A method for preparing a microcapsule of a maillard polyunsaturated fatty acid oil

Abstract

The present application relates to the technical field of microcapsules, and specifically provides a preparation method of Maillard polyunsaturated fatty acid oil microcapsules.The polyunsaturated fatty acid oil in the Maillard polyunsaturated fatty acid oil microcapsule provided by the present application has a mass ratio of not less than 40%, and the moisture content is 2-4%;the Maillard reaction product used in the present application is prepared from inulin, glucose, lactose and sodium caseinate.By adding inulin to the Maillard reaction system, the problem of poor reconstitution of the polyunsaturated fatty acid oil microcapsule prepared by using glucose, lactose and sodium caseinate as the Maillard reaction product can be solved, and the shelf life stability of the microcapsule can be improved.

Description

Technical Field

[0001] This invention relates to the field of microcapsule technology, and in particular to a method for preparing Maillard 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, functional fatty acids in polyunsaturated fatty acid oils, such as ARTA and DHA, are easily oxidized due to their structure, producing unpleasant odors and affecting the oil's function. Therefore, microencapsulation technology is commonly used to protect ARTA 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. For example, CN103549442A uses spray drying to prepare DHA algal oil powder with an oil loading rate of 33-50%; CN102228257A improves the stability of high-content microcapsules by improving antioxidants; CN110613025A uses compound emulsifiers to reduce the surface oil of high-content microcapsules; and CN110613025A microcapsule powder encapsulates 45-80% of oils such as MCT and olive oil.

[0004] In seeking solutions for the stability of microcapsules containing high levels of polyunsaturated fatty acids, the applicant has focused on Maillard reaction products, which possess high thermal and oxidative stability. Whey protein, sodium caseinate, soy protein isolate, amino acids, and other proteins, as well as sugars such as glucose, lactose, and maltodextrin, are commonly used raw materials for preparing Maillard products. For example, the paper "Preparation of Maillard Reaction Products and Their Application in Mixed Oil Microcapsules" discloses the Maillard reaction product of sodium caseinate and maltodextrin as a wall material for encapsulating mixed oils. CN105685770A discloses the use of whey protein, casein, amino acids, lactose, and monosaccharides to prepare Maillard reaction products for encapsulating oils. Summary of the Invention

[0005] In the process of encapsulating polyunsaturated fatty acid oils using Maillard reaction products, the applicant discovered that the oil microcapsule products encapsulated using a Maillard reaction product-based complex carbohydrate system of sodium caseinate, glucose, and lactose performed poorly in reconstitution and dispersion experiments. Furthermore, subsequent stability experiments revealed poor product stability within the shelf life.

[0006] Further investigation revealed that the reason for its poor stability was that during the preparation of polyunsaturated fatty acid oil microcapsules with high oil loading rate, the hydrophobic oil accounted for 50% or more of the system, and the aqueous phase in the emulsion system tended to migrate to the surface. During the drying process, it was easy to lose water quickly, and the product would be over-dried, resulting in poor product stability during the shelf life and the appearance of a fishy smell.

[0007] These technical issues are not present or are difficult to detect in standard-content Pufa microcapsules or other fat-soluble nutrient microcapsules.

[0008] To address the aforementioned problems, in a first aspect, the present invention provides a Maillard polyunsaturated fatty acid oil microcapsule. In the microcapsule of the present invention, the Maillard reaction product is prepared from inulin, glucose, lactose, and sodium caseinate; the mass percentage of polyunsaturated fatty acid oil in the microcapsule raw material is not less than 40%, and the content of fatty acids with a carbon chain length of more than 20 and more than 4 unsaturated double bonds in the polyunsaturated fatty acid oil is not less than 40%, and the water content of the Maillard polyunsaturated fatty acid oil microcapsule is 2-4%.

[0009] The microcapsule raw materials refer to the total amount of raw materials other than water.

[0010] The polyunsaturated fatty acid oils described in this invention are not limited to any particular source and can be derived from microbial fermentation, marine fish extraction, plant extraction, etc. Conventionally in the art, oils are often named after the most abundant unsaturated fatty acid component, such as DHA oil, ARA oil, etc. Among these, DHA oil, with its rich unique flavor and the highest number of double bonds, is the most difficult to process. In a preferred embodiment of this invention, DHA algal oil is selected as the encapsulated oil.

