A method for preparing a high oil load polyunsaturated fatty acid oil fat microcapsule

Abstract

The application provides a preparation method of high-load polyunsaturated fatty acid oil microcapsules. The preparation method of the high-load polyunsaturated fatty acid oil microcapsules comprises the following steps: (1) dissolving a water-soluble protein wall material in water to obtain an aqueous phase; (2) adding polyunsaturated fatty acid oil to the aqueous phase and performing shear emulsification; and (3) adjusting the solid content of the system obtained in the step (2) to 50-55% to obtain an emulsion. The content of the polyunsaturated fatty acid oil in the polyunsaturated fatty acid oil microcapsules is not less than 40 wt%, and the content of fatty acids with a carbon chain length of more than 20 and an unsaturated double bond of more than 4 in the polyunsaturated fatty acid oil is not less than 40%. The high-load polyunsaturated fatty acid oil microcapsule product obtained by the preparation method has low moisture content, is fluffy, has good instant solubility, has good brewing performance, and has good sensory stability during the shelf life.

Description

Technical Field

[0001] This invention relates to the field of polyunsaturated fatty acid preparation, and more specifically, to a method for preparing high-oil-loading polyunsaturated fatty acid oil microcapsules. Background Technology

[0002] Polyunsaturated fatty acid oils, such as arachidonic acid (ARA) oils and docosahexaenoic acid (DHA) oils, have a wide range of biological functions in biological systems. They can regulate lipid metabolism and immunity, and possess functions such as anti-cancer activity, prevention and treatment of cardiovascular diseases, promotion of growth and development, and regulation of gene expression. The many functional characteristics of polyunsaturated fatty acids are widely understood by consumers. However, ARA and DHA oils are easily oxidized due to their structure, producing unpleasant odors and affecting their functionality. Therefore, microencapsulation technology is commonly used to protect ARA and DHA oils with encapsulating materials, improving their stability and flavor.

[0003] Existing technologies have developed methods for preparing microcapsules with high content of polyunsaturated fatty acids. However, in the preparation of high-oil-loading polyunsaturated fatty acid microcapsules, the hydrophobic oil accounts for 50% or more of the system, which differs significantly from the systems established for conventional polyunsaturated fatty acid products. Furthermore, the aqueous phase in the emulsion system tends to migrate to the surface, leading to rapid water loss during the drying process in large-scale production. This results in over-drying of the product, affecting not only its sensory properties but also discoloration within its shelf life, impacting downstream applications. This technical problem is either absent or difficult to detect in microcapsules with conventional polyunsaturated fatty acid content or in microcapsules containing conventional carotenoid fat-soluble nutrients, as described in CN107594597B. Summary of the Invention

[0004] To address, or at least partially address, the aforementioned problems, the primary objective of this invention is to provide a method for preparing high-oil-loading polyunsaturated fatty acid microcapsules. This method aims to increase the solids concentration, thereby raising the emulsion viscosity, which is highly beneficial for the formation of large droplets during drying, particularly spray drying. During the drying process, particles freshly atomized are drawn upwards by the airflow within the drying tower, encountering subsequently atomized droplets and other suspended fine powders, re-wetting them, and adhering them to form large particle aggregates. This process is repeated multiple times, resulting in larger particles. However, a high oil content causes rapid water loss, hindering proper adhesion and aggregation, and leading to over-drying of the product. The method of this invention solves the problem of excessively low moisture content due to over-drying while simultaneously making the product particles more fluffy and increasing their density, further improving their instant solubility. The high-oil-loading microcapsule product obtained using this method is not over-dried, ensuring sensory stability during its shelf life and exhibiting excellent reconstitution properties.

[0005] Although existing microcapsule technologies all mention the solids concentration, from a perspective understandable to those skilled in the art, different emulsion formulations have different conventional solids contents due to varying viscosities. For example, in starch emulsion formulations, due to the large differences in the molecular weight of modified starch, the solids content often does not have a fixed range depending on the starch characteristics and processing requirements. Emulsions with protein emulsifiers and nonionic surfactants have lower viscosity, allowing for solids contents as high as 70%. However, emulsions with whole protein or whole protein compound emulsifier formulations containing whey protein have higher viscosity, and for ease of processing, their solids content is often adjusted to between 20-40%, for example, CN113974165A selected a solids content of 35%.

