, calcium lignin sulfonate, soy protein, and gelatin, preferably gelatin;

[0028] The amount of the protective colloid is 0.1 to 20 times the mass of β-carotene, preferably 2 to 5 times;

[0029] The amount of water used is 0.1 to 50 times the mass of gelatin, preferably 1 to 10 times.

[0030] Preferably, the microcapsule particles in step d) are isomerized at 70-90°C, preferably 80-85°C.

[0031] Preferably, the isomerization in step d) is carried out under nitrogen protection.

[0032] Preferably, the isomerization time in step d) is 1 to 5 h, preferably 1 to 2 h.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] 1) The β-carotene particles in the microcapsules of the present invention are encapsulated in a specific oil in the form of nano-dispersion, with a dense water-soluble protective film on the outside, and are finally isomerized, with little content loss, high and controllable trans content of the product, small color difference, and high bioavailability;

[0035] 2) The method has simple process and is easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a particle size diagram of the β-carotene microcapsules obtained in Example 1;

[0037] Figure 2 This is a particle size diagram of the β-carotene microcapsules obtained in Example 2;

[0038] Figure 3 This is a particle size diagram of the β-carotene microcapsules obtained in Comparative Example 2. DETAILED DESCRIPTION

[0039] The present invention is described in detail below in conjunction with the embodiments. In order to facilitate comparative explanation of the advantages of the present invention, a comparison of the comparative examples is also provided.

[0040] Example 1

[0041] At 50°C, 25.0g of β-carotene crystals, 12.5g of dl-α-tocopherol, 2.5g of VC ester, and 25.0g of coconut oil were dissolved in 250.0g of chloroform to prepare an oil phase; 75.0g of gelatin and 110.0g of sucrose were dissolved in 300.0g of water to prepare a water-soluble protective colloid; the oil phase was added to the water-soluble protective colloid under high-speed shear conditions, homogenized under high pressure, and the residual solvent was removed, and β-carotene microcapsules were obtained by spray granulation, with a particle size of 180.1nm and an all-trans content of 74.81%. The microcapsule particles were isomerized at 85°C for 2h, and the all-trans content was 86.76%. The particle size of the product is shown in Figure 1 , detailed results are shown in Table 1.

[0042] Example 2

[0043] At 50°C, 25.1g of β-carotene crystals, 12.6g of dl-α-tocopherol, 2.6g of VC ester, and 50.0g of coconut oil were dissolved in 250.0g of chloroform to prepare an oil phase; 75.0g of gelatin and 85.0g of sucrose were dissolved in 300.0g of water to prepare a water-soluble protective colloid; the oil phase was added to the water-soluble protective colloid under high-speed shear conditions, homogenized under high pressure, and the residual solvent was removed, and β-carotene microcapsules were obtained by spray granulation, with a particle size of 181.5nm and an all-trans content of 73.36%. The microcapsule particles were isomerized at 85°C for 2h, and the all-trans content was 90.88%. The particle size of the product is shown in Figure 2 , detailed results are shown in Table 1.

[0044] Example 3

[0045] At 50°C, 25.0g of β-carotene crystals, 12.6g of dl-α-tocopherol, 2.5g of sodium VC, and 50.0g of coconut oil were dissolved in 251.0g of chloroform to prepare an oil phase; 145.0g of calcium lignin sulfonate and 15.0g of sucrose were dissolved in 300.0g of water to prepare a water-soluble protective colloid; the oil phase was added to the water-soluble protective colloid under high-speed shear conditions, homogenized under high pressure, and the residual solvent was removed, and spray granulation was performed to obtain β-carotene microcapsules with a particle size of 168.1nm and an all-trans content of 72.25%. The microcapsule particles were isomerized at 85°C for 2h, and the all-trans content was 85.82%. The detailed results are shown in Table 1.

[0046] Example 4

[0047] At 50°C, 25.3g of β-carotene crystals, 12.4g of dl-α-tocopherol, 2.6g of sodium VC, and 50.0g of coconut oil were dissolved in 506.0g of dichloromethane to prepare an oil phase; 75.3g of gelatin and 85.5g of sucrose were dissolved in 300.0g of water to prepare a water-soluble protective colloid; the oil phase was added to the water-soluble protective colloid under high-speed shear conditions, homogenized under high pressure, and the residual solvent was removed, and spray granulation was performed to obtain β-carotene microcapsules with a particle size of 188.1nm and an all-trans content of 73.63%. The microcapsule particles were isomerized at 85°C for 2h, and the all-trans content was 89.88%. The detailed results are shown in Table 1.