[0011] Inulin is often used in microcapsules as a small molecule prebiotic or dietary fiber along with a filler. Inulin is three times more hygroscopic than itself, and direct application in spray drying processes can easily cause it to stick to the walls and subsequently absorb moisture.

[0012] This invention combines inulin with protein, allowing some of the inulin's hydroxyl groups to participate in protein binding. This neutralizes the moisture retention effect of the two, avoiding the processing disadvantages of inulin application while ensuring that the high-oil-loading polyunsaturated fatty acid microcapsule product is not excessively dried. This solves the problem of poor stability in high-oil-loading polyunsaturated fatty acid microcapsule products encapsulated with Maillard products obtained using the sodium caseinate-glucose-lactose system within their shelf life.

[0013] Furthermore, this invention unexpectedly discovered that using inulin together with sodium caseinate, glucose, and lactose as a Maillard reaction system can solve the problem of poor reconstitution properties in oil microcapsule products.

[0014] The Maillard polyunsaturated fatty acid oil microcapsules provided by the present invention, by weight, contain sodium caseinate accounting for 8-12% and carbohydrates accounting for 16-25% of the microcapsule raw materials, including inulin, glucose and lactose; inulin accounts for 6-9% of the microcapsule raw materials.

[0015] The Maillard polyunsaturated fatty acid oil microcapsules provided by this invention, wherein the mass ratio of inulin, glucose and lactose in the raw materials for preparing the Maillard reaction product is (6-9):(5-8):(5-8).

[0016] The Maillard polyunsaturated fatty acid oil microcapsules provided by this invention, by weight, contain polyunsaturated fatty acid oils accounting for 40-55%, sodium caseinate accounting for 8-12%, inulin accounting for 6-9%, glucose accounting for 5-8%, lactose accounting for 5-8%, antioxidant accounting for 3-6%, anti-caking agent accounting for 0.2-1%, and the remainder being fillers.

[0017] Preferably, the Maillard polyunsaturated fatty acid oil microcapsule raw material further includes a pH adjuster and / or chelating agent at a weight ratio of 0.0001-1%, which may be selectively added depending on the raw material. In one specific embodiment of the present invention, the pH may be kept at its natural state, and the chelating agent may be omitted.

[0018] The Maillard polyunsaturated fatty acid oil microcapsules provided by the present invention contain antioxidants including, but not limited to, one or more of the following: sodium ascorbate, ascorbic acid, ascorbyl palmitate, vitamin E, and phospholipids.

[0019] The anti-caking agents include, but are not limited to, one or more of the following: tricalcium phosphate, silicon dioxide, microcrystalline cellulose, and magnesium stearate;

[0020] The filler is not limited here, but in some preferred embodiments, it may be one or both of solid corn syrup and maltodextrin.

[0021] In the Maillard polyunsaturated fatty acid oil microcapsules provided by this invention, by weight, the proportion of sodium caseinate is 9-10%, inulin is 6-9%, glucose is 6-7%, and lactose is 6-7%.

[0022] Secondly, the present invention also provides a method for preparing the above-mentioned Maillard polyunsaturated fatty acid oil microcapsules, comprising:

[0023] (1) Dissolve sodium caseinate, glucose, lactose and inulin in water, stir thoroughly, adjust the pH to 8-10, raise the temperature to 80-90℃, maintain the temperature for 30-120 min, and stir thoroughly.

[0024] (2) Add solid corn syrup and antioxidant, stir thoroughly to dissolve, and obtain an aqueous phase;

[0025] (3) Add the polyunsaturated fatty acid oil to the aqueous phase obtained in step (2) and shear it to obtain an emulsion;

[0026] (4) The emulsion obtained in step (3) is homogenized under high pressure and then dried;

[0027] (5) Add an anti-caking agent and dry mix.

[0028] In the preparation method of Maillard polyunsaturated fatty acid oil microcapsules provided by the present invention, the drying in step (4) is spray drying, with an inlet air temperature of 160-180°C and an outlet air temperature of 60-80°C.