[0006] In the applicant's related high-content microcapsule patents, a solids content of 35% was selected. However, due to limitations in equipment processing scale, the pilot-scale pressure was limited to 20 bar. Therefore, the pilot-scale samples did not exhibit the moisture content issue encountered in large-scale production as presented in this patent. The patent addressed the impact of vitamin C content on the sensory properties of the powder. This invention, however, addresses a ton-scale industrial production environment, where ensuring product stability involves far more complex factors.

[0007] The method for preparing high-oil-loading polyunsaturated fatty acid microcapsules provided by the present invention includes the following steps:

[0008] (1) Dissolve the water-soluble protein wall material in water to obtain an aqueous phase;

[0009] (2) Add the polyunsaturated fatty acid oil to the aqueous phase and shear emulsify it;

[0010] (3) Adjust the solid content in the system obtained in step (2) to 50-55% to obtain an emulsion;

[0011] The polyunsaturated fatty acid oil microcapsules contain a mass percentage of polyunsaturated fatty acid oil of not less than 40%, and the polyunsaturated fatty acid oil contains a content of fatty acids with a carbon chain length of more than 20 and more than 4 unsaturated double bonds of not less than 40%.

[0012] In this invention, "the content of fatty acids with a carbon chain length of 20 or more and unsaturated double bonds of 4 or more in the polyunsaturated fatty acid oil is not less than 40%" specifically means that the content of fatty acids with a carbon chain length of 20 or more and unsaturated double bonds of 4 or more in the polyunsaturated fatty acid oil is not less than 50 wt%. In the embodiments of this invention, the polyunsaturated fatty acid oil includes, but is not limited to, one or more of DHA, DPA, EPA, and ARA. For example, the DHA oil mentioned in this invention contains DPA, EPA, ARA, etc., in addition to DHA, but the main component is DHA. In a preferred embodiment of this invention, the content of polyunsaturated fatty acid oil in the high-oil-loading polyunsaturated fatty acid oil microcapsules is 40-55 wt%.

[0013] In a preferred embodiment of the present invention, to further improve the stability of the obtained product, cellulose and its derivatives can be added before adjusting the solids in the system. A preferred step includes: adding cellulose and its derivatives to the system obtained in step (2), shearing, and adjusting the solids content in the system to 50-55% to obtain an emulsion. Preferably, the amount of cellulose and its derivatives added is such that the content of cellulose and its derivatives in the polyunsaturated fatty acid oil microcapsules is 0.05-0.3 wt%.

[0014] In specific embodiments of this invention, cellulose and its derivatives include, but are not limited to, one or more of sodium hydroxymethyl cellulose, sodium carboxymethyl cellulose, and sodium hydroxypropyl cellulose, chosen to ensure easy solubility in emulsions. No particular limitation is made on their selection; however, higher addition amounts may affect the smoothness of the protein system's spray process. This invention selects cellulose and its derivatives in combination with other components to improve the product's moisture retention capacity while reducing the impact of differences in other components, resulting in better product stability and improved sensory characteristics.

[0015] In a specific embodiment of the present invention, the water-soluble protein wall material used in the present invention comprises sodium caseinate and / or whey protein. When the water-soluble protein wall material contains sodium caseinate, the amount of sodium caseinate added is preferably such that the content of sodium caseinate in the polyunsaturated fatty acid oil microcapsules is 6-16 wt%. When the water-soluble protein wall material contains whey protein, the amount of whey protein added is preferably such that the content of whey protein in the polyunsaturated fatty acid oil microcapsules is 4-14 wt%. In an optional embodiment, the water-soluble protein wall material may also comprise sodium caseinate and whey protein, and the amounts added respectively can be the preferred amounts described above.