[0048] Comparative Example 1

[0049] At 50°C, 25.2g of β-carotene crystals, 12.5g of dl-α-tocopherol, 2.4g of sodium VC, and 50.0g of palm kernel oil were dissolved in 252.1g of chloroform to prepare an oil phase; 75.2g of gelatin and 85.6g of sucrose were dissolved in 300.0g of water to prepare a water-soluble protective colloid; the oil phase was added to the water-soluble protective colloid under high-speed shear conditions, homogenized under high pressure, and the residual solvent was removed, and spray granulation was performed to obtain β-carotene microcapsules with a particle size of 190.2nm and an all-trans content of 72.51%. The microcapsule particles were isomerized at 85°C for 2h, and the all-trans content was 87.22%. The detailed results are shown in Table 1.

[0050] Comparative Example 2

[0051] At 50°C, 25.0g of β-carotene crystals, 12.6g of dl-α-tocopherol, and 2.4g of VC ester were dissolved in 250.0g of chloroform to prepare an oil phase; 75.4g of gelatin and 135.4g of sucrose were dissolved in 300.0g of water to prepare a water-soluble protective colloid; the oil phase was added to the water-soluble protective colloid under high-speed shear conditions, homogenized under high pressure, and the residual solvent was removed, and β-carotene microcapsules were obtained by spray granulation, with a particle size of 177.4nm and an all-trans content of 74.16%. The microcapsule particles were isomerized at 85°C for 2h, and the all-trans content was 68.68%. The particle size of the product is shown in Figure 3 , detailed results are shown in Table 1.

[0052] Table 1

[0053]

[0054] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A method for preparing high all-trans β-carotene microcapsules, characterized in that: The following steps are involved: a) mixing and dissolving β-carotene crystals, vegetable oil, an antioxidant and an organic solvent to obtain a β-carotene oil solution; b) mixing and emulsifying the β-carotene and the protective colloid aqueous solution, and evaporating the organic solvent to obtain a β-carotene emulsion; c) spray granulating and drying the β-carotene emulsion to obtain low trans-content β-carotene microcapsules; d) heating the low trans-content β-carotene microcapsules for isomerization to obtain high all-trans β-carotene microcapsules; In step a), the vegetable oil contains 40-60 wt% of long-chain saturated fatty acids, and the number of carbon atoms in the long-chain saturated fatty acids is 12-16.

2. The method for preparing high all-trans β-carotene microcapsules according to claim 1, characterized in that: In step a), the vegetable oil contains 40-60 wt% of lauric acid, preferably coconut oil, palm kernel oil or babassu oil, more preferably coconut oil; The mass ratio of beta-carotene to vegetable oil is (0.1-5):1, preferably 0.5:

1.

3. The method for preparing high all-trans β-carotene microcapsules according to claim 1, characterized in that: In step a), the organic solvent is one or more of dichloromethane, chloroform, ethyl acetate and propyl acetate.

4. The method for preparing high all-trans β-carotene microcapsules according to claim 1, characterized in that: In step a), the antioxidant is selected from one or more of TBHQ, VC palmitate, tocopherol, BHT, and ethoxyquinoline, preferably dl-α-tocopherol; The amount of the antioxidant used is 0.1 to 5 times the mass of β-carotene, and most preferably 0.1 to 0.2 times.

5. The method for preparing high all-trans β-carotene microcapsules according to claim 1, characterized in that: In step b), the emulsification method is one or more of high-pressure homogenization emulsification, online pipeline high-shear emulsification, and ultra-gravity emulsification.

6. The method for preparing high all-trans β-carotene microcapsules according to claim 1, characterized in that: In step b), the protective colloid is selected from one or more of octenyl succinate starch, gum arabic, sodium lignin sulfonate, calcium lignin sulfonate, soy protein, and gelatin, preferably gelatin; The amount of the protective colloid is 0.1 to 20 times the mass of β-carotene, preferably 2 to 5 times; The amount of water used is 0.1 to 50 times the mass of gelatin, preferably 1 to 10 times.

7. The method for preparing high all-trans β-carotene microcapsules according to claim 1, characterized in that: In step d), the microcapsule particles are isomerized at 70-90°C, preferably at 80-85°C.

8. The method for preparing high all-trans β-carotene microcapsules according to claim 1, characterized in that: In step d), the isomerization is carried out under nitrogen protection.

9. The method for preparing high all-trans β-carotene microcapsules according to claim 1, characterized in that: In step d), the isomerization time is 1 to 5 hours, preferably 1 to 2 hours.

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