[0029] As a specific embodiment of the present invention, the method for preparing Maillard polyunsaturated fatty acid oil microcapsules includes:

[0030] a. Dissolve sodium caseinate, glucose, lactose, and inulin in water, stir thoroughly, then adjust the pH to 8.0 with NaOH, raise the temperature to 80-90℃, maintain the temperature for 30-60 minutes, and stir thoroughly.

[0031] b. Add solid corn syrup and antioxidant sodium VC to the material obtained in a, stir thoroughly to dissolve, and obtain an aqueous phase;

[0032] c. Add the polyunsaturated fatty acid oil to the above aqueous phase and shear at 10000 r / min for 5-10 min;

[0033] d. The above emulsion is homogenized 2-3 times using a high-pressure homogenizer at 800 bar;

[0034] e. Spray drying conditions are: air inlet temperature 160-180℃, air outlet temperature 60-80℃, maintaining a certain air inlet volume and feeding speed;

[0035] f. Add tricalcium phosphate and dry mix.

[0036] Other parameters in the preparation process, such as solid content and spray pressure, are conventional choices in the field, with the aim of ensuring that the emulsion can be successfully sprayed out and formed, and are not limited here.

[0037] This invention also provides the application of inulin in improving the reconstituteability of Maillard polyunsaturated fatty acid oil microcapsules; the Maillard reaction product is prepared from inulin, glucose, lactose and sodium caseinate, and the content of polyunsaturated fatty acid oil in the microcapsules is not less than 40%.

[0038] The beneficial effects of this invention are as follows:

[0039] (1) The present invention increases the hydrophilicity of the Maillard reaction system and improves the emulsification ability by adding inulin to the Maillard reaction, thereby achieving good reconstitution properties of the microcapsule product.

[0040] (2) By adding inulin to the Maillard reaction, this invention can ensure that the microcapsule product with high oil loading is not over-dried while keeping the spray drying process unchanged, thereby improving the sensory quality of the product and ensuring its stability during the shelf life. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. In this embodiment, the DHA oil is DHA algal oil, wherein the DHA content is 41%, and the total content of fatty acids with four or more unsaturated double bonds, including DHA / EPA / DPA / ARA, is 54%.

[0042] Example 1: Preparation method of Maillard DHA lipid microcapsules

[0043] In this embodiment of the invention, apart from water, sodium caseinate accounts for 10% of the microcapsule raw material by weight, and the sugars are glucose, lactose and inulin, wherein glucose accounts for 6% of the microcapsule raw material, lactose accounts for 7% of the microcapsule raw material and inulin accounts for 8% of the microcapsule raw material.

[0044] The antioxidant sodium VC accounts for 5% of the microcapsule raw materials.

[0045] The anti-caking agent tricalcium phosphate accounts for 0.6% of the microcapsule raw materials.

[0046] DHA algal oil accounts for 50% of the raw materials for microcapsules.

[0047] The remaining components of the microcapsule raw material are sodium hydroxide to adjust the pH of the feed solution to 8 and solid corn syrup as a filler.

[0048] The final DHA content in the microcapsules prepared with this formula can reach more than 20%.

[0049] This embodiment provides a method for preparing Maillard DHA lipid microcapsules, including:

[0050] a. Dissolve sodium caseinate, glucose, lactose, and inulin in water, stir thoroughly, then adjust the pH to 8.0 with NaOH, raise the temperature to 80℃, maintain the temperature for 40 minutes, and stir thoroughly.

[0051] b. Add solid corn syrup and the antioxidant sodium vitamin C, and stir thoroughly to dissolve;

[0052] c. Add DHA oil to the above aqueous phase and shear at 10000 r / min for 5-10 min. The DHA oil accounts for 50% of the emulsion solids.

[0053] d. The above emulsion is homogenized 2-3 times using a high-pressure homogenizer at 800 bar;

[0054] e. Spray drying conditions are: air inlet temperature 160-180℃, air outlet temperature 60-80℃, maintaining a certain air inlet volume and feeding speed;

[0055] f. Add tricalcium phosphate and dry mix.