[0016] In a preferred embodiment of the present invention, filler materials and / or antioxidants may be added to the aqueous phase in step (1). If a moisture-retaining agent is added in a specific embodiment, the filler materials and / or antioxidants are preferably added after the moisture-retaining agent. The antioxidants of the present invention include, but are not limited to, one or more of sodium ascorbate, ascorbic acid, ascorbyl palmitate, vitamin E, and phospholipids. The ingredients listed in the present invention are those more in line with infant formula standards, but the selection can be made based on the characteristics of the antioxidants. In a specific embodiment of the present invention, the amount of antioxidant added is such that the antioxidant content in the polyunsaturated fatty acid oil microcapsules is 3-6 wt%. The filler materials in the present invention may include, but are not limited to, corn syrup and / or maltodextrin. After adding other ingredients, the amount of filler material added is the remainder. The ingredients listed in the present invention are those more in line with infant formula standards, but the selection can be made based on the formulation requirements.

[0017] In one specific embodiment of the present invention, the shearing conditions in step (2) can be: shearing speed of 10000 r / min and shearing time of 5-10 min.

[0018] In one specific embodiment of the present invention, in step (3), the solid content in the system can be adjusted to 50-55% by calculating and controlling the aqueous phase content.

[0019] In a preferred embodiment of the present invention, the aqueous phase in step (1) further includes a moisture-retaining agent. That is, the preparation method of step (1) includes: dissolving the water-soluble protein wall material in water, adding the moisture-retaining agent, mixing well, and obtaining the aqueous phase. In a preferred specific embodiment, the moisture-retaining agent can be a phosphate, including but not limited to one or more of disodium hydrogen phosphate, sodium dihydrogen phosphate, sodium tripolyphosphate, and trisodium phosphate, which can be selected and combined according to the actual reaction environment and pH adjusters. In a preferred embodiment of the present invention, the amount of moisture-retaining agent added is preferably such that the content of moisture-retaining agent in the polyunsaturated fatty acid oil microcapsules is 0.1-1.0 wt%.

[0020] In a preferred embodiment of the present invention, the preparation method further includes the following step: homogenizing the emulsion obtained in step (3) and then spray drying it. The spray drying pressure is preferably 110-170 bar. Since emulsions with conventional content do not experience water separation, high pressure can produce finer particles. However, in the system of the present invention, lowering the spray pressure is highly advantageous for forming larger droplets during the spray drying process. The spray pressure range selected in the present invention is lower than that of conventional methods; further lower pressure would lead to bed collapse. Other preferred spray drying conditions are an inlet air temperature of 160-180°C and an outlet air temperature of 60-80°C.

[0021] In specific embodiments of the present invention, the homogenization conditions are not limited and can be chosen by those skilled in the art. For example, the pressure condition can be a conventional 800 bar. Alternatively, continuous or discontinuous system equipment can be selected for implementation.

[0022] In specific embodiments of the present invention, the process typically includes adding an anti-caking agent to the dried product and dry-mixing it. The anti-caking agent is preferably selected from one or more of tricalcium phosphate, silica, microcrystalline cellulose, and magnesium stearate. The amount of anti-caking agent added is preferably such that the content of the anti-caking agent in the polyunsaturated fatty acid oil microcapsules is 0.2-1.0 wt%. Additionally, in specific embodiments of the present invention, a pH adjuster may or may not be added as needed.

[0023] Another object of the present invention is to provide high oil-carrying polyunsaturated fatty acid oil microcapsules obtained by the above preparation method.

[0024] The high-oil-loading polyunsaturated fatty acid microcapsules provided by this invention contain 40-55 wt% polyunsaturated fatty acid oils, with at least 50 wt% of fatty acids having more than 20 carbon chains and more than 4 unsaturated double bonds, 6-16 wt% sodium caseinate, 4-14 wt% whey protein, and 2-4 wt% water. Another objective of this invention is to provide high-oil-loading polyunsaturated fatty acid microcapsules with the above-mentioned characteristics. Preferably, the high-oil-loading polyunsaturated fatty acid microcapsules contain 0.1-1.0 wt% water-retaining agent and 0.05-0.3 wt% cellulose and its derivatives.