[0056] Example 2

[0057] The difference between this embodiment and Embodiment 1 is that, in this embodiment, apart from water, sodium caseinate accounts for 9% of the microcapsule raw material by weight, glucose accounts for 7% of the microcapsule raw material, lactose accounts for 7% of the microcapsule raw material, and inulin accounts for 8% of the microcapsule raw material; the filler content varies with the changes in other components.

[0058] The preparation method used in this embodiment is the same as that in Example 1.

[0059] Example 3

[0060] The difference between this embodiment and Embodiment 1 is that, in this embodiment, apart from water, sodium caseinate accounts for 10% of the microcapsule raw material by weight, glucose accounts for 8% of the microcapsule raw material, lactose accounts for 8% of the microcapsule raw material, and inulin accounts for 5% of the microcapsule raw material.

[0061] The preparation method used in this embodiment is the same as that in Example 1.

[0062] Example 4

[0063] The difference between this embodiment and Embodiment 1 is that, in this embodiment, apart from water, sodium caseinate accounts for 10% of the microcapsule raw material by weight, glucose accounts for 5% of the microcapsule raw material, lactose accounts for 5% of the microcapsule raw material, and inulin accounts for 15% of the microcapsule raw material.

[0064] The preparation method used in this embodiment is the same as that in Example 1.

[0065] Comparative Example 1

[0066] This comparative example uses conventional Maillard DHA lipid microcapsules. The difference between this comparative example and Example 1 is that, apart from water, sodium caseinate accounts for 10% of the microcapsule raw material by weight, glucose accounts for 10% of the microcapsule raw material, lactose accounts for 10% of the microcapsule raw material, and inulin is not added to the microcapsule raw material.

[0067] The preparation method used in this comparative example is the same as that in Example 1, including:

[0068] a. Dissolve sodium caseinate, glucose, and lactose in water and stir thoroughly. Then adjust the pH to 8.0 with NaOH, raise the temperature to 80℃, maintain the temperature for 40 minutes, and stir thoroughly.

[0069] b. Add solid corn syrup and the antioxidant sodium vitamin C, and stir thoroughly to dissolve;

[0070] c. Add DHA oil to the above aqueous phase and shear at 10000 r / min for 5-10 min. The DHA oil accounts for 50% of the emulsion solids.

[0071] d. The above emulsion is homogenized 2-3 times using a high-pressure homogenizer at 800 bar;

[0072] e. Spray drying conditions are: air inlet temperature 160-180℃, air outlet temperature 60-80℃, maintaining a certain air inlet volume and feeding speed;

[0073] f. Add tricalcium phosphate and dry mix.

[0074] Comparative Example 2

[0075] This comparative example uses the same proportions of raw materials as in Example 1, except that, by weight, sodium caseinate accounts for 10% of the microcapsule raw material, glucose accounts for 6%, lactose accounts for 7%, and inulin accounts for 8%. The antioxidant sodium vitamin C accounts for 5%, the anti-caking agent tricalcium phosphate accounts for 0.6%, and DHA algal oil accounts for 50%.

[0076] In this comparative example, the preparation method of Maillard DHA lipid microcapsules includes:

[0077] a. Dissolve sodium caseinate, glucose, and lactose in water and stir thoroughly. Then adjust the pH to 8.0 with NaOH, raise the temperature to 80℃, maintain the temperature for 40 minutes, and stir thoroughly.

[0078] b. Add solid corn syrup, antioxidant sodium VC, and inulin, and stir thoroughly to dissolve;

[0079] c. Add DHA oil to the above aqueous phase and shear at 10000 r / min for 5-10 min. The DHA oil accounts for 50% of the emulsion solids.

[0080] d. The above emulsion is homogenized 2-3 times using a high-pressure homogenizer at 800 bar;

[0081] e. Spray drying conditions are: air inlet temperature 160-180℃, air outlet temperature 60-80℃, maintaining a certain air inlet volume and feeding speed;

[0082] f. Add 0.6% tricalcium phosphate and dry mix.

[0083] Comparative Example 3

[0084] The difference between this comparative example and Example 1 is that, in this comparative example, in addition to water, sodium caseinate accounts for 10% of the microcapsule raw material, glucose accounts for 10% of the microcapsule raw material, lactose accounts for 10% of the microcapsule raw material, and inulin accounts for 10% of the microcapsule raw material.

[0085] The preparation method used in this comparative example is the same as that in Example 1.

[0086] Experimental Example

[0087] This experiment tested the properties, sensory characteristics, and appearance of the microcapsules in the examples and comparative examples. After storing the microcapsule products at 37°C and 75% humidity for 3 months, the product stability (moisture content, odor, and taste) was tested. The results are shown in Table 1.

[0088] The reconstitution test method and standard are as follows: Reconstitution 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, observe the surface and internal condition 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 moderate insoluble substances observed; "3" points represent a large amount of insoluble substances observed; and "4" points represent a large amount of insoluble substances observed.

[0089] Moisture content was measured using a Karl Fischer moisture analyzer.

[0090] Table 1. Results of moisture content, reconstitution properties, and stability tests of the microcapsules.

[0091]

[0092] As shown in Table 1, the Maillard reaction system composed of glucose, lactose and sodium caseinate encapsulates polyunsaturated fatty acids, which can lead to poor reconstitution properties. During the 3-month storage period, a slightly fishy taste may appear (see Comparative Example 1).

[0093] Comparative Example 2 confirmed that when inulin is used directly as the wall material in Maillard polyunsaturated fatty acid oil microcapsules, the microcapsules not only have a strong fishy smell during the 3-month storage period, but also have increased moisture content due to the water absorption of inulin.

[0094] When inulin is added to the Maillard reaction system, the amount of sugar needs to be adjusted. Excessive sugar content has a significant impact on the stability of the system, as shown in Comparative Example 3.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A Maillard polyunsaturated fatty acid oil microcapsule, characterized in that, The Maillard reaction product is prepared from inulin, glucose, lactose, and sodium caseinate; 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%; the water content of the microcapsules is 2-4%. By weight, the microcapsule raw material comprises 40-55% polyunsaturated fatty acid oil, 8-12% sodium caseinate, 6-9% inulin, 5-8% glucose, 5-8% lactose, 3-6% antioxidant, 0.2-1% anti-caking agent, and the remainder is filler.

2. The Maillard polyunsaturated fatty acid oil microcapsules according to claim 1, characterized in that, The raw materials also include pH adjusters and / or chelating agents.

3. The Maillard polyunsaturated fatty acid oil microcapsules according to claim 1 or 2, characterized in that, The antioxidants include one or more of the following: sodium ascorbate, ascorbic acid, ascorbyl palmitate, vitamin E, and phospholipids; The anti-caking agent includes one or more of the following: tricalcium phosphate, silicon dioxide, microcrystalline cellulose, and magnesium stearate.

4. The Maillard polyunsaturated fatty acid oil microcapsules according to claim 1 or 2, characterized in that, By weight, the microcapsule raw materials contain 9-10% sodium caseinate, 6-9% inulin, 6-7% glucose, and 6-7% lactose.

5. The method for preparing Maillard polyunsaturated fatty acid oil microcapsules according to any one of claims 1-4, characterized in that, include: (1) Dissolve sodium caseinate, glucose, lactose and inulin in water, adjust the pH to 8-10, heat to 80-90℃, maintain for 30-120 min, and stir thoroughly; (2) Add solid corn syrup and antioxidant, stir thoroughly to dissolve, and obtain an aqueous phase; (3) Add the polyunsaturated fatty acid oil to the aqueous phase obtained in step (2) and shear it to obtain an emulsion; (4) The emulsion obtained in step (3) is subjected to high-pressure homogenization and then dried; (5) Add an anti-caking agent and dry mix.

6. The preparation method according to claim 5, characterized in that, The drying process described in step (4) is spray drying, with an inlet air temperature of 160-180℃ and an outlet air temperature of 60-80℃.

7. The use of inulin in the preparation of Maillard polyunsaturated fatty acid oil microcapsules according to any one of claims 1-4, to improve their reconstitution properties and stability; the Maillard reaction product is prepared from inulin, glucose, lactose and sodium caseinate.

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