[0025] The high-oil-loading (polyunsaturated fatty acid content not less than 40 wt%) polyunsaturated fatty acid oil microcapsules obtained using the preparation method provided by this invention are not excessively dried. Simultaneously, the product's bulk density increases, its instant solubility is further improved, and its stability during shelf life is well guaranteed. The high-oil-loading polyunsaturated fatty acid oil microcapsules obtained using the preparation method provided by this invention have low moisture content, are bulky, have good instant solubility, excellent reconstitution properties, and good sensory stability during shelf life. Detailed Implementation

[0026] The specific embodiments of the present invention will be described in further detail below with reference to the examples. These examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0027] The component content of the microcapsules obtained in the embodiments and comparative examples of the present invention and the spray drying pressure values ​​in the preparation methods are shown in Table 1 below. The preparation methods of polyunsaturated fatty acid oil microcapsules provided in the embodiments and comparative examples of the present invention include the following steps (the systems listed in this embodiment do not require special pH adjustment):

[0028] a. Dissolve the water-soluble wall material sodium caseinate and whey protein powder in water according to the specified ratio, add the moisture retention agent, and stir thoroughly to dissolve;

[0029] b. Add filler and antioxidant, stir thoroughly to dissolve, and obtain the aqueous phase;

[0030] c. Add the polyunsaturated fatty acid oil to the above aqueous phase and shear at 10000 r / min for 10 min;

[0031] d. Finally, add the cellulose derivative, shear for 2 minutes to ensure the solid content is 50%, and obtain the emulsion;

[0032] e. The above emulsion is homogenized 2-3 times using a high-pressure homogenizer at 800 bar;

[0033] f. Spray drying conditions are: inlet air temperature 170±5℃, outlet air temperature 70±5℃;

[0034] g. Add an anti-caking agent and dry mix to obtain the desired result.

[0035] Table 1. Content of components and preparation conditions in the microcapsules obtained in the examples and comparative examples.

[0036]

[0037]

[0038] In Table 1, the contents in parentheses represent the mass content of the substance in the obtained polyunsaturated fatty acid oil microcapsules. "-" indicates that the microcapsules do not contain this component. The DHA oil, derived from algae, contains 40% DHA, and the total content of fatty acids with four or more unsaturated double bonds, including DHA / EPA / DPA / ARA, is 60%.

[0039] Diffusion rate test method: Add the sample to 40℃ warm water at a ratio of 6.5% and start timing. Measure the time required for the powder to go from contacting the liquid surface to completely sinking below the surface; this is the diffusion rate. Then stir with a glass rod at 3 rpm for 15 seconds, let stand, and observe the surface and internal conditions of the solution and score it. "0" points represent no obvious insoluble substances observed; "1" points represent a small amount of insoluble substances observed; "2" points represent a moderate amount of insoluble substances observed; "3" points represent a large amount of insoluble substances observed; "4" points represent a large amount of insoluble substances observed.

[0040] The appearance and properties of the polyunsaturated fatty acid oil microcapsules obtained in the examples and comparative examples are shown in Table 2.

[0041] Table 2 Appearance and properties of microcapsules

[0042]

[0043] Finally, the method of this invention is merely a preferred embodiment and is not intended to limit the scope of protection of this invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for preparing high-oil-loading polyunsaturated fatty acid oil microcapsules, characterized in that, Includes the following steps: (1) Dissolve the water-soluble protein wall material in water to obtain an aqueous phase; (2) Add the polyunsaturated fatty acid oil to the aqueous phase and shear emulsify it; (3) Adjust the solid content in the system obtained in step (2) to 50-55% to obtain an emulsion; homogenize the emulsion and then spray dry it; the spray drying pressure is 110-170 bar; The polyunsaturated fatty acid oil microcapsules contain polyunsaturated fatty acid oils with a mass ratio of not less than 40%, and the polyunsaturated fatty acid oils contain fatty acids with a carbon chain length of more than 20 and more than 4 unsaturated double bonds with a content of not less than 40%. In step (1), the water-soluble protein wall material includes sodium caseinate and / or whey protein; the content of sodium caseinate in the polyunsaturated fatty acid oil microcapsules is 6-16 wt%; and the content of whey protein in the polyunsaturated fatty acid oil microcapsules is 4-14 wt%.

2. The preparation method according to claim 1, characterized in that, Step (3) specifically includes: adding cellulose and its derivatives to the system obtained in step (2), shearing, adjusting the solid content in the system to 50-55%, and obtaining an emulsion; The amount of cellulose and its derivatives added is 0.05-0.3 wt% of the polyunsaturated fatty acid oil microcapsules. The cellulose and its derivatives include, but are not limited to, one or more of sodium hydroxymethyl cellulose, sodium carboxymethyl cellulose, and sodium hydroxypropyl cellulose.

3. The preparation method according to claim 1 or 2, characterized in that, The aqueous phase also includes filler materials and / or antioxidants; the antioxidant content in the polyunsaturated fatty acid oil microcapsules is 3-6 wt%. The filler material includes, but is not limited to, solid corn syrup and / or maltodextrin; the antioxidant includes, but is not limited to, one or more of sodium ascorbate, ascorbic acid, ascorbyl palmitate, vitamin E, and phospholipids.

4. The preparation method according to claim 1 or 2, characterized in that, In step (1), the aqueous phase also includes a moisture-retaining agent; the moisture-retaining agent is a phosphate, including but not limited to one or more of disodium hydrogen phosphate, sodium dihydrogen phosphate, sodium tripolyphosphate, and trisodium phosphate.

5. The preparation method according to claim 4, characterized in that, In step (1), the content of the moisture retention agent in the polyunsaturated fatty acid oil microcapsules is 0.1-1.0 wt%.

6. A high-oil-carrying-weight polyunsaturated fatty acid oil microcapsule, characterized in that, The high-oil-loading polyunsaturated fatty acid oil microcapsules contain 40-55 wt% polyunsaturated fatty acid oils, with at least 50 wt% of fatty acids having more than 20 carbon chains and more than 4 unsaturated double bonds, 6-16 wt% sodium caseinate, 4-14 wt% whey protein, and 2-4 wt% water. The preparation method of the high-oil-loading polyunsaturated fatty acid oil microcapsules includes the following steps: (1) Dissolve the water-soluble protein wall material in water to obtain an aqueous phase; the water-soluble protein wall material includes sodium caseinate and whey protein; (2) Add the polyunsaturated fatty acid oil to the aqueous phase and shear emulsify it; (3) Adjust the content of solids in the system obtained in step (2) to 50-55% to obtain an emulsion; homogenize the emulsion and then spray dry it; the spray drying pressure is 110-170 bar.

7. The high oil-carrying polyunsaturated fatty acid oil microcapsule according to claim 6, characterized in that, Step (3) specifically includes: adding cellulose and its derivatives to the system obtained in step (2), shearing, adjusting the solid content in the system to 50-55%, and obtaining an emulsion; The amount of cellulose and its derivatives added is 0.05-0.3 wt% of the polyunsaturated fatty acid oil microcapsules. The cellulose and its derivatives include, but are not limited to, one or more of sodium hydroxymethyl cellulose, sodium carboxymethyl cellulose, and sodium hydroxypropyl cellulose.

8. The high oil-carrying polyunsaturated fatty acid oil microcapsule according to claim 6, characterized in that, The aqueous phase also includes filler materials and / or antioxidants; the antioxidant content in the polyunsaturated fatty acid oil microcapsules is 3-6 wt%. The filler material includes, but is not limited to, solid corn syrup and / or maltodextrin; the antioxidant includes, but is not limited to, one or more of sodium ascorbate, ascorbic acid, ascorbyl palmitate, vitamin E, and phospholipids.

9. The high oil-carrying polyunsaturated fatty acid oil microcapsule according to claim 6, characterized in that, In step (1), the aqueous phase also includes a moisture-retaining agent; the moisture-retaining agent is a phosphate, including but not limited to one or more of disodium hydrogen phosphate, sodium dihydrogen phosphate, sodium tripolyphosphate, and trisodium phosphate.

10. The high oil-carrying polyunsaturated fatty acid oil microcapsule according to claim 9, characterized in that, In step (1), the content of the moisture retention agent in the polyunsaturated fatty acid oil microcapsules is 0.1-1.0 wt%.

